JP5833429B2 - Semiconductor manufacturing equipment - Google Patents

Description

  The present invention relates to an apparatus for manufacturing a semiconductor by growing crystals on the surface of a substrate placed in a reaction chamber, and more particularly to an apparatus structure suitable for a flow channel type MOCVD (Metal Organic Chemical Vapor Deposition).

  Semiconductor manufacturing apparatuses having various structures are used depending on the type of substrate, the substrate installation structure, the reaction gas supply method, and the like. In recent years, MOCVD apparatuses capable of controlling the film thickness on the atomic layer order are frequently used.

  As an example of a typical MOCVD apparatus, the structure of a flow channel type MOCVD apparatus is shown in FIG. In this MOCVD apparatus, a flow channel 2 for forming a gas flow layer of a material gas is provided in a reaction chamber 1, and a substrate 5 is installed facing the flow channel 2 while being fixed to a susceptor 4. . Material gas supply pipes 6 and 7 are connected to the flow channel 2 at one end side, and a material gas is introduced into the flow channel 2, and surplus material gas and gas by-produced by the reaction are discharged to the other end side. For this purpose, an exhaust pipe 3 is connected. A heater 10 is disposed on the side of the susceptor 4 opposite to the substrate mounting surface, and the susceptor 4 is heated from the back side to control the substrate temperature. When the crystal grown on the substrate is gallium nitride (GaN), the crystal growth temperature is higher by 200 ° C. to 300 ° C. than AlGaAs or AlGaInP, and is higher than 1000 ° C. Control of the substrate temperature is extremely important for crystal growth with a uniform composition and film thickness. For this reason, the space (heater chamber) in which the heater 10 is disposed is partitioned by the partition wall 12, and the heat shield plate 110 is disposed around the heater 10 to block the substrate mounting surface of the susceptor from the radiant heat of the heater.

  Further, in the conventional MOCVD apparatus, the heater partitioned by the partition 12 is used to protect the heater terminal and the susceptor rotating mechanism in the heater chamber and prevent the material gas used for crystal growth from entering the heater chamber. An inert gas (purge gas) such as nitrogen is allowed to flow into the room. The purge gas is heated at the same time as cooling the internal structural components, and reaches a high temperature close to the susceptor temperature when exhausted from the heater chamber.

  As described above, MOCVD in which crystal growth is performed at a high temperature and temperature control is extremely important has the following problems. One is that the region between the heater chamber partition wall 12 and the end of the susceptor 4 is heated on the gas upstream side of the flow channel 2 by the radiant heat from the susceptor 4 and the heater 10 and the purge gas heated to a high temperature. The problem is that the material gas is thermally decomposed and deposited in the region. As a result, the problem that the use efficiency of material gas falls and the frequency | count of cleaning of a flow channel increase arise.

  Further, in the horizontal type MOCVD in which gas is supplied in the horizontal direction as shown in FIG. 8, a gas stagnation layer is formed immediately above the substrate, and the material gas supplied to the horizontal gas flow layer is the stagnation layer. In order to obtain a high quality epitaxial crystal growth film, it is very important that a gas flow that diffuses into the substrate and reaches the substrate is formed. However, as described above, when deposits are formed on the upstream side of the flow channel, the deposits increase in thickness and detach, disturb the gas flow, and inhibit the crystal growth process through the thermochemical decomposition reaction. There is a fear.

  Various solutions have been proposed for the problems of these MOCVD apparatuses. For example, Patent Documents 1 and 2 propose a structure in which a cooling container is installed in the lower part on the upstream side of the flow channel and the refrigerant is circulated in the cooling container.

Japanese Unexamined Patent Publication No. 2000-1000072 Japanese Patent Laid-Open No. 2001-23902

  The conventional technology described above is to install a cooling container upstream of the flow channel to prevent deposits from being generated on the flow channel. As shown in FIG. 1, when the position of the cooling container is close to the susceptor, the side surface of the susceptor is also cooled, so that the susceptor outer peripheral temperature is lowered and the temperature uniformity of the susceptor substrate mounting surface is affected. Arise. Further, the upstream portion of the flow channel where the cooling vessel is not installed is still heated to a high temperature by the purge gas, and there remains a problem that deposits are likely to occur. Further, as described in Patent Document 1, when the susceptor is covered with a reflector and a cooling container is disposed outside the susceptor, there is no problem that the side surface of the susceptor is cooled, but the flow around the susceptor and the cooling container is installed. A region where deposits are likely to occur is left in the region between the channel portions. That is, these conventional techniques are not sufficient means for solving the above-mentioned problems of the MOCVD apparatus. In addition, when installing a supply path for supplying a cooling container or a refrigerant in a reaction container exposed to a high temperature, it is necessary to use an expensive and difficult-to-process heat resistant material for the material of these containers and pipes . Therefore, advanced manufacturing technology and high manufacturing cost are required.

  Accordingly, an object of the present invention is to provide a semiconductor manufacturing apparatus that can suppress problems of high temperature on the gas upstream side of the flow channel, in particular, unnecessary gas consumption and generation of deposits associated therewith, with a simple configuration. .

  In order to solve the above problems, the semiconductor manufacturing apparatus of the present invention is provided with means for controlling the gas flow of the purge gas flowing into the heater chamber, and the temperature of the region upstream of the gas in the flow channel is higher than necessary by controlling the gas flow. To prevent becoming.

That is, the semiconductor manufacturing apparatus of the present invention includes a reaction vessel, a susceptor installed in the reaction vessel and mounting a substrate, a flow channel for supplying a material gas along the surface of the substrate mounted on the susceptor, A heater installed on the opposite side of the substrate mounting surface of the susceptor, a heat shield plate disposed so as to surround the heater, and a purge gas supply means for supplying a purge gas to the reaction vessel, the heat shield plate, A plurality of side surface heat shield plates disposed at a distance from each other, wherein the plurality of side surface heat shield plates have an extension surface of the plate surface (that is, a direction parallel to the plate surface) intersecting a bottom surface of the flow channel; The end is disposed with a gap between the bottom surface of the flow channel, and when the side heat shield is closer to the heater inside and the side far from the heater is outer, the outer side of the side heat shield is Through A purge gas flow path is formed between the plurality of side surface heat shield plates and the gap between the side surface heat shield plates and the heater via a gap between the end of the side surface heat shield plate and the bottom surface of the flow channel. Gas flow control means is provided.

The ends of the multiple side heat shield plate of the semiconductor manufacturing apparatus of the present invention, the distance from the flow channel bottom, from the outside to the inside, is arranged to be smaller.

  The semiconductor manufacturing apparatus of the present invention controls the flow path of the purge gas supplied into the reaction vessel and creates a flow of the purge gas toward the susceptor along the bottom surface of the flow channel between the susceptor and the gas upstream side. The upstream side of the flow channel can be efficiently cooled without adding expensive parts, and it is possible to solve various problems such as accumulation of deposits in the region and inhibition of crystal growth caused by the deposits. it can. Further, since the purge gas flow is formed from the outside of the susceptor toward the susceptor, it is supplied to the bottom surface of the flow channel before being heated by the heater or the susceptor, so that it can be efficiently cooled. Further, since the temperature of the purge gas rises while flowing along the bottom surface of the flow channel and hits the side surface of the susceptor, there is no possibility of excessively cooling the side surface of the susceptor.

  Further, the semiconductor manufacturing apparatus of the present invention has a configuration in which the distance between the end portion of the heat shield plate constituted by a plurality of side surface heat shield plates and the flow channel is gradually narrowed from the outside toward the inside, so that from the outside. Inflow of the introduced purge gas can be facilitated, and can be reliably guided between all the side heat shield plates, and the function of the heat shield plate can be enhanced. Thereby, the secondary radiation from a heat shield can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the outline | summary of the semiconductor manufacturing apparatus of 1st embodiment of this invention, (a) is A-A 'sectional drawing of an apparatus, (b) is a sectional side view. The figure which shows the detailed structure of the thermal-insulation board 11 and purge gas flow path of the semiconductor manufacturing apparatus of FIG. It is a figure which shows the crystal growth film thickness of a flow channel floor board and a substrate surface, (a) is the case of 1st embodiment, (b) is the case of 2nd embodiment, (c) is the case of the conventional apparatus shown in FIG. (D) is a figure explaining the positions P1 and P2 in (a)-(c). Side sectional view which shows the outline | summary of the semiconductor manufacturing apparatus of 2nd embodiment of this invention. The figure which shows the detailed structure of the heat-shielding board and purge gas flow path of the semiconductor manufacturing apparatus of FIG. Sectional drawing which shows an example of the crystal film which a crystal grows with the semiconductor manufacturing apparatus of this invention The figure explaining the film thickness measurement point of the crystal film in the example Diagram showing an example of conventional semiconductor manufacturing equipment

  Embodiments of a semiconductor manufacturing apparatus according to the present invention will be described below with reference to the drawings.

<First embodiment>
FIG. 1 shows an outline of the semiconductor manufacturing apparatus of this embodiment. Fig.1 (a) is AA 'sectional drawing of the side sectional view shown in (b), (b) is side sectional drawing. This semiconductor manufacturing apparatus is a flow channel type MOCVD apparatus, which is a reaction vessel 1 hermetically sealed to the outside, a gas supply pipe 6 installed in the reaction vessel 1 and for supplying a material gas to one end side 2a, 7, a flow channel 2 having an opening open to the other end 2b, an exhaust pipe 3 installed on the other end 2b of the flow channel 2, a susceptor 4 supporting the substrate 5, and a susceptor 4, a heater 10 installed on the opposite side of the substrate mounting surface, a heat shield plate 11 installed so as to surround the heater 10, and a heater chamber that separates the heater 10 and the heat shield plate 11 from other spaces in the reaction vessel 1. A partition wall 12 and a rotation mechanism 13 for rotating the susceptor 4 are provided.

  The reaction vessel 1 has an opening (not shown) for taking in and out the substrate on the surface facing the end face to which the gas supply pipes 6 and 7 are connected, and the reaction is completed by sealing the opening with a lid during the reaction. After that, the lid can be opened and the substrate can be taken in and out. Further, purge gas supply pipes 8 and 9 for supplying an inert gas such as nitrogen are connected to the space outside the flow channel 2 in the reaction vessel 1. In this embodiment, two systems of purge gas supply pipes are provided: a supply pipe 8 for supplying purge gas to the outside of a space (heater chamber) surrounded by a heater chamber partition wall, and a supply pipe 9 for supplying the heater chamber. The supply pipe 9 has a plurality of gas outlets and supplies purge gas from a plurality of locations in the heater chamber. The purge gas supplied from the purge gas supply pipe 8 flows in the reaction vessel excluding the flow channel 2 and the heater chamber, thereby cooling the reaction vessel. The purge gas supplied from the supply pipe 9 is controlled in flow by a heat shield plate 11 described later to cool the space between the heat shield plate 11 and the partition wall 12 and the upstream side of the flow channel 2.

  The purge gas may be any gas that does not corrode members in the reaction vessel such as the susceptor 4, the heater 10, and the heat shield plate 11. Specifically, nitrogen gas, hydrogen gas, argon gas, or the like can be used. In order to efficiently cool the flow channel floor plate described later, it is preferable to use a mixed gas of hydrogen that is extremely light and excellent in diffusibility and nitrogen that has viscosity and easily maintains a gas flow. Specifically, a mixed gas of hydrogen: nitrogen = 0: 1 to 3: 1 is preferable. Particularly, when crystal growth is performed at a high temperature of 1000 ° C. or higher, for example, when GaN-based crystal growth is performed, hydrogen: nitrogen = 1: 3. A gas mixture of ˜3: 1 is preferred. Note that a mixed gas of argon gas and hydrogen may be used instead of nitrogen.

  The flow channel 2 is composed of a main body 21 and a bottom plate 22, and a circular opening for attaching the susceptor 4 is formed in the bottom plate 22. The bottom plate 22 can be removed from the main body 21 together with the upper portion of the susceptor 4 and taken out from the opening of the reaction vessel 1 when the substrate 5 is taken in and out. Further, a partition plate 23 for separating the gas flow path is provided on the gas upstream side 2a of the flow channel 2, that is, the side where the gas supply pipes 6 and 7 are connected. It is divided. For example, a material gas such as an organic metal is supplied from the upper gas supply pipe 6, and a carrier gas such as hydrogen or nitrogen is supplied from the upper gas supply pipe 7, whereby the material gas flows in the horizontal direction. Layers are carried to the stagnation layer on the substrate and diffuse into the stagnation layer.

  The exhaust pipe 3 includes an opening 31 having an opening larger than the size (vertical and horizontal sizes) of the exhaust-side end 2 b opened in the flow channel 2, the opening, and the exhaust port 19 of the reaction vessel 1. And the opening of the opening 31 is disposed so as to face the end 2 b on the exhaust side of the flow channel 2. The exhaust pipe 3 is connected to a lifting mechanism (not shown). When the substrate 5 is taken in and out, the exhaust pipe 3 descends from the position shown in FIG. 1 and the substrate 5 and the flow channel are opened from the opening of the reaction vessel 1. Two bottom plates 22 can be taken out or inserted. During the reaction, the exhaust pipe 3 is raised to a position where the opening 31 faces the illustrated flow channel end 2b.

  The susceptor 4 is made of a material having good thermal conductivity, for example, a material of a carbon material such as graphite coated with a SiC film. In the illustrated embodiment, the upper susceptor 41 and the lower susceptor both have a disk shape. It consists of 42 two members. A recess for mounting the substrate 5 is formed on the upper surface of the upper susceptor 41, and the lower susceptor 42 is connected to the rotation mechanism 13. The diameter of the susceptor 4 (upper susceptor 41 and lower susceptor 42) is narrower than the width of the flow channel main body 21, as shown in FIG. 1 (a), so that the substrate 5 mounted on the upper susceptor 41 can be securely attached. It is comprised so that reaction may advance, covered with a gas layer. When the rotation mechanism 13 rotates, the lower susceptor 42 and the upper susceptor 41 rotate as a unit, and the substrate 5 fixed to the upper susceptor 41 can be rotated.

  The heater 10 is a cylindrical heater having an upper surface area that is substantially the same as the bottom surface of the susceptor 42. The heater 10 controls the susceptor 4 so that the substrate 5 reaches a predetermined temperature by the heat from the heated susceptor 4. Has been. The substrate temperature controlled by the heater 10 varies depending on the type of substrate and the type of crystal grown on the substrate. For example, when a gallium nitride crystal is grown on a sapphire substrate, the temperature is 1000 ° C. or higher.

  Heat from the heater 10 is transmitted to the susceptor 4 mainly by heat radiation and heat conduction by the purge gas flowing in the heater chamber. In order to efficiently transfer the heat from the heater 10 to the susceptor 4 and to block transmission to other members, the side surface (surrounding) and the back surface (surface opposite to the surface facing the susceptor) of the heater 10 are blocked. A heat plate 11 (side heat shield plate 111, bottom heat shield plate 112) is installed.

  The heat shield plate 11 insulates the radiant heat of the side surface and the bottom surface of the heater 10 and the susceptor 4, has a function of preventing a temperature drop at the outer periphery of the susceptor and a flow channel heating prevention function. Are arranged in a state where a plurality of sheets are stacked. By adopting a structure in which a plurality of heat shield plates are stacked with a small gap therebetween, the effects of shielding radiant heat and air insulation are multiplexed, so that excellent heat insulation can be obtained.

  Further, a gap for the purge gas to flow is provided between the upper end portion of the side heat shield plate 111 and the lower surface of the flow channel floor plate 22. The size of the gap is preferably about 0.2 mm to 2.0 mm. If it is narrower than 0.2 mm, the purge gas becomes poor and the cooling effect is reduced. If the width is larger than 2.0 mm, the heat radiation of the heater 10 reaches the upstream portion of the flow channel floor plate 22 (upstream side of the material gas), and the cooling effect is also lowered.

  The thickness of each plate material constituting the heat shield plate 11 is not particularly limited, but is about 0.2 mm to 0.6 mm, and the thickness may be different between the heat shield plate close to the heater and the far heat shield plate, Further, the side heat shield plate 111 and the bottom heat shield plate 112 may have different thicknesses. The distance between the heater 10 and the side heat shield is about 0.6 mm, the distance between the heater 10 and the bottom heat shield is about 1.0 mm, and the distance between the side heat shields is about 0.8 mm. The interval between them is about 1.5 mm.

Specifically, the material of the heat shield plate 11 is a high temperature heat-resistant metal such as molybdenum (Mo), inconel, or hastelon, or a high temperature such as alumina, boron nitride (BN), or pyrolytic boron nitride (PBN). A heat-resistant ceramic is mentioned. Among them, PBN has excellent properties such as high temperature heat resistance and thermal shock resistance, suppression of thermal decomposition under NH ₃ atmosphere, and stable reflectance for a long period of time. can get.

The materials constituting the plurality of heat shield plates may be the same or different. For example, the materials can be selected so that the thermal conductivity decreases from the inside toward the outside as viewed from the heater 10. By properly using the materials in this way, the heat from the heater 10 can be effectively blocked.
As the heat shield plate located on the outermost side of the side heat shield plates 111, Mo, BN, PBN, Hastelon, Inconel, etc. can be used as in the other heat shield plates, but somewhat such as Invar, SUS, etc. It is also possible to use a material having low heat resistance.

  The heat shield plate 11 also has a function of controlling the flow path of the inert gas introduced from the purge gas supply pipes 8 and 9. The control function of the gas flow path by the heat shield plate 11 will be described in detail later.

  In this embodiment, the heater chamber partition wall 12 is a water-cooled jacket type partition wall, and is disposed in close contact with the floor plate 22 of the flow channel 2 so as to cover the lower susceptor 42, the heater 10, and the heat shield plate 11. However, a notch portion is formed on the side close to the exhaust pipe 13 in order to discharge the purge gas from the space between the floor plate 22. In addition, although the water-cooled bucket type partition is provided with a water inlet and a water outlet for circulating water, it is omitted in the figure. The heater chamber partition 12 is made of a material having good characteristics such as heat resistance, workability, and weldability. Examples of such materials include SUS304, SUS316, SUS316L, Inconel, Hastelloy, and the like.

  Next, details of the heat shield plate 11 in the present embodiment and control of the gas flow path by the details will be described. FIG. 2 shows a detailed structure of the heat shield plate 11. The structure shown in FIG. 2 is arranged on the upstream side portion of the flow channel 2 of the apparatus shown in FIG. 1, the upper part of the partition wall, the upper part of the side heat shield plate 111, the susceptor 4, the heater 10, and below. It is the fragmentary sectional view which shows a part of the right side of the back surface heat shield plate 112. In the figure, thin arrows indicate the flow of purge gas.

  As described above, the side heat shield plate 111 and the bottom heat shield plate 112 are each composed of a plurality of sheets. Among the side heat shield plates 111, the heat shield plate 111 a disposed outside has an end on the bottom side of the reaction vessel 1 that extends below the other side heat shield plates and bends toward the center of the vessel. And has a function as a heat shield and a function of guiding purge gas to the back surface of the flow channel floor. In order to realize this function, the purge gas supply pipe 9 is disposed such that a part of the plurality of gas outlets is located between the partition wall 12 and the outer heat shield plate 111a. With the arrangement of the outlet and the end of the side heat shield plate 111a extending to near the bottom of the container and being bent, the purge gas supplied from the outlet of the purge gas supply pipe 9 is supplied to the heat shield plate 111a and the partition wall. 12 is induced.

  Further, the end portion of the side heat shield plate 111 close to the flow channel 2 is arranged so that the end portions of the plurality of heat shield plates are positioned with steps. Specifically, the end portion of the heat shield plate closest to the heater 10 is the highest (closest to the flow channel), and the position of the end portion decreases from the heater 10 toward the outside. With this structure, when the purge gas that is guided between the heat shield plate 111a and the partition wall 12 and reaches the upper end of the heat shield plate 111a flows horizontally along the back surface of the flow channel floor plate 22 as described above. In addition, it hits the end of the heat shield plate following the outermost heat shield plate 111a and is sequentially sent between adjacent heat shield plates. In this way, the purge gas flows horizontally between the heat shield plates at the upper end of the side heat shield plate 111, and the upstream side of the flow channel floor plate 22 is cooled in order from the gas supply side, By flowing between the heat shield plates, the radiant heat from the heater 10 is prevented from moving toward the flow channel floor plate 22 in cooperation with the heat shield plate 111.

  Due to the heat shielding effect by the heat shielding plate 111 and the cooling effect on the back surface of the flow channel by the purge gas flowing through the upstream end of the heat shielding plate 111, the upstream side of the flow channel extends from the portion in contact with the partition wall 12 to the contact point with the susceptor. Both the heating by the radiant heat and the heating by the heat conduction of the purge gas can be cut off, and the deposition of the material gas and the inhibition of the crystal growth by the deposit due to the temperature rise can be prevented. In addition, since the temperature of the purge gas gradually increases as it approaches the susceptor 4 from the side close to the partition wall 12, there is no problem that the ambient temperature of the susceptor 4 is excessively cooled by the purge gas.

  In the embodiment shown in FIG. 1, the side heat shield plate 111 a is provided on all side surfaces of the heater 10, that is, on the upstream side and downstream side of the material gas. However, the deposition of the material gas becomes a problem. Is the upstream side of the material gas of the flow channel 2 and there is no need to actively cool the downstream side of the material gas, so the side heat shield plate 111a located on the outermost side passes through the center of the susceptor 4 and the material gas flow. It may be provided only on the upstream side of the gas flow with the orthogonal plane as the boundary. However, when it is provided on the entire circumference as shown in the figure, the gas ventilation in the heater portion is improved, so that the effect of suppressing the heater deterioration can be obtained.

  Graphs conceptually showing the crystal growth film thickness of the MOCVD apparatus are shown in FIGS. In the graph shown in FIG. 3, the horizontal axis represents the position of the apparatus in the horizontal direction, P <b> 1 represents the position of the inner end of the water-cooled jacket type partition wall 12, and P <b> 2 represents the position of the outer end of the susceptor 4. FIG. 3D shows the positions P1 and P2. The vertical axis of the graph indicates the growth film thickness, the alternate long and short dash line indicates the film thickness when the susceptor does not rotate, and the solid line indicates the state where the film thickness is averaged by rotation. FIG. 3A shows the case of the MOCVD apparatus of the present embodiment, FIG. 3C shows the case of the MOCVD apparatus having the structure shown in FIG. 8, and the dotted line in the graph of FIG. ) (Solid line) is shown as a comparative example.

  As shown in FIG. 3 (c), in the conventional apparatus, the back surface on the upstream side of the flow channel floor plate is susceptible to radiant heat from the susceptor or heater, and the temperature between the outer end of the heat shield plate and the partition wall 12 is high. On the other hand, in the apparatus of this embodiment, since the purge gas having a low temperature can flow between the outer end of the heat shield plate and the partition wall 12, the upstream side of the flow channel floor plate can be flown. The back surface is efficiently cooled, and the consumption of the material gas and the deposition of the reaction product of the material gas can be suppressed on the floor plate upstream of the flow channel. As a result, the amount of material gas diffusing into the stagnation layer on the substrate 5 increases, and as shown in FIG. 3A, the growth film thickness can be made thicker than that of the conventional device.

  As described above, according to the present embodiment, the heat shield plate installed in parallel with the inner side of the partition wall 12 is composed of a plurality of plate members, and the heat shield plate and the partition wall 12 arranged on the outermost side. By forming a gas flow path through which the purge gas flows, a rise in temperature from the upstream side of the flow channel floor plate 22, that is, from the partition wall to the outer periphery of the susceptor can be suppressed, and deposition of reaction products on the floor plate can be suppressed. it can.

  In addition, the present embodiment actively cools the upstream side of the flow channel floor plate by controlling the gas flow, and can be realized only by changing the structure and arrangement of the heat shield plate used conventionally. It is possible to provide a device that eliminates the need for an additional cooling container or the like for cooling the battery, and that is highly effective with a simple structure.

<Second embodiment>
FIG. 4 shows an outline of the semiconductor manufacturing apparatus of this embodiment. FIG. 4 is a side sectional view of the MOCVD apparatus as in the first embodiment. In FIG. 4, elements common to FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, differences from the first embodiment will be mainly described.

  Also in this embodiment, the gas flow path that flows through the heater chamber independently of the flow path of the purge gas that flows from the purge gas supply pipe 8 into the reaction vessel 1 is formed, and the side heat shield that surrounds the side surface of the heater 10 It is the same as in the first embodiment that the plate 111 is composed of a plurality of heat shield plates and the end portions close to the flow channel 2 have a step. However, in this embodiment, a heat shield plate corresponding to the purge gas guide heat shield plate 111a in the first embodiment is not provided, and the positions of the lower end portions of the plurality of side surface heat shield plates 111 are: They are on the same level. In this embodiment, the purge gas guide cylinder 14 is provided outside the heater chamber partition wall 12, and a purge gas flow path is provided from the outside of the heater chamber partition wall 12 through the gap between the partition wall 12 and the flow channel 2. Is a feature.

  That is, this MOCVD apparatus is provided with a purge gas guide tube 14 surrounding the partition wall 12 outside the water cooling jacket type heater chamber partition wall 12, and the reaction vessel 1 is provided between the heater chamber partition wall 12 and the purge gas guide tube 14. A third purge gas supply pipe 15 for supplying the purge gas is connected.

  The purge gas guide cylinder 14 is a cylindrical member having a size surrounding the water-cooled jacket type partition wall 12 and can be formed of a thick plate such as PBN or BN. The gap between the partition wall 12 and the guide tube 14 is not limited, but is about 1 to 3 mm. The purge gas guide tube 14 has a lower end fixed to the bottom of the reaction vessel 1 and a flow channel 2 fixed to the upper end. Therefore, the space surrounded by the purge gas guide cylinder 14 is a closed space. The purge gas supply pipe 15 is connected to the reaction vessel 1 between the connection portion between the purge gas guide tube 14 and the reaction vessel 1 and the connection portion between the heater chamber partition wall 12 and the reaction vessel 1.

  Further, in order to form a flow path for the purge gas supplied from the purge gas supply pipe 15, the heater chamber partition 12 is disposed with a gap between the flow channel floor plate 22. The space | interval of a clearance gap should just be a grade which can ensure a gas flow path, and is specifically about 0.2 mm-2.0 mm.

  The heat shield plate 11 includes a plurality of side surface heat shield plates 111 and a plurality of bottom surface heat shields 112 as in the first embodiment. The plurality of side surface heat shields 111 are formed with a gap serving as a gas flow path between the upper end and the flow channel 2, and the size of the gap is from the inside to the outside when the side close to the heater 10 is the inside. It is the same as that of 1st embodiment that it arrange | positions so that it may become large. However, in this embodiment, the dimensions of the plurality of side surface heat shield plates 111 are all the same, and the position of the lower end thereof is substantially the same level as the bottom surface heat shield plate located at the lowermost side.

  On the other hand, a lower partition 16 is provided in a lower part of a space (heater chamber) in which the heater 10 and the heat shield plate 11 are arranged, and separates the heater chamber and the lower space. The lower partition wall 16 can be formed of a thick plate such as BN or PBN in the same manner as the purge gas guide tube 14. A heater chamber exhaust pipe 17 is connected to the lower partition wall 16, and the purge gas flowing through the heater chamber is exhausted from the exhaust pipe 17. An exhaust pipe 18 is provided on the bottom surface of the reaction vessel 1 separately from the flow channel exhaust pipe 3 for exhausting surplus material gas and by-product gas. The heater chamber exhaust pipe 17 is connected to the exhaust pipe 18. Has been.

  The flow of purge gas in the above configuration will be described with reference to FIG. In FIG. 5, thin arrows indicate the flow of purge gas. The purge gas supplied from the purge gas supply pipe 15 connected to the bottom of the reaction vessel 1 hits the bottom of the flow channel 2 through the flow path between the heater chamber partition wall 12 and the purge gas guide tube 14 as shown in the figure. The gas flows in the horizontal direction through the gap between the partition wall 12 and the flow channel and flows into the heater chamber. The gas flow in the horizontal direction sequentially hits the heat shield plates arranged so as to have a step, and flows into gaps between adjacent heat shield plates. Further, the horizontal gas flow that has passed through the heat shield plate closest to the heater 10 flows between the heat shield plate and the heater, passes through the back surface heat shield plate 112 disposed on the lower side of the heater 10, and the exhaust pipe. 17 is discharged.

  On the other hand, the purge gas supplied from the purge gas supply pipe 9 cools the space below the heater chamber and is discharged from the exhaust pipe 18 as shown by thin arrows in FIG.

  In the MOCVD apparatus of this embodiment, the purge gas supplied from the purge gas supply pipe 15 can form a gas flow that flows along the bottom surface of the flow channel before it is heated in the heater chamber, so that the flow channel effectively Temperature rise can be suppressed. This suppresses thermal decomposition of the material gas on the upstream side of the material gas in the flow channel close to the susceptor, thereby realizing an increase in the material gas used for crystal growth, that is, an increase in the growth film thickness. Further, it is possible to prevent thermal decomposition products and the like from accumulating on the flow channel. Furthermore, in the MOCVD apparatus of this embodiment, the position of the upper end portion of the heat shield plate is shifted in the vertical direction (a step is provided), so that the horizontal gas flow that flows along the bottom surface of the flow channel can be reliably ensured. It can branch into the gap between a plurality of heat shield plates, and the heat shield effect by the heat shield plates can be improved.

  Furthermore, in this embodiment, the purge gas supply path to the heater chamber is divided into a gas flow path for generating a horizontal gas flow on the bottom surface of the flow channel and a gas flow path for cooling the lower portion of the heater chamber. The lower part can be effectively cooled, and the heat shielding effect with the outside can be enhanced.

  The growth film thickness of the MOCVD apparatus of this embodiment is shown in FIG. In this graph, the vertical and horizontal axes and the graph indicated by the solid line and the alternate long and short dash line are the same as those in FIG. 3A described in the first embodiment. As can be seen from the comparison with the growth film thickness of the conventional apparatus shown in FIG. 3C, in the apparatus of this embodiment, the purge gas at a low temperature along the bottom surface of the flow channel extending from the purge gas guide tube to the outer periphery of the susceptor. Therefore, the back surface of the flow channel floor board is efficiently cooled. As a result, consumption due to thermal decomposition of the material gas on the gas upstream side of the flow channel and deposition on the floor plate due to reaction products of the material gas can be suppressed.

  Further, since the purge gas that is hardly heated can be supplied into the heater chamber from the upper end of the heater chamber partition wall 12, the heat between the susceptor and the partition wall 12 can be compared with that in the first embodiment (FIG. 3A). An inclination can be made high and wasteful consumption of material gas can be suppressed more effectively. As a result, the grown film thickness can be further increased.

  The preferred embodiment of the present invention has been described above. However, the present invention is limited to the above embodiment as long as it includes means for generating a horizontal cooling gas flow between the partition wall on the bottom surface of the flow channel and the outer periphery of the susceptor. Various modifications are possible without this. For example, in the second embodiment, the configuration including the lower partition 16 that divides the heater chamber and the lower portion thereof has been described. However, instead of the lower partition, the flow of the purge gas that flows downward from the side heat shield plate 111 is not hindered. A flow path control plate for controlling the flow path of the purge gas blown from the purge gas supply pipe 9 may be arranged.

  Moreover, it is an example for implementing this invention to the material and numerical value which were quoted in the above embodiment, and this invention is not limited to these numerical values.

  Further, in the above embodiment, the MOCVD apparatus has a structure in which the substrate is mounted on the upper surface of the susceptor and the flow channel is arranged on the upper side. However, the flow channel is arranged on the lower side of the substrate mounting surface of the susceptor. The present invention can be similarly applied to the above-described apparatus (or an apparatus having a structure in which the substrate mounting surface of the susceptor is vertically disposed).

<Example 1>
Crystal growth of a GaN film composed of a low-temperature GaN layer and a high-temperature GaN layer as shown in FIG. 6 was performed using the MOCVD apparatus having the structure shown in FIG. 1 (first embodiment).

  This MOCVD apparatus is an apparatus for a 2-inch substrate. The radius of the susceptor and the heater is 60 mm, and the distance from the center of the susceptor to the water-cooled jacket type partition is 72 mm. Between the heater and the partition, five heat shield plates were disposed as side heat shield plates, and six heat shield plates were disposed on the back surface of the heater. The innermost heat shield plate (first heat shield plate) among the side heat shield plates is a PBN plate having a thickness of 0.3 mm, and the second to fourth heat shield plates are Mo plates having a thickness of 0.2 mm. . In the arrangement, the first heat shield plate was placed 1.0 mm away from the heater, and the heat shield plate interval was set to 0.8 mm. A purge gas induction heat shield plate made of an Invar plate having a thickness of 0.8 mm was arranged outside the fourth heat shield plate by 0.8 mm apart. The distance between the purge gas induction heat shield and the water-cooled jacket type partition was set to 1.5 mm.

  In addition, the distance between the upper end of the first heat shield and the back surface of the flow channel floor plate is 0.3 mm, the distance from the second heat plate to the fourth heat shield plate, the distance from the upper end to the back surface of the flow channel floor plate, in order They were 0.6 mm, 1.2 mm, and 2.0 mm. The distance between the upper end of the outermost purge gas induction heat shield and the back surface of the flow channel floor was 1.5 mm. The clearance between the purge gas induction heat shield and the water-cooled jacket type partition was set to 1.5 mm.

  If the bottom heat shield is the first to sixth heat shields in the order from the heater, the first and second heat shields use 0.3 mm thick PBN plates, and the third to sixth heat shields are thick. A 0.5 mm Mo plate was used. The first heat shield plate was separated from the heater by 1.0 mm, and the second heat shield plate to the sixth heat shield plate were arranged at 1.5 mm intervals.

As the substrate, a single crystal substrate (diameter: 2 inches) of c-plane sapphire (α-alumina) off 0.5 ° in the m-axis direction is used, TMG (trimethylgallium) as an organic metal material, and NH ₃ as a hydride material. Was used. The organometallic material gas and the hydride material gas were mixed and supplied from the material gas supply pipe 6. Hydrogen gas was flowed from the same gas supply pipe 6 as a carrier gas for the material gas, and the flow rate was adjusted to 8 L / min together with the material gas. Further, a gas in which hydrogen: nitrogen was mixed at a ratio of 1: 1 was supplied from the material gas supply pipe 7 so that the flow rate was 26 L / min. Further, as a purge gas, a mixed gas of hydrogen gas: nitrogen gas = 1: 1 was flowed from the purge gas supply pipes 8 and 9 at a flow rate of 8 L / min.

  First, a gas in which hydrogen gas and nitrogen gas are mixed at a ratio of 1: 1 is supplied from the material gas supply pipe 7 at a flow rate of 26 L / min, the susceptor temperature is 1000 ° C., the pressure in the reaction chamber is 100 kPa, and the sapphire substrate is 10 Annealed for a minute.

Next, the susceptor temperature was lowered to 550 ° C., the pressure was kept at the same 100 kPa, TMG was supplied from the material gas supply pipe 6 at 30 μmol / min, NH ₃ was supplied at 4 L / min, and a low-temperature GaN layer was formed to 10 nm on the sapphire substrate. Next, the susceptor temperature was raised to 1050 ° C., the pressure was kept at the same 100 kPa, and the low-temperature GaN layer was annealed for 7 minutes.

Thereafter, the susceptor temperature is set to 1030 ° C., the pressure is kept at the same 100 kPa, TMG is supplied from the material gas supply pipe 22 at 45 μmol / min, NH ₃ is supplied at 4 L / min, and a high temperature GaN layer is grown on the low temperature GaN layer for 1 hour. did.

<Example 2>
Using the MOCVD apparatus having the structure shown in FIG. 4 (second embodiment), a GaN film composed of a low-temperature GaN layer and a high-temperature GaN layer is grown on a sapphire substrate under the same conditions as in Example 1 except for the purge gas supply conditions. It was

  This MOCVD apparatus is an apparatus for a 2-inch substrate. The radius of the susceptor and the heater is 60 mm, and the distance from the center of the susceptor to the water-cooled jacket type partition is 70 mm. Between the heater and the partition, four heat shield plates were disposed as side heat shield plates, and six heat shield plates were disposed on the heater rear surface. The innermost heat shield plate (first heat shield plate) among the side heat shield plates is a PBN plate having a thickness of 0.3 mm, and the second to fourth heat shield plates are Mo plates having a thickness of 0.2 mm. . The arrangement was such that the first heat shield plate was separated from the heater by 0.6 mm, and the intervals from the first heat shield plate to the fourth heat shield plate were all 1.0 mm intervals. The distance between the fourth heat shield and the water-cooled jacket type partition was 0.5 mm.

  In addition, the distance between the upper end of the first heat shield and the back surface of the flow channel floor plate is 0.3 mm, the distance from the second heat shield plate to the fourth heat shield plate, and the distance from the upper end to the back surface of the flow channel floor plate in order. 0.5 mm, 1.0 mm, and 1.5 mm. The distance between the water-cooled jacket type partition wall and the back surface of the flow channel floor plate was 1.0 mm.

  If the bottom heat shield is the first to sixth heat shields in the order from the heater, the first and second heat shields use 0.3 mm thick PBN plates, and the third to sixth heat shields are thick. A 0.5 mm Mo plate was used. The first heat shield plate was separated from the heater by 1.0 mm, and the second heat shield plate to the sixth heat shield plate were arranged at 1.5 mm intervals.

  As in the first embodiment, the purge gas is a mixed gas of hydrogen gas: nitrogen gas = 1: 1. The purge gas supply pipe 8 has a flow rate of 8 L / min, the purge gas supply pipe 9 has a flow rate of 2 L / min, and the purge gas supply pipe 15 has a flow rate. Flowed at 6 L / min.

<Comparative example>
As a comparative example, a GaN layer was grown on a sapphire substrate under the same conditions as in Example 1 except for the purge gas supply conditions using the MOCVD apparatus shown in FIG. The apparatus shown in FIG. 8 has a structure in which a flat plate-shaped susceptor (thickness: 5 mm) having the same substrate mounting surface and recess diameter as in Examples 1 and 2 is employed, and a heater is disposed on the back side of the susceptor. The heat generation area of the heater is the same as the heat generation area of the heaters of Examples 1 and 2. The water-cooled jacket type partition wall was used in close contact with the flow channel in the same manner as in Example 1, and an exhaust notch formed on the downstream side of the material gas. The heat shield plate was composed of a side heat shield plate made of BN having a thickness of 3 mm on the heater side surface, and two bottom heat shield plates made of BN having a thickness of 3 mm on the heater back surface. The purge gas was supplied from purge gas supply pipes provided inside the heater chamber and outside the heater chamber, respectively.

<Evaluation>
<< Film thickness >>
Since the material gas is likely to decompose on the flow channel floor plate under the growth conditions of the high-temperature GaN film having a susceptor temperature exceeding 1000 ° C., the film thickness of the high-temperature GaN film generated in Examples 1 and 2 and the comparative example is The effect of the present invention was confirmed by measurement. As shown in FIG. 7, the film thickness is measured using a reflection interferometer using a white light source that utilizes the difference between the refractive index of the sapphire substrate (1.7) and the refractive index of the GaN crystal (2.4). And 5 points from the center of the substrate at 5 points including the center. Table 1 shows the average value and the film thickness increase rate based on the film thickness of the comparative example.

<< Maintenance frequency interval >>
The film formation according to the above-described Examples 1 and 2 and the comparative example is repeatedly executed, and the state of the deposit accumulated on the flow channel floor plate portion on the upstream side of the susceptor is observed each time, and the deposit is peeled off and swollen. The number of repetitions until was counted. The results are shown in Table 1.

  As is clear from the results shown in Table 1, both Examples 1 and 2 showed an effect of increasing the film thickness with respect to the comparative example. The effect of increasing the film thickness can be considered as an improvement in material usage efficiency. If the material usage rate of the comparative example is 100%, the material usage rate is 15% in the example and 36% in the example 2. Can be said to have improved. That is, according to the present invention, the amount of material gas used can be reduced by an amount corresponding to the improvement in material gas use efficiency, so that the manufacturing cost can be reduced. At the same time, the manufacturing time is shortened, so that productivity can be improved.

  In addition, in the comparative example, the observation result of the visual observation of the deposit is that the flow channel floor plate from the outer periphery of the susceptor to the inner peripheral edge of the water-cooled jacket type heater chamber partition becomes a yellow stain due to the deposit in one crystal growth, After several times of growth, the color became dark brown, and about 12 times the deposits began to peel off. On the other hand, in Example 1, the stain (coloring) of the same flow channel floor plate portion was thinner than that of the comparative example, showed a light brown color after several growths, and the deposits did not peel up to about 19 times. In Example 2, the adhesion of dirt was further reduced from that in Example 1, and peeling did not occur until about 23 times. From these results, according to the present invention, the replacement frequency of the flow channel floor board can be reduced, and the production efficiency of the LED can be improved by shortening the cleaning time.

<< Evaluation of crystallinity >>
The defect density of the GaN layer was evaluated by X-ray diffraction (XRD) measurement of the GaN layers grown in Examples 1 and 2 and the comparative example. It is known that GaN crystal growth on a sapphire substrate forms a domain because it is a heterogeneous crystal growth. The defect density is tilted with respect to the substrate crystal axis (tilting) and rotation of the crystal axis (twist). Sting). The tilting can be evaluated by the half width of the (002) ω rocking curve of the XRD, and the twisting can be evaluated by the half width of the (102) ω rocking curve. The smaller these values, the smaller the defect density. Table 2 shows the half width of the (002) ω rocking curve and the half width of the (102) ω rocking curve obtained by XRD measurement after the fifth crystal growth.

表２に示す結果からも明らかなように、比較例の（００２）ω、（１０２）ωに比べ、実施例１及び実施例２では、半値幅が減少していること、すなわち欠陥密度が減少していることが確認された。これは、基板上流において、材料ガス流の基板表面に至る流れを阻害する原因となる堆積物の生成が、比較例に比べ実施例１、２では抑制された結果、安定した「淀み層」が形成されたためと考えられる。

As is apparent from the results shown in Table 2, in Example 1 and Example 2, the half-value width is reduced, that is, the defect density is reduced, in comparison with (002) ω and (102) ω in the comparative example. It was confirmed that This is because, in the upstream of the substrate, the generation of deposits that hinder the flow of the material gas flow to the substrate surface was suppressed in Examples 1 and 2 compared to the comparative example, and as a result, a stable “stagnation layer” was formed. It is thought that it was formed.

  By applying the present invention to a manufacturing apparatus for manufacturing a light-emitting diode, a laser diode, or the like, particularly an MOCVD apparatus, productivity can be improved and a high-quality semiconductor product can be provided.

Claims (6)

A reaction vessel, a susceptor installed in the reaction vessel and for mounting a substrate, a flow channel for supplying a material gas along the surface of the substrate mounted on the susceptor, and a susceptor on the opposite side of the substrate mounting surface In a semiconductor manufacturing apparatus, comprising: a heater, a heat shield plate disposed so as to surround the heater, and a purge gas supply means for supplying a purge gas to the reaction vessel,
The heat shield plate includes a plurality of side surface heat shield plates arranged at intervals from each other, and the plurality of side surface heat shield plates have an extension surface of the plate surface intersecting a bottom surface of the flow channel and an end portion thereof. Arranged with a gap between the bottom of the flow channel,
When the side heat shield plate is closer to the inner side and the side farther from the heater is the outer side, the end portions of the plurality of side heat shield plates have distances from the bottom surface of the flow channel toward the inner side from the outer side. Are disposed so as to be small , pass through the outside of the side surface heat shield plate, pass through the gap between the end of the side surface heat shield plate and the bottom surface of the flow channel, and between the plurality of side surface heat shield plates and A semiconductor manufacturing apparatus comprising gas flow control means for forming a purge gas flow path passing through a gap between the inside of the side heat shield plate and the heater. The semiconductor manufacturing apparatus according to claim 1,
A heater chamber partition wall is provided so as to surround a space (heater chamber) in which the heater and the heat shield plate are disposed, and the purge gas supply means supplies a purge gas to a space other than the heater chamber. A semiconductor manufacturing apparatus comprising: a pipe; and a second purge gas supply pipe for supplying a purge gas to the heater chamber. The semiconductor manufacturing apparatus according to claim 2,
The gas flow control means includes a side heat shield disposed on the outermost side among the plurality of side heat shields, and the outermost side heat shield is a length in a direction intersecting a bottom surface of the flow channel. Is longer than the other side heat shield plates, and a gas blow-out port from the second purge gas supply pipe is disposed between the outermost side heat shield plate and the heater chamber partition. Semiconductor manufacturing equipment. The semiconductor manufacturing apparatus according to claim 2,
The heater chamber partition is arranged with a gap between the bottom surface of the flow channel,
The gas flow control means includes a purge gas guide cylinder disposed so as to surround the heater chamber partition wall, and a gas outlet from the second purge gas supply pipe is provided between the purge gas guide cylinder and the heater chamber partition wall. A semiconductor manufacturing apparatus which is arranged. The semiconductor manufacturing apparatus according to claim 4,
A second partition that partitions the heater chamber partitioned by the heater chamber partition into a space in which the heater and the heat shield plate are disposed and a space other than that (second space);
The second partition wall has a gap between the end of the side heat shield plate and the bottom surface of the flow channel, and a gap between the plurality of side heat shield plates and the inside of the side heat shield plate and the heater. A semiconductor manufacturing apparatus comprising exhaust means for exhausting the purge gas flowing through the purge gas flow path passing through the reaction container. The semiconductor manufacturing apparatus according to claim 5,
2. The semiconductor manufacturing apparatus according to claim 1, wherein the purge gas supply means includes a third purge gas supply pipe for supplying purge gas to the second space partitioned by the second partition.

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