JPS636627B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vapor phase growth apparatus for epitaxial growth and CVD, and particularly relates to uniform heating of a substrate subjected to vapor phase growth. .

[Prior art and its problems]

In general, a vapor phase growth apparatus heats the substrate by placing the substrate on a susceptor that is heated to a red-hot state by a heating source such as a resistance heater, RF coil, or infrared lamp, and then injects a reactive gas onto the surface of the substrate. When brought into contact with each other, a vapor phase growth layer is formed on the surface. By the way, in order to obtain a vapor-grown layer with a uniform thickness and to suppress the occurrence of slips when the substrate is single crystal, the temperature difference in the plane direction and thickness direction of the substrate is kept small to make the entire substrate uniform. It is necessary to maintain the temperature at a certain temperature and heat it. The front surface of the substrate is cooled by contact with the reaction gas and heat is radiated, so the surface temperature becomes lower than the back surface that is in contact with the susceptor, causing the substrate to warp and contact with the susceptor to become localized. As the temperature increases, the temperature distribution within the plane deteriorates, causing slips. Therefore, conventionally, as shown in FIG. 8, a carbon susceptor 3 is placed in a reaction chamber 2 formed by a quartz reaction vessel 1, and a substrate 4 is placed on the upper surface of the susceptor 3 in the figure. A lamp 5, which is a heat source, is placed above the reaction vessel 1 in the figure.
The susceptor 3 and the substrate 4 are simultaneously irradiated with infrared light, heating the susceptor 3 to a red-hot state and heating the substrate 4 placed thereon from the back side. There is a method that heats the substrate 4 directly from the surface, and it is said that this reduces the occurrence of slips, but slips may occur due to the temperature imbalance between the susceptor 3 and the substrate 4 during the heating process. It is also said to cause In order to solve this problem, the susceptor 3 is heated from the back side by an RF coil (not shown), and the direct heating of the substrate 4 by the lamp 5 is used as an auxiliary to remove the temperature imbalance between the susceptor 3 and the substrate 4. It is also proposed that

However, in the method described above in which the substrate 4 is brought into contact with the susceptor 3 and the substrate 4 is heated mainly by heat conduction from the susceptor 3, the state of contact between the two depends on the surface condition of the susceptor 3, the warpage of the substrate 4, etc. This makes it difficult to obtain a uniform temperature distribution within the plane of the substrate 4, and when heating the substrate 4 directly with the lamp 5, the reflector 6
Even if the distribution of the infrared light irradiation intensity is adjusted using
directly affects, and also turns lamp 5 ON and OFF.
There is a drawback that the temperature of the substrate 4 and the susceptor 3 become unbalanced when the temperature is increased or decreased due to the temperature fluctuation, resulting in temperature unevenness in the substrate 4.
In order to stabilize the contact state between the susceptor 3 and the substrate 4, it has conventionally been proposed to provide a very shallow curved recess at the substrate placement position of the susceptor 3; Even at its deepest point, the gap between the recess and the back surface of the substrate 4 is extremely small, 0.1 mm or less. It is difficult to accurately form the shape of the base, including the shape of the bottom surface, and in reality, sufficient uniform heating is not possible, often resulting in slips.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides first and second heating plates made of carbon that are disposed opposite to each other in a reaction chamber, and a heating device that supplies heating energy to each of these heating plates. and a substrate support section that positions the substrate approximately parallel between the two heating plates, and this substrate support section covers most or all of the front and back surfaces of the substrate, excluding the vicinity of the outer periphery, with a distance between the two heating plates. They were made to face each other.

[Effect]

In the present invention, both the front and back surfaces of the substrate are heated by infrared light generated from first and second heating plates spaced apart from each other and by indirect heat conduction through space. The first and second heating plates are heated to a red-hot or incandescent state by heating energy supplied from a heating source such as an RF coil or lamp, but these heating plates are made of carbon and have high thermal conductivity. Therefore, even if the distribution of heating energy supply to these parts is not uniform, the entire surface is heated to a nearly uniform temperature, and the infrared rays from the heating plate are scattered in all directions, so that the entire surface of the board can be heated evenly. It heats uniformly, and the temperature unevenness of the substrate is kept very small compared to the temperature unevenness of the heating plate. Therefore, the temperature distribution within the plane of the substrate can be made uniform, and the amount of heating on both the front and back sides can be set appropriately depending on the heating degree of both heating plates. Since it is completely separated from the heating plate, the entire board is heated evenly without any effect of heat conduction due to the temperature difference between the board and the heating plate, and the heating plate has an appropriate heat capacity, so the heating of the board is soft. This also suppresses the occurrence of temperature unevenness due to sudden changes in heating on and off.

〔Example〕

FIG. 1 showing one embodiment of the present invention will be described below. 11 is a base plate, 12 is a bell gear made of quartz as a reaction vessel, and 13 is a coil cover also made of quartz, which together form a reaction chamber 14.

Inside the reaction chamber 14, a hollow rotating shaft 15 extends through the base plate 11, and a disk-shaped first heating plate 16 made of carbon is attached to the upper end of the hollow rotating shaft 15. Above the first heating plate 16, a disk-shaped second heating plate 18 made of carbon is provided in parallel via a plurality of pillars 17 made of quartz or ceramics such as Si ₃ N ₄ . There is. Said first,
The second heating plates 16 and 18 are preferably coated with SiC like commonly used susceptors, but their thickness is different from that of conventional susceptors (those that support the substrate). It should be relatively thin.

A first RF coil 19, which is a heating source for the first heating plate 16, is provided inside the coil cover 13.
On the other hand, above the bell gear 12 is a second heating plate 1.
A second RF coil 20 which is a heating source of 8 is provided so as to be movable up and down together with the bell gear 12.

A gas supply pipe 21 passes through the hollow rotating shaft 15, and a nozzle part 22 at the upper end thereof is located between the first and second heating plates 16, 18, and supplies purge gas outward. It is designed to blow out reactive gases. Further, the base plate 11 is provided with an exhaust port 23 for the reaction chamber 14 .

A plurality of support rings 24 are arranged on the first heating plate 16, each supporting the outer peripheral part of the substrate 25, and supporting the substrate 25 between the first and second heating plates 16,
18 and approximately parallel to these (may be slightly inclined). The support ring 24 is made of carbon, Si, SiC, quartz or
It is made of ceramics such as Si ₃ N ₄ . This support ring 24 is a space 2 between the back surface of the substrate 25 (lower surface in FIG. 1) and the first heating plate 16.
6 is almost closed, but the nozzle part 22
A notch 27 is provided on the opposite side, and a substrate suction tool (not shown) is inserted into the space 26 to suction the back surface of the substrate 25 to allow the substrate 25 to be carried in and out.

Next, the operation of this device will be explained. First,
High frequency power is supplied to the second RF coils 19 and 20, and the first and second heating plates 16 and 18 corresponding thereto are heated by induction. By forming these heating plates 16 and 18 thinly, they can be heated to a predetermined temperature with a small output of electric power. Both heating plates 16,
18 is made of carbon and has high thermal conductivity, so the entire body is heated to a relatively uniform temperature and becomes red-hot or incandescent. Infrared light is emitted from the surfaces of these heating plates 16 and 18 so as to be scattered in all directions, and radiantly heats both the front and back surfaces of the substrate 25 that is spaced apart between them. So heating plate 1
Even if there is some temperature unevenness in the substrates 6 and 18, a more uniform distribution of infrared light is irradiated over the entire substrate 25. In addition, the atmosphere around the substrate 25 is the same as that of the heating plate 1.
6 and 18, the substrate 25
is also heated by it.

Therefore, the temperature of the entire substrate 25 is raised uniformly, with almost no difference in temperature between the front and back surfaces or within the plane.

Note that since the substrate 25 dissipates more heat from the outer periphery than from the center, the support ring 24 is made of carbon,
It is made of a material that generates heat when exposed to infrared light, such as Si or SiC, and its heat capacity and degree of contact with the substrate 25 are appropriately determined to prevent a drop in temperature at the outer periphery of the substrate 25, or It is preferable that the support ring 24 is formed of a thermally poor conductor such as quartz or ceramics such as Si ₃ N ₄ to suppress heat radiation from the outer periphery of the substrate 25 . Also,
When this support ring 24 is formed of a thermally poor conductor such as quartz or ceramics, an effect of suppressing heat exchange due to conduction between the substrate 25 and the first heating plate 16 supporting it can be obtained. .

During heating of the substrate 25, from the nozzle section 22,
A purge gas such as H ₂ or a reaction gas is blown out and flows along the surface of the substrate 25 . Therefore, the board 25
The front surface dissipates more heat than the back surface surrounded by the support ring 24, and a temperature difference tends to occur between the front and back surfaces. This temperature difference between the front and back is caused by the second heating plate 18
Set their outputs so that the heating by the first heating plate 16 is stronger than the heating by the first heating plate 16, or
Alternatively, by installing the substrate 25 closer to the second heating plate 18 than the first heating plate 16, or by changing the thickness of the first heating plate 16 and the second heating plate 18, resolved.

Because of the support ring 24, the gas blown out from the nozzle section 22 does not flow freely in the space 26 on the back side of the substrate 25, and the temperature drop and fluctuation of the substrate 25 due to this gas flow is small. Being held down.

As described above, according to this apparatus, the entire substrate 25 is heated to a more uniform temperature. In this state, a reaction gas is ejected from the nozzle portion 22 to perform vapor phase growth. At this time, the reaction gas contacts not only the surface of the substrate 25 but also the heating plates 16 and 18 to form a vapor phase growth layer, but this causes almost no decrease in thermal efficiency, and the heating plates 16 and 18 are kept at high temperatures. Therefore, a strong layer is formed and no dust is generated from this layer. Furthermore, even when the temperature is lowered after the completion of vapor phase growth, this apparatus can gently lower the temperature of both the front and back sides of the substrate 25 under substantially the same conditions, so that the occurrence of slips during the temperature drop can be suppressed.

FIG. 2 shows another embodiment of the present invention, in which the first heating plate 16 is installed on the coil cover 13 via a quartz spacer 28, and the hollow rotating shaft 15a
A circular plate-shaped substrate support stand 29 made of quartz is attached to the upper end of the board. A through hole 30 is provided at the position where the substrate 25 is placed on the substrate support stand 29,
The upper part of this through hole 30 is made of carbon, Si or SiC.
The substrate 25 is placed thereon via a support ring 31 made of .

In this embodiment, the first and second heating plates 16, 18
and the substrate 25 are completely separated, and the substrate 25 is completely separated from the first and second heating plates 16 and 18.
Rotating and moving each board 25
This makes it possible to achieve even more uniform heating.

In this example, carbon, Si or
The support ring 31 made of SiC prevents the temperature of the outer peripheral portion of the substrate 25 from decreasing due to heat generated by the infrared light. From this point of view, the support ring 31 and the substrate support stand 29 are integrated and the whole is made of carbon.
It may be made of Si or SiC. Further, since quartz has good heat retention properties, the support ring 31 may be omitted and the substrate 25 may be placed directly on the substrate support stand 29. Furthermore, when the substrate support stand 29 is made of quartz, the through hole 30 may not be provided, and it may have only a recessed portion or may have a simple plate shape.

In the embodiment shown in FIG. 2, the substrate support 29 extends outward from near the nozzle portion 22 in a flat plate shape, and the surface of the substrate 25 substantially coincides with the surface of the substrate support 29. , the gas flow is undisturbed and the gas preheated by the substrate support 29 is applied to the substrate 2.
Since it flows along the surface of the substrate 25, it has the advantage that a more uniform vapor phase growth layer can be obtained and at the same time the substrate 25 can be heated more stably.

FIG. 3 shows still another embodiment of the present invention, in which a recess 32 is provided in the first heating plate 16a, and a substrate 25 is directly installed at the entrance of this recess 32. The outer circumference of the substrate 25 only slightly contacts the first heating plate 16a, and most of the back surface is sufficiently separated from the first heating plate 16a by the recess 32, and heating is performed as shown in FIG. In this embodiment, substantially the same effects as in the case where the support ring 24 is made of carbon can be obtained.

In this embodiment, a support ring (not shown) made of a thermally poor conductor such as quartz or ceramics is fitted into the entrance of the recess 32, or a plurality of support pins are provided upright within the recess 32. , the substrate 25 may be supported via the support ring or support pin.

FIG. 4 shows another embodiment of the substrate support part of the embodiment shown in FIG.
A quartz plate 33 covers the entire back surface of the substrate 25.
, and a substrate 25 is placed thereon. This can be similarly applied to the embodiment shown in FIG.

In this way, since the quartz plate 33 transmits infrared light, the substrate 25 can be heated in the same way as without it, and since the quartz plate 33 is a poor thermal conductor and has good heat retention, temperature fluctuations in the substrate 25 can be prevented. can be further suppressed.

FIG. 5 shows an example in which the present invention is applied to a horizontal vapor phase growth apparatus, where 40 is a tube made of quartz forming a reaction chamber 41, 42 is a first heating plate made of carbon, and 43 is also made of carbon. These heating plates 42 and 43 are heated to a red-hot or incandescent state by first and second heating lamps 44 and 45 respectively provided outside the tube 40. It's becoming like that. Both heating plates 42, 4
A substrate support stand 47 also made of quartz is provided with a slight inclination between the substrates 3 and 3 via a plurality of pillars 46 made of quartz. This board support stand 47 has basically the same structure as the board support stand 29 shown in FIG. 2 except that the overall shape is a rectangular plate shape, and 48 is a through hole, and 49 is a through hole. This is a support ring made of carbon, Si, or SiC provided in the hole 48 portion. Although this support ring 49 is formed as one continuous member that connects the plurality of through holes 48 to each other, it goes without saying that it may be divided into individual members. Note that 50 and 51 are reflective plates.

The first and second heating plates 42 in this embodiment,
Even if 43 is not provided, the substrate 25 can be heated by the lamps 44 and 45, but as described above, by using the carbon first and second heating plates 42 and 43, the heat from the lamps 44 and 45 can be heated. Even if the distribution of infrared light is uneven, the heating plates 42, 4
3 has good thermal conductivity, so it is heated substantially uniformly, and since the heating is performed via these heating plates 42 and 43, the distribution of the irradiation intensity of the radiation light on the substrate 25 can be made more uniform. Note that horizontal vapor phase growth apparatuses using RF coils have been said to have problems in uniform heating of the susceptor, but according to the present invention, even if the lamps 44 and 45 are replaced with RF coils, the substrate 25 can be heated evenly. Can be heated evenly.

In this embodiment, as shown in FIG. 5, the reactive gas is supplied only between the substrate support stand 47 and the second heating plate 43, and the reaction gas is A purge gas such as H ₂ is allowed to flow between the tube 40 and the first and second heating plates 42 and 43 even during vapor phase growth. Such a configuration can also be applied to the above-described FIGS. 1 to 3 by separately providing a purge nozzle section.

FIG. 6 shows still another embodiment of the present invention, in which a device similar to that shown in FIG.
The substrate support stand 47a is made horizontally elongated and erected by the support 52 so that the substrate support 47a is positioned approximately vertically, and the first and second heating plates 42, 43 and the first and second lamps 44, 4 are installed.
5. The reflecting plates 50 and 51 are also erected as shown in the figure. By locating the substrate 25 substantially vertically in this manner, foreign matter falling from above can be prevented from adhering to the surface of the substrate 25.

FIG. 7 shows a modification of FIG. 6, in which a support ring 49a is fitted to a substrate support stand 47b having a trapezoidal cross section, and a substrate 2 is attached to both ends of this support ring 49a.
5 are installed respectively. This is suitable when the substrate 25 has a property of partially transmitting infrared light, such as Si, and each of the substrates 25, 25 is heated from both the front and back sides, although at different rates. Also, the space 5 between the substrates 25, 25
3 is heated to a high temperature by the substrate itself and the support ring 49a, so uniform heating with almost no difference in temperature between the front and back surfaces can be achieved.

Next, in order to clarify the effects of the present invention, typical experimental examples will be shown.

For the experiment, an apparatus roughly compatible with the method shown in FIG. 5 was used. The heating plates 42 and 43 are made of SiC-coated graphite and are approximately square, measuring 180 mm x 180 mm, and 10 mm thick. Both heating plates 42 and 43 are connected in parallel by four pillars made of SiC-coated graphite. A quartz ring with a diameter of 135 mm is placed approximately on the center of the first heating plate 42, and the wafer is placed in a wafer storage groove formed at the upper end of this quartz ring. Wafer 25 was then placed. Six lamps (maximum output 6K.W.) were used as the first and second heating lamps 44 and 45, respectively.

Using the above-mentioned apparatus, a [100]N type 5-inch wafer 25 was placed on the quartz ring, and H ₂ gas as a carrier gas was supplied at 60/min and SiCl ₄ as a reaction gas was supplied at 5 g/min. 15 minutes at °C.
Vapor phase growth (epitaxial growth) was performed.

As a result, an epitaxial film with a thickness of 12 μm was obtained, and when it was irradiated with a spotlight and visually inspected for slips, there were no slips at all.

On the other hand, for comparison, it is approximately square of 180mm x 180mm.
25 wafers are placed on a 10mm thick SiC coated susceptor.
The epitaxial growth was carried out under the same conditions as above, using a device that heats the film directly from above with six lamps, and the film thickness was 11 μm, which is almost the same as above. However, slips with a total length of 60 to 80 mm were observed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to maintain a more uniform temperature distribution over the entire substrate, including both in the plane of the substrate and in the thickness direction on the front and back sides, during all heating processes including temperature raising and cooling processes. This makes it possible to more reliably suppress the occurrence of uneven thickness and slips in the vapor-phase grown layer, which are problems in vapor-phase growth.
This is especially effective for large-diameter substrates that are prone to slipping.

[Brief explanation of the drawing]

1 to 3 are schematic sectional views showing different embodiments of the present invention, FIG. 4 is a partially enlarged sectional view showing other specific examples of the substrate support, and FIGS. 5 and 6 are schematic sectional views showing different embodiments of the present invention. FIG. 5 is a schematic longitudinal cross-sectional view, FIG. 6 is a schematic cross-sectional view, and FIG. 7 is a cross-sectional view showing other specific examples of the substrate support section in FIG. 6. , FIG. 8 is a schematic sectional view of a conventional device. 14,41...Reaction chamber, 16,42...First heating plate, 18,43...Second heating plate, 19,2
0...RF coil (heating source), 24, 31, 49,
49a...Support ring, 25...Substrate, 29,2
9a, 47, 47a, 47b...Substrate support stand, 3
0, 48... Through hole, 32... Recess, 33... Quartz plate, 44, 45... Lamp (heat source).

Claims (1)

[Scope of Claims] 1. First and second heating plates made of carbon that are provided opposite to each other in a reaction chamber, and a heating source that supplies heating energy to the first and second heating plates, respectively; a substrate support section for positioning the substrate substantially parallel between the first and second heating plates; A vapor phase growth apparatus characterized in that the heating plates are arranged to face each other at intervals. 2. The vapor phase growth apparatus according to claim 1, wherein the heating source is an RF coil. 3. The vapor phase growth apparatus according to claim 1, wherein the heating source is an infrared lamp. 4. The vapor phase growth apparatus according to claim 1, 2 or 3, wherein the substrate support part is ring-shaped to support the outer peripheral part of the substrate. 5. The air conditioner according to claim 1, 2 or 3, wherein the substrate support part is formed in the shape of a plate having a plurality of through holes, and the substrate is installed in the through holes. Phase growth device. 6 The plate-like part is made of quartz, and the through-hole part is made of carbon, Si, or
6. The vapor phase growth apparatus according to claim 5, further comprising a ring made of SiC. 7. The vapor phase growth apparatus according to claim 1, 2 or 3, wherein the substrate support part is a plate made of quartz. 8. The air conditioner according to claim 7, characterized in that the substrate support part is composed of a quartz plate and a ring made of carbon, Si, or SiC that is installed on the plate and supports the outer periphery of the substrate. Phase growth device. 9. The air conditioner according to claim 1, 2 or 3, wherein a recess is formed in one of the first and second heating plates, and a substrate support part is formed at the entrance of the recess. Phase growth device. 10. The vapor phase growth apparatus according to any one of claims 1 to 9, wherein the substrate support section positions the substrate substantially vertically.