JP2901546B2 - Semiconductor device manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a semiconductor device, and more particularly to an apparatus for performing various processes such as heating a silicon substrate or forming a thin film by vapor deposition while heating the silicon substrate. The present invention relates to a substrate heating device.

[0002]

2. Description of the Related Art Generally, in a process of manufacturing a semiconductor device, a process of forming various thin films on the surface of a silicon substrate is required as a pretreatment. As a process for forming such a thin film, for example, there is a CVD method. FIG. 5 shows an example of a conventional ultra-high vacuum CVD apparatus. The chamber is composed of a growth chamber 8 and a heater chamber 9, both of which are separated by a single crystal silicon substrate 4 as a substrate to be grown and a susceptor 10 supporting the single crystal silicon substrate. Then, the growth chamber 8 and the heater chamber 9 are set to a high vacuum of 1E-8 Torr or less by the turbo pumps 7A and 7B, respectively. Further, a heater 5 is disposed below the silicon substrate 4, and the heat of the heater 5 heats the silicon substrate 4 to a desired temperature. Further, a gas introduction pipe 6 is connected to the growth chamber 8, and various gases are introduced.

In such a CVD apparatus, a silicon film is grown by introducing a growth gas such as silane or disilane from a gas introduction pipe 6. By adding germane to the growth gas simultaneously with disilane, an epitaxial film of the SiGe alloy can be grown on the single crystal silicon substrate 4. The doping of the grown film is performed by introducing diborane at the same time as the growth gas in the case of the P type, and by introducing phosphone in the case of the N type.

During the silicon growth, the temperature inside the susceptor 10 is high at the same time as the silicon substrate 4, so that film deposition also occurs in the area inside the susceptor 10 near the silicon substrate 4. If the susceptor is quartz, the film deposited on the susceptor 10 will be polycrystalline silicon. This polycrystalline silicon peels off as the growth is repeated, which causes a gap between the susceptor 10 and the silicon substrate 4 and causes dust. In order to avoid this, the susceptor 10 is conventionally composed of an internal susceptor 1 and an external susceptor 2 as shown in plan and sectional views in FIGS. 6 (a) and 6 (b). It is composed of silicon. Thereby, even if polycrystalline silicon is formed on internal susceptor 1, peeling thereof is prevented, and the above-mentioned problem is solved.

[0005]

The structure for performing the processing while heating the silicon substrate using the susceptor is not limited to the above-mentioned ultra-high vacuum CVD apparatus, but is performed by various heat processing apparatuses. However, in such a structure that heats the silicon substrate while supporting the peripheral portion of the silicon substrate with the susceptor, the heat of the peripheral side surface of the silicon substrate is radiated through the susceptor, so that the temperature drop in the peripheral portion is reduced. It will be significant. FIG. 7 shows a temperature distribution of a conventional 6-inch silicon substrate. This temperature distribution is 620
The temperature gradient from the center to the periphery is shown by an isotherm when the temperature is set to ° C., and was determined from the growth rate of the polycrystalline silicon film on the silicon oxide film. The growth was performed under conditions where the growth rate was sensitive to temperature. One width of the isotherm represents 1 ° C. As you can see from this figure,
It can be seen that the temperature sharply decreases in the peripheral part. The temperature differs by as much as 10 ° C. between the center and the periphery 1 cm from the outside.

If the in-plane temperature distribution of the silicon substrate becomes non-uniform due to such a temperature drop in the peripheral portion of the silicon substrate, the growth thickness and the doping concentration in the entire surface of the silicon substrate vary, and the silicon substrate becomes uneven. The characteristics of the semiconductor element manufactured in each of the central part and the peripheral part of the semiconductor device become uneven, and the manufacturing yield is reduced.

Japanese Patent Application Laid-Open No. 3-148829 discloses that a guard member having a temperature close to the temperature of the silicon substrate is provided around the silicon substrate to reduce the temperature difference between the susceptor and the silicon substrate. A technique for preventing variations in the heat treatment based on the temperature is described, but this technique is only for reducing the temperature difference between the susceptor and the silicon substrate, and is intended to make the in-plane temperature distribution of the silicon substrate uniform. Then it is not very effective.

It is an object of the present invention to provide an apparatus for manufacturing a semiconductor device capable of making the in-plane temperature distribution of a silicon substrate uniform.

[0009]

According to the present invention, there is provided a manufacturing apparatus for supporting a peripheral portion of a single crystal silicon substrate in a chamber by a susceptor and heating the silicon substrate, wherein the susceptor is located on an outer peripheral side. External susceptor and front
The inside of the inner peripheral side that directly contacts and supports the silicon substrate
And the internal susceptor is made of silicon.
And surrounds the periphery of the silicon substrate.
The silicon cover is arranged as described above . In this case, the silicon cover is in contact with the internal susceptor
It is preferable that Further, it is preferable that the silicon cover is formed in an annular shape and is disposed around the silicon substrate at a predetermined distance from the peripheral portion of the silicon substrate. Further, it is preferable that the silicon cover is divided and formed in the circumferential direction.

[0010] In the present invention, the stepped portion in the thickness direction is formed on the inner peripheral portion of the inner susceptor, the silicon substrate is preferably configured to be supported in a state of being housed in the step portion.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings. FIGS. 1A and 1B show a first embodiment of the present invention.
FIGS. 6A and 6B are a plan view and a cross-sectional view of a main part of the embodiment. For example, assuming that the silicon substrate is applied to the ultrahigh vacuum CVD apparatus shown in FIG. For the structure. In FIG. 1, reference numeral 4 denotes a silicon substrate as a single-crystal circular wafer, and reference numeral 10 denotes a susceptor for supporting the peripheral portion of the silicon substrate 4 to be fixedly supported in a chamber of a CVD apparatus. The susceptor 10 is composed of an annular inner susceptor 1 and an outer susceptor 2 having different diameters, similarly to the conventional susceptor shown in FIG. The inner susceptor 1 has an outer peripheral portion supported by the inner susceptor 1.
The silicon substrate 4 is supported in a state where the rear surface of the outer peripheral portion thereof is in contact with the inner peripheral surface of the silicon substrate 4. The internal susceptor 1 is made of silicon, and the external susceptor 2 is made of quartz.

In this embodiment, an annular silicon cover 3 is provided as a heat storage cover on the surface of the susceptor in the outer peripheral region of the silicon substrate 4. Here, the radial distance between the silicon cover 3 and the silicon substrate 4 was set to 5 mm with respect to the silicon substrate having a diameter of 6 inches.

According to such a configuration, this configuration is shown in FIG.
After being set in an ultra-high vacuum CVD apparatus as shown in FIG. 1 and heated by the heater 5, the in-plane temperature distribution of the silicon substrate 4 at that time is shown in FIG. Here, the central part of the silicon substrate 4 is set to 620 ° C.
The temperature gradient towards the periphery is indicated by isotherms. One width of the isotherm represents 1 ° C. In this case,
The temperature is measured from the growth rate of the polycrystalline silicon film on the silicon oxide film. From this result, conventionally, 10 ° C.
The temperature difference between the central portion and the peripheral portion (1 cm from the outside) was 5 ° C., confirming that the temperature drop in the peripheral portion was improved.

The reason why the in-plane temperature non-uniformity of the silicon substrate is reduced is as follows. That is, the silicon cover 3 absorbs heat radiated from the peripheral portion of the silicon substrate 4 and is thereby gradually heated to a temperature close to the temperature of the silicon substrate 4. And once heated,
This time, the silicon cover 3 serves as a heat source, and heat radiation from the silicon cover 3 heats the peripheral portion of the silicon substrate 4 and simultaneously heats the susceptor 10. Therefore,
As much heat as the heat in the peripheral portion of the silicon substrate 4 is radiated through the susceptor 10 is applied from the silicon cover 3 to the peripheral portion of the silicon substrate 4, and eventually the silicon substrate 4 is heated to a substantially uniform state. Will be done. Here, the reason why silicon is used as the heat storage cover is to make the degree of heat radiation the same as that of the silicon substrate. That is, if the specific heat of the heat storage cover is smaller than that of silicon, it is difficult to obtain the desired effect.

The silicon substrate 4 and the silicon cover 3
Is large, the effect of the silicon cover 3 on the temperature rise due to heat radiation around the silicon substrate 4 becomes small,
Conversely, if the interval is small, the heating effect increases, and the temperature rise becomes excessive. According to the experiment of the present inventor, although there are some fluctuations depending on the thickness and the radial dimension of the silicon cover 3, if the interval is larger than 1 cm, it is difficult to expect the above-mentioned effects by the silicon cover 3. It has been confirmed that it is necessary to set the distance within an interval smaller than 1 cm.

FIGS. 3A and 3B are a plan view and a sectional view of a second embodiment of the present invention. In this embodiment, the thickness of the internal susceptor 1 and the external susceptor 2 is formed to be thicker than the thickness of the silicon substrate 3, and the lower surface of the internal susceptor 1 is formed to be flush with the lower surface of the external susceptor 2. A step portion 1a is provided on the upper surface of the internal susceptor 1 to make this portion thinner, and the lower surface of the outer peripheral portion of the silicon substrate 4 is supported in contact with the step portion 1a. In this case, it is preferable that the upper surface of the silicon substrate 4 be lower than the upper surface of the internal susceptor 1. The silicon cover 3A is provided as a heat storage cover. In this case, the silicon cover 3A is divided into four in the circumferential direction, and an appropriate space is provided between adjacent silicon covers. The distance between the inner wall of the step 1a of the internal susceptor 1 and the silicon substrate 4 was 5 mm. The distance between the silicon substrate 4 and the silicon cover 3A is the same as in the first embodiment.

FIG. 4 is a diagram showing an in-plane temperature distribution in the silicon substrate according to the second embodiment. The temperature at the center of the silicon substrate 4 is 620 ° C., and one width of the isotherm represents 1 ° C. As a result, the temperature difference between the central portion and the peripheral portion (1 cm from the outside) of the silicon substrate 4 was 2 ° C., which indicates that the temperature distribution was further improved as compared with the first embodiment. This is because the internal susceptor 1 supporting the outer peripheral portion of the silicon substrate 4 is made thin by the stepped portion 1a, so that heat radiation through the internal susceptor 1 is suppressed, and the surface height of the silicon substrate 4 is reduced to the surface of the silicon cover 3A. It is considered that this is because direct heat radiation from the peripheral portion of the silicon substrate 4 is suppressed because it is at a position lower than the height. Further, by dividing the silicon cover 3A into four parts in the circumferential direction, it is possible to prevent deformation due to thermal strain.

The present invention is not limited to the above embodiments, and the material of the heat storage cover is not limited to silicon, but may be made of silicon depending on the degree of unevenness of the in-plane temperature of the silicon substrate. A material having a large specific heat or a material having a small specific heat can be appropriately selected. Also, the radial dimension and the number of divisions of the heat storage cover can be appropriately adjusted. Further, in some cases, when both the internal susceptor and the heat storage cover are made of silicon and can be processed, both can be formed integrally.

[0019]

As described above, the present invention relates to a manufacturing apparatus for performing heating while a peripheral portion of a silicon substrate is supported in a chamber by a susceptor.
External susceptor and directly in contact with the silicon substrate
And an internal susceptor on the inner peripheral side
Is made of silicon and the periphery of the silicon substrate
Since the silicon cover is arranged so as to surround the enclosure, heat can be transferred between the silicon substrate and the silicon cover, and the temperature of the peripheral portion of the silicon substrate becomes lower than that of the central portion of the silicon substrate. Non-uniformity of the in-plane temperature distribution can be suppressed, and various processes for the silicon substrate can be uniformed in the plane, so that a semiconductor device with a high production yield can be manufactured. Incidentally, according to the present invention, the temperature difference between the central part and the peripheral part of the 6-inch silicon substrate could be improved from 10 ° C. to 2 ° C.

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an in-plane temperature distribution of the silicon substrate according to the first embodiment.

FIG. 3 is a plan view and a cross-sectional view of a second embodiment of the present invention.

FIG. 4 is a diagram illustrating an in-plane temperature distribution of a silicon substrate according to a second embodiment.

FIG. 5 is a schematic configuration diagram of an ultra-high vacuum CVD apparatus as an example of a heat treatment apparatus to which the present invention is applied.

FIG. 6 is a plan view and a cross-sectional view showing a configuration of a conventional susceptor.

FIG. 7 is a diagram showing a conventional in-plane temperature distribution of a silicon substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal susceptor 2 External susceptor 3, 3A Heat storage cover (silicon cover) 4 Silicon substrate 5 Heater 6 Gas introduction pipe 7A, 7B Turbo pump 8 Growth chamber 9 Heater chamber 10 Susceptor

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-245264 (JP, A) JP-A-4-211117 (JP, A) JP-A-5-70287 (JP, A) JP-A-5-27087 90165 (JP, A)

Claims (6)

(57) [Claims] The method according to claim 1 peripheral portion of a single crystal silicon substrate is supported in the chamber by the susceptor, in the apparatus for manufacturing a semiconductor device for heating with respect to the silicon substrate, the support
The sceptor is composed of an outer susceptor on the outer peripheral side and an inner susceptor on the inner peripheral side which directly contacts and supports the silicon substrate.
And the internal susceptor is made of silicon.
Both apparatus for manufacturing a semiconductor device characterized by placing the silicon <br/> cover so as to surround the periphery of the silicon substrate. 2. The internal susceptor and the silicon cover.
2. The apparatus for manufacturing a semiconductor device according to claim 1, wherein Wherein the silicon cover is formed in an annular shape, a semiconductor according <br/> to claim 1 or 2 and the peripheral portion of the silicon substrate are disposed at predetermined intervals around the silicon substrate Equipment manufacturing equipment. 4. The apparatus for manufacturing a semiconductor device according to claim 3 distance between the silicon substrate and the silicon cover is within 1 cm. 5. The method for manufacturing a semiconductor device according to claim 1, wherein said silicon cover is formed so as to be divided in a circumferential direction. 6. A stepped portion in the thickness direction on the inner peripheral portion of the internal susceptor is formed, the silicon substrate in any of claims 1 to 5 is supported in a state of being housed in the step portion
An apparatus for manufacturing a semiconductor device as described in the above .