JP4870580B2 - Vapor growth equipment - Google Patents

Description

The present invention relates to a vapor deposition equipment for depositing a thin film on a substrate, particularly, it relates to a vapor deposition equipment having a reaction chamber in which the opposing surfaces of the substrate which is heated to a high temperature are formed of quartz glass.

The vapor phase growth apparatus heats a substrate held on a susceptor in a reaction chamber to a predetermined temperature, introduces a source gas from a gas introduction pipe into the reaction chamber, and vapor-deposits a thin film on the surface of the substrate. As a kind of vapor phase growth apparatus, a susceptor is rotatably arranged in a reaction chamber formed in a flat cylindrical shape, and a substrate holder for holding a substrate is arranged on the outer periphery of the susceptor so as to be able to rotate and revolve. A self-revolving vapor phase growth apparatus is known in which a source gas is introduced from a gas introduction pipe penetrating through the susceptor toward the outer periphery. (For example, refer to Patent Document 1).
JP 2006-108312 A

  In a reaction chamber of a general vapor phase growth apparatus, a surface facing a high-temperature substrate is formed of quartz glass having excellent heat resistance and low reactivity with a source gas. Since this quartz glass has almost no infrared absorption, the decomposition product of the raw material adheres to the surface in contact with the raw material gas after repeated vapor phase growth several times from the new state or the state after cleaning, and the reaction chamber Until the substrate facing surface becomes dirty to some extent, heat (infrared rays) escapes to the outside of the reaction chamber, so that the thermal environment is not stable and the reproducibility of the thin film is not sufficient.

  For this reason, when using a reaction chamber that is new or cleaned, the surface in contact with the source gas in the reaction chamber is intentionally soiled by introducing the source gas into the reaction chamber, and is in a thermally stable state. And that is done. For this reason, not only productivity is lowered, but also material costs are greatly affected.

  On the other hand, when the surface in contact with the source gas in the reaction chamber, particularly the substrate facing surface, is contaminated with decomposition products and the like, the thermal environment in the reaction chamber becomes stable as described above, but is caused by the deposits. Particles are mixed in the thin film and cause the performance of the thin film to deteriorate.

The present invention, the thermal environment in the reaction chamber irrespective of the state of soiling of the quartz glass forming the reaction chamber can be stabilized, vapor deposition equipment capable of improving the reproducibility and quality of the obtained thin film The purpose is to provide.

In order to achieve the above object, the basic structure of the vapor phase growth apparatus of the present invention is that the substrate held by the susceptor in the reaction chamber is heated and the source gas is introduced into the reaction chamber from the gas introduction pipe. In the vapor phase growth apparatus that performs vapor phase growth on the surface of the substrate, at least the substrate-facing surface of the reaction chamber is formed of quartz glass, and the outer surface of the substrate-facing surface formed of the quartz glass absorbs infrared rays larger than the quartz glass. An infrared absorbing plate having a capability is provided , and a heat reflecting plate is disposed further outside the infrared absorbing plate .

Furthermore, the applied configuration in the vapor phase growth apparatus of the revolving type vapor phase growth apparatus of the present invention, the in basic configuration, a disc-shaped said susceptor which holds and rotates the plurality of substrates on an outer peripheral portion a flat cylindrical chamber accommodating a, thereby forming the reaction chamber to the susceptor side of the compartment drawing board by providing the quartz glass partition plate, through the center of the chamber and the partition plate susceptor Bei example a gas inlet pipe for introducing a raw material gas toward the outer peripheral portion from the central portion, characterized in that a said infrared absorbing plate to the reaction chamber the outer surface side of the front Symbol partition plate, in particular, the partition plate peripheral It is characterized by being divided into a plurality of directions.

In the both structures, the infrared-absorbing plate, carbon, boron nitride, mixtures of silicon nitride and boron nitride, yttrium oxide, silicon, Ru can be formed of any germanium.

  According to the vapor phase growth apparatus of the present invention, by providing an infrared absorbing plate on the substrate-facing surface in the reaction chamber made of quartz glass, the surface of the substrate-facing surface with respect to infrared rays is a surface in contact with the source gas by repeating vapor phase growth. It is possible to make the raw material decomposition products, etc., adhere to a certain extent, and the raw material decomposition products, etc., adhere to some extent from the first vapor phase growth operation using a new or cleaned reaction chamber. It is possible to stabilize the thermal environment in the reaction chamber. Therefore, a thin film with good reproducibility can be obtained even if the thin film is vapor-phase grown using a new or washed reaction chamber. In particular, the thermal environment in the reaction chamber is maintained regardless of adhesion of decomposition products by starting vapor phase growth with an infrared absorbing plate after replacing the reaction chamber with a new one or a clean state after cleaning. Can be made constant, and a reproducible and high-quality thin film can be obtained.

  1 and 2 show an embodiment in which the present invention is applied to a self-revolution type vapor phase growth apparatus. FIG. 1 is a sectional front view, and FIG. 2 is a sectional view taken along line II-II in FIG. In this vapor phase growth apparatus, a susceptor 13 made of disc-shaped carbon and a concentric circle on the outer peripheral portion of the susceptor 13 are equidistantly disposed in a flat cylindrical chamber 12 having a gas introduction pipe 11 disposed in the upper center. A plurality of substrate holders 14 arranged, and a partition plate 16 made of quartz glass that is disposed above the susceptor 13 to partition the chamber 12 up and down and form a reaction chamber 15 on the susceptor 13 side. Yes.

  The chamber 12 is formed of stainless steel or the like having excellent corrosion resistance. The chamber body 17 is opened at the upper side on the anti-susceptor side, and the chamber body 17 is airtightly attached to the upper portion of the peripheral wall of the chamber body 17 via an O-ring 18. And a chamber lid 19 to be formed. A rotation drive shaft 20 for rotating the susceptor 13 is provided at the center of the bottom of the chamber body 17. By rotating the susceptor 13 with the rotation drive shaft 20, the substrate holder 14 holding the substrate 21 is moved to the susceptor. While revolving with respect to the center of 13, it is rotated by a rotating gear mechanism 22 provided on the outer periphery of the susceptor 13.

  Also, below the substrate holder 14, a heater 24 housed in the reflector 23 is disposed in a ring shape as a heating means for heating the substrate 21, and a ring-shaped exhaust passage 25 is disposed on the outer peripheral side of the susceptor 13. Is provided. An insertion port 19a for inserting the gas introduction pipe 11 is provided at the center of the chamber lid 19, and a cylindrical guide tube 26 is provided in an airtight manner at the opening edge of the insertion port 19a. . In addition, two heat reflecting plates 27 formed in a disk shape having a through hole in the center are provided below the chamber lid 19.

  The partition plate 16 is a small-diameter ring-shaped inner periphery made up of a large-diameter ring-shaped outer peripheral-side partition plate 16a disposed on the outer peripheral side and a plurality of divided bodies disposed on the inner peripheral side and divided in the circumferential direction. The side partition plate 16 b and the central partition plate 16 c provided at the lower end of the gas introduction pipe 11 are formed. The outer peripheral side partition plate 16 a is placed on the inner periphery of the peripheral wall of the chamber body 17. The state is fixed at a predetermined position. Further, a knob portion 16d is projected from the upper surface of the inner peripheral partition plate 16b, and the inner peripheral partition plate 16b is placed on the inner peripheral edge of the outer peripheral partition plate 16a. The peripheral edge is placed on the outer peripheral edge of the central partition plate 16c and is detachable.

  The chamber lid 19 is attached to the elevating means 28 via a plurality of brackets 28 a provided on the outer peripheral portion, and is provided on the guide cylinder 26 projecting from the central portion of the chamber lid 19 and the upper portion of the gas introduction pipe 11. A bellows 29, which is a cylindrical expansion and contraction member, is airtightly attached between the upper flange 11a and the chamber lid 19 is raised while operating the elevating means 28 in the ascending direction to contract the bellows 29. It is formed so that 17 openings can be opened.

  The gas introduction pipe 11 is composed of a multiple pipe 31 in which a plurality of pipes having different diameters are concentrically arranged to define a plurality of gas flow paths, and the upper outer periphery of the multiple pipe 31 is formed by the upper flange 11a. It is kept airtight. Further, the lower end portion of the tube disposed on the outermost periphery of the multiple tube 31 is expanded and integrated with the central partition plate 16c, and the lower end portion of the tube disposed on the inner peripheral side is the susceptor 13. The nozzle part 11b which introduces source gas in parallel with the susceptor upper surface from the center part of the susceptor 13 toward the outer peripheral part is formed. Further, a gas supply for supplying each source gas from a plurality of source gas supply sources (not shown) to each gas flow path in the multiplex pipe 31 is provided at the base portion (upper end portion in this embodiment) of the gas introduction pipe 11. Tubes 31a and 31a are connected to each other.

  In the self-revolving vapor deposition apparatus formed in this way, in this embodiment, on the outer surface of the portion through which the substrate 21 passes while rotating on the upper surface of the inner peripheral partition plate 16b, An infrared absorbing plate 32 is provided so as to cover the surface. The infrared absorbing plate 32 is formed of a thin plate made of a material having an infrared absorbing capacity larger than that of the quartz glass of the inner peripheral side partition plate 16b that forms the reaction chamber 15, and like the inner peripheral side partition plate 16b, It is provided in a ring shape by combining the fan-shaped divided bodies 32a divided into about 4 to 6 pieces so as to avoid the central gas introduction pipe 11 and be detachable.

  Any material can be used for the infrared absorbing plate 32 as long as it has a larger infrared absorbing ability than quartz glass. In consideration of various conditions such as substrate heating temperature, distance from the substrate surface, and material workability. Usually, it is preferably formed of carbon, boron nitride, a mixture of silicon nitride and boron nitride, yttrium oxide, silicon, or germanium. Moreover, the thickness of the infrared ray absorbing plate 32 is arbitrary, and it may be formed with a thickness that does not break during attachment / detachment or cleaning, for example, a thickness of several mm.

  Thus, by providing the infrared absorbing plate 32 on the outer surface of the portion facing the substrate 21 on the outer surface of the inner peripheral side partition plate 16b made of quartz glass, it is preferably adhered to the outer surface of the inner peripheral side partition plate 16b. When the infrared absorbing plate 32 is provided in the state, the amount of infrared rays radiated from the reaction chamber 15 to the outside can be controlled, and the inner peripheral side partition plate 16b in a clean state after being new or cleaned is used for the first time. And the thermal environment in the reaction chamber 15 when the decomposition product of the raw material adheres to the inner surface of the inner peripheral side partition plate 16b in contact with the raw material gas when performing the vapor phase growth operation. Can do. Therefore, the properties of the thin film deposited on the substrate 12 can be made uniform even when the inner peripheral side partition plate 16b which is new or clean after cleaning is used or after the vapor phase growth operation is repeated a plurality of times. .

  Further, in the case of a vapor phase growth apparatus having an observation window 33 for observing the state of the substrate 21 from the outside of the reaction chamber 15, in order to secure an optical path necessary for observation from the observation window 33, It is necessary to provide the infrared absorbing plate 32 with a slit similar to the provided slit 27a.

  The type of the vapor phase growth apparatus is arbitrary. As shown in this embodiment, the vapor deposition apparatus is not limited to the one in which only the ceiling surface of the reaction chamber is formed of quartz glass, but the one in which the entire reaction chamber is formed of quartz glass. Further, it can be applied to a horizontal type vapor phase growth apparatus. Moreover, it is not necessary to divide | segment, if there is no trouble in the attachment or detachment of the infrared rays absorption board from a board | substrate opposing surface, and a heat | fever reflection board can also be abbreviate | omitted depending on board | substrate temperature. Further, in the self-revolution type vapor phase growth apparatus shown in the present embodiment, it is only necessary to place the infrared absorbing plate 32 on the outer surface (upper surface) of the inner peripheral side partition plate 16b. In the case of the apparatus, it is necessary to hold the infrared ray absorbing plate on the lower surface of the substrate facing surface of the reaction chamber using any holding means. Moreover, the vapor phase growth conditions are not particularly limited.

  Each of the following examples was performed using a susceptor having 10 substrates mounted in the vapor phase growth apparatus having the configuration shown in the embodiment. First, a doughnut-shaped integrated infrared absorbing plate made of graphite carbon and having a thickness of 3 mm is placed on a partition plate (inner peripheral side partition plate) on the side facing the substrate. A thin film having a well structure was grown eight times continuously, and the change with time of the wavelength was examined. All sample preparation was performed under atmospheric pressure, and the sample structure was 6 × [InGaN (thickness 2.2 nm) / GaN (thickness 10 nm)] / Si-doped GaN (thickness 4 μm) / low-temperature grown GaN (thickness) 25 nm) / C-plane sapphire substrate.

  High purity ammonia was used as the nitrogen source gas, and a mixed gas of hydrogen and nitrogen was used as the carrier gas. Trimethylindium was used as the In material, trimethylgallium as the Ga material, and nitrogen-based 10 ppm silane as the Si material. The partition plate used was a clean one washed only once, and the growth experiment was repeated without washing the second and subsequent times. As a comparative experiment, a similar experiment was performed without using an infrared absorbing plate. FIG. 3 shows the relationship between the number of times of growth and the emission wavelength obtained by the photoluminescence measuring device, and the wavelength was an average of 10 of the 2-inch substrate center wavelengths. It can be seen from FIG. 3 that the change in wavelength during growth is very small by placing the infrared absorbing plate on the partition plate. From this result, it can be seen that providing an infrared absorbing plate on the partition plate is very effective in suppressing wavelength shift during growth.

  Further, as the infrared absorbing plate, a divided infrared absorbing plate obtained by dividing the above-described donut-shaped integrated infrared absorbing plate into four parts was used, and the integrated type and the divided type were compared. FIG. 4 shows the relationship between the number of times of growth when the thin film is grown six times and the emission wavelength obtained by the photoluminescence measuring device. From the result of FIG. 4, it can be seen that there is almost no difference in the emission wavelength from the quantum well between the case of using the integrated infrared absorbing plate and the case of using the four-part infrared absorbing plate. From this, it can be seen that the infrared absorbing plate provided on the partition plate is effective in suppressing the wavelength shift in both the integral type and the divided type.

  Two types of infrared absorbing plates, each made of graphite carbon and boron nitride and divided into 3 mm thick donut-shaped plates, are used. High purity ammonia is used as nitrogen source gas, trimethyl gallium is used as Ga source, and carrier gas is used as carrier gas. Using a mixed gas of hydrogen and nitrogen, the time-dependent change of the growth rate was investigated when the structure of GaN / low-temperature grown GaN (thickness 25 nm) / C-plane sapphire GaN film was vapor-phase grown for 1 hour. For comparison, a GaN film was grown under the same conditions when no infrared absorbing plate was provided. In addition, the same vapor phase growth apparatus as Example 1 was used, the partition board used what was wash | cleaned only once, and the growth experiment was repeated without wash | cleaning after the 2nd time.

  FIG. 5 shows the relationship between the number of growths and the film thickness, and the film thickness was an average of 10 sheets with a 2-inch substrate center film thickness. From FIG. 5, it was found that there was almost no change in the growth rate with time when a graphite carbon quadrant infrared absorber was used and when a boron nitride quadrant infrared absorber was used. On the other hand, it was found that when there was no infrared absorbing plate, the growth rate changed greatly with the number of growths. From this, it can be seen that a stable film thickness can be obtained by providing an infrared absorbing plate on the partition plate.

  A GaN film was grown under the same conditions as in Example 2 using an infrared absorbing plate made of graphite carbon and having a donut-shaped plate having a thickness of 3 mm divided into four. First, similarly to each of the above examples, the partition plate washed only for the first growth was used, and the growth experiment was repeated without cleaning the partition plate for the second and subsequent times. FIG. 6 shows the relationship between the number of times of growth and the half width of the (002) XRD rocking curve (average of 10 sheets at the center of the 2-inch substrate) including the result when no infrared absorbing plate is provided. From FIG. 6, when the infrared absorbing plate is provided, the half-value width is always about 300 seconds, and when the infrared absorbing plate is not provided, the half-value width decreases from 470 seconds to 320 seconds with the number of growth. I understand that. Since the crystallinity is better as the XRD rocking curve half width is smaller, it can be seen that GaN having good crystallinity can always be obtained by using an infrared absorbing plate regardless of the degree of contamination of the partition plate.

  In addition, when each vapor phase growth operation was replaced with a partition plate cleaned and cleaned, and a GaN film was grown under the same conditions with an infrared absorption plate, it was obtained in each vapor phase growth operation. The half width of the GaN film was constant for about 300 seconds. Therefore, by replacing the partition plate with a clean partition plate before starting the vapor phase growth operation, an infrared absorption plate is provided on the reaction chamber outer surface side of the partition plate to start the vapor phase growth. It can be seen that the influence of particles due to decomposition products adhering to the inner surface of the plate can be minimized and a higher quality thin film can be obtained.

1 is a cross-sectional front view of a vapor phase growth apparatus showing a first embodiment of the present invention. It is II-II sectional drawing of FIG. The experimental result of Example 1 is shown and it is a figure showing the relationship between the presence or absence of an infrared rays absorption board, the frequency | count of growth, and a photo-luminescence light emission wavelength. FIG. 9 shows experimental results of Example 1, and is a diagram illustrating a relationship between the number of growth times, the photoluminescence emission wave, and the length when an integral type and a split type are used as an infrared absorbing plate. It shows the experimental result of Example 2, and is a figure showing the relationship between the presence or absence of an infrared ray absorbing plate, the number of times of growth, and the growth rate. FIG. 10 shows experimental results of Example 3, and is a diagram showing the relationship between the presence / absence of an infrared absorbing plate, the number of times of growth, and the half width of the XRD rocking curve of (002).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Gas introduction pipe, 11a ... Upper flange, 11b ... Nozzle part, 12 ... Chamber, 13 ... Susceptor, 14 ... Substrate holder, 15 ... Reaction chamber, 16 ... Partition plate, 16a ... Outer peripheral side partition plate, 16b ... Inner circumference Side partition plate, 16c ... center partition plate, 16d ... knob part, 17 ... chamber body, 18 ... O-ring, 19 ... chamber lid, 19a ... insertion port, 20 ... rotational drive shaft, 21 ... substrate, 22 ... rotating gear mechanism , 23 ... reflector, 24 ... heater, 25 ... exhaust passage, 26 ... guide tube, 27 ... heat reflecting plate, 27a ... slit, 28 ... lifting means, 28a ... bracket, 29 ... bellows, 31 ... multiple tube, 31a ... gas Supply pipe, 32 ... Infrared absorbing plate, 32a ... Fan-shaped divided body, 33 ... Observation window

Claims (4)

In the vapor phase growth apparatus that heats the substrate held on the susceptor in the reaction chamber and introduces a source gas from a gas introduction pipe into the reaction chamber to perform vapor phase growth on the surface of the substrate,
Forming at least the substrate-facing surface of the reaction chamber with quartz glass;
On the outer surface of the substrate facing surface formed of the quartz glass, an infrared absorbing plate having an infrared absorbing ability larger than that of the quartz glass is provided ,
A vapor phase growth apparatus characterized in that a heat reflecting plate is disposed further outside the infrared absorbing plate . A flat cylindrical chamber which accommodates a disc-shaped said susceptor for holding and rotating a plurality of substrates on the outer peripheral portion, the reaction chamber to the susceptor side of the compartment drawing board by providing the quartz glass partition plate and forming said chamber and e Bei a gas inlet pipe for introducing a raw material gas toward the outer peripheral portion from the susceptor center through the center of the partition plate, the infrared to the reaction chamber the outer surface side of the front Symbol partition plate The vapor phase growth apparatus according to claim 1 , further comprising an absorption plate. 3. The vapor phase growth apparatus according to claim 2, wherein the partition plate is divided into a plurality of parts in the circumferential direction. 4. The infrared absorbing plate is formed of any one of carbon, boron nitride, a mixture of silicon nitride and boron nitride, yttrium oxide, silicon, and germanium. The vapor phase growth apparatus described.

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