JP4160018B2 - Anti-hydrofluoric acid etching material, optical pattern etching method, and semiconductor device manufacturing method - Google Patents

Description

The present invention relates to a method for producing a resistant hydrofluoric acid etching materials as well as optical pattern etching method and a semiconductor device using the same.

The optical pattern etching method includes a coating process, an exposure process, a development process, and an etching process of a hydrofluoric acid- resistant etching material, and is a fine processing technique that cuts a substrate with an arbitrary pattern.
One of the elemental technologies used for LSI (Large Scale Integrated circuit) substrate fabrication,
In recent years, MEMS (Micro Electro Mechanical System) such as optical scanning devices, LED (Light Emitting)
It is also applied to the production of semiconductor devices such as diodes.

In particular, in the optical pattern etching technique described above, when an etching process is performed using hydrofluoric acid, sacrificial layer etching of an optical scanning device including a movable element structure and an optical waveguide having low hydrofluoric acid resistance, or light emission made of a compound semiconductor is used. It is expected to be applied to LED frosting, which roughens the device surface and increases the light extraction efficiency. At this time, it is desirable to use concentrated hydrofluoric acid in the etching step from the viewpoint of shortening the manufacturing method.

However, dilute hydrofluoric acid etching is the mainstream in LSI substrate fabrication, and the photosensitive etching material developed for conventional LSI substrate fabrication (see Patent Document 1) has low hydrofluoric acid resistance,
There was no anti- hydrofluoric acid etching material applicable to concentrated hydrofluoric acid. For this reason, when performing concentrated hydrofluoric acid etching, a portion made of a material having low resistance to hydrofluoric acid has to be formed after the hydrofluoric acid etching process, resulting in a problem that the manufacturing method becomes complicated and prolonged.
JP 2002-372784 A

The present inventors have made research on resistance to hydrofluoric acid resistant hydrofluoric acid etching material, I found the following.

That is, when the hydrofluoric acid etching was found that the resistance to hydrofluoric acid etching material itself corrosion decomposed phenomenon, a phenomenon that erodes the substrate hydrofluoric acid penetrates into the interface of the anti-hydrofluoric acid etching material and the substrate occurs. Therefore, the resistance to hydrofluoric acid etching material excellent in resistance to hydrofluoric acid, is required to comprise a hydrofluoric acid corrosion degradation resistance and hydrofluoric acid penetration resistance.

The present invention is, in view of the above circumstances, resistant hydrofluoric acid etching material excellent in resistance to hydrofluoric acid, concentrated hydrofluoric acid etching capable optical pattern etching method, and simplified, a manufacturing method of a semiconductor device capable of achieving shortening It is to provide.

According to one aspect of the present invention, a resin comprising only two types of repeating units represented by the formula (1)
And a photoacid generator that generates an acid by light.
Fees are provided. (In Formula (1), R1 and R3 are a hydrogen atom or a methyl group, R2
Has one or two hydroxyl groups, adamantane, tricyclodecane, norbornane,
One of isobornane, cyclohexane and cyclooctane, and R4 represents a ketone group.
Adamantane, tricyclodecane, norbornane, isobornane, cyclohex
Either sun or cyclooctane, and the ratio of m: n is in the range of 30:70 to 70:30
The )

According to another aspect of the present invention, on a substrate made of a semiconductor or quartz glass,
Forming a hydrofluoric acid-resistant etching material, and then pattern-exposing the substrate;
A step of heating the substrate, and then developing the substrate using an alkaline developer.
And hydrofluoric acid etching using a solution having a hydrofluoric acid concentration of 30% to 50% on the substrate
An optical pattern etching method is provided.

According to another aspect of the present invention, a sacrificial layer made of quartz glass is formed on a semiconductor substrate.
Forming a semiconductor device structure on the sacrificial layer; and on the semiconductor substrate.
2. A step of forming a portion made of a material having low resistance to hydrofluoric acid;
A step of coating the portion made of the material having low resistance to hydrofluoric acid with a ching material, and then
Removing the sacrificial layer using a solution having a hydrofluoric acid concentration of 30% to 50% on the semiconductor substrate;
A method for manufacturing a semiconductor device is provided.

According to another aspect of the present invention, a portion made of a highly hydrofluoric acid resistant material is provided on a semiconductor substrate.
A step of forming and from a material having a low hydrofluoric acid resistance on a portion made of the material having a high hydrofluoric acid resistance.
A step of forming a region to be formed, and the hydrofluoric acid resistance using the hydrofluoric acid resistant etching material of claim 1
A step of coating a portion made of a low-density material, and then a solution having a hydrofluoric acid concentration of 30% to 50%
And etching a portion made of a material having high resistance to hydrofluoric acid using
A method for manufacturing a semiconductor device is provided.

Note that the hydrofluoric acid- resistant etching material refers to a material that can be applied to hydrofluoric acid etching and has photosensitivity.

A semiconductor device refers to a device including a single element or a compound of a semiconductor element that can be manufactured using a semiconductor microfabrication technique.

In addition, quartz glass refers to high-purity quartz glass capable of using a fine processing technique. In general, such quartz glass contains 1 ppb or less of each metal element as an impurity.

The present invention can provide resistance to hydrofluoric acid etching material excellent in resistance to hydrofluoric acid, concentrated hydrofluoric acid etching capable optical pattern etching method, and a method of manufacturing a semiconductor device capable of achieving simplification shortened.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment, and the overlapping description is abbreviate | omitted. Also,
Each figure is a schematic diagram for facilitating explanation and understanding of the invention, and its shape, dimensions, ratio, etc. are different from the actual device, but these are appropriately determined in consideration of the following explanation and known technology. The design can be changed.
(First embodiment)
The hydrofluoric acid resistant etching material of the first embodiment is characterized by comprising a resin and a photoacid generator that generates an acid upon exposure. Hereinafter, the resin, the photoacid generator and other compounds will be described in detail.
1) Resin The resin according to the first embodiment is composed of only two types of repeating units (hereinafter referred to as segments) represented by the following formula (1). For convenience, the main chain, the first segment including R2 and the second segment including R4 will be described separately. The first segment and the second segment are randomly incorporated into the main chain.

(In the formula (1), R1 and R3 are hydrogen atoms or methyl groups, R2 is one of adamantane, tricyclodecane, norbornane, isobornane, cyclohexane and cyclooctane having one or two hydroxyl groups, R4 is one of adamantane, tricyclodecane, norbornane, isobornane, cyclohexane and cyclooctane having one ketone group, and the ratio of m: n is in the range of 30:70 to 70:30.
The main chain is an acrylate in which R1 and R3 are hydrogen atoms, or a methacrylate in which R1 and R3 are methyl groups. These acrylic resins having an acrylic skeleton are superior in resistance to hydrofluoric acid compared to resins having other skeletons.

From the viewpoint of improving the resolution performance during optical patterning, R1 and R3 are preferably acrylates composed of hydrogen atoms.

The first segment is an aliphatic cyclic compound (hereinafter referred to as “aliphatic compound”) bonded to tertiary carbon (carbon in which all four bonds are bonded to carbon) via the tertiary carbon and having a substituent described later. Ring) R2
It is a dissolution inhibiting group for an alkaline developer and has a function of improving resolution.

By providing a tertiary carbon between the alicyclic ring and the first segment, the first segment is desorbed and decomposed under heating conditions using a strong acid as a catalyst to generate a carboxylic acid. By the decomposition reaction of the first segment, the resin of the first embodiment becomes soluble in the alkaline developer. Because of this characteristic, the resin of the first embodiment can be used as a hydrofluoric acid- resistant etching material. In addition, the acid as a catalyst is produced by exposing a photoacid generator.

The alicyclic ring of R2 is composed of any one of adamantane, tricyclodecane, norbornane, isobornane, cyclohexane and cyclooctane. Since these alicyclic rings are bulky, the main chain can be protected from hydrofluoric acid and contribute to hydrofluoric acid corrosion decomposition resistance. Note that adamantane, tricyclodecane, norbornane and isobornane have a bridge structure and are rigid, and thus contribute to hydrofluoric acid corrosion decomposition resistance.

From the viewpoint of hydrofluoric acid corrosion decomposition resistance, adamantane having the most rigid and chemically stable structure is preferable.

The substituent provided in R2 has one or two hydroxyl groups. Hydroxyl groups have high substrate adhesion and contribute to hydrofluoric acid penetration resistance. When the number of hydroxyl groups is 3 or more, the solubility in an alkali developer becomes extremely high due to the improvement in hydrophilicity. As a result, pattern formation at the time of photo patterning becomes difficult, and the resolution at the time of photo patterning is extremely lowered, which is not suitable.

From the viewpoint of the balance between solubility in an alkali developer and substrate adhesion, the case where there is one hydroxyl group is most preferable.

A 2nd segment consists of alicyclic R4 provided with the substituent mentioned later, and is provided with the function which raises hydrofluoric acid tolerance.

The alicyclic ring of R4 has the same characteristics as the alicyclic ring of R2. Moreover, since it is the same as that of the alicyclic ring of R2, since resin superposition | polymerization becomes easy, it is preferable.

The substituent provided by R4 includes one ketone group. Ketone groups have higher substrate adhesion than hydroxyl groups and contribute to hydrofluoric acid penetration resistance. In addition, it is unsuitable for the number of ketone groups to be two or more, since it becomes difficult to polymerize a monomer that is a raw material for the resin.

As a substituent, for example, a carboxylic acid group has low resistance to hydrofluoric acid, and therefore has high polarity and low solubility in a general resist solvent. Since it falls extremely, it is unsuitable. In addition, the lactone group is unsuitable because it reacts with an acid or an alkali to open a ring to generate a carboxylic acid, and thus has low resistance to hydrofluoric acid.

For the ratio of the first segment to the second segment, the ratio of m: n is from 30:70 to 70:
Preferably it is within the range of 30. Within this range, the function of each segment is effectively exhibited. That is, when m is 30 or more, the resolution at the time of optical patterning is improved, and n
When is 30 or more, hydrofluoric acid resistance is improved.

The upper limit of the molecular weight of the resin is about 100,000 in view of solubility during development, and is preferably about 40 to 50,000 in order to maintain micron order resolution.

As explained above, according to the resin of the first embodiment, since it has excellent hydrofluoric acid resistance and photosensitivity, it can be used as a hydrofluoric acid- resistant etching material.

Further, according to the resin of the first embodiment, since it consists of two types of segments, it is easy to polymerize, and it is also preferable that optimization of the alicyclic ring and composition ratio to be adjusted depending on the application is easy. .

Further, according to the resin of the first embodiment, the carbon-carbon double bond is not included inside, so that π
There is no light absorption by the electron cloud, and it is excellent in transparency in the ultraviolet, visible, and infrared regions from a wavelength of about 190 nm to about 1 μm. Therefore, it can be used as it is as an optical component such as a photochemical semiconductor device such as an optical waveguide.

As a resin synthesis method, for example, the resin can be synthesized according to the flowchart shown in FIG.
2) Photoacid generator The photoacid generator (PAG Photo Acid Generator) may be any compound that generates an acid by light.

For example, arylonium salts, naphthoquinonediazide compounds, diazonium salts, sulfonate compounds, sulfonium compounds, sulfamide compounds, iodonium compounds, sulfonyldiazomethane compounds, and the like can be used.

Specific examples of these compounds include triphenylsulfonium triflate, diphenyliodonium triflate, 2,3,4,4-tetrahydroxybenzophenone-4-naphthoquinone diazide sulfonate, 4-N-phenylamino-2- Methoxyphenyldiazonium sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium p-ethylphenyl sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium 2-naphthyl sulfate, 4-N-phenylamino- 2-methoxyphenyldiazonium phenylsulfate, 2,5-diethoxy-4-N-4'-methoxyphenylcarbonylphenyldiazonium 3-carboxy-4-hydroxyphenylsulfate, 2-methoxy-4-N-phenylphenyldiazonium 3 -Carboxy-4-hydroxyphenyl sulfate, diph Enylsulfonylmethane, diphenylsulfonyldiazomethane, diphenyldisulfone, α-methylbenzoin tosylate, pyrogallol trimesylate, benzoin tosylate, MPI manufactured by Midori Chemical
-103 (CAS.NO. [87709-41-9]), BDS-105 (manufactured by Midori Chemical)
CAS. NO. [145612-66-4]), NDS-103 (CAS.
NO. [110098-97-0]), MDS-203 (CAS.
127855-15-5]), Pyrogallol tritosylate (CAS.
20032-64-8]), Midori Chemical DTS-102 (CAS.NO. [75482)
-18-7]), Midori Chemical DTS-103 (CAS.NO. [71449-78-0]
] MDS-103 (CAS.NO. [127279-74-7]), Midori Chemical MDS-105 (CAS.NO. [116808-67-4]), Midori Chemical MDS-205 ( CAS No. [81416-37-7]), BMS- by Midori Chemical
105 (CAS.NO. [149934-68-9]), TMS-105 (manufactured by Midori Chemical)
CAS. NO. [127820-38-6]), Midori Chemical NB-101 (CAS.N)
O. [20444-09-1]), Midori Chemical NB-201 (CAS.NO. [445
0-68-4]), DNB-101 (CAS. NO. [114719-51] manufactured by Midori Chemical.
-6]), Midori Chemical DNB-102 (CAS.NO. [131509-55-2])
, Midori Kagaku DNB-103 (CAS.NO. [132898-35-2]), Midori Kagaku DNB-104 (CAS.NO. [132898-36-3]), Midori Kagaku D
NB-105 (CAS.NO. [132898-37-4]), Midori Chemical DAM-1
01 (CAS.NO. [1886-74-4]), Midori Chemical DAM-102 (CAS
. NO. [2833-24-0]), DAM-103 (CAS.
14159-45-6]), Midori Chemical DAM-104 (CAS.NO. [13029)
0-80-1], CAS. NO. [130290-82-3]), DAM- by Midori Chemical
201 (CAS.NO. [2832-50-1]), Midori Chemical CMS-105, Midori Chemical DAM-301 (CAS. No. [138529-81-4]), Midori Chemical SI-105 (CAS No. [34694-40-7]), NDI-1 manufactured by Midori Chemical
05 (CAS. No. [133710-62-0]), Midori Chemical EPI-105 (C
AS. No. [135133-12-9]) and the like. Furthermore, the compounds shown below can also be used.

Among the photoacid generators described above, conjugated polycyclic aromatic compounds such as arylonium salts having a naphthalene skeleton or a dibenzothiophene skeleton, sulfonate compounds, sulfonyl compounds, and sulfamide compounds are transparent and resistant to short-wavelength light. It is advantageous in terms of sex.

Specifically, naphthalene ring, pentalene ring, indene ring, azulene ring, heptalene ring,
Biphenylene ring, as-indacene ring, s-indacene ring, acenaphthylene ring, fluorene ring, phenalene ring, phenanthrene ring, anthracene ring, fluoranthene ring, acephenanthrylene ring, acanthrylene ring, triphenylene ring, pyrene ring, chrysene ring , Naphthacene ring, preaden ring, picene ring, perylene ring, pentaphen ring, pentacene ring, tetraphenylene ring, hexaphen ring, hexacene ring, rubicene ring, coronene ring, trinaphthylene ring, heptaphen ring, heptacene ring, pyranthrene ring, ovalen ring , Dibenzophenanthrene ring, benz [a] anthracene ring, dibenzo [a, j] anthracene ring, indeno [1, 2
-a] Indene ring, anthra [2,1-a] naphthacene ring, 1H-benzo [a] cyclopent [j] sulfonyl or sulfonate compound having anthracene ring; naphthalene ring, pentalene ring, indene ring, azulene ring, heptalene ring , Biphenylene ring, as-indacene ring,
s-indacene ring, acenaphthylene ring, fluorene ring, phenalene ring, phenanthrene ring,
Anthracene ring, fluoranthene ring, acephenanthrylene ring, aceanthrylene ring, triphenylene ring, pyrene ring, chrysene ring, naphthacene ring, preaden ring, picene ring, perylene ring, pentaphen ring, pentacene ring, tetraphenylene ring, hexaphen Ring, hexacene ring, rubicene ring, coronene ring, trinaphthylene ring, heptaphene ring, heptacene ring, pyranthrene ring, ovalene ring, dibenzophenanthrene ring, benz [a] anthracene ring, dibenzo [a, j] anthracene ring, indeno [1, 2-a] Indene ring, anthra [2,1-a]
Naphthalene ring, 1H-benzo [a] cyclopent [j] 4-quinonediazide compound having anthracene ring; naphthalene ring, pentalene ring, indene ring, azulene ring, heptalene ring, biphenylene ring, as-indacene ring, s-indacene ring, Acenaphthylene ring, fluorene ring, phenalene ring, phenanthrene ring, anthracene ring, fluoranthene ring, acephenanthrylene ring, acanthrylene ring, triphenylene ring, pyrene ring, chrysene ring, naphthacene ring, preaden ring, picene ring, perylene ring , Pentaphen ring, pentacene ring, tetraphenylene ring, hexaphen ring, hexacene ring, rubicene ring, coronene ring, trinaphthylene ring, heptaphen ring, heptacene ring, pyrantolen ring, ovarene ring, dibenzophenanthrene ring, benz [a] anthracene ring, di Down zone [a, j] anthracene ring, indeno [1,2-a]
And salts with sulfonium or iodonium triflate having an indene ring, anthra [2,1-a] naphthacene ring, 1H-benzo [a] cyclopent [j] anthracene or the like in the side chain.

In particular, a sulfonyl or sulfonate compound having a naphthalene ring or an anthracene ring; a 4-quinonediazide compound having a naphthalene ring or an anthracene ring into which a hydroxyl group has been introduced; a sulfonium or iodonium triflate having a naphthalene ring or an anthracene ring in the side chain Salts are preferred.

Among such photoacid generators, triphenylsulfonium triflate, diphenyliodonium triflate, trinaphthylsulfonium triflate, dinaphthyliodonium triflate, dinaphthylsulfonylmethane, NAT-105 (manufactured by Midori Chemical)
CAS. No. [137867-61-9]), NAT-103 (CAS.
No. [13582-00-8]), NAI-105 (CAS.
85342-62-7]), Midori Chemical TAZ-106 (CAS. No. [69432).
-40-2]), Midori Chemical NDS-105, Midori Chemical PI-105 (CAS.
No. [41580-58-9]), s-alkylated dibenzothiophene triflate,
Preferred is s-fluoroalkylated dibenzothiophene triflate (manufactured by Daikin).
Among these, triphenylsulfonium triflate, trinaphthyl sulphonium triflate, dinaphthyl iodonium triflate, dinaphthyl sulphonylmethane, NAT-105 (CAS. No. [137867-61-9]) manufactured by Midori Kagaku, NDI-105 (CAS. No. [133710-62-0]) made by Midori Chemical, N made by Midori Chemical
AI-105 (CAS. No. [85342-62-7]) is particularly preferable.

In 1st Embodiment, the preferable compounding quantity of a photo-acid generator is 0.001-50 mol% with respect to the whole other solid content, More preferably, it is 0.01-40 mol%, Most preferably It is in the range of 0.1 to 20 mol%. That is, if it is less than 0.001 mol%, it is difficult to form a pattern with high resolution, and if it exceeds 50 mol%, the mechanical strength may be impaired when a film is formed.

3) Others The hydrofluoric acid- resistant etching material of the first embodiment is usually prepared as a varnish by dissolving these compounds in an organic solvent and filtering.

Examples of the organic solvent include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, and methyl isobutyl ketone, methyl cellolbu, methyl cellosolve acetate,
Cellosolve solvents such as ethyl cellosolve acetate and butyl cellosolve acetate, ester solvents such as ethyl acetate, butyl acetate, isoamyl acetate and γ-butyrolactone, glycol solvents such as propylene glycol monomethyl ether acetate, dimethyl sulfoxide, hexamethylphosphoric triamide Nitrogen-containing solvents such as dimethylformamide and N-methylpyrrolidone, and mixed solvents to which dimethylsulfoxide, dimethylformaldehyde, N-methylpyrrolidinone and the like are added to improve solubility can be used.

Propionic acid derivatives such as methyl methyl propionate, lactic acid esters such as ethyl lactate, and PGMEA (propylene glycol monoethyl acetate) are also preferred because of their low toxicity.

These organic solvents can be used alone or as a mixture of two or more thereof. Further, isopropyl alcohol, ethyl alcohol, methyl alcohol, butyl alcohol, n-
Aliphatic alcohols such as butyl alcohol, s-butyl alcohol, t-butyl alcohol, and isobutyl alcohol, and aromatic solvents such as toluene and xylene may be contained.

Furthermore, an alkali-soluble resin for improving the solubility in an alkaline developer during development, a resinous compound having the property of increasing the solubility in an alkaline developer upon irradiation with radiation for improving the resolution during photopatterning, development Occasionally generated by dissolution inhibitor to reduce solubility in alkaline developer, cross-linking agent to maintain pattern shape of hydrofluoric acid- resistant etching material after photo patterning, surfactant for coating film modification, photoreaction An amine additive for preventing acid deactivation may be contained.
(Second Embodiment)
The optical pattern etching method of the second embodiment is characterized in that hydrofluoric acid etching is performed using the hydrofluoric acid-resistant etching material of the first embodiment.

The optical pattern etching method of the second embodiment includes a resist coating process, an exposure process, a heating process, a developing process, and an etching process using hydrofluoric acid.

First, in the resist coating process, the hydrofluoric acid- resistant etching material of the first embodiment is formed on a substrate made of semiconductor or quartz glass by using a spin coating method or the like.

Then, in the exposure step, it is irradiated with light of an arbitrary pattern resistance to hydrofluoric acid etching material using a mask. In the exposure step, the photoacid generator generates an acid.

Next, in a heating (PEB: Post Exposure Bake) step, heat is applied to the substrate. In the exposed portion that has been acid-catalyzed in the previous step, the tertiary carbon between the alicyclic ring R2 and the main chain reacts in the heating step, causing decomposition of the first segment and generation of carboxylic acid. By the decomposition reaction of the first segment, the hydrofluoric acid- resistant etching material at the exposed portion changes from alkali-insoluble to alkali-soluble. The heating temperature (PEB temperature) is preferably from 100 ° C. to 160 ° C., and the heating time is preferably from 80 seconds to 100 seconds. In order to react the elimination reaction of the first segment with PEB for several minutes, heating at 100 ° C. or higher is necessary. In addition, since the elimination reaction proceeds at 160 ° C. or higher even without acid, patterning becomes difficult.

Next, in the development step, the substrate is immersed in an alkaline developer. In the development process, the hydrofluoric acid- resistant etching material in the exposed part is dissolved. For example, for alkali developer concentration:
In the case of a general tetrahydroammonium hydroxide (TMAH) developer for semiconductor resist, a concentration of 0.05% or more and 0.5% or less is preferable, and about 0.12% is more preferable. In general, T
Since the concentration of MAH developer is 2.38%, a desired developer can be obtained by diluting with water about 20 times. The developing time at this density is 30 seconds or more and 90 seconds or less, but is adjusted as appropriate depending on the density.

Next, in the etching step, the substrate is immersed in a solution having a hydrofluoric acid concentration of 30% to 50%. When the hydrofluoric acid concentration is 30% or more, the dipping process is shortened. In general, the hydrofluoric acid stock solution has a concentration of 46 to 50% (see Iwanami Shoten's Physical and Chemical Dictionary). In the etching process, the exposed substrate is cut.

Finally, when removing the resist, the entire surface of the substrate is exposed and immersed in an alkaline developer to remove the hydrofluoric acid resistant etching material.

  Examples of the substrate include a semiconductor substrate and a quartz glass substrate.

In the case of a semiconductor substrate, compound semiconductors such as GaP, GaAs, GaAsP, AlGaAs, InGaAsP, GaInAlP, and InP, and single semiconductors such as Si and Ge are listed.

In the case of a quartz glass substrate, in order to suppress reflection at the lower part of the substrate, it is preferable to provide an antireflection lower layer film at the lower part of the substrate.

As described above, according to the second embodiment, etching using a high-concentration hydrofluoric acid solution is possible, so that the optical pattern etching method can be shortened.

(Third embodiment)
The method for manufacturing a semiconductor device according to the third embodiment includes, for example, a step of forming a sacrificial layer made of quartz glass on a semiconductor substrate, a step of forming an element structure made of a semiconductor on the sacrificial layer, forming a portion made of a low resistance to hydrofluoric acid material, then a step of coating a portion to be a low hydrofluoric acid resistance material using a resistant hydrofluoric acid etching material of the first embodiment, then, And a step of removing the sacrificial layer using a hydrofluoric acid solution on the semiconductor substrate.

Hereinafter, the case where the semiconductor device is an optical scanning device will be described as an example and described in detail. First,
An example of the optical scanning device will be described with reference to FIGS.

FIG. 2A is a schematic top view of the optical scanning device. FIG. 2B is an enlarged schematic view of a portion surrounded by a circle in FIG. FIG. 3 is a schematic sectional view taken along the central axis of the beam-like structure 11 of the optical scanning device.

As shown in FIGS. 2A and 2B, the scanned light passes from the light source 16 through the optical waveguide structure 15 that guides the light, the condensing structure 19, and the like at the tip of the beam-like structure 11. The light is emitted from an exit end 17 of an optical waveguide.

A comb-shaped drive mechanism 12 is used for the beam-like structure 11 and a structure that generates a force to be used for operating the beam. The structure 18 that connects the beam-like structure and the power structure is composed of a stabilizing spring structure 13, a bellows spring structure 14, and a beam-like structure that couples them.

The optical scanning device having these structures vibrates the optical waveguide exit end 17 by vibrating the beam-like structure 11, thereby enabling the light from the light source 16 to be scanned. . The beam vibration direction 20 shown by the arrow in FIG. 2B indicates the direction of light scanned by this apparatus.

As shown in FIG. 3, the SOI substrate 21 serving as the substrate of the element structure is composed of an Si substrate layer 2101 in order from the lower layer.
, SiO2 layer 2102 and Si active layer 2103. On this SOI substrate 21, the light source 16 and the light collecting structure 1 described above
9. An optical waveguide structure 15 is formed.

In the case of this optical scanning device, the optical waveguide structure 15 is cited as a material having low resistance to hydrofluoric acid, and the step of performing hydrofluoric acid etching is a step of manufacturing a movable part of the element structure (for example, a beam-like structure 11). That is, it is performed in a step of removing the SiO 2 layer 2102 which becomes a sacrifice layer.

  A method for manufacturing the optical scanning device shown in FIGS. 2 and 3 will be described.

  First, after forming the optical waveguide structure 15 on the SOI substrate, an element structure is formed.

Thereafter, a portion made of a material having low resistance to hydrofluoric acid is covered with the hydrofluoric acid-resistant etching material of the first embodiment. Covered parts include light source 16, optical waveguide structure 15 (beam-like structure
11, the light converging structure 19, and the exit end 17 of the optical waveguide). On the other hand, the movable parts of the element structure such as the comb-shaped drive mechanism 12, the stabilization spring structure 13, the bellows spring structure 14, and the structure 18 that connects the beam-like structure and the power structure are exposed. Note that the SiO 2 layer 2102 immediately below the beam-like structure 11 is exposed.
Thereafter, hydrofluoric acid etching is performed to remove the SiO 2 layer 2102 as a sacrificial layer, and the movable part of the element structure is released from the Si substrate layer 2101. Details are the same as in the method of the second embodiment.

Thus, by coating the anti-hydrofluoric acid etching material of the first embodiment, without destroying the optical waveguide structure 15 comprising a low hydrofluoric acid resistance material, an element structure by removing the sacrificial layer Can be movable.

At this time, if the hydrofluoric acid etching material is not photosensitive and the process of performing hydrofluoric acid etching after forming the optical waveguide structure 15 is impossible, the SOI substrate having a movable part after the hydrofluoric acid etching process and having a complicated structure The optical waveguide structure 15 is formed in 21, which complicates the semiconductor device manufacturing process.

Further, when the concentration of hydrofluoric acid during the hydrofluoric acid etching is low, the hydrofluoric acid etching process is prolonged.

The semiconductor device manufacturing method of the third embodiment includes, for example, a step of forming a portion made of a material having high hydrofluoric acid resistance on a semiconductor substrate, and a step of forming hydrofluoric acid on the portion made of a material having high hydrofluoric acid resistance. A step of forming a portion made of a material having low resistance, a step of covering the portion made of a material having low resistance to hydrofluoric acid using the hydrofluoric acid resistant etching material of the first embodiment, and then using a hydrofluoric acid solution And a step of etching a portion made of a material highly resistant to hydrofluoric acid.

Hereinafter, the case where the semiconductor device is an LED will be described as an example in detail. First, an example of the LED will be described with reference to FIG.

  FIG. 5 is a schematic cross-sectional view of an LED.

The LED shown in FIG. 5 includes a compound semiconductor substrate 25 made of n-GaP having a first electrode 29 made of Au on its lower surface, and a clad layer 2601 made of n-InAlP, I
A light emitting layer 26 composed of an active layer 2602 made of nGaAlP and a cladding layer 2603 made of p-InAlP to form a heterostructure, and a current diffusion layer 27 made of p-GaP formed on the light emitting layer
And a second electrode 28 and a wiring electrode pattern 30 made of Au formed on the current diffusion layer.

In the case of this LED, the first electrode 29, the second electrode 28, and the wiring electrode pattern 30 are cited as materials having low resistance to hydrofluoric acid, and the step of performing hydrofluoric acid etching is a step of performing a frost treatment on the surface of the current diffusion layer 27 To be done.

Note that the frost treatment refers to a treatment for forming irregularities by performing hydrofluoric acid etching on the compound semiconductor surface of the LED chip. Increasing the surface area of the compound semiconductor of the LED chip has the effect of improving light extraction efficiency.

  An LED manufacturing method will be described by taking the LED shown in FIG. 5 as an example.

First, MOCVD (Metal Organic Chemical Vapor Deposition) method, MBE (Molecular Bea
m Epitaxy) using a known technique such as the cladding layer 2601 and the active layer 260 on the compound semiconductor substrate 25.
2. The clad layer 2603 and the current diffusion layer 27 are sequentially formed.

Next, the first electrode 29, the second electrode 28, and the wiring electrode pattern 30 are formed using a known lithography technique, sputtering technique, electrolytic plating technique, and the like.

Next, after applying the hydrofluoric acid resistant etching material of the first embodiment on the current diffusion layer 27 by using a spin coat method or the like, the pattern is formed so as to cover the second electrode 28 and the wiring electrode pattern 30. Exposure, PEB, development, hydrofluoric acid etching, and removal of the protective film were performed using the mask on which was formed. Details are the same as in the method of the second embodiment. Of these, the hydrofluoric acid etching step corresponds to a so-called frost treatment.

Thereafter, dicing was performed to divide the chip, and wirings were connected to the first electrode 29 and the second electrode 28 to complete the LED shown in FIG.

At this time, if the hydrofluoric acid etching material is not photosensitive and the hydrofluoric acid etching process is impossible after the first electrode 29, the second electrode 28, and the wiring electrode pattern 30 are formed, the surface of the concavo-convex surface after the frost treatment is not obtained. The first electrode 29, the second electrode 28, and the wiring electrode pattern 30 are formed, and the manufacturing process of the LED becomes complicated, or the first electrode 29, the second electrode of the compound semiconductor
It becomes difficult to perform a frost treatment on the formation surface of the electrode 28 and the wiring electrode pattern 30, and the light extraction efficiency cannot be improved.

Further, when the concentration of hydrofluoric acid during the hydrofluoric acid etching is low, the hydrofluoric acid etching process is prolonged.

Needless to say, a frost treatment can also be performed on the surface of the compound semiconductor substrate 25 provided with the first electrode 29 using the same method.

Examples of LED materials other than those illustrated are as follows. Compound semiconductor substrate 2
Examples of 5 include n-GaAs, n-GaP, and p-GaP. Examples of the current diffusion layer 27 include p-InAlP and p-GaP. As the first electrode 29, AuGa
/ As, AuGe / As and the like. Examples of the second electrode 28 include AuZn / Au.

As described above, according to the third embodiment, an optical pattern etching method using a high-concentration hydrofluoric acid solution is possible, and the semiconductor device manufacturing method can be simplified and shortened.

Further, according to the third embodiment, there is no need to remove the hydrofluoric acid resistant etching material of the first embodiment. This is because, as described above, the resin of the first embodiment is transmissive in a wide wavelength range. For this reason, the semiconductor device manufacturing method of the third embodiment is particularly preferable for photochemical semiconductor devices such as optical scanning devices and LEDs.

Examples will be described below, but the present invention is not limited to the examples described below unless the gist of the present invention is exceeded.

For resistant hydrofluoric acid etching material according to the first embodiment, (Test A) hydrofluoric acid resistance test, (
Test B) Process test, (Test C) Main chain, alicyclic and substituent test, (Test D) Composition dependency test, (Test E) Optical scanning device manufacturing test.

(Test A) Hydrofluoric acid resistance test The hydrofluoric acid corrosion resistance of the resin itself was investigated.

As Example A1, a resin (m: n = 50: 50) represented by the formula (2) was immersed in an aqueous solution having a hydrofluoric acid concentration shown in Table 1. As hydrofluoric acid, 49% concentrated hydrofluoric acid (Tokyo Kasei) is used.
Diluted as appropriate.

  The resin represented by formula (2) was synthesized using the synthesis method described above.

As Comparative Example A1, as the anti- hydrofluoric acid etching material for novolak resin, OFPR-
800 (Tokyo Ohka) was used.

As a comparative example A2, as a hydrofluoric acid- resistant etching material for polyvinylphenol resin,
TDUR-P015 (Tokyo Ohka) was used.

As Comparative Example A3, polymethyl methacrylate (PMMA) (Mw = 15000, Model No. 424,
Manufacturing company Scientific Polymer Product Inc.) was used.

From the results shown in Table 1, the hydrofluoric acid corrosion decomposition resistance of Example A1 is 30% or more, while the hydrofluoric acid corrosion decomposition resistance of Comparative Examples A1 to A3 is 25% or less. Therefore, since the hydrofluoric acid- resistant etching material of the first embodiment is excellent in hydrofluoric acid corrosion decomposition resistance, the hydrofluoric acid immersion process can be shortened.

On the other hand, when Comparative Examples A1 to A3 were applied to a substrate and immersed in a hydrofluoric acid aqueous solution having a concentration of 49%, Comparative Examples A1 to A3 had poor substrate adhesion and low resistance to intrusion of hydrofluoric acid, and thus easily peeled off. I understood that. On the other hand, as will be described later in (Test B) to (Test D), the hydrofluoric acid- resistant etching material of the first embodiment has high hydrofluoric acid penetration resistance, and is used as the hydrofluoric acid-resistant etching material. Is possible.

These withstand hydrofluoric acid etching material of the first embodiment is different from the known etching material, it can be seen that excellent resistance to hydrofluoric acid.

The substrate was also subjected to the same experiment as the hydrofluoric acid resistant etching material.

As a result, the substrate GaP substrate can be etched with hydrofluoric acid with a concentration of about 20%, but when etching a quartz glass substrate (QA made by Asahi Glass), the immersion process will be prolonged unless the concentration is 30% or more. It was. For this reason, when a quartz glass substrate is used, the hydrofluoric acid- resistant etching material of the first embodiment is particularly preferable.

(Test B) Process test A process test of optical photography was performed.

Resin represented by formula (2) and (4,7-Dihydroxy-1-naphthalenyl) dimethylsu as photoacid generator
lfonium trifluoromethanesulfonic acid (NDS-165) (manufactured by Midori Kagaku) was used and adjusted to 1 wt% with respect to the resin. As the organic solvent, propylene glycol monomethyl ether acetate (PGMEA) (manufactured by Wako Pure Chemical Industries, Ltd.) was used, and the varnish was adjusted so that the resin concentration was 20 wt%.

The rotational speed of the spin coat was set to 1500 rpm, and the hydrofluoric acid resistant etching material was applied on the substrate shown in Table 2. Thereafter, the solvent was vaporized by prebaking at 120 ° C. for 90 seconds. At this time, the film thickness of the hydrofluoric acid- resistant etching material was 0.86 μm.

Next, using a mask containing a line pattern, a balanced exposure tool (Canon model number PLA-501)
Then, g-line of a mercury lamp was irradiated at an exposure amount of 400 mJ / cm2. Irradiation was 1: 1 1: 1 exposure, which was performed by directly bonding the mask and substrate.

  Next, the substrate was heated on a hot plate at 110 ° C. (PEB temperature) for 90 seconds.

Next, as an alkali developer, an aqueous tetramethylammonium hydroxide solution (TMAH 2.3
8%) (Tama Chemical Model No. AD-10) diluted with pure water as shown in Table 2 and developed for 60 seconds, then using an ultra-deep shape measuring microscope (Keyence Model No. VK-8500) The surface was observed and the resolution was confirmed.

  Thereafter, the substrate was immersed in concentrated hydrofluoric acid (Tokyo Kasei) having a concentration of 49% for 10 minutes.

Next, after irradiating the substrate with an exposure dose of 400 mJ / cm2 with g-line of a mercury lamp with an equilibrium exposure device PLA-501,
Thereafter, it was heated on a hot plate at 110 ° C. for 90 seconds. Finally, alkaline developer (AD-10 (TMAH2.
38%) (Tama Chemical) was immersed in a stock solution for 60 seconds, and all the hydrofluoric acid resistant etching material was dissolved and removed. The surface of the obtained substrate was observed using an ultra-deep shape measuring microscope (Keyence model number VK-8500) to confirm the resolution.

Table 2 shows the resolution of the hydrofluoric acid- resistant etching material after the development process and the resolution of the substrate after the entire process.

From the results shown in Example B3 and Example B4 of Table 2, the photolithographic method of the second embodiment can resolve a pattern of about 8 μmL / S with mercury lamp g-line exposure and has excellent resolution. I understand.

Further, from Examples B3 and B4 , it is understood that the dilution of the alkaline developer is preferably 20 times.

(Test C) Main chain, alicyclic and substituent test (Example C1)
Example B3 except that the resin represented by formula (2) (m: n = 50: 50) was used and the PEB temperature was 120 ° C.
The same test was conducted.

(Example C2)
A test was performed in the same manner as in Example C1 except that the resin represented by formula (3) (m: n = 50: 50) was used.

(Example C3)
A test was performed in the same manner as in Example C1 except that the resin represented by formula (4) (m: n = 40: 60) was used.

(Example C4)
A test was performed in the same manner as in Example C1 except that the resin represented by formula (5) (m: n = 40: 60) was used.

(Example C5)
A test was performed in the same manner as in Example C1 except that the resin represented by formula (6) (m: n = 50: 50) was used.

(Example C6)
A test was performed in the same manner as in Example C1 except that the resin represented by formula (7) (m: n = 60: 40) was used.

  The test results are shown in Table 3.

Example C1 has higher resolution and hydrofluoric acid resistance than Example C2. Therefore, it can be seen that acrylate is preferable to methacrylate for the main chain.

Example C1 has higher resolution and hydrofluoric acid resistance than Example C3. Therefore, it can be seen that the number of hydroxyl groups is most preferably one.

Example C4 has a higher resolution than that of Example C1 and Examples C5 to C6, although the resistance to hydrofluoric acid is somewhat inferior. Therefore, a resin using cyclohexane for the alicyclic ring is preferably used for applications requiring higher resolution.

Although the resolution and hydrofluoric acid resistance required differ depending on the application, it is generally considered practical if the resolution is several tens of μmL / S and the hydrofluoric acid resistance is about 5 minutes.

(Test D) Composition Dependency Test With respect to the resin shown in Formula (2), the same test as in (Test B) was performed with a different m: n composition ratio.

  The test results are shown in Table 4.

As shown in Examples D3 to D7, it is preferable that the ratio of m: n is in the range of 30:70 to 70:30 because both the resolution and the resistance to hydrofluoric acid are high.

In addition, the said m: n composition ratio shown in Table 4 has shown with the monomer ratio charged at the time of resin polymerization. The resin polymerization method of the first embodiment is a synthesis method that provides a relatively high yield, and there is little difference between the monomer ratio charged during resin synthesis and the segment ratio m: n after resin polymerization,
Within the error range.

However, for example, in a method that shortens the reaction time, the reaction starts from a monomer that is easily reacted, and the bulky segments tend to decrease. For this reason, since a monomer ratio and a segment ratio may differ, adjustment is needed suitably. Considering the variation by this synthesis method, the preferable composition range in the monomer ratio is that the ratio of m: n is from 25:75 to 75.
: It is considered to be within the range of 25.

(Test E) Optical Scanning Device Manufacturing Test The optical scanning device shown in FIGS. 2 and 3 was manufactured using the hydrofluoric acid resistant etching material of the present embodiment. For the manufactured optical scanning device, the width of the beam at the center of the element, which is the key to scanning, is 10
μm and length is 1300 μm.

  A method of manufacturing the optical scanning device shown in FIGS. 2 and 3 will be described with reference to FIG.

  FIG. 4 is a schematic partial cross-sectional view for explaining a method for manufacturing the optical scanning device.

As shown in FIG. 4A, the substrate used in the device fabrication process is an SOI substrate 21, which is fabricated by bonding a Si active layer 2103 to a Si substrate layer 2101 via a SiO 2 layer 2102. Has been. In (Test E), an SOI substrate 21 manufactured by Toshiba Ceramics Co., which comprises non-doped silicon for the Si substrate layer 2101, 2 μm for the SiO 2 layer 2102, and n-type highly doped silicon for the active silicon layer 2103.
Was used.

As shown in FIG. 4B, a resist layer 22 is applied on the SOI substrate 21. Thereafter, a beam-like structure 11, which is a component of the optical scanning device, a structure 18 that connects the beam-like structure and the power structure, and a movable element structure including a comb-shaped drive mechanism 12 and an optical waveguide structure 15 The corresponding part is exposed.

As shown in FIG. 4C, a metal thin film layer 23 is formed at an exposed location by using CVD (Chemical Vapor Deposition). Thereafter, the resist layer 22 is peeled off, and a metal thin film layer corresponding to the element structure
Get 23 patterns.

As shown in FIG. 4D, a material to be the optical waveguide structure 15 is applied on the SOI substrate 21 on which the pattern of the metal thin film layer 1230 is formed.

  As shown in FIG. 4 (e), a resist layer 22 is applied on the material to be the optical waveguide structure 15.

As shown in FIG. 4F, exposure / development is performed to protect the upper surface of the portion that becomes the optical waveguide structure 15.

As shown in FIG. 4G, the portion other than the portion that becomes the optical waveguide structure 15 is cut by RIE (Reactive ion etching). At this time, the Si active layer 2103 is also cut on the surface without the metal thin film layer 23.

As shown in FIG. 4H, after removing the resist layer 22, the optical waveguide structure 15 is protected using the hydrofluoric acid resistant material of the first embodiment.

As shown in FIG. 4 (i), the SiO2 layer 2102 as a sacrificial layer is removed by hydrofluoric acid etching. In this step, the element structure becomes movable. The detailed conditions at this time are the same as in (Test B).

As described above, since the optical scanning device manufactured in (Test E) can perform sacrificial layer etching after the optical waveguide structure 15 is manufactured, the manufacturing method can be simplified and shortened.

As mentioned above, although embodiment of this invention was described, this invention is not restricted to these, In the category of the summary of the invention as described in a claim, it can change variously. In addition, the present invention can be variously modified without departing from the scope of the invention in the implementation stage. Furthermore, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

The flowchart which showed the synthetic | combination method of resin of 1st Embodiment. FIG. 10 is a schematic top view of the optical scanning device exemplified in the third embodiment. The partial cross section schematic diagram of the optical scanning device illustrated in 3rd Embodiment. Sectional schematic diagram for demonstrating the manufacturing method of the optical scanning device in a test (E). The cross-sectional schematic diagram of LED illustrated in 3rd Embodiment.

Explanation of symbols

11 Beam-like structure
12 comb drive mechanism
13 Stabilized spring structure
14 Bellows spring structure
15 Optical waveguide structure
16 Light source
17 Optical waveguide exit end
18 Structure that connects the beam-like structure and the power structure
19 Condensing structure
20 Beam vibration direction
21 SOI substrate
2201 Si substrate layer
2202 SiO2 layer
2203 Si active layer
22 resist layer
23 Metal thin film layer
24 Hydrofluoric acid resistant material
25 Compound semiconductor substrate
26 Light emitting layer
2601 cladding layer
2602 active layer
2603 cladding layer
27 Current spreading layer
28 Second electrode
29 First electrode
30 Wiring electrode pattern

Claims (4)

A resin consisting only of two types of repeating units represented by the following formula (1);
A hydrofluoric acid- resistant etching material comprising a photoacid generator that generates an acid by light.

(In Formula (1), R1 and R3 are a hydrogen atom or a methyl group,
R2 is one of adamantane, tricyclodecane, norbornane, isobornane, cyclohexane and cyclooctane having one or two hydroxyl groups,
R4 is one of adamantane, tricyclodecane, norbornane, isobornane, cyclohexane and cyclooctane having one ketone group;
The ratio of m: n is in the range of 30:70 to 70:30. ) Forming a resistant hydrofluoric acid etching material according to claim 1 on a substrate of a semiconductor or quartz glass,
Then, pattern exposing the substrate,
Heating the substrate;
Thereafter, developing the substrate with an alkali developer;
And a step of performing hydrofluoric acid etching using a solution having a hydrofluoric acid concentration of 30% to 50% on the substrate. Forming a sacrificial layer made of quartz glass on a semiconductor substrate;
Forming an element structure made of a semiconductor on the sacrificial layer;
Forming a portion made of a material having low hydrofluoric acid resistance on the semiconductor substrate;
Thereafter, a step of coating a portion made of a material lower in the resistance to hydrofluoric acid with resistant hydrofluoric acid etching material of claim 1,
And a step of removing the sacrificial layer using a solution having a hydrofluoric acid concentration of 30% to 50% on the semiconductor substrate. Forming a portion made of a highly hydrofluoric acid resistant material on a semiconductor substrate;
Forming a portion made of a material having a low hydrofluoric acid resistance on a portion made of the material having a high hydrofluoric acid resistance;
A step of coating a portion made of a material lower in the resistance to hydrofluoric acid with resistant hydrofluoric acid etching material of claim 1,
And a step of etching a portion made of a material having high hydrofluoric acid resistance using a solution having a hydrofluoric acid concentration of 30% to 50% .

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