JPH10166263A - Wafer polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing device with higher polishing precision. SOLUTION: A wafer polishing device has a platen with a polishing pad pasted to the surface, one or more wafer holding head 27 to hold one face of a wafer to be polished and put the other face of the wafer in contact with the polishing pad and a head driving mechanism to relatively move the wafer holding head 27 with the platen for polishing the other face of the wafer with the polishing pad. The wafer holding head 27 is provided with a disc carrier 30 to hold one face of the wafer to be polished, a retainer ring 31 concentrically arranged on the outer periphery of the carrier 30 to be displaceable to the axial direction of the head, a head mainbody 28 cylindrically formed to concentrically arrange the retainer ring inside and support the retainer ring on the inner periphery, the first diaphragm 29A extended between the carrier and the retainer ring and the second diaphragm 29B extended between the retainer ring and the head mainbody.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer polishing apparatus for polishing a surface of a semiconductor wafer or the like forming an integrated circuit.

[0002]

2. Description of the Related Art As a wafer polishing apparatus of this kind, a disk-shaped platen having a polishing pad attached to a surface thereof and a plurality of wafer polishing apparatuses for holding one surface of a wafer to be polished and bringing the other surface of the wafer into contact with the polishing pad. It is widely known that a wafer holding head and a head driving mechanism for rotating these wafer holding heads relative to a platen are used, and polishing is performed by supplying a slurry containing abrasive grains between a polishing pad and a wafer. ing.

As a wafer polishing apparatus of this type, for example, US Pat. No. 5,205,082 discloses an apparatus employing a wafer holding head as shown in FIG. This wafer holding head has a hollow head body 1.
And a diaphragm 2 stretched horizontally in the head body 1
And a carrier 4 fixed to the lower surface of the diaphragm 2, and into an air chamber 6 defined by the diaphragm 2,
By supplying pressurized air from a pressurized air source 10 through a shaft 8, the carrier 4 has a floating head structure capable of pressing the carrier 4 downward. Such a floating head structure has an advantage that the contact pressure of the wafer against the polishing pad can be made uniform.

A retainer ring 12 is arranged concentrically on the outer periphery of the carrier 4, and this retainer ring 12 is also fixed to the diaphragm 2. The lower end of the retainer ring 12 projects below the carrier 4, thereby holding the outer periphery of the wafer attached to the lower surface of the carrier 4. By holding the outer periphery of the wafer in this manner, a problem that the wafer being polished comes off the carrier 4 can be prevented.
Further, it is stated that overpolishing at the outer peripheral portion of the wafer can be prevented by surrounding the wafer with a retainer ring 12 and polishing the lower end of the retainer ring 12 at the same height as the lower surface of the wafer.

[0005]

However, the above-mentioned wafer polishing apparatus has the following problems. In other words, as the diameter of the wafer to be polished increases, higher polishing accuracy is required over the entire surface of the wafer having an increased area, and it is necessary to further uniform the contact pressure of the wafer with the polishing pad. was there.

[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a wafer polishing apparatus capable of obtaining higher polishing accuracy.

[0007]

The present invention has the following features to attain the object mentioned above. That is, in the wafer polishing apparatus according to claim 1, one or two or more of a platen having a polishing pad adhered to a surface thereof, and one or more of holding a surface of a wafer to be polished and bringing the other surface of the wafer into contact with the polishing pad. A wafer holding head, and a head drive mechanism for polishing the other surface of the wafer with the polishing pad by moving the wafer holding head relative to the platen, wherein the wafer holding head is the one surface of the wafer to be polished. A disc-shaped carrier for holding the carrier, a retainer ring concentrically disposed on the outer periphery of the carrier and capable of being displaced in the head axis direction, and the retainer ring formed in a cylindrical shape and disposed concentrically and inside and an inner periphery. A head body that supports the retainer ring in a plane, and is stretched between the carrier and the retainer ring to connect them; And one of the diaphragm, techniques wherein and a second diaphragm annular connecting the stretched between the retainer ring and said head body is employed.

In this wafer polishing apparatus, the first diaphragm is stretched between the carrier and the retainer ring and connects them, and the second annular ring is stretched between the retainer ring and the head body and connects them. Because it has a diaphragm, compared to the case with one diaphragm,
Since the diaphragm is divided into two, the followability to the movement of the carrier is improved, and the contact pressure of the wafer is made more uniform. In addition, the first diaphragm and the second diaphragm
The diaphragm can be set differently, for example, different in rigidity or material, and the width of the flexible part can be set different from each other, so various settings are possible for the movement of the carrier and the retainer ring Becomes

According to a second aspect of the present invention, in the wafer polishing apparatus according to the first aspect, the retainer ring has substantially the same axis as the outer peripheral portion of the first diaphragm stretched on the upper surface thereof. And a connecting ring fixed to the first diaphragm, the inner ring of the second diaphragm being disposed above the outer edge of the first diaphragm. Is done.

[0010] In this wafer polishing apparatus, since the inner edge of the second diaphragm is arranged above the outer edge of the first diaphragm and is stretched, the inner edge of the first diaphragm and the outer edge of the second diaphragm are stretched. Are arranged so as to overlap in the axial direction, so that the outer diameter of the entire wafer holding head can be reduced as compared with the case where the second diaphragm is arranged on the same plane on the radially outer side of the first diaphragm. .

According to a third aspect of the present invention, in the wafer polishing apparatus according to the first or second aspect, a technique is employed in which the first diaphragm has higher rigidity than the second diaphragm.

In this wafer polishing apparatus, since the first diaphragm has higher rigidity than the second diaphragm, the first diaphragm, which directly receives the movement of the carrier, has high uniformity over the entire circumference of the carrier. Can be mounted with precision.

According to a fourth aspect of the present invention, in the wafer polishing apparatus of the third aspect, the first diaphragm is formed of the same material as the second diaphragm and is thicker than the second diaphragm. The set technology is adopted.

In this wafer polishing apparatus, the first diaphragm is formed of the same material as the second diaphragm and is set to be thicker than the second diaphragm, so that the rigidity of the first diaphragm can be easily made of the same material. Can be higher.

According to a fifth aspect of the present invention, in the wafer polishing apparatus according to any one of the first to fourth aspects, the first diaphragm is formed of a tetrafluoroethylene resin-based material. Adopted.

In this wafer polishing apparatus, since the first diaphragm is formed of a tetrafluoroethylene resin-based material, high dimensional accuracy and mounting accuracy can be obtained over the entire circumference of the first diaphragm, and uniformity can be obtained. High rigidity can be obtained.

According to a sixth aspect of the present invention, in the wafer polishing apparatus according to any one of the first to fifth aspects, the second diaphragm employs a technique in which a rubber is coated on a polyester thin film. .

In this wafer polishing apparatus, since the second diaphragm has a structure in which the polyester thin film is coated with rubber, it has high flexibility in the axial direction and high strength in the plane direction and high airtightness.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a wafer polishing apparatus according to the present invention will be described with reference to FIGS.

First, the overall structure will be briefly described with reference to FIG. 2. In the figure, reference numeral 21 denotes a base.
A disk-shaped platen 22 is horizontally installed at the center of the platen. The platen 22 is rotated about an axis by a platen drive mechanism provided in the base 21. A polishing pad 23 is attached to the entire upper surface of the platen.

Above the platen 22, a plurality of columns 24
The upper mounting plate 25 is horizontally fixed via the. A disk-shaped carousel (head driving mechanism) 26 is fixed to the lower surface of the upper mounting plate 25, and a total of six wafer holding heads 27 facing the platen 22 are mounted on the carousel 26.
Is provided. These wafer holding heads 27
As shown in FIG. 3, at the same distance from the center of the carousel 26, the carousel 26 is arranged at every 60 degrees around the central axis of the carousel 26, and is each planet-rotated by the carousel 26.
However, the number of wafer holding heads 27 is not limited to six, but may be one to five or seven or more.

Next, the wafer holding head 27 will be described with reference to FIG. The wafer holding head 27 includes a hollow head main body 28 which is disposed perpendicular to the axis and whose lower end is opened, a first diaphragm 29A and a second diaphragm 29B stretched inside the head main body 28, and a first diaphragm It has a disc-shaped carrier 30 fixed to the lower surface of 29A, and a retainer ring 31 concentrically arranged on the outer periphery of the carrier 30.

The head main body 28 has a disk-shaped top plate 28a.
And a cylindrical peripheral wall portion 28b fixed to the outer periphery of the top plate portion 28a.
6 is coaxially fixed to the shaft 33. On the inner peripheral surface of the peripheral wall portion 28b, a mounting portion 34 of an annular step portion protruding radially inward over the entire circumference is formed.

The carrier 30 is formed of a material having high rigidity such as ceramic and has a constant thickness.
No elastic deformation. The retainer ring 31 is formed concentrically with a slight gap between the retainer ring 31 and the outer peripheral surface of the carrier 30.
Up and down independently.

A retainer 31A is formed on the outer peripheral edge of the upper end of the retainer ring 31 so as to protrude outward in the radial direction. Part 31
A is held by an annular stopper 35 at the lower end of the peripheral wall 28b. The stopper 35 is
It is formed so as to protrude radially inward from the lower peripheral edge of the peripheral wall portion 28b and to abut on the outer periphery of the retainer ring 31 with a slight clearance or to surround the retainer ring 31.

On the upper surface of the carrier 30, the inner edge of the first diaphragm 29A is arranged on the same axis, and on the upper surface of the retainer ring 31, the outer edge of the first diaphragm 29A is arranged. I have. On the upper surface of the inner edge of the first diaphragm 29A, the first
The first fixing ring 41 is disposed.
Is a first fixing ring 41 and a first diaphragm 2
The first diaphragm 29A is fixed to the carrier 30 with the first diaphragm 29A sandwiched by a plurality of bolts 42 passing through 9A.

On the upper surface of the outer edge of the first diaphragm 29A, a connecting ring 43 is disposed along the same axis, and on the upper surface of the connecting ring 43, the inner edge of the second diaphragm 29B is disposed. Have been. Then, the second diaphragm 29B has the same axis as the second diaphragm 29B on the upper surface.
Of the second fixing ring 44
Is a state in which the first diaphragm 29A and the second diaphragm 29B are sandwiched by a plurality of bolts 45 passing through the first diaphragm 29A, the connecting ring 43, the second diaphragm 29B, and the second fixing ring 44, respectively. It is fixed to the retainer ring 31.

Further, the outer edge of the second diaphragm 29B is placed on the mounting portion 34, and a third fixing ring 46 is disposed on the upper surface of the outer edge along the same axis. The third fixing ring 46 includes a plurality of bolts 47 passing through the second diaphragm 29B and the third fixing ring 46.
As a result, the second diaphragm 29B is fixed to the mounting portion 34 while being sandwiched therebetween. The first diaphragm 29A and the second diaphragm 29B are formed of an elastic material such as various rubbers, and the first diaphragm 29A
The film thickness is set to be thicker than the second diaphragm 29B.

The flexible portion of the second diaphragm 29B, that is, the portion between the portion held by the mounting portion 34 and the portion held by the connecting ring 43 is the flexible portion of the first diaphragm 29A, that is, the retainer ring. The width is set wider than the portion between the holding portion 31 and the holding portion by the carrier 30. Therefore, the second diaphragm 29B can bend more largely in the vertical direction (axial direction) than the first diaphragm 29A, and the flexibility in this direction is high.

On the other hand, a flow path is formed in the shaft 33,
Head body 28, carrier 30, first diaphragm 2
The fluid chamber 50 formed by the 9A and the second diaphragm 29B is connected through a flow path to a pressurized air source 51 which is a pressure adjusting mechanism. Then, by adjusting the fluid pressure in the fluid chamber 50 by the pressurized air source 51, the first diaphragm 29A and the second diaphragm 29B are displaced up and down, and the pressing pressure of the carrier 30 against the polishing pad 23 changes. I do. As the fluid, it is generally sufficient to use air, but other types of gas or liquid may be used if necessary.

When polishing is performed, the wafer is suction-fixed by suction holes (not shown) formed on the lower surface of the carrier 30 by being connected to suction means (not shown) such as a vacuum pump.

In the wafer polishing apparatus having the above configuration,
The carrier 30 is attached to the first diaphragm 29A and the second diaphragm 29B which are stretched to the head main body 28 via the connecting ring 43, and adjusts the fluid pressure applied to the fluid chamber 50, thereby pressing the carrier 30 downward. In this state, the contact pressure of the wafer against the polishing pad 23 is made uniform, and the polishing process is performed.

That is, in the wafer polishing apparatus according to the first embodiment, the first diaphragm 29A which is stretched between the carrier 30 and the retainer ring 31 and connects them, and the stretcher between the retainer ring 31 and the head main body 28 is provided. And a second diaphragm 29B for connecting these members, so that the diaphragm is divided into two compared to the case of one diaphragm, so that the followability to the movement of the carrier 30 is improved, The contact pressure of the wafer is made more uniform.

Further, since the inner edge of the second diaphragm 29B is arranged and stretched above the outer edge of the first diaphragm 29A, the outer edge of the first diaphragm 29A and the inner edge of the second diaphragm 29B are stretched. Are overlapped in the axial direction, the outer diameter of the entire wafer holding head 27 is smaller than that in the case where the second diaphragm 29B is arranged on the same plane on the radially outer side of the first diaphragm 29A. Can be kept small.

Further, the first diaphragm 29A is connected to the second diaphragm 29A.
Is thicker than the diaphragm 29B, and has high rigidity.
Can be attached with high uniformity over the entire circumference of the carrier 30 with high accuracy, and the polishing accuracy is further improved. Also, the first diaphragm 2
Since the rigidity of the second diaphragm 2A is high, the followability to the fine movement of the carrier 30 is improved.
Since the flexibility of 9B is high, it is possible to sufficiently cope with large movements of the carrier 30 and the retainer ring 31.

Next, a second embodiment of the wafer polishing apparatus according to the present invention will be described with reference to FIG.

The difference between the second embodiment and the first embodiment is that the first diaphragm 29A and the second diaphragm 29 of the wafer holding head 27 in the first embodiment are different.
B is formed of rubber films having different thicknesses, whereas the first diaphragm 61A of the wafer holding head 60 according to the second embodiment is, as shown in FIG. , And Teflon (a registered trademark of DuPont), and the second diaphragm 61B is made of a polyester thin film coated with rubber.

That is, since the first diaphragm 61A is formed of a tetrafluoroethylene resin-based material having high processing accuracy, high dimensional accuracy and mounting accuracy can be obtained over the entire circumference of the first diaphragm 61A. In addition, uniform rigidity can be obtained. In addition, since the second diaphragm 61B has a structure in which the polyester thin film is coated with rubber, the second diaphragm 61B has flexibility in the axial direction and high strength in the plane direction, and high airtightness can be obtained.

Therefore, the second diaphragm 61
By adopting B, while having excellent followability to the movement of the carrier 30 in the axial direction, leakage of the working fluid acting on the second diaphragm 61B is reliably prevented, and rotation from the head main body 28 is prevented. The force is applied to the retaining ring 31 and the carrier 3 via the second diaphragm 61B.
Good transmission to zero.

The present invention includes the following embodiments. (1) Although the suction by the suction holes is used as the means for holding the wafer on the lower surface of the carrier 30, other holding means may be employed. For example, a wafer may be attached to the lower surface of the carrier via a wafer attachment sheet. The wafer-attached sheet is formed of a water-absorbing material such as a nonwoven fabric, and absorbs the wafer by surface tension when absorbing water. Further, the wafer may be attached to the lower surface of the carrier via wax.

(2) Although the first diaphragm 29A and the second diaphragm 29B in the first embodiment are made of rubber, they may be made of other materials. For example, a thick film made of a tetrafluoroethylene resin-based material may be applied to the first diaphragm, and a thin film made of the thin film may be applied to the second diaphragm. (3) Although the first diaphragms 29A and 61A are formed in an annular shape, they may be formed in a circular shape.

[0042]

According to the present invention, the following effects can be obtained. (1) According to the wafer polishing apparatus of the first aspect, there is provided the first diaphragm stretched between the carrier and the retainer ring, and the second diaphragm stretched between the retainer ring and the head main body. Therefore, as compared with the case where the number of the diaphragms is one, the followability to the movement of the carrier can be improved, and the contact pressure of the wafer can be made more uniform. Therefore, high polishing accuracy can be obtained, and a good polished surface with high flatness can be obtained even with a large-diameter wafer. Further, since the first diaphragm and the second diaphragm can be set differently from each other, various settings can be made with respect to the movement of the carrier and the retainer ring, and the polishing corresponding to the type and size of the wafer can be performed. The conditions can be finely adjusted.

(2) According to the wafer polishing apparatus of the second aspect, since the inner edge of the second diaphragm is disposed and stretched above the outer edge of the first diaphragm, the entire outer surface of the wafer holding head is stretched. The diameter can be reduced, and the device can be downsized.

(3) According to the wafer polishing apparatus of the third aspect, since the first diaphragm has higher rigidity than the second diaphragm, the first diaphragm which directly receives the movement of the carrier is moved around the entire circumference of the carrier. , And can be attached with high uniformity and high accuracy, and the polishing accuracy can be further improved.

(4) According to the wafer polishing apparatus of the fourth aspect, since the first diaphragm is formed of the same material as the second diaphragm and is set thicker than the second diaphragm, the same material is used. Thus, the rigidity of the first diaphragm can be easily increased.

(5) According to the wafer polishing apparatus of the fifth aspect, since the first diaphragm is formed of a tetrafluoroethylene resin-based material, the dimension is high over the entire circumference of the first diaphragm. Accuracy and mounting accuracy can be obtained, and uniform rigidity can be obtained. Therefore, high followability to the movement of the carrier can be obtained.

(6) According to the wafer polishing apparatus of the sixth aspect, since the second diaphragm has a structure in which rubber is coated on the polyester thin film, it has flexibility in the axial direction and high strength in the plane direction. And high airtightness can be obtained. Therefore, in this wafer device,
It has excellent followability to the movement of the carrier in the axial direction, reliably prevents leakage of the working fluid acting on the second diaphragm, and reduces the rotational force from the head body.
Good transmission to the retainer ring and the carrier via the second diaphragm can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a wafer holding head in a first embodiment of a wafer polishing apparatus according to the present invention.

FIG. 2 is a front view showing the overall configuration of the wafer polishing apparatus according to the present invention.

FIG. 3 is a plan view showing an arrangement state of a wafer holding head and a platen of the apparatus.

FIG. 4 is a sectional view showing a wafer holding head in a second embodiment of the wafer polishing apparatus according to the present invention.

FIG. 5 is a sectional view showing a wafer holding head in a conventional example of a wafer polishing apparatus according to the present invention.

[Explanation of symbols]

 Reference Signs List 22 platen 23 polishing pad 26 carousel (head driving mechanism) 27 wafer holding head 28 head main body 28a top plate 28b peripheral wall 29A, 61A first diaphragm 29B, 61B second diaphragm 30 carrier 31 retainer ring 43 connecting ring 50 Fluid chamber 51 Pressurized air source

Claims (6)

[Claims] 1. A platen having a polishing pad attached to a surface thereof, one or more wafer holding heads for holding one surface of a wafer to be polished and bringing the other surface of the wafer into contact with the polishing pad, and these wafers A head drive mechanism for polishing the other surface of the wafer with the polishing pad by moving a holding head relative to the platen, wherein the wafer holding head has a disc shape for holding the one surface of the wafer to be polished. A carrier ring concentrically disposed on the outer periphery of the carrier and displaceable in the head axis direction; and a cylindrically formed retainer ring disposed concentrically and internally to support the retainer ring on an inner peripheral surface. A first diaphragm stretched between the carrier and the retainer ring and connecting the carrier and the retainer ring; Wafer polishing apparatus characterized tensioned by comprising a second diaphragm annular connecting the between the head body and nulling. 2. The wafer polishing apparatus according to claim 1, wherein the retainer ring has a first surface attached to an upper surface thereof.
A connection ring fixed substantially coaxially on the outer edge of the diaphragm, the connection ring having an inner edge of the second diaphragm on an upper surface thereof and an outer edge of the first diaphragm. A wafer polishing apparatus, which is arranged and stretched upward. 3. The wafer polishing apparatus according to claim 1, wherein said first diaphragm has higher rigidity than said second diaphragm. 4. The wafer polishing apparatus according to claim 3, wherein the first diaphragm is formed of the same material as the second diaphragm and is set to be thicker than the second diaphragm. Wafer polishing equipment. 5. The wafer polishing apparatus according to claim 1, wherein the first diaphragm is formed of a tetrafluoroethylene resin-based material. 6. The wafer polishing apparatus according to claim 1, wherein the second diaphragm is formed by coating a polyester thin film with rubber.