JP2001345314A - Device and method for heat treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the processing temperature in a heat treatment while uniform treatment is secured by preheating a process gas in a heating section provided outside a treatment chamber. SOLUTION: In a reaction tube 2 the internal pressure of which is reduced to a prescribed degree of vacuum, film formation is performed on the surfaces of wafers at a prescribed processing temperature by introducing an N2O gas and an SiH2Cl2 gas into the tube 2. At the time of introducing the N2O gas, the gas is preheated by heating a heating chamber 51 installed in the introducing path of the N2O gas by means of a heater element 53. In addition, an orifice 6 is formed in the introducing path of the N2O gas between the heating chamber 51 and reaction tube 2. Since the pressure in the heating chamber 51 becomes higher than that in the tube 2 due to the pressure loss in the orifice 6 even in a reduced-pressure process, the process gas can be preheated at high heating efficiency in the heating chamber 51 and, accordingly, the process temperature can be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus and a method for performing a film forming process on an object to be processed such as a semiconductor wafer.

[0002]

2. Description of the Related Art A CVD (Chemical Vapor Depositio) is one of the film forming processes as a semiconductor device manufacturing process.
There is a process called n). In this method, a processing gas is introduced into a reaction tube, and a film is formed on a surface of a semiconductor wafer (hereinafter, referred to as a “wafer”) by a chemical vapor reaction. As one of apparatuses for performing such a film forming process in batch, there is a vertical heat treatment apparatus. This apparatus comprises, for example, as shown in FIG. 5, a vertical reaction tube 12 provided on a cylindrical manifold 11 and a heater 13 provided so as to surround the reaction tube 12. A gas introduction pipe 14 that has entered through the manifold 11 and an exhaust pipe 15 that is connected to the manifold.
It is comprised including.

In such an apparatus, a large number of wafers W are held in a shelf on a holder 16 called a wafer boat, and are carried into the reaction tube 12 through the opening at the lower end of the manifold 11, and a gas supply source is provided. A processing gas was introduced into the reaction tube 12 from 17 via a gas introduction tube 14 to perform a film forming process.
At this time, the processing gas is decomposed by being heated by the heater 13 in the reaction tube 12, and is further heated to a reaction temperature or higher to perform a predetermined reaction. Thus, a predetermined film is formed.

[0004]

By the way, when the film is formed on the wafer W by the above-described apparatus, as shown in FIG. 6, the film thickness at the central portion of the wafer tends to be larger than that at the peripheral portion.
The reason is considered as follows. That is, in the above-described vertical heat treatment apparatus called a batch furnace, the processing gas is introduced into the reaction tube 12 by the gas introduction pipe 14, and the processing gas is supplied to the wafer W held by the wafer boat 16 around the wafer W. Since the gas is supplied from the edge side and flows on the wafer from the peripheral portion toward the central portion, the concentration of the processing gas is higher in the central portion of the wafer than in the peripheral portion.

In the process of raising the temperature of the wafer to the processing temperature, the amount of heat radiation at the peripheral portion of the wafer W becomes larger than at the central portion, so that the temperature at the central portion of the wafer W becomes higher than that at the peripheral portion. As described above, due to the temperature difference and the concentration difference of the processing gas generated between the peripheral portion and the central portion of the wafer W, the central portion of the wafer W having a higher temperature and the concentration of the processing gas forms a film on the peripheral portion. It is presumed that the reaction is accelerated, whereby the film thickness at the central portion of the wafer W becomes larger than the peripheral portion.

On the other hand, in a semiconductor manufacturing process, a low-temperature process is desired in order not to adversely affect a film formed in a previous step of a device and to save energy. However, the phenomenon that the film thickness at the central portion of the wafer becomes large tends to become more remarkable when the process temperature is lowered. Therefore, it is difficult to realize a low-temperature process with the current apparatus.

Therefore, the present inventor has proposed that the processing gas be supplied to the reaction tube 12.
Before the gas is introduced into the reaction tube 12, it is activated by preheating to a predetermined temperature by a heater (not shown) provided outside the reaction tube 12, and a sufficiently heated processing gas is introduced into the reaction tube 12. A technique for lowering the process temperature in the reaction tube 12 is being studied. The heater includes, for example, a heating chamber for heating by introducing a processing gas, and a heater provided outside the heating chamber and heating the heating chamber. In this technique, since the processing gas is preliminarily heated by a heater to a temperature close to, for example, a decomposition temperature, a sufficiently activated processing gas is introduced into the film formation region, and when the processing gas reaches the periphery of the wafer, the processing gas is sufficiently heated. A reaction is taking place. For this reason, the reaction state at the center and the reaction state at the peripheral part are the same, so that a process with high film thickness uniformity can be performed even if the process temperature in the reaction tube 12 is low.

[0008] However, in the low pressure CVD process in which the process is performed by reducing the pressure in the reaction tube 12, the pressure inside the heater is also reduced.
When the pressure is reduced to about orr, convection hardly occurs.
In addition, when the pressure in the heater is low, the partial pressure of the processing gas also becomes small, so that heat conduction due to convection of the processing gas in the heater hardly occurs. For this reason, heat is not transferred to the inside of the heater, the heat transfer efficiency to the processing gas is low, and it is difficult to heat the processing gas to a temperature at which the processing gas is sufficiently activated.

The present invention has been made under such circumstances, and an object of the present invention is to provide a method of, for example, forming a film on an object to be processed by supplying a processing gas preheated by a heating unit to a reaction vessel. The object of the present invention is to provide a heat treatment apparatus and a method thereof which can obtain high uniformity in the film thickness of a formed film by being supplied to the substrate and contribute to a low process temperature.

[0010]

According to the present invention, an object to be processed is loaded into a reaction vessel depressurized to a predetermined degree of vacuum by a vacuum exhaust means, and the inside of the reaction vessel is heated to a predetermined processing temperature. In a heat treatment apparatus for supplying a processing gas into a reaction vessel through a gas introduction path and performing a process on an object to be processed, the heat treatment apparatus is provided in the gas introduction path and performs the processing before supplying the processing gas to the reaction vessel. A heating unit for heating a gas to a predetermined temperature, and an orifice formed in the gas introduction passage between the heating unit and the reaction vessel, wherein the pressure in the heating unit is reduced by the pressure loss of the orifice. In a state where the pressure is higher than the pressure of the reaction vessel, the processing gas is supplied from the gas introduction path into the heating section, thereby preheating the processing gas to a predetermined temperature, and supplying the preheated processing gas to the reaction vessel. This The features. Here, as the heating unit, one provided with a heating chamber for heating the processing gas and a heater unit for heating a heating chamber provided so as to surround the heating chamber is used.

In such a heat treatment apparatus, the processing gas is supplied to a heating section provided outside the reaction vessel,
A step of preheating the processing gas; and a step of introducing the preheated processing gas into the reaction vessel.
The step of preheating the processing gas forms an orifice having a smaller inner diameter than the gas introduction path in a gas introduction path provided between the heating unit and the reaction vessel, and the pressure loss of the orifice causes A heat treatment method is performed in which the heating is performed in a state where the pressure of the heating unit is higher than the pressure of the reaction vessel.

With this configuration, even when the depressurization process is performed in the reaction vessel, the degree of decompression in the heating section becomes smaller than that in the reaction vessel due to the pressure loss of the orifice. For this reason, convection occurs sufficiently in the heating section, and the partial pressure of the processing gas also increases, so that the heating section is sufficiently heated to the inside, and the heating efficiency of the processing gas is improved. As described above, since the processing gas can be preheated in the heating unit to a predetermined temperature, for example, a temperature at which the processing gas is activated to a degree that does not decompose, the process temperature in the reaction vessel can be reduced, and a film is formed even in such a low-temperature process. High uniformity of the film thickness can be ensured.

According to another aspect of the present invention, an object to be processed is carried into a reaction vessel, the interior of the reaction vessel is heated to a predetermined processing temperature, and a processing gas is supplied into the reaction vessel through a gas introduction path. In a heat treatment apparatus that performs processing on a processing body,
A heating unit provided in the gas introduction path, for heating the processing gas to a predetermined temperature before supplying the processing gas to the reaction vessel, and the gas introduction path between the heating unit and the reaction vessel, It consists of a double pipe consisting of a pipe and an outer pipe provided at an interval outside of the pipe. The processing gas is supplied into the heating section from the gas introduction path to preheat the processing gas to a predetermined temperature. The process gas is supplied to the reaction vessel through an inner pipe of the gas introduction path.

In such a heat treatment apparatus, the gas introduction path between the heating section and the reaction vessel is formed of a double pipe, and the preheated processing gas is supplied to the reaction vessel via the inner pipe. The heat radiation of the processing gas flowing through the inside of the double pipe is suppressed, and the processing gas can be introduced into the reaction vessel while maintaining a high temperature.

At this time, the outer pipe of the double pipe of the gas introduction path may be bent to form a flange, and the flange and the reaction vessel may be joined via a sealing member.
In this case, since the temperature of the outer tube is lower than that of the inner tube, the gas introduction path and the reaction vessel can be joined without deteriorating the resin sealing member by heat, for example.

According to still another aspect of the present invention, an object to be processed is carried into a reaction vessel depressurized to a predetermined degree of vacuum by a vacuum exhaust means, and the inside of the reaction vessel is heated to a predetermined processing temperature.
In a heat treatment apparatus for supplying a processing gas into a reaction vessel through a gas introduction path and performing processing on an object to be processed, a gas chamber provided in the gas introduction path and through which the processing gas flows, and a gas chamber, A partition for dividing the processing gas into a plurality of gas flow directions, a ventilation hole formed in the partition and having an inner diameter smaller than the gas introduction path, and heating an upstream gas chamber of the divided gas chambers. And a heater unit for heating the heating chamber, which is provided so as to surround the heating chamber,
A process gas is supplied into the heating chamber from the gas introduction path in a state where the pressure of the heating chamber is higher than the pressure of the reaction vessel due to the pressure loss of the ventilation hole formed in the partition wall. The gas is preheated to a predetermined temperature, and the preheated processing gas is supplied to the reaction vessel. Even in such a configuration, the degree of pressure reduction in the heating chamber becomes smaller than that in the reaction vessel due to the pressure loss of the ventilation hole, and thus the heating efficiency of the processing gas in the heating chamber is improved.

Here, a ventilation resistor is provided inside the heating chamber,
It is desirable to bring the ventilation resistor into contact with the processing gas and preheat the processing gas to a predetermined temperature. In this case, the heating efficiency of the processing gas is further improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of a vertical heat treatment apparatus for carrying out the method of the present invention will be described with reference to FIG. 2 in FIG.
Is a reaction tube having a double tube structure including an inner tube 2a and an outer tube 2b made of, for example, quartz, and a metal cylindrical manifold 21 is provided below the reaction tube 2. .

The inner tube 2a has an open upper end, and is supported on the inner side of the manifold 21. Outer tube 2b
The upper end is closed, and the lower end is air-tightly joined to the upper end of the manifold 21. In this example, a reaction vessel is constituted by the inner tube 2a, the outer tube 2b, and the manifold 21. 22 is a base plate.

As shown in FIG. 2, for example, as shown in FIG. 2, a large number of, for example, about 60 wafers W to be processed are placed in the reaction tube 2 in a horizontal state and are vertically spaced from each other. The wafer boat 23 is placed on a shelf 23 in the form of a shelf. The wafer boat 23 is held on a lid 24 via a heat insulating cylinder (heat insulating body) 25. The lid 24 is a wafer boat 2
Boat elevator for loading and unloading 3 into and from the reaction tube 2
Mounted on the upper end of the reaction vessel 26, and has a role of closing the lower end opening of the manifold 21, ie, the lower end opening of the reaction vessel constituted by the reaction tube 2 and the manifold 21. It is. In FIG. 2, reference numeral 27 denotes a wafer board.
This is a transfer arm for transferring the wafer W to the wafer 21.

A heater 28 as a heating means is provided around the reaction tube 2 so as to surround it. The heater 28 is composed of, for example, a heating resistor, and a control unit described later performs temperature control based on a temperature profile of a film forming process input in advance.

The manifold 21 has a first gas introduction pipe 3 serving as a gas introduction path for supplying an N 2 O (dinitrogen monoxide) gas as a first processing gas into the reaction tube 2,
SiH2Cl2 (dichlorosilane) as a second processing gas
Second gas introduction pipe 4 for supplying gas into reaction tube 2
Are arranged in the circumferential direction, and respective gases are introduced into the reaction tube 2 from the first and second gas supply sources 31 and 41 outside the apparatus through the gas supply tubes 3 and 4. It is supposed to be.

The first and second gas introduction pipes 3
Gas flow rate control units 32 and 42 for controlling the gas flow rate are interposed in 1 and 41, respectively. The gas flow controllers 33 and 43 indicate parts including a gas flow controller and a valve. Based on a control signal from the controller, the gas flow controllers 33 and 43 are based on a program for introducing a processing gas at the time of a film forming process, which is input in advance. The timing of opening and closing is controlled, whereby the timing of introduction of the processing gas is controlled. An exhaust pipe 43 is connected to the manifold 21 so as to open between the inner pipe 2a and the outer pipe 2b, and the inside of the reaction pipe 2 can be maintained at a predetermined reduced pressure atmosphere by a vacuum exhaust means (not shown). It has become.

Next, the supply system of the N2O gas as the first processing gas will be described. Downstream of the gas flow control unit 31 of the first gas introduction pipe 3, a heater 5 serving as a heating unit for preheating the N 2 O gas to a predetermined temperature, and an orifice 6 are connected to the heater 5. It is installed in this order on the upstream side.

As shown in FIG. 3, for example, the heater 5 has a first gas introduction pipe 3 outside the vertical heat treatment apparatus.
And a heating chamber 51 made of, for example, transparent quartz provided so as to shut off the first gas introduction pipe 3.
It has. The heating chamber 51 includes, for example, the gas introduction pipe 3.
It is constituted by a cylindrical heating tube whose inside diameter is larger than the inside diameter of the tube, and is arranged so that the length direction thereof is aligned with the gas ventilation direction, and the inside thereof is filled with a ventilation resistor 52, for example, a large number of transparent quartz cullets. ing.

An example of the heating chamber 51 is as follows.
When the inner diameter of the first gas introduction pipe 3 is, for example, 20 mm, the heating chamber 51 has an inner diameter of, for example, 60 mm to 80 mm,
The length in the ventilation direction is, for example, about 100 mm to 200 mm, and the size of the quartz cullet filled in the heating chamber 51 is, for example, about φ1 to φ10. For example, a heater element 5 serving as a heater portion is provided around the outer periphery of the heating chamber 51 in the ventilation direction.
3 is spirally wound. This heater element 5
Reference numeral 3 denotes a string-shaped body formed by knitting a plurality of bundles of fibers made of a metal having a small amount of metal impurities, for example, a thin high-purity carbon of about 10 microns, and forming the string-shaped body with a sealing member made of a ceramic body, such as an outer member. It is formed in a spiral shape by enclosing it in a quartz (eg, transparent quartz) tube having a diameter of more than ten millimeters, and generates heat when energized. In the figure, reference numeral 54 denotes a power supply unit to the heater element, and 55 denotes a sealing terminal.

The heating chamber 51 and the heater element 53 are covered by a heating section main body 50 made of a tubular heat insulator. The heating section main body 50 has, for example, a cooling medium in a ventilation direction along the heater element 53. For example, a cooling jacket 56 for flowing cooling water is formed. Cooling water is supplied to the cooling jacket 56 by a cooling water supply unit 57. For example, a temperature detecting unit 58, such as a thermoelectric device, is provided between the cooling jacket 56 and the heater element 53 inside the heating unit main body 50. A pair is provided.
The control unit C outputs a control signal to the power supply unit 54 and the cooling water supply unit 57 based on the internal temperature detected by the thermocouple in this manner. The cooling water supply amount is controlled so that the heating chamber 51 is adjusted to a predetermined temperature by the interaction between the heating of the heater element 53 and the cooling of the cooling jacket 56.

As described above, in the heater 5, the heating chamber 51
Is a heat exchanging unit. The processing gas is introduced into the heating chamber 51 adjusted to a predetermined temperature, and brought into contact with the processing gas and the ventilation resistor 52, so that the processing gas reaches the predetermined temperature. It is preheated.

The first gas introduction pipe 3 is configured such that a downstream portion of the heating chamber 51 is a double pipe of an inner pipe 3a and an outer pipe 3b provided outside the inner pipe 3a with a space therebetween. Yes,
The other end of the outer tube 3b is bent and formed as a flange portion 33, and is connected to, for example, a side wall of the manifold 21 via a resin sealing member 34, for example, an O-ring. On the other hand, the inner pipe 3a is provided as the first gas introduction pipe 3 so as to protrude into the inside of the manifold as described above. The processing gas preheated by the heating chamber 51 flows through the inner tube 3 a and is introduced into the reaction tube 2 through the orifice 6.

The orifice 6, as shown in FIG.
It refers to a portion where the pipe diameter is sharply reduced. In this example, for example, the inner diameter of the outer pipe 3b does not change, only the inner diameter of the inner pipe 3a is reduced, and the inner diameter of the orifice 6 is smaller than the inner diameter of the inner pipe 3a. For example, the inner pipe 3a is set to about 1/50 to 1/2.
On the upstream side and the downstream side of the orifice 6, there are provided ramps 61 and 62 for connecting the inner pipe 3a and the orifice 6, and the inner diameter of the upstream ramp 61 gradually narrows to the orifice 6. The inner diameter of the downstream slope 62 gradually widens.

As an example of the orifice 6, the inner diameter of the outer pipe 3b of the double pipe downstream of the heating chamber 41 is, for example, φ10 to φ18, and the inner diameter of the inner pipe 3a is, for example, φ2 to φ2.
6, orifice 6 has an inner diameter of, for example, φ0.1
~ Φ2, the length is, for example, about 0.1 mm to 1 mm,
The length of each of the upstream slope 61 and the downstream slope 62 is, for example, about 0.1 mm to 1 mm, respectively.

Next, the present method performed by the above-described apparatus will be described by taking as an example a case where an oxide film called an HTO film (High Temperature Oxide) is formed. Where HTO
The film is composed of, for example, a silicon oxide film (SiO2 film), a silicon nitride film (Si3 N4), and a silicon oxide film (SiO2 film) called an ONO film interposed between a floating gate and a control gate of a flash memory. It is applied as a silicon oxide film used in a three-layer structure.

More specifically, first, a plurality of wafers W to be processed are held in a shelf shape on a wafer boat 23, and the boat elevator 26 is raised to open a lower end opening in the reaction tube 2. The processing atmosphere is heated to a predetermined temperature, for example, 720 ° C. by the heater 28, and the opening at the lower end of the manifold 21, that is, the wafer loading / unloading port of the reaction vessel is hermetically sealed by the lid 24. Then, under a heating atmosphere, the inside of the reaction vessel is evacuated to a predetermined degree of vacuum, for example, 0.1 Torr to 1 Torr by a vacuum exhaust means (not shown) through an exhaust pipe 43.
Reduce pressure to about

On the other hand, in the heater 5, the heater element 53
The heating chamber 51 is heated by a combination of the heating by the cooling water and the cooling by the flow of the cooling water, and the ventilation resistor 52 is heated to a predetermined temperature, for example, 500 ° C. to 900 ° C., where the N 2 O gas as the first processing gas is added. At a predetermined flow rate, for example, 100 sccm to 1000
Supply in sccm. At this time, the pressure in the reaction tube 2 is reduced to about 0.1 Torr to 1 Torr as described above. However, since the orifice 6 is formed between the heater 5 and the reaction tube 2, this orifice 6 The pressure in the heating chamber 51 is, for example, 200 Torr to 700 T due to the pressure loss at
orr.

The heating chamber 51 thus heated to a predetermined temperature
The N2O gas is passed through the inside of the inside, and the N2O gas is passed through the ventilation resistor 52.
Is preheated to a temperature that activates the N2O gas to such an extent that the N2O gas is not decomposed, that is, a temperature close to the decomposition temperature, for example, 500 ° C. to 850 ° C. It is introduced into the reaction tube 2.

In this manner, N 2 O gas as the first processing gas and SiH 2 Cl 2 as the second processing gas are placed in the reaction tube 2.
The gas is supplied from the gas supply sources 31, 41 to the gas introduction pipe 3,
4 at a predetermined flow rate into the reaction tube 2 (specifically, into a reaction vessel comprising the reaction tube 2 and the manifold 21);
Thereby, the pressure in the reaction tube 2 is set to, for example, 0.1 Torr to
At 1 Torr, a silicon oxide film is formed on the surface of the wafer W.

At this time, by supplying these processing gases, a silicon oxide film is formed on the wafer W according to the following reaction.

3N 2 O + SiH 2 Cl 2 → SiO 2 + H
2O + 3N2 + Cl2 Here, the processing gas is the inner tube 2 of the reaction tube 2.
a, while being supplied to the surface of the wafer W mounted on the wafer boat 23 and rising, reaching the upper end of the inner tube 2a, and flowing down the gap between the inner tube 2a and the outer tube 2b. And
The exhaust gas is exhausted from the exhaust pipe 43, and the processing gas is uniformly supplied to the wafer W mounted on the wafer boat 23, so that a silicon oxide film is formed on the wafer W.

After the formation of the predetermined silicon oxide film, the introduction of the processing gas is stopped, the surface temperature of the wafer W is lowered to a predetermined temperature, and the processing gas is introduced during the film formation. A purge gas, for example, N2 gas is introduced from, for example, two of the gas introduction tubes 3 and 4, and the pressure inside the reaction tube 2 is returned to normal pressure. Then, the boat elevator 26 is lowered to open the carry-in / out port at the lower end of the reaction tube 2, and the wafer boat 23 is carried out of the reaction tube 2.

According to such an embodiment, since the processing gas preheated by the heater 5 is supplied to the reaction tube 2, a so-called low-temperature process in which the process temperature of the reaction tube 2 is lowered is performed. Even in this case, a film formation process with high in-plane uniformity can be performed. That is, as described in the section of “Problems to be Solved by the Invention”, the temperature of the wafer W is higher in the central portion of the wafer W than in the peripheral portion, and the processing gas flows from the peripheral portion of the wafer W to the central portion. When the process temperature is lowered from about 750 ° C. to 830 ° C. to about 720 ° C., a processing gas with a low degree of decomposition and a low degree of decomposition is supplied to the peripheral portion of the wafer. Will be done. On the other hand, a processing gas having a higher degree of decomposition in which the decomposition reaction has progressed is supplied to the central portion of the wafer because the temperature and the gas concentration are higher than the peripheral portion. For this reason, the film forming reaction proceeds more easily in the central portion than in the peripheral portion of the wafer W, and the thickness of the film formed thereby becomes larger in the central portion.

On the other hand, as in the present invention, when the processing gas preheated to a temperature at which the decomposition reaction does not proceed in the heater 5 so that the decomposition reaction does not proceed, for example, a temperature close to the decomposition temperature, is introduced into the reaction tube 2, When the process temperature in the reaction tube 2 is 720
Even if the temperature is as low as about ° C., since the processing gas introduced into the reaction tube 2 has already been preheated to a temperature close to the decomposition temperature, the temperature of the processing gas exceeds the decomposition temperature before reaching the wafer periphery through the reaction tube 2. The heated processing gas is supplied to the peripheral portion of the wafer where the decomposition reaction has sufficiently proceeded.

As described above, the processing gas in the state where the degree of decomposition is substantially the same is supplied to the peripheral portion and the central portion of the wafer W, so that the processing gas is maintained substantially the same over the entire surface of the wafer W. The film formation reaction proceeds, and high in-plane uniformity of the film thickness formed by the film formation reaction can be secured.

At this time, in the heater 5 for preheating the processing gas, the ventilation resistor 52 is provided in the heating chamber 51 and the processing gas is heated by contacting the ventilation gas 52, so that the processing gas is efficiently supplied. The temperature can be raised. That is, by filling the heating chamber 51 with the ventilation resistor 52,
Since the processing gas flows through the heating chamber 51 while contacting the ventilation resistor 52, the residence time of the processing gas becomes longer,
Further, the heating is performed by a combination of convection heating of the processing gas itself heated by the heater element 53 and heating by heat transfer from the ventilation resistor 52.

When a quartz cullet having a size of about φ1 to φ10 is filled in the heating chamber 51 as the ventilation resistor 52, the entire surface area of the quartz cullet 52 is large.
A large heat transfer surface area can be secured, and the temperature of the processing gas can be increased more efficiently.

At this time, since the orifice 6 is formed in the processing gas introducing pipe 3 between the heater 5 and the reaction pipe 2, even when the depressurizing process is performed in the reaction vessel, the processing gas is sufficiently supplied. Can be heated to temperature. That is, since a pressure loss occurs in the orifice 6, the pressure on the upstream side becomes larger than the pressure on the downstream side. For this reason, even if the pressure in the reaction vessel 2 is reduced to, for example, about 0.1 Torr to 1 Torr, the pressure in the heating chamber 51 on the upstream side of the orifice 6 becomes 200, for example.
Torr to about 700 Torr. On the other hand, when the orifice 6 is not provided, the reaction vessel 2 is set to, for example, 0.
When the pressure is reduced to about 1 Torr to 1 Torr, the heating chamber 51
The internal pressure is reduced to, for example, about 0.2 Torr to 1 Torr.

By providing the orifice 6 in this manner, the degree of decompression in the heating chamber 51 is reduced. Therefore, even if convection in the heating chamber 51 is less likely to occur, the degree is small. Since the partial pressure also increases, heat conduction due to convection of the processing gas in the heater 5 is more likely to occur than when the orifice 6 is not provided. For this reason, heat is sufficiently transmitted to the inside of the heater 5, so that the efficiency of heat transfer to the processing gas is improved, the processing gas can be heated to a predetermined temperature in a short time, and a low-temperature process can be realized. Can be.

Actually, the pressure inside the reaction tube 2 was set to 0.1 to 1 Torr by using a heat treatment apparatus having the same configuration as that of the above-described embodiment.
r, the process temperature in the reaction tube 2 is 720 ° C., and the heating chamber 51
Is set to 500 ° C to 900 ° C, N2O gas and SiH2C
l2 is 100 sccm to 1000 sccm, 100
The film is introduced at a flow rate of about sccm to 300 sccm to perform a film forming process, and the in-plane uniformity of the film thickness of the silicon oxide film formed on these wafers W is measured using a film thickness measuring device (Ellipsometer).
As a result, the N2O gas can be sufficiently preheated by passing the N2O gas into the heating chamber 51 at the flow rate, and the uniformity of the film thickness of the formed film can be obtained even in a low-temperature process. It was confirmed that high processing could be performed.

Further, since the downstream side of the heater 5 is a double pipe, the following effects can be obtained. That is, the heating chamber 51 and the reaction tube 2
Are connected by a single gas introduction pipe, the end of the single pipe is formed as a flange, and this flange is connected to the reaction pipe 2.
Are connected to each other with a resin sealing member (O-ring) interposed therebetween. In such a configuration, the processing gas discharged from the heating chamber 51 is, for example, 450 ° C. to 850 ° C.
Since the temperature is as high as about ° C., the gas introduction path is heated by the gas aeration. For this reason, the temperature of the flange becomes higher than the heat resistance temperature of the resin seal member, for example, 250 ° C., and the heat of the flange may deform the resin seal member 34, thereby deteriorating the airtightness.

On the other hand, when a double pipe is used as in the present invention, the processing gas flows through the inner pipe 3a, so that the outer pipe 3b
Does not come into contact with the outer tube 3b, so that heat does not occur in the outer tube 3b due to contact with the processing gas, so that the temperature does not rise as much as the inner tube 3a. Therefore, if a flange 33 is formed by the outer tube 3b and a resin sealing member 34 is interposed between the flange 33 and the reaction tube 2 to connect the two, the temperature of the outer tube will be lower than that of the resin sealing member 34. Since the temperature does not exceed the heat resistant temperature, the heat of the flange 33 causes the resin-made sealing member 3
There is no risk of deformation of 4 and reliability is improved.

When the gas introducing pipe 3 is a double pipe, the outer pipe 3b is interposed between the inner pipe 3a through which the gas flows and the outside air, and the inner pipe 3a does not come into contact with the outside air. The degree of cooling by the outside air becomes smaller. For this reason, the amount of heat released when the heated processing gas passes through the inner pipe 3a is reduced, so that the temperature of the processing gas is prevented from lowering and the processing gas is kept activated by preheating. Can be introduced into the reaction tube 2.

Next, another embodiment will be described with reference to FIGS. In this example, a gas chamber 7 configured by combining a heating chamber and an orifice is provided in a gas introduction path (first gas introduction pipe 3) so as to close the introduction path. The gas chamber 7 has three chambers 7a, 7b, 7c arranged in the ventilation direction, and these chambers 7a to 7c
Is a partition wall 7 having ventilation holes 71a and 71b, which form an orifice and have an inner diameter smaller than the inner diameter of the first gas introduction pipe 3.
2a and 72b. Here, the first room 7a on the upstream side and the third room 7c on the downstream side respectively have the first room 7a.
Is connected, and a second room 7b is provided between the first room 7a and the third room 7c.

The first chamber 7a is configured as a heating chamber, and is filled with a ventilation resistor 73 made of, for example, quartz cullet, as shown in FIG. 74 are wound.
The ventilation resistor 73 and the heater element 74 are configured in the same manner as in the above-described embodiment.

In such a configuration, the second room 7b and the third room 7c are provided adjacent to the heating room 7a, and the orifices 71a and 71b are provided at the connecting portions thereof. When the pressure in the reaction tube 2 is reduced, the pressure in each of the rooms 7a to 7c increases in the order of the first room 7a> the second room 7b> the third room 7c due to the pressure loss at the orifice. For this reason, the degree of decompression in the first chamber 7a is minimized, so that convection occurs sufficiently in this room 7a and heat is sufficiently transmitted to the inside of the heating chamber, so that the processing gas heating efficiency is improved, The gas can be sufficiently heated to a predetermined temperature.

In the above, in the heating chambers 51 and 7a, the processing gas may be heated by convection of the processing gas without filling the inside with the ventilation resistors 52 and 73. As the ventilation resistors 52 and 73, foamed quartz, porous SiC, or the like can be used in addition to quartz cullet.

Further, in the above-described example, the second gas S
The decomposition temperature of iH2Cl2 gas is lower than that of N2O gas,
Even if the preheating is not performed, only the N2O gas as the first processing gas is preheated because the decomposition reaction occurs sufficiently by heating in the reaction tube 2, but the SiH2Cl2 gas may be preheated. .

Further, according to the present invention, not only a low pressure CVD process but also a process gas such as HCl (hydrogen chloride) gas and O
It can also be applied to a normal pressure process in which the reaction of the following formula is caused using 2 (oxygen) gas.

2HCl + O2 → H2O + Cl2 The present invention is not limited to the batch type vertical heat treatment apparatus described above, but is also effective when a film is formed by a single-wafer heat treatment apparatus. It can be performed. Furthermore, the present invention is not limited to the formation of a silicon oxide film, but can be applied to the formation of a polysilicon film, a silicon oxide film by TEOS, a silicon nitride film, and the like.
Further, the present invention can be applied to formation of an oxide film such as dry oxidation, wet oxidation, and HCl oxidation other than the CVD film formation process.

[0058]

As described above, according to the present invention, the processing gas is preheated to a predetermined temperature by the heating unit provided outside the reaction vessel and then supplied to the reaction vessel, so that the processing gas can be uniformly processed. The process temperature can be reduced while ensuring the performance. In this case, even in the depressurization process, by providing an orifice between the heating unit and the reaction vessel, the degree of decompression in the heating unit can be reduced, and the processing gas can be heated with high heating efficiency in the heating unit.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an example of an embodiment of a vertical heat treatment apparatus of the present invention.

FIG. 2 is a perspective view showing a part of the vertical heat treatment apparatus.

FIG. 3 is a sectional view showing a heater and an orifice used in the vertical heat treatment apparatus.

FIG. 4 is a perspective view and a sectional view showing a gas chamber used in another embodiment of the vertical heat treatment apparatus.

FIG. 5 is a cross-sectional view showing a conventional vertical heat treatment apparatus.

FIG. 6 is a characteristic diagram showing a relationship between a film thickness and a position on a wafer.

[Explanation of symbols]

 W semiconductor wafer 2 reaction tube 2a inner tube 2b outer tube 3 first gas introduction tube 5 heater 51 heating chamber 52 ventilation resistor 53 second heating means 6 orifice 7 gas chamber 71a, 71b ventilation hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F27D 7/06 F27D 7/06 A 21/00 21/00 A H01L 21/22 511 H01L 21/22 511S F Term (reference) 4K030 AA03 AA06 AA24 BA40 BA44 BB12 CA12 EA01 KA04 KA25 KA45 KA46 LA15 4K056 AA09 BA04 4K061 BA11 CA21 FA07 FA14 GA04 4K063 AA05 AA15 BA12 CA01 DA09 DA13 DA33 5F045 AA11 AE02 EC05 EJ09 EK09 GB05 GB15

Claims (13)

[Claims] An object to be processed is loaded into a reaction vessel depressurized to a predetermined degree of vacuum by a vacuum evacuation means, the inside of the reaction vessel is heated to a predetermined processing temperature, and the inside of the reaction vessel is introduced into the reaction vessel through a gas introduction path. In a heat treatment apparatus that supplies a processing gas and performs processing on an object to be processed, the heating apparatus is provided in the gas introduction path and heats the processing gas to a predetermined temperature before supplying the processing gas to the reaction vessel. And an orifice formed in the gas introduction passage between the heating unit and the reaction vessel, with the pressure in the heating unit being higher than the pressure of the reaction vessel due to the pressure loss of the orifice. A heat treatment apparatus for supplying a processing gas into a heating unit from a gas introduction path, thereby preheating the processing gas to a predetermined temperature, and supplying the preheated processing gas to the reaction vessel. 2. An object to be processed is carried into the reaction vessel, the inside of the reaction vessel is heated to a predetermined processing temperature, and a processing gas is supplied into the reaction vessel through a gas introduction path. A heating unit provided in the gas introduction path for heating the processing gas to a predetermined temperature before supplying the processing gas to the reaction vessel; and a heating unit between the heating unit and the reaction vessel. The gas introduction path comprises a double pipe consisting of an inner pipe and an outer pipe provided at an interval outside the inner pipe, and supplies the processing gas into the heating unit from the gas introduction path to bring the processing gas to a predetermined temperature. A heat treatment apparatus, comprising: preheating and supplying the preheated processing gas to the reaction vessel via an inner pipe of the gas introduction path. 3. The reaction vessel according to claim 2, wherein the outer pipe of the double pipe of the gas introduction path is bent to form a flange, and the flange and the reaction vessel are joined via a seal member. Heat treatment equipment. 4. An orifice comprising: a vacuum exhaust means for reducing the pressure of the reaction vessel to a predetermined degree of vacuum; and an orifice formed in an inner pipe of the gas introduction passage between the heating section and the reaction vessel. Due to the pressure loss, the processing gas is supplied from the gas introduction path into the heating unit in a state where the pressure of the heating unit is higher than the pressure of the reaction vessel, thereby preheating the processing gas to a predetermined temperature, 4. A heated processing gas is supplied to the reaction vessel.
The heat treatment apparatus according to the above. 5. A heating unit comprising: a heating chamber for heating a processing gas; and a heater unit for heating a heating chamber provided to surround the heating chamber. Item 5. The heat treatment apparatus according to any one of Items 1 to 4. 6. An object to be processed is carried into a reaction vessel depressurized to a predetermined degree of vacuum by a vacuum evacuation means, and the inside of the reaction vessel is heated to a predetermined processing temperature, and is then introduced into the reaction vessel through a gas introduction path. In a heat treatment apparatus for supplying a processing gas and performing processing on an object to be processed, a gas chamber provided in the gas introduction path and through which the processing gas flows, and a plurality of the gas chambers in a direction in which the processing gas flows. A partition for dividing, a ventilation hole formed in the partition, having an inner diameter smaller than the gas introduction path, and an upstream gas chamber among the divided gas chambers is a heating chamber, and surrounds the heating chamber. And a heater unit for heating the heating chamber, provided in such a manner that the pressure of the heating chamber is higher than the pressure of the reaction vessel due to the pressure loss of the ventilation hole formed in the partition wall. , Heating room from gas introduction path Process gas supply, thereby the processing gas is preheated to a predetermined temperature, the heat treatment apparatus characterized by supplying the pre-heated process gas into the reaction vessel. 7. A heat treatment apparatus holds a large number of objects to be processed in a holding device in a shelf shape, loads the objects into a vertical reaction container, and heats the inside of the reaction container to a predetermined processing temperature by heating means surrounding the reaction container. The heat treatment apparatus according to any one of claims 1 to 6, wherein the heat treatment apparatus is a vertical heat treatment apparatus for heating. 8. A process according to claim 5, wherein a ventilation resistor is provided inside the heating chamber, and the ventilation gas is brought into contact with the processing gas to preheat the processing gas to a predetermined temperature. Heat treatment equipment. 9. The heat treatment apparatus according to claim 5, wherein the heating chamber is preheated to a temperature at which the processing gas is activated so as not to decompose the processing gas. 10. The heat treatment apparatus according to claim 5, wherein the heater section is configured by enclosing a resistance heating element having a small amount of metal impurities in ceramics. 11. The heat treatment apparatus according to claim 10, wherein the resistance heating element is made of a high-purity carbon material. 12. The heat treatment apparatus according to claim 10, wherein the ceramic is quartz. 13. A heat treatment method in which a processing gas is supplied into a reaction vessel while heating the processing target in a reaction vessel reduced in pressure to a predetermined degree of vacuum, and the processing is performed on the processing target. A step of supplying the processing gas to a heating unit provided outside the vessel to preheat the processing gas; and a step of introducing the preheated processing gas into the reaction vessel. In the step of preheating the gas, an orifice having an inner diameter smaller than that of the gas introduction path is formed in a gas introduction path provided between the heating section and the reaction vessel. A heat treatment method, wherein the pressure is set higher than the pressure of the reaction vessel.