JPS61215291A - Vapor-phase growth apparatus - Google Patents

Abstract

PURPOSE:To enable the uniform heating of a substrate suppressing the influence of the flow of gas, by placing a substrate on a susceptor interposing a holder made of a refractory heat-insulating material therebetween and forming a space between the substrate and the susceptor to inhibit the free flow of the reaction gas. CONSTITUTION:The vapor-phase growth apparatus is placed in the reaction chamber 3. The substrate 8 is placed on the susceptor 3 heated with the heater 5 interposing a holder 10 made of a refractory heat-insulator such as quartz, ceramic, etc., between the substrate 8 and the susceptor 3. A nearly closed pace 13 is formed between the substrate 8 and the susceptor 4 to inhibit the free flow of the reaction gas.

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 more particularly to uniform heating of a substrate subjected to vapor phase growth.

[Prior art]

In general, a vapor phase growth apparatus heats the substrate by placing the substrate on a susceptor that generates heat using a heating source such as a resistance heater, an RF coil, or an infrared lamp. 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 slip when the substrate is a single crystal, it is necessary to heat the entire substrate more uniformly.The entire back surface of the substrate is in contact with the susceptor. If the substrate is placed in such a manner, the entire substrate is often not heated uniformly due to the condition of the surface of the susceptor, the presence of foreign matter, and the warping of the substrate due to heating. Therefore, conventionally, it has been proposed to form a recess in the substrate mounting part of the susceptor to support the outer periphery of the substrate and provide a space on the back side, and the shape of the recess also provides more uniform heating. Various proposals have been made for this purpose.

However, even if a recess is provided in the susceptor, if the substrate is placed directly on the susceptor, the contact area with the susceptor will be heated more strongly than other areas, and the slip may extend from this contact area or the vapor growth layer may It has the disadvantage of causing uneven thickness. In contrast, by protruding a quartz rod above the susceptor,
A system in which the substrate is placed on top of this has also been proposed, but experiments have shown that in this case, carrier gas and reaction gas also flow between the substrate and the susceptor, so the temperature of the entire substrate remains constant. It turned out that instead of becoming stable, slipping occurred.

[Purpose of the invention]

An object of the present invention is to heat the entire substrate more uniformly to more completely suppress the occurrence of slip and uneven thickness of the vapor-grown layer.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention includes a substrate placed on the susceptor via a support made of a heat-resistant poor conductor such as quartz or ceramics, and a reaction gas is introduced between the substrate and the susceptor. A nearly closed space is formed to suppress free flow, and by doing so, the influence of gas flow is suppressed and the substrate can be heated extremely uniformly and stably.

[Embodiment 1] Figures 1 to 3 showing an embodiment of the present invention will be explained below. Fig. 1 shows an outline of the case where the present invention is applied to a vertical vapor phase growth apparatus, in which 1 is a pace plate, 2 is a
is a bell jar, which forms a reaction chamber 3. 4 is a susceptor, 5 is an R'F coil, 6 is a nozzle for spouting a reaction gas, and 7 is an exhaust port. Since these configurations are similar to those conventionally known, detailed explanations will be omitted.

Reference numeral 10 denotes a ring-shaped support made of quartz (hereinafter referred to as ring), which is shown enlarged in FIGS. It has a stepped portion 11 that fits into it, and supports the outer peripheral portion of the substrate g. This stepped portion 11 is preferably formed so that the contact area with the substrate 8 is made as small as possible. The height of the ring 10, when placed on the susceptor 4, is the height of the lower surface (back surface) of the substrate 8 supported by the ring 10.
and the susceptor surface of the part facing this, that is, ring 1
A gap of 1 to 20 mm, preferably several mm, is formed between the susceptor surface and the susceptor surface.

A notch 12 is provided on the left side of the ring 10 in FIGS. 2 and 3, that is, on the downstream side with respect to the flow A of gas ejected from the nozzle 6 shown in FIG. A substrate suction member (not shown) is inserted into the lower surface of the substrate 8 from a portion thereof, and the substrate 8 can be loaded and unloaded by suctioning the lower surface.

Next, the operation of this device will be explained. The susceptor 4 is heated to a red-hot state by the RF coil 5. At this time, the substrate 8 is heated by conduction from the susceptor 4 via the beam/girder 10, but since the beam/girder 10 is quartz and has low thermal conductivity, the degree of heating due to conduction is small. In addition, the ring 10 and the substrate 8
By keeping the contact area small, the heating due to conduction can be kept small.

The red-hot susceptor 4 emits infrared light, that is, radiant light, in a relatively wide wavelength range with peak wavelengths around l and l□.

This radiant light uniformly irradiates the lower surface of the substrate 8 which is opposed to the substrate 8 at an interval, thereby heating the substrate 8. The substrate 8 is Si
In this case, 50 to 70 units of the radiant light are transmitted through the substrate 8, which seems to have poor heating efficiency.For this reason, the difference in temperature increase rate between the upper and lower surfaces of the substrate 8, that is, the front and back surfaces, is Smaller and more evenly heated throughout.

In the reaction chamber 3, H2 gas is flowed from the nozzle 6 during the temperature raising process to raise the substrate 8 to a predetermined vapor phase growth temperature, and during vapor phase growth, a reaction gas is flowed together with H2- gas as a carrier gas. Since the space 13 between the substrate 8 and the susceptor 4 is substantially closed by the ring 10, the gas does not freely flow into the space 13. Note that the cutout 12 is provided in the gas/gage 10, but since this is located on the downstream side with respect to the gas flow A, the flow of gas into the space 13 is slightly suppressed. Therefore, the back side of the substrate 8 is always kept in a stable temperature state.

Therefore, even when a gas such as a reaction gas flows, the temperature of the substrate 8 is stable, and the entire substrate 8 is heated more uniformly without being strongly heated locally, so that the substrate 8 does not slip. , a vapor-grown layer of uniform thickness can be obtained.

4 and 5 show another embodiment of the present invention, in which a recess 14 into which the substrate 8 is inserted in and out is provided in the substrate mounting portion of the susceptor 4a, and the substrate 8 is inserted into the recess 14. A plurality of bottles 15 serving as supports are provided so that the surface of the substrate 80 and the surface of the susceptor 4a are substantially aligned.

In this embodiment, the edge of the recess 14 and the substrate g
By setting a relatively small gap between the outer periphery of the substrate 8 and the susceptor 4a, a substantially closed space 1 is created between the substrate 8 and the susceptor 4a.
6. In addition, 17 is the substrate 6
This is a notch provided in the susceptor 4a for loading and unloading.

In this embodiment, since the surface of the susceptor 4a and the surface of the substrate 8 are almost the same, the gas flow is smooth, and the gas preheated by the susceptor 4a reaches the surface of the substrate 8 as it is. The temperature of the substrate S becomes more stable,
A vapor-grown layer with a more uniform thickness can be obtained, and
It is possible to completely prevent the occurrence of blemishes.

In the embodiment shown in FIGS. 4 and 5, a part of the outer periphery of the substrate 8 may come into direct contact with the susceptor 4a. In order to prevent uneven heating due to this partial contact, it is preferable to fit a quartz ring (not shown), which is a poor thermal conductor, onto the inner peripheral surface of the recess 14.

FIG. 6 shows a further embodiment of the invention, a ring I similar to ring 10 shown in FIGS. 2 and 3.
Oa is provided in a recess 14a provided in the susceptor 4b, and the surface of the substrate g and the surface of the susceptor 4b are made to coincide with each other by approximately #1.

FIG. 7 shows still another embodiment of the present invention, in which, like the embodiment shown in FIG. A cover 18 made of quartz or carbon is attached to the susceptor 4.
The surface of the susceptor 4 is covered with the cover 18, and at the same time, the surface of the cover +g is substantially aligned with the surface of the substrate 8 to smooth the gas flow.

FIG. 8 shows still another embodiment of the present invention, in which the substrate 8 is supported by protruding from the surface of the susceptor 4 by the same pins 15 as shown in FIG. A cover 18a similar to the cover 18 in the figure is provided, and this cover 18a
The substrate 8 is fitted with a relatively small gap, and the cover 18a, the substrate 8, and the susceptor 4 form a substantially closed space 19. Note that the cover l g shown in FIGS. 7 and 8,
Since l ga is thin and cools quickly, the substrate 8 after vapor phase growth
The effect of quickly and safely taking out the material can be obtained.

FIG. 9 shows still another embodiment of the present invention, in which a quartz plate 20 of approximately the same size as the substrate 8 is provided on the back side of the substrate 8.
A space 2I is formed under the quartz plate 20 by supporting the substrate 8 by means of a quartz plate 20 via the quartz plate 20.

Even in this case, since the quartz plate 20 transmits most of the radiant light as described above, sufficient heating can be achieved, and not only the outer circumference but also the entire back surface of the substrate 8 is supported via the quartz plate 20. , it becomes possible to further equalize the heat and stabilize the temperature.

The above-mentioned embodiment is based on the ring IQ l loa, job
Although we have shown an example in which 1biy15 is made of quartz, these supports are made of F3i3N4, S +3 N4, and AI! 203
It is also possible to use ceramics that are highly heat resistant and have poor thermal conductivity, such as ceramics, or those whose surfaces are coated with Si3N4 or SiC to prevent contamination. Furthermore, the present invention is applicable not only to vertical type but also to various types of vapor phase growth apparatuses such as horizontal type and barrel type, and can also be used as a heating means for a susceptor.
It can be applied not only to coils but also to various other devices such as resistance heaters and infrared heating.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to stably heat the substrate without locally heating the substrate, and it is possible to more completely suppress the occurrence of slip and the occurrence of thickness unevenness of the vapor-grown layer. In particular, the yield in vapor phase growth of large-diameter substrates can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing one embodiment of the present invention, FIG. 2 is a partially enlarged plan view taken along the Z arrow in FIG. 1, and FIG. 3 is a sectional view taken along the line FIG. 4 is a partially enlarged plan view showing another embodiment of the present invention, FIG. 5 is a sectional view taken along the line ■-v in FIG. 4, and FIGS. 6 to 9 are respectively different embodiments of the present invention. It is a partially enlarged sectional view showing. 3...Reaction chamber, 414a14b...Susceptor, 5...RF' coil, 6...
Nozzle, 8...Substrate, 10, loa,
IOb...Ring (support), 12, 17.
...Notch, +3. +6.19.21...
・Nearly closed space, +4. I4a... recess,
15... Pin (support body), 20... Quartz plate.

Claims (1)

[Claims] 1. In a vapor phase growth apparatus in which a substrate is placed on a susceptor which is located in a reaction chamber and heated by a heat source, and the substrate is heated, the substrate is made of heat-resistant material such as quartz or ceramics. The susceptor is placed on the susceptor via a support made of a thermally poor conductor, and a substantially closed space is formed between the substrate and the susceptor so as to suppress the free flow of the reaction gas. Phase growth device. 2. The vapor phase growth apparatus according to claim 1, wherein the support body is ring-shaped to support the outer peripheral edge of the substrate. 3. The vapor phase growth apparatus according to claim 2, wherein a part of the ring-shaped support is notched. 4. The vapor phase growth apparatus according to claim 1, characterized in that a recess is formed in the substrate mounting portion of the susceptor so that the surface of the substrate is positioned substantially in line with the surface of the susceptor. 5. The vapor phase growth apparatus according to claim 4, wherein the recess of the susceptor is formed to be slightly larger than the substrate, and the recess and the substrate form a substantially closed space. 6. The vapor phase growth apparatus according to claim 5, wherein the support body is a plurality of pins. 7. The susceptor is provided with a cover having a surface substantially aligned with the surface of the substrate placed on the susceptor and a hole formed slightly larger than the substrate. The vapor phase growth apparatus according to item 1. 8. The vapor phase growth apparatus according to claim 7, wherein a substantially closed space is formed by the substrate, the susceptor, and its cover. 9. The vapor phase growth apparatus according to claim 8, wherein the support body is a plurality of pins. 10. Claim 1, characterized in that the substrate is installed on a support via a quartz plate of approximately the same size as the substrate.
Vapor phase growth apparatus described in Section 1.