JP2013138164A - Semiconductor manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing device in which surface temperature of a susceptor on which a substrate is mounted is kept uniform and a crystal film of which variation in film thickness is reduced is formed on the substrate.SOLUTION: Relating to thickness of a susceptor 4 on which a substrate is mounted, a central portion of a substrate mounting surface is thickest and the thickness gradually decreases as advances toward a peripheral part, the shape on the side opposite to the substrate mounting surface being almost conical. Around the susceptor 4, a cylindrical heater 5 is arranged which has the same height as the maximum thickness of the susceptor. As a result, the inclination of radiation heat reception value per a unit area which is generated toward the peripheral part from the central portion of the susceptor rear surface is balanced with the inclination of heat transmission value that is transmitted from the susceptor rear surface to a front surface, thereby almost uniformizing temperature distribution on the substrate mounting surface.

Description

  The present invention relates to an apparatus for manufacturing a semiconductor by growing crystals on the surface of a substrate installed in a reaction chamber, and more particularly to a semiconductor manufacturing apparatus characterized by the structure of a susceptor on which a substrate is installed.

  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 (Metal Organic Chemical Vapor Deposition), which can control the film thickness on the atomic layer order, has been frequently used. Semiconductor manufacturing apparatuses such as MOCVD include a susceptor that supports a substrate and a heater that heats the substrate via the susceptor as a common basic configuration.

  In order to manufacture a semiconductor having good characteristics, a crystal having a uniform composition and film thickness is required to be grown on a substrate. The uniformity of the substrate temperature is extremely important for realizing the formation of a uniform film thickness. For this reason, the susceptor that supports the substrate is required to have high thermal uniformity. In the conventional semiconductor manufacturing apparatus, the susceptor and the heater are surrounded by a heat shield plate to prevent heat from being transmitted to the outside of the heat shield plate, and the susceptor is efficiently heated. Nevertheless, it is difficult to achieve high temperature uniformity across the entire surface of the substrate. In particular, the growth temperature of a GaN (gallium nitride) -based semiconductor crystal is as high as about 1050 ° C., the amount of radiant heat from the susceptor is very large, and soaking control of the susceptor is difficult.

  A general susceptor and heater structure and temperature distribution are shown in FIG. In FIG. 10, the right end corresponds to the center of the susceptor, and the portion on the right side of the center is omitted. The omitted portion has a structure and temperature distribution that is inverted at the center of the susceptor. FIG. 10A shows the temperature distribution on the surface of the susceptor in a semiconductor device having a structure in which the heater 50 is disposed on the side opposite to the substrate mounting surface of the susceptor 40 (hereinafter, the substrate mounting surface is the front surface and the opposite side is referred to as the back surface). FIG. As illustrated, a heater 50 is disposed on the back side of the susceptor 40. When viewed from the surface side of the susceptor 40, the area of the heater 50 is substantially the same as the area of the susceptor 40, and the heat radiated from the heater 50 is transmitted substantially uniformly over the entire surface of the susceptor 40. On the other hand, heat radiation from the susceptor 40 is performed from the side surface side though a heat shield plate is provided. For this reason, the surface of the susceptor exhibits a temperature distribution in which the temperature is highest at the center of the susceptor and decreases toward the periphery.

  On the other hand, as shown in FIG. 10B, in the semiconductor device having the structure in which the heater 55 is arranged on the side surface of the susceptor 40, the problem of heat radiation from the side surface of the susceptor 40 is solved, but the heat is conducted from the heater 55. Since heat decreases toward the center due to the thermal resistance (heat loss) of the susceptor itself, the temperature distribution is such that the temperature is high around the susceptor and the temperature decreases toward the center.

  Conventionally, improvement of the heater has been mainly proposed as a technique for improving the uniformity of the susceptor temperature, particularly as a method for solving the problem of the temperature around the susceptor being lowered. For example, Patent Document 1 discloses a structure in which the temperature of the outer peripheral portion is higher than that of the central portion by making the cross-sectional shape of the heater arranged on the back side of the susceptor different between the central portion and the outer peripheral portion. . Further, in Patent Document 2, a heater is disposed on the outer periphery of an annular holder that supports the substrate, and a heater is disposed outside a rotating unit that rotates the annular holder and the like, in addition to the heater disposed at the lower portion of the substrate. A structure is disclosed. Further, in Patent Document 3, the substrate is supported by a ceramic disk (disk-shaped ceramic heater) with a built-in heater, and the surface opposite to the substrate mounting surface of the disk-shaped ceramic heater is formed into a spherical shape so that the heat dissipation of the heater is achieved. It has been proposed to improve the performance and to equalize the substrate mounting surface.

Japanese Patent Laid-Open No. 03-080530 JP 2009-170676 A Japanese Patent Publication No. 07-070491

  Although the technique described in Patent Document 1 is simple, in order to optimize the cross-sectional shape of the heater and make the susceptor temperature uniform, it is necessary to repeat trial and error in order to find the optimum shape. There is a problem that it takes time and labor to manufacture the heater. Moreover, since the temperature of the outer peripheral part of the heater becomes high, the thermal deterioration of the outer peripheral part is accelerated and the heater life is short.

  In the technique described in Patent Document 2, since the outer heater and the external heater are provided separately from the main heater installed on the lower side of the substrate, the number of heaters and the heater control system are increased, and the apparatus is There is a problem of increasing complexity.

  The technique described in Patent Document 3 requires a great deal of trial and error in order to optimize the shape of the plate-shaped ceramic heater for equalizing the temperature. Moreover, since the heater and the susceptor are integrated, if one of them needs to be removed, the whole must be removed. For example, if deposits such as gallium nitride with high crystal hardness adhere to the susceptor, it is necessary to remove it from the device, remove it by wet etching, etc., and reattach it. In that case, the heater electrode must also be removed and attached. It becomes. Further, it is necessary to protect the electrodes from being damaged during the wet etching cleaning. Alternatively, even if the susceptor portion is not damaged, it is necessary to replace the entire susceptor when the heater has reached the end of its life.

  The present invention solves the problems of the prior art described above, eliminates the need for much labor and cost in manufacturing and maintenance, and realizes high heat uniformity on the susceptor surface with a relatively simple configuration. It is an issue to provide.

  In order to solve the above-mentioned problems, the present invention employs a susceptor shape in which a heater for heating a substrate is disposed on the side surface of the susceptor, and the amount of radiant heat received by the side surface is inclined from the susceptor center toward the periphery. As a result, the amount of radiant heat and the amount of heat transferred from the back surface of the susceptor to the front surface (substrate mounting surface) can be balanced as a whole susceptor, and soaking can be achieved.

  That is, the semiconductor manufacturing apparatus of the present invention includes a reaction chamber, a susceptor that is installed in the reaction chamber and mounts the substrate, and a heating unit that heats the susceptor from the side surface. The susceptor has a surface on which the substrate is mounted (substrate mounting). The thickness in the direction perpendicular to the surface) decreases from the center to the periphery of the substrate mounting surface.

  The shape of such a susceptor is substantially a conical shape, that is, a substantially triangular shape in a cross section passing through the center of the substrate mounting surface and perpendicular to the substrate mounting surface, and two sides of the triangle (sides other than the sides of the substrate mounting surface) ) May be straight or curved.

  The heating means preferably has a cylindrical shape. The length of the cylinder in the axial direction is preferably equal to or greater than the maximum thickness of the susceptor. The heating means is disposed outside the side surface of the susceptor or close to the back surface of the peripheral portion of the substrate mounting surface.

  The semiconductor manufacturing apparatus of the present invention divides the space in parallel with the substrate mounting surface into a space between the susceptor having a shape that becomes thinner from the central portion toward the peripheral portion and a heating unit that heats the substrate from the side surface. It is characterized by arranging a heat shield.

  Heat from heating means arranged to heat the susceptor from the side heats the conical surface from the outer periphery of the susceptor toward the center. That is, the entire back surface of the susceptor can be heated. The back surface of the susceptor that receives this radiant heat has an inclined shape from the peripheral part toward the central part, and when divided by a plane parallel to the substrate mounting surface, the area of the divided area is smaller near the central part, Grows toward the part. Therefore, the amount of radiant heat per unit area received by the susceptor increases as the distance from the center increases, and the temperature of the heat receiving surface increases.

  On the other hand, since the susceptor surface temperature is lower than the back surface temperature, heat flows from the back surface to the front surface. At this time, since the distance from the inclined back surface to the substrate mounting surface, that is, the thickness of the susceptor becomes thinner from the central portion toward the peripheral portion, the heat loss transmitted through the susceptor and transmitted to the susceptor surface is reduced from the peripheral portion. Grows toward the center. This loss of conduction heat cancels out the gradient of the amount of radiant heat received by the heat receiving surface described above, and as a result, it is possible to achieve soaking on the substrate mounting surface.

  In particular, when the space between the substrate and the heating means is divided into zones, the amount of heat received at the side surface of the susceptor corresponding to each zone can be made uniform, and higher temperature equalization can be realized.

1 is an overall schematic diagram showing a first embodiment of a semiconductor manufacturing apparatus of the present invention. It is a figure which shows the susceptor of the apparatus of FIG. 1, (a) is the figure seen from the top, (b) is a sectional side view. It is the top view and side view which show the cylindrical heater used for the apparatus of FIG. 1, (a) is a horizontal heater, (b) A vertical heater, (c) is a cylindrical heater without a slit. The figure explaining the relationship between the size of the susceptor of 1st embodiment, and the height of a heater (A)-(e) is sectional drawing which shows the susceptor shape of 1st embodiment-5th embodiment, respectively. The whole outline | summary which shows 6th embodiment of the semiconductor manufacturing apparatus of this invention, and the figure which shows the upper surface and side cross section of a susceptor Overview of conventional semiconductor manufacturing equipment Sectional drawing which shows the structure of the crystal film manufactured in the Example The figure which shows the temperature measurement position of the susceptor in an Example. It is a figure explaining the heat distribution in this invention and the susceptor of the conventional semiconductor manufacturing apparatus, (a) when a heater is arrange | positioned on a susceptor back surface, (b) when a heater is arrange | positioned on the susceptor side surface, (c) is this The arrangement of the first embodiment of the invention is shown. The figure which shows the whole semiconductor manufacturing apparatus outline | summary of 7th embodiment. (A), (b) is the top view and side view of a heater chamber of the semiconductor manufacturing apparatus of FIG. It is a figure explaining the function of the heat shield of 7th embodiment, (a) shows the case where there is no heat shield, and (b) shows the case where a heat shield is arranged. The figure which shows an example of the support structure of a heat shield The figure which shows the other example of the support structure of a heat shield The figure which shows the whole semiconductor manufacturing apparatus outline | summary of 8th embodiment. (A), (b) is the top view and side view of a heater chamber of the semiconductor manufacturing apparatus of FIG.

  Hereinafter, embodiments in which the present invention is applied to an MOCVD apparatus will be described with reference to the drawings.

  FIG. 1 is a diagram showing an outline of an MOCVD apparatus to which the present invention is applied. The MOCVD apparatus 100 is an apparatus for growing a compound semiconductor crystal on a substrate such as a sapphire, silicon, gallium nitride substrate, or silicon carbide substrate using an organometallic material. The gas supply pipe 2 for supplying the material gas into the reaction vessel 1 and the gas supply pipe 2 are connected, and the flow channel 3 installed in the reaction vessel 1 and the substrate 9 are mounted on the substrate 9 mounted thereon. A susceptor 4 disposed facing the flow channel 3 so as to be in contact with the material gas flowing through the flow channel 3, a heater 5 disposed around the susceptor 4, and a heat shield plate 6 surrounding the susceptor 4 and the heater 5. , A rotating mechanism 7 that rotates the susceptor 4, and a partition wall 8 that partitions a space (heater chamber) in which the heater 5 and the heat shield 6 are disposed from other spaces of the reaction vessel 1. It is equipped with a.

  A purge gas supply pipe 10 for supplying an inert gas into the reaction container 1 and an exhaust pipe 13 are connected to the reaction container 1 in addition to a gas supply pipe 2 for supplying a material gas. The structure is such that the material gas diffused into the container 1 is exhausted. In the illustrated example, the purge gas supply pipe 10 is provided with two systems (11, 12) on the heater chamber side and the outside thereof. The inert gas supplied from the purge gas supply pipes 11 and 12 may be any gas that does not corrode the susceptor 4, the heater 5, the heat shield plate 6, and the like. Specifically, nitrogen gas, hydrogen gas, argon gas, or the like is used. It is done.

  In addition to the organic metal gas, a plurality of types of material gases such as hydrogen gas and nitrogen gas are used. The gas supply pipe 2 is provided with a plurality of gas supply pipes 21 and 22 (two in the figure) according to the types of these gases. Inside the flow channel 3, a flow path is partitioned for each gas, and these gases are mixed and reacted at the upper part of the substrate 9. A flow channel exhaust pipe 14 is connected downstream of the flow channel 3. The end of the flow channel exhaust pipe 14 is accommodated in the exhaust pipe 13 of the reaction vessel 1, and surplus material gas that has not been used for the reaction, by-product gas generated by the reaction, etc. from the exhaust pipe 13 to the reaction vessel 1. It is discharged outside.

  The partition wall 8 can be constituted by a water-cooled jacket type partition wall 8 and thermally shuts off the high temperature and the outside of the heater chamber and prevents the material gas and the like from flowing into the heater chamber. The heat shield plate 6 is a plate material made of a low thermal conductivity material, for example, boron nitride (BN) or pyrolytic boron nitride (PBN), on the side surface and the bottom surface side so as to surround the bottom surface of the susceptor 4 and the heater 5. Arranged in a stacked state.

  The susceptor 4 is made of a material having a good thermal conductivity, for example, a surface of a carbon material such as graphite coated with a SiC film, has a substantially conical shape, and is a surface that is the bottom surface of the cone (the top surface in FIG. 2). ) Is arranged in the reaction vessel 1 so as to be a substrate mounting surface.

  The shape of the susceptor 4 will be described in detail with reference to FIG. 2A is a view of the susceptor 4 of the apparatus shown in FIG. 1 as viewed from above, and FIG. 2B is a view showing a side cross section including the center of the substrate mounting surface. As shown in the figure, the substrate mounting surface 41 of the susceptor 4 is formed with a recess 42 for mounting the substrate 9 slightly inside from the outer periphery. An annular portion between the outer periphery of the recess 42 and the outer periphery of the susceptor 4 is referred to as a peripheral portion 43. The diameter φ of the substrate mounting surface of the susceptor 4 is smaller than the width W when the flow channel 3 is viewed from above, so that the substrate 9 mounted in the recess 42 of the susceptor is surely in contact with the material gas (mixed gas). It has become.

  As shown in the cross-sectional view of FIG. 2B, the shape of the susceptor 4 on the side opposite to the substrate mounting surface (back surface side) is a portion (rim portion) 44 having a diameter equal to the diameter φ of the substrate mounting surface, and the following. When expressed in terms of the height of the susceptor 4 in a direction perpendicular to the substrate mounting surface 41 (that is, the thickness of the susceptor 4), the thickness is the thickest at the central portion and becomes thinner toward the peripheral portion. Yes. The relationship between the diameter φ of the substrate mounting surface and the maximum thickness T can be determined from the relationship between the height of the heater 5 described later and the diameter φ of the substrate mounting surface, and the relationship between the height of the heater and the maximum thickness t of the susceptor. As an example, if the diameter φ of the upper surface of the susceptor is 60 mm, the rim portion 43 has a thickness of 2 mm and the conical portion has a height of 15 mm.

  The center of the back surface of the susceptor 4 is connected to a rotation mechanism 7 provided outside the reaction vessel 1, and the susceptor 4 is rotated by the rotation mechanism 7 during the reaction. As a result, the crystal growth on the substrate 9 mounted on the susceptor 4 can be progressed evenly.

  The heater 5 has a cylindrical shape whose diameter is larger than the diameter φ of the susceptor 4, and has a plurality of slits along the circumference of the cylinder or in the axial direction, so that a substantial gap between the electrodes from one to the other of the electrode terminals is formed. A long distance is formed. The height H of the heater 5 is approximately the same as the thickness T of the central portion of the susceptor 4, and thus the heater 5 surrounds the entire back surface side of the susceptor 4.

  The cylindrical heater 5 has a horizontal type and a vertical type depending on how the slits are inserted, and any of them can be adopted. An example of the cylindrical heater 5 is shown to Fig.3 (a)-(c). FIG. 3A is a horizontal heater in which slits are formed along the circumferential direction of the cylinder, and FIG. 3B is a vertical heater in which slits are alternately formed from the upper and lower sides in the axial direction of the cylinder. In both cases, both electrodes are electrically and physically connected, and are connected to a power source (not shown) outside the reaction vessel 1. In principle, a cylindrical heater having no slit as shown in FIG. 3C can also be employed.

The size of the heater 5 in the cylindrical axis direction, that is, the height H, is preferably designed so that the area of the inner surface of the cylinder formed by the heater 5 is substantially equal to the area of the upper surface of the susceptor 4. As a result, the amount of heat generated by the heater 5 becomes the same as the amount of heat generated by the heater 50 having a structure in which the heater 50 having the same area is disposed on the back surface of the plate-shaped susceptor 40 as shown in FIG. For example, assuming that the radius of the susceptor and the radius of the cylinder formed by the heater 5 are both r (= φ / 2), assuming that the area of the upper surface of the susceptor 4 (the area of the inner surface of the cylinder) is S, S = π × r ² Therefore, the height H = S ÷ (2πr) = r / 2. That is, the height H of the heater 5 may be equal to ½ of the radius r of the susceptor 4.

  Next, the effect of soaking according to the present embodiment will be described with reference to FIG. FIG. 10C is a diagram showing the temperature distribution, the side cross section, and the heat collection effect of the susceptor as seen from above, in order from the top. When the area of the heater 5 is the same as the area of the upper surface of the susceptor 4 and the height of the heater 5 is the same as the height of the susceptor 4, a heater having the same area is disposed on the lower surface of the flat susceptor 4 (FIG. )) The same amount of heat is radiated to the entire back surface of the susceptor. The radiation direction of the radiant heat from the heater 5 has a spread, but the component orthogonal to the cylinder axis has the largest amount of radiation and is uniform along the cylinder axis. However, the area of the back surface of the susceptor 4 that receives radiant heat is the largest at the periphery of the susceptor 4 and decreases toward the center. Therefore, the amount of heat received by the unit area of the susceptor is the largest in the center, and this amount of heat received is maximized. The amount of heat per unit area is inversely proportional to the circumference of the cone.

  On the other hand, when heat is transferred from the back surface of the susceptor 4 to the substrate mounting surface by heat conduction, a heat loss proportional to the distance between the back surface of the susceptor and the substrate mounting surface is received. The distance between the back surface of the susceptor and the substrate mounting surface and the radius of the cone at the distance are in an inversely proportional relationship in the present embodiment in which the susceptor shape is a cone. Therefore, the change (decrease or increase) in the amount of radiant heat per unit area in the height direction of the cone on the back surface is offset by the heat loss due to the change in the distance between the back surface and the substrate mounting surface, and is finally received by the substrate mounting surface. The heat becomes almost uniform, and the temperature uniformity of the substrate mounting surface can be realized.

  According to this embodiment, the cylindrical heater 5 is disposed on the outer periphery of the susceptor 4 and the shape of the susceptor 4 on the side opposite to the substrate mounting surface is conical, so that the heater is provided on the back surface of the flat susceptor. The same amount of heat as in the case of arrangement can be supplied to the susceptor, and heat removal from the side surface of the susceptor can be prevented. Further, since the height of the cylindrical heater is substantially the same as the height of the conical susceptor, heat from the heater can be supplied to the entire back surface of the susceptor. That is, according to the structure of the present embodiment, the problem of heat extraction from the side surface when the heater is arranged on the back surface of the susceptor and the temperature drop around the susceptor, and the central portion of the susceptor when the heater is arranged on the side surface. The problem of the heat conduction loss and the lowering of the susceptor center temperature can be solved at the same time.

  Furthermore, according to the present embodiment, the radiation heat received by the susceptor back surface from the cylindrical heater and the conduction heat reaching the substrate mounting surface from the susceptor back surface can be quantitatively balanced. A uniform temperature distribution can be achieved.

  Although the basic embodiment of the present invention has been described above, the shape of the susceptor and the arrangement of the heater can be variously changed without departing from the spirit of the invention. Hereinafter, a modification example will be described.

<Second to fifth embodiments>
5 (a) to 5 (e) show various embodiments of susceptor shape. In the figure, dotted lines indicate the boundaries of each region when the cone is divided into three regions (peripheral portion, central portion, and middle peripheral portion) by a plane parallel to the bottom surface. FIG. 5A is the susceptor having the basic conical back surface according to the first embodiment described above. In this embodiment, as described above, the amount of radiant heat per unit area received by the back surface of the susceptor changes linearly from the top to the bottom of the cone. Therefore, the area of the heat receiving surface increases in proportion to the circumference of the cone. Fig. 5 (b) shows a susceptor with a conical conical surface bulging outward. The area receiving the radiant heat from the heater suddenly increases near the apex of the cone and gradually increases as it approaches the periphery. become. That is, compared with the embodiment shown in FIG. 5A, the amount of heat received by the peripheral portion increases, and a region (heat receiving zone) where the amount of heat received increases is generated in the peripheral portion.

  FIG. 5 (c) shows a susceptor with a conical conical surface recessed inward, and the area that receives the radiant heat from the heater gradually increases in the portion close to the apex of the cone, and increases as it approaches the peripheral portion. It becomes steep. That is, as compared with the embodiment shown in FIG. 5A, the amount of heat received by the susceptor center increases, and the heat receiving zone moves toward the center.

  5B and 5C show a case where the slope of the line connecting the apex of the cone and the outer periphery of the bottom surface changes monotonously in the susceptor-shaped cross-sectional view shown in FIGS. 5D and 5E. ) Is the case with inflection points. However, in FIG. 5D, the change in the inclination near the apex and the vicinity is large, and the surface temperature is low in the region between the susceptor center and the periphery (the middle periphery). In FIG.5 (e), the change of the inclination in the area | region between a vertex and a peripheral part is large, and surface temperature becomes high in the area | region (mid-circumference part) between a susceptor center and a peripheral part.

  By changing the shape of the susceptor as shown in these embodiments, the shape of the heat receiving surface of the radiant heat from the heater is changed so that the area per unit area (peripheral part, center part, middle part) is received per unit area. The amount of heat can be adjusted.

<Sixth embodiment>
FIG. 6 shows an embodiment in which the heaters are arranged differently. The same elements as those in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted. In the embodiment shown in FIG. 2, the structure in which the heater is arranged outside the peripheral portion of the susceptor is shown. However, in this embodiment, the heater 5 is arranged below the peripheral portion 43 excluding the concave portion 42 on which the substrate 9 is mounted. ing. The structure of the heater is the same as that of the first embodiment, and a cylindrical shape shown in FIG. 3 can be adopted.

  In the present embodiment, the susceptor 4 employs a susceptor having a shape in which a conical conical surface is convex outward (the shape shown in FIG. 5B). Further, the diameter φ of the bottom surface of the conical portion 45 formed on the back surface side of the susceptor 4 is smaller than the diameter φ of the substrate mounting surface of the susceptor, and a flat region (flat portion) 46 is formed on the back surface of the rim portion 44. . The heater 5 is disposed in the vicinity of the flat portion 46. As an example, if the diameter φ of the upper surface of the susceptor is 60 mm, the thickness of the rim portion is 1 mm, the diameter of the conical portion 45 is 54 mm, and the height is 13 mm.

The conical portion 45 of the susceptor 4 receives the heat radiated from the heater 5 toward the center of the cylinder, conducts heat toward the substrate mounting surface 41, and achieves soaking of the substrate mounting surface. Although it is the same as that of 1st embodiment, since the shape of a cone part is made into convex shape, it has the structure where a heat receiving zone moves outside compared with 1st embodiment, and the amount of heat receiving on the outer peripheral side increases. .
In the present embodiment, since the thin rim 44 having the flat portion 46 is provided on the outer periphery of the susceptor, the heater 5 can be disposed close to the back surface of the susceptor, and heat utilization efficiency can be increased. . Moreover, since the heat which goes upwards from the heater 5 is interrupted | blocked by the flat part, the effect that it can suppress that the reaction product of material gas accumulates on the peripheral part 41 of a board | substrate mounting surface can also be acquired.

  In the illustrated embodiment, the conical shape is a convex shape outward (FIG. 5B), and the temperature of the outer peripheral portion is increased, but other shapes shown in FIG. 5 are adopted. You can also.

<Seventh embodiment>
This embodiment is based on the structure of the first to sixth embodiments described above, and is characterized in that a heat shield plate is arranged around the susceptor in parallel with the substrate mounting surface of the susceptor, and the temperature distribution of the substrate mounting surface Is further improved.

  Hereinafter, an apparatus in which this embodiment is applied to the MOCVD apparatus of the first embodiment will be described with reference to FIGS. 11 and 12. FIG. 11 is a diagram showing an overall outline of the MOCVD apparatus of this embodiment, and FIGS. 12A and 12B are a top view and a side view of the heater chamber. In FIG.11 and FIG.12, the same element as 1st embodiment is shown with the same code | symbol.

  The MOCVD apparatus of this embodiment is characterized by the structure between the susceptor and the heater that heats the susceptor from the side surface, and the other configuration is the same as that of the first embodiment.

  The susceptor 4 has a shape in which the conical shape is inverted, and the upper surface corresponding to the bottom surface of the cone is a substrate mounting surface on which the substrate 9 is mounted, and a recess for mounting the substrate 9 is formed. The rotating shaft of the rotating mechanism is connected to the bottom surface of the susceptor 4 corresponding to the apex of the cone, and the susceptor 4 can rotate around the rotating shaft.

  Around the rotating shaft below the bottom surface of the susceptor 4, a plurality of disk-shaped heat shield plates 61 are arranged with a predetermined interval. The function of these heat shield plates 61 is to prevent the heat of the heater 5 from escaping to the outside, and has a diameter equal to or larger than the diameter of the heater 5 and is a space in which the susceptor 4 and the heater 5 are placed. Is shielded from the outside. The heat shielding can be efficiently performed by alternately arranging the heat shielding plates 61 and the air layers existing between the heat shielding plates. From the above viewpoint, the number of the heat shielding plates, the thickness of the heat shielding plates, and the shielding. The spacing between the hot plates, ie the thickness of the air layer, is designed. Specifically, 2 to 8 heat shield plates 61 having a thickness of about 0.2 mm to 0.3 mm are arranged at intervals of about 0.5 mm. These heat shield plates 61 are made of a material having heat resistance and good thermal conductivity such as PBN, BN, and Mo. In particular, it is preferable that the uppermost heat shielding plate 6 exposed to a high temperature or the upper heat shielding plate 6 including the uppermost step is made of PBN having high corrosion resistance.

  A cylindrical heat shield plate 63 is disposed so as to surround the heater 5 and the heat shield plate 61. The function of the heat shield plate 63 is to shield the space in which the susceptor 4 and the heater 5 are placed from the outside in the same manner as the heat shield plate 61 disposed below the susceptor 4. Are arranged concentrically with an interval of about 0.2 mm. These cylindrical heat shield plates 63 are fixed to the bottom plate of the flow channel 3 so as to have the above spacing. The disc-shaped heat shield plate 61 is fixed to the innermost heat shield plate 63.

  The heater 5 is composed of a substantially cylindrical heater as shown in FIGS. 3A to 3C, and the height of the cylinder is the height from the substrate mounting surface to the bottom surface of the susceptor 4 (that is, the maximum thickness of the susceptor 4). ), Substantially covering the side surface of the susceptor 4 and heating the susceptor 4 from the side surface.

  A cylindrical space 55 surrounded by the heater 5 is a space having an inverted conical shape on the back surface of the susceptor 4 as a recess, and a plurality of donut-shaped heat shield plates 65 are disposed in this space, the main plane of which is the substrate mounting surface. They are arranged in parallel. The plurality of heat shield plates 65 all have the same outer diameter, but the inner diameter differs according to the change in the diameter of the susceptor 4, is small on the bottom surface side of the susceptor 4, and increases as the substrate mounting surface is approached.

  These donut-shaped heat shield plates 65 divide the space 55 into a plurality of zones, and control the direction of radiant heat from the heater 5 toward the side surface of the susceptor 4 in each zone. It has a different function. The function of the heat shield plate 65 will be described with reference to FIG. 13A shows a case where a heat shield plate is not provided (first embodiment), and FIG. 13B shows a case where a heat shield plate is provided, and is a structural diagram of an apparatus including a heater 5 and a susceptor 4 in the center. The temperature distribution on the substrate mounting surface is shown above, and the spread of radiant heat from the heater is shown below. Since the structure, temperature distribution, and radiant heat behavior are symmetric with respect to the center of the susceptor 4, only one side (left side) is shown from the center of the susceptor 4, and the other side (right side) is not shown. doing.

  As shown to Fig.13 (a), the radiant heat emitted from the cylindrical heater 5 goes to the center part of a cylinder. Here, a case where a heater in which the heating portion is divided into three in the axial direction of the cylinder as shown in FIG. 3A is used is shown. In correspondence with the division of the heater 5, the heater 5, the susceptor 4, When the space between is divided into regions parallel to the substrate mounting surface, the amount of radiant heat that travels in the direction parallel to the substrate mounting surface from the heater 5 is the same in the upper, middle, and lower stages. However, since the radiant heat from the heater 5 radiates Lambertian as shown in the lower diagram of FIG. 13A, the radiant heat from both the upper and lower stages is collected in the middle stage. On the other hand, since only the radiant heat from the middle stage is added to the radiant heat of the upper stage and the lower stage, the amount of heat collected is smaller than that of the middle stage. As a result, the heat received by the side surface of the susceptor 4 is relatively small in the vicinity of the susceptor 4 and in the vicinity of the center thereof, and relatively in the middle thereof. As a result, as shown in the upper diagram of FIG. 13A, the substrate mounting surface has a high temperature distribution in the middle periphery. Note that the temperature distribution in FIG. 13 is exaggerated for the sake of explanation, and is actually a distribution close to the temperature distribution shown in FIG.

  On the other hand, when the heat shield plate 65 is arranged as shown in FIG. 13B, the space 55 between the heater 5 and the susceptor 4 is divided into zones by the heat shield plate 65, so that the heater 5 The radiant heat radiated from the center is prevented from spreading in the vertical direction and stays in the zone, and heat collection to the middle stage as shown in FIG. 13 (a) does not occur (lower figure in FIG. 13 (b)). As a result, the side surface (bottom surface) of the susceptor 4 has almost the same amount of heat received for each zone. On the other hand, since the heat receiving surface of the susceptor 4 becomes smaller as it goes downward, the amount of heat received per unit area becomes smaller as it goes toward the lower step (bottom surface of the susceptor 4), but the distance to the substrate mounting surface goes from the central part of the susceptor toward the peripheral part. Therefore, the increase in the amount of heat received per unit area and the heat loss due to the distance are offset, and as a result, as shown in the upper diagram of FIG. 13B, the amount of heat reaching the substrate mounting surface of the susceptor 4 is It becomes almost uniform at the center and the periphery.

  BN, PBN, or the like can be used as the material of the heat shield plate 65, but PBN is suitable because it is exposed to a higher temperature than the heat shield plate 61 and the heat shield plate 63. The thickness of the heat shield plate 65 is preferably about 0.1 mm to 0.3 mm in order to maintain the function of dividing the space into regions and the mechanical strength. The number of the heat shield plates 65 varies depending on the diameter and thickness of the susceptor 4 (distance from the substrate mounting surface to the bottom surface), but if the number of the heat shield plates 65 is too large and the interval is narrowed, the heat from the heater 5 is reduced. Since there is a possibility of reducing the utilization efficiency, it is preferable to arrange the number so that the interval between the heat shield plates is equal to or less than the interval between the heat shield plates 61 arranged on the lower side. Specifically, it is preferable to arrange about 1 to 8 sheets at intervals of 2 mm to several mm.

  An example of a structure for fixing the heat shield plate 65 is shown in FIGS. In both figures, (a) is a view of the heater and the susceptor as viewed from above, (b) is a side view of the heater and a top view of the heat shield plate, and (c) is a side sectional view schematically showing the support structure. In the example shown in FIG. 14, a heater having the horizontal heating element shown in FIG. 3A is used as the heater 5, and the heat shield plate 65 is placed on the heating element of each stage constituting the heater 5. Structure. Therefore, the heat shield plate 65 has an outer diameter that is substantially the same as or slightly larger than that of the heater 5, and has a shape in which a part of the outer circumference corresponding to the connecting portion of the heating element at each stage is cut out. This support structure is advantageous in that it can be divided into zones according to the number of heating elements of the heater 5 and is a simple support structure.

  In the example shown in FIG. 15, a heater provided with the vertical heating element shown in FIG. 3B is used as the heater 5, and the heat shield plates 65 (plurality) having substantially the same outer diameter as the inner diameter of the heater 5 are used. It is the structure connected with the connection tool which is not illustrated so that it may become a desired space | interval. This connector may be integrated with the connector for connecting the lower heat shield 61 or may be independent of the connector and is directly or indirectly fixed in the reaction vessel. This support structure requires a connector separately from the heat shield, but has the advantage of a high degree of freedom in zone division.

  According to this embodiment, by arranging the heat shield plate 65 that divides the space between the heater 5 and the side surface of the susceptor 4 into a plurality of zones, the movement of radiant heat spreading radially beyond the zones is suppressed, and the center Heat collection to the part can be suppressed, and the amount of heat received on the side surface of the susceptor 40 can be made substantially equal for each zone. This balances the effect of increasing the amount of heat received by the area of the side surface of the susceptor (decreasing effect) and the effect of decreasing the amount of conduction heat by the distance from the side surface to the upper surface (increasing effect), thereby improving the uniformity of temperature distribution on the substrate mounting surface. be able to.

  As described above, the case where the seventh embodiment is applied to the semiconductor manufacturing apparatus of the first embodiment has been described. However, in the present embodiment, a heat shield plate 65 is provided in the space between the heater 5 and the susceptor 4. It is also possible to apply this feature to the susceptors of the second to fifth embodiments. For example, the shape of the susceptor is not limited to an inverted conical shape, and can take various shapes as shown in FIGS. 5B to 5E. Also, as shown in FIG. It is also possible to adopt a structure in which the heater 5 is arranged.

<Eighth embodiment>
In addition to the features of the seventh embodiment described above, the semiconductor manufacturing apparatus of this embodiment is characterized in that a groove for inducing heat is provided in the susceptor, which further improves temperature uniformity on the substrate mounting surface. It is intended. Hereinafter, an apparatus in which this embodiment is applied to the MOCVD apparatus of the first embodiment will be described with reference to FIGS. 16 and 17.

  FIG. 16 is a diagram showing an overall outline of the MOCVD apparatus of this embodiment, and FIGS. 17A and 17B are a top view and a side view of the heater chamber. 16 and 17, the same elements as those in the first and seventh embodiments are denoted by the same reference numerals.

  Also in the MOCVD apparatus of this embodiment, the susceptor 40 has a generally inverted conical shape, a substrate mounting surface is formed on the surface which is the bottom surface of the cone, and a cylindrical heater so as to surround the side surface of the susceptor 40. 5 is arranged. Surrounding the susceptor 40 and the heater 5 are heat shield plates 61 and 63 that block heat from the outside, and a donut-shaped heat shield plate 65 is provided between the susceptor 40 and the heater 5. The material, size, number and fixing method of the heat shield plates 61, 63, 65 are the same as those of the seventh embodiment.

  The susceptor 40 is formed with a cylindrical groove 41 extending in the vertical direction from the side surface (bottom surface) corresponding to the arrangement of the heat shield plate 65. The groove 41 is provided to guide the movement of heat in the vertical direction when the heat received by the side surface of the susceptor 40 is transmitted to the substrate mounting surface. The heat conducted in the susceptor 40 also spreads radially like the radiant heat from the heater 5. Therefore, when there is no groove, heat is likely to gather from the peripheral portion at the center of the susceptor. By providing the groove, the heat receiving amount made uniform for each zone by the heat shield plate 65 can be directed to the vertical direction as it is and conducted to the substrate mounting surface. For this reason, the groove 41 is located at a position corresponding to the inner peripheral end of the heat shield plate 65 of the susceptor 40, more precisely from a position where the extension line of the plate surface of the heat shield plate 65 contacts the susceptor 40, from the upper surface of the susceptor. It is preferable to extend vertically up to a predetermined depth.

  The number, depth, and width of the grooves 41 are preferably determined in an appropriate range in consideration of the strength of the susceptor, and the number of the grooves 41 is equal to or less than the number of the heat shield plates 65. In the illustrated example, six heat shield plates 65 are arranged from the heat shield plate 65 located on the bottom surface of the susceptor, and correspond to the first and sixth heat shield plates in order to maintain the strength of the susceptor. Four grooves 41 are formed at positions corresponding to the fourth to fifth heat shield plates 65 without providing grooves at the positions. When the number of heat shield plates to be arranged is small, it is possible to provide the same number of grooves as the heat shield plates. The depth of the groove 41 is preferably such that the distance from the upper surface of the susceptor to the bottom of the groove is constant in the case where a plurality of grooves are formed, and the distance may be within a range that can maintain the strength of the susceptor. Is preferably about 20 to 30% of the height (thickness from the top surface to the bottom surface). As an example, in the case of a susceptor having a diameter of 60 mm, an inverted conical portion height of 15 mm, and a cylindrical portion height of 2 mm as shown in FIG. 16, the distance from the susceptor top surface to the groove bottom is about 3.5 mm.

  As described above, the groove 41 divides the susceptor 40 vertically to control the direction of heat conduction in the susceptor 40 in the vertical direction. If the width is too wide, the heat conduction of the susceptor 40 is inhibited. From such a viewpoint, in the example of a susceptor having a diameter of 60 mm and a height of 17 mm, the width of the groove 41 is preferably about 0.2 mm to 0.5 mm, more preferably about 0.2 mm to 0.3 mm.

  According to the present embodiment, the radiant heat from the heater 5 first reaches a side surface of the susceptor 40 with a substantially uniform amount of heat for each zone divided by the heat shield plate 65. The heat received by the side surface of the susceptor spreads to the upper surface side by conduction. At this time, since the susceptor 40 is divided into vertical regions corresponding to the zones divided by the grooves, the regions are thermally conducted in the vertical direction. The heat spreads radially between the bottom of the groove and the substrate mounting surface, thereby eliminating the temperature difference between the bottom of the groove where there is almost no heat conduction and the susceptor part where heat conduction was performed, and finally the susceptor. A uniform temperature distribution can be obtained on the upper substrate mounting surface 40.

  The case where the present embodiment is applied to the apparatus of the first embodiment has been described above, but the present embodiment can be combined with the apparatuses of the second to fifth embodiments as in the seventh embodiment.

  As described above, each embodiment in which the present invention is applied to a flow channel type MOCVD apparatus has been described. However, the present invention is not limited to the flow channel type MOCVD apparatus, and various types of MOCVD apparatuses such as a two-flow type, In addition, any semiconductor manufacturing apparatus that heats a substrate and forms a film on the substrate, such as an MBE apparatus, can be applied.

<Examples 1 and 2>
Using the MOCVD apparatus having the susceptor structure (first embodiment) shown in FIG. 2 and the MOCVD apparatus having the susceptor structure (sixth embodiment) shown in FIG. Were grown to form a crystal film having a laminated structure shown in FIG. 8 (Examples 1 and 2). In Example 1, as the susceptor, the diameter of the substrate mounting surface is 60 mm, the diameter of the concave portion on which the substrate is placed is 54 mm, the height of the rim portion is 2 mm, and the diameter of the bottom surface of the conical portion is the same as that of the substrate mounting surface. A conical susceptor having a length of 15 mm was used. In Example 2, the susceptor has a substrate mounting surface diameter of 60 mm, a recess mounting diameter of 54 mm, a rim portion height of 1 mm, a conical bottom surface diameter of 54 mm, and a height of 13 mm. Was used.

The substrate is a c-plane sapphire (α-alumina) single crystal substrate (2 inches = 50.8 mm) that is 0.5 ° off in the m-axis direction, TMG (trimethylgallium) as the organometallic material, and hydride material. NH ₃ was used. Further, from the start of the reaction to crystal growth, hydrogen gas was supplied from the material gas supply pipe 21 as a carrier gas for the material gas so that the flow rate combined with the material gas was 8 L / min. As purge gas, a mixed gas of hydrogen gas: nitrogen gas = 1: 1 was flowed from the purge gas supply pipes 11 and 12 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 22 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 at 30 μmol / min and NH ₃ was supplied at 4 L / min from the material gas supply pipe 22, and a low-temperature GaN layer was formed to 20 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. The average film thickness of the generated high-temperature GaN layer was 4.50 μm in Example 1 and 4.49 μm in Example 2.

<Comparative example>
As a comparative example, a GaN layer was grown on a sapphire substrate under the same conditions as in Examples 1 and 2 using the MOCVD apparatus having the susceptor structure shown in FIG. The apparatus shown in FIG. 7 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 used, 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 configuration excluding the susceptor and the heater is the same as that of the MOCVD apparatus of Examples 1 and 2. The average film thickness of the generated high-temperature GaN layer was 4.45 μm.

  About the apparatus of an Example and a comparative example, susceptor temperature and film thickness T1-T3 of the produced | generated high temperature GaN film | membrane were measured. The susceptor temperature was measured using a pyrometer at a total of three points, as shown in FIG. 9, including a center P3 and two points P2 and P1 that are 12.5 mm and 25 mm away from the center, respectively. The results are shown in Table 1.

  Further, the film thicknesses T1 to T3 of the high-temperature GaN layer at three points where the temperature was measured were measured. The film thickness was measured using a reflection interferometer using a white light source, utilizing the difference between the refractive index of the sapphire substrate (1.7) and the refractive index of the GaN crystal (2.4). The results are shown in Table 2.

  As can be seen from the results shown in Tables 1 and 2, in the comparative apparatus, the temperature near the center of the susceptor rose and a large temperature distribution was generated. For this reason, the thickness of the generated high-temperature GaN layer also varied greatly. On the other hand, in the apparatuses of Examples 1 and 2, the susceptor temperature variations were 13 ° C. and 16 ° C., respectively. Also, the film thickness of the comparative example was 19.8%, compared with 6.89% in Example 1 and 8.46% in Example 2, and the film thickness distribution was improved. Admitted.

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor manufacturing apparatus which can suppress the variation in crystal film thickness and can perform efficient crystal growth is provided. Thereby, the quality and yield of the LED device can be improved.

DESCRIPTION OF SYMBOLS 1 ... Reaction container, 2 ... Gas supply pipe, 21 ... 1st gas supply pipe, 22 ... 2nd gas supply pipe, 3 ... Flow channel, 4, 40 ... Susceptor, DESCRIPTION OF SYMBOLS 5 ... Heater, 6 ... Heat shield, 7 ... Rotation mechanism, 8 ... Partition, 9 ... Substrate, 10 (11, 12) ... Purge gas supply pipe, 13 ... Exhaust pipe,... Susceptor, 41... Groove, 55... Space (space between susceptor and heater), 61, 63, 65.

Claims (14)

A semiconductor manufacturing apparatus comprising: a reaction chamber; a susceptor that is installed in the reaction chamber and on which a substrate is mounted; and a heating unit that heats the susceptor from a side surface,
The susceptor has a shape in which a thickness in a direction perpendicular to a surface (substrate mounting surface) on which the substrate is mounted becomes thinner from a central portion to a peripheral portion of the substrate mounting surface. The semiconductor manufacturing apparatus according to claim 1,
2. The semiconductor manufacturing apparatus according to claim 1, wherein the heating means has a cylindrical shape, and the axial length of the cylinder is equal to or greater than the maximum thickness of the susceptor. In the semiconductor manufacturing apparatus according to claim 1 or 2,
The semiconductor manufacturing apparatus, wherein the susceptor has a triangular cross section passing through the center of the substrate mounting surface and perpendicular to the substrate mounting surface. In the semiconductor manufacturing apparatus according to claim 1 or 2,
When the surface opposite to the substrate mounting surface is the back surface, the susceptor passes through the center of the substrate mounting surface and in a cross section perpendicular to the substrate mounting surface, the center of the back surface and the susceptor peripheral side end portion A semiconductor manufacturing apparatus characterized in that a side to be connected is a curve. In the semiconductor manufacturing apparatus according to any one of claims 1 to 4,
The semiconductor manufacturing apparatus according to claim 1, wherein the heating unit has a cylindrical shape and is disposed outside a side surface of the susceptor. In the semiconductor manufacturing apparatus according to any one of claims 1 to 4,
The semiconductor manufacturing apparatus according to claim 1, wherein the heating means has a cylindrical shape, and has a diameter at least one end equal to or smaller than the diameter of the susceptor, and is disposed close to the back surface side of the susceptor peripheral portion. The semiconductor manufacturing apparatus according to any one of claims 1 to 6,
The semiconductor manufacturing apparatus according to claim 1, wherein the heating means has a cylindrical shape, and an area of an inner surface is substantially equal to an area of a substrate mounting surface of the susceptor. The semiconductor manufacturing apparatus according to claim 2,
The semiconductor manufacturing apparatus according to claim 1, wherein the heating means has a constant diameter. The semiconductor manufacturing apparatus according to claim 1,
One or more heat shield plates are arranged between the heating means and the susceptor in parallel with the substrate mounting surface. The semiconductor manufacturing apparatus according to claim 1,
When the back surface of the susceptor having a maximum thickness from the substrate mounting surface is a bottom portion, the heat shield plate is disposed between the bottom portion and the substrate mounting surface. Semiconductor manufacturing equipment. The semiconductor manufacturing apparatus according to claim 9 or 10,
A plurality of second heat shields are provided on the outside from the bottom of the susceptor,
2. The semiconductor manufacturing apparatus according to claim 1, wherein a distance between the plurality of heat shield plates arranged between the heating means and the susceptor is wider than a distance between the plurality of second heat shield plates. The semiconductor manufacturing apparatus according to any one of claims 9 to 11,
The semiconductor manufacturing apparatus, wherein the susceptor has one or more grooves formed in a direction perpendicular to the substrate mounting surface. The semiconductor manufacturing apparatus according to claim 12,
The groove of the susceptor is formed to extend in a direction perpendicular to the substrate mounting surface from a position where an extension line of the plate surface of the heat shield plate disposed between the heating means and the susceptor abuts. A semiconductor manufacturing apparatus. The semiconductor manufacturing apparatus according to claim 12 or 13,
The semiconductor manufacturing apparatus according to claim 1, wherein the groove of the susceptor is cylindrical.

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