JP2014201496A - Method of manufacturing semiconductor device and hydride vapor-phase growth apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make deposits formed on a substrate uniform in film thickness.SOLUTION: A method of manufacturing a semiconductor device includes a step of supplying reaction gas to a substrate 133 so as to form deposits (for example, a GaN layer 160) on the substrate 133 by a hydride vapor-phase growth method. In the step of forming the deposits, the deposits are formed in a state in which an air current change member 170 which changes a flow of the reaction gas is arranged in an area upstream from a peripheral edge part of the substrate 133 or an area nearby it in the flow direction of the reaction gas to face the peripheral edge part or the area nearby it.

Description

  The present invention relates to a semiconductor device manufacturing method and a hydride vapor phase growth apparatus.

  Nitride-based semiconductors such as gallium nitride (GaN) have a large band gap and a direct transition type between band transitions, and thus are expected to be developed into short wavelength light emitting devices and electronic devices. As a method for obtaining such an element, there is a method for producing an element structure by epitaxially growing a nitride-based semiconductor on a substrate (Patent Document 1).

  However, since there is no base substrate having a lattice constant matching that of gallium nitride (GaN), a hydride vapor phase epitaxy (HVPE) or organometallic chemical vapor phase is formed on a heterogeneous substrate such as sapphire or SiC. A GaN crystal of several μm to several hundred μm is grown in advance by using a vapor phase growth method such as a growth method (MOCVD), and a device structure is produced thereon. Among these growth methods, HVPE, in particular, has a high growth rate and is suitably used for growing a nitride-based semiconductor layer into a thick film or producing a GaN substrate.

JP 2001-181097 A

  In various vapor deposition methods, it is always required to make the thickness of the deposit formed on the substrate uniform, and the hydride vapor deposition method is no exception.

  According to the inventor's knowledge, when deposits are formed on a substrate by hydride vapor phase epitaxy, the thickness of the deposits on the peripheral edge of the substrate is thicker than the thickness of the deposits in the other regions. May occur.

  The present invention has been made in view of the above problems, and provides a method for manufacturing a semiconductor device and a hydride vapor phase growth apparatus capable of making the thickness of a deposit formed on a substrate uniform.

The present invention includes a step of supplying a reactive gas to a substrate and forming a deposit on the substrate by a hydride vapor phase growth method,
In the step of forming the deposit, the air flow changing member that changes the flow of the reaction gas is more reactive than the peripheral portion or the region near the peripheral portion or the region near the peripheral portion of the substrate. Provided is a method for manufacturing a semiconductor device, wherein the deposit is formed in a state of being disposed on the upstream side of a gas.

  According to this manufacturing method, in the state where the airflow changing member that changes the flow of the reaction gas is disposed in a region facing the peripheral portion of the substrate or a region facing the peripheral portion of the substrate, Form. Thereby, the growth of the deposit on the peripheral portion of the substrate can be moderately suppressed, and as a result, the thickness of the deposit on the substrate can be made uniform over the entire surface.

The present invention also includes a holding unit for holding the substrate so that a deposit can be formed on the substrate by a hydride vapor phase growth method.
A gas supply unit for supplying a reactive gas to the substrate held by the holding unit;
An airflow changing member for changing the flow of the reaction gas;
Have
Provided is a hydride vapor phase growth apparatus in which the airflow changing member is arranged on the upstream side of the reactive gas with respect to the peripheral edge or the vicinity thereof so as to face the peripheral edge of the substrate or the vicinity thereof. To do.

  According to the present invention, the thickness of the deposit formed on the substrate can be made uniform.

It is typical sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 1st Embodiment. 1 is a schematic cross-sectional view showing a hydride vapor phase growth apparatus according to a first embodiment. It is a figure which shows an airflow change member, Among these, (a) is the figure which looked at the airflow change member in the direction perpendicular to a board | substrate, (b) is an airflow change member in a direction parallel to the surface direction of a board | substrate. FIG. It is a figure which shows an example of the positional relationship of an airflow change member and a board | substrate when seeing an airflow change member and a board | substrate in a surface orthogonal direction with respect to a board | substrate. It is a figure which shows an example of the positional relationship of an airflow change member and a board | substrate when seeing an airflow change member and a board | substrate in a surface orthogonal direction with respect to a board | substrate. It is a figure which shows an example of the positional relationship of an airflow change member and a board | substrate when seeing an airflow change member and a board | substrate in a surface orthogonal direction with respect to a board | substrate. It is a figure which shows an example of the positional relationship of an airflow change member and a board | substrate when seeing an airflow change member and a board | substrate in a surface orthogonal direction with respect to a board | substrate. It is a typical side view of the GaN substrate manufactured by the manufacturing method of the semiconductor device concerning a 1st embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 2nd Embodiment. It is typical sectional drawing which shows the hydride vapor phase growth apparatus which concerns on 2nd Embodiment. It is a figure which shows the modification 1 of an airflow change member, and shows the positional relationship of an airflow change member and a board | substrate when seeing an airflow change member and a board | substrate in a surface orthogonal direction with respect to a board | substrate. It is a figure which shows the modification 2 of an airflow change member, and shows the positional relationship of an airflow change member and a board | substrate when seeing an airflow change member and a board | substrate in a surface orthogonal direction with respect to a board | substrate. It is a typical side view of the GaN substrate manufactured by the manufacturing method of the semiconductor device concerning a comparison form. It is a figure which shows the growth rate ratio of the deposit of the center vicinity of a board | substrate and each position on a board | substrate. It is a figure which shows the growth rate ratio of the deposit of the center vicinity of a board | substrate and each position on a board | substrate. It is a figure which shows the relationship between the distance from the outer periphery end of a board | substrate, and the growth thickness of a deposit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[First Embodiment]
FIG. 1 is a schematic cross-sectional view for explaining the method for manufacturing the semiconductor device according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing a hydride vapor phase growth apparatus (hereinafter referred to as HVPE apparatus) 120 according to the first embodiment. FIG. 8 is a schematic side view of a GaN substrate 180 manufactured by the semiconductor device manufacturing method according to the first embodiment.

  As shown in FIG. 1, in the method for manufacturing a semiconductor device according to the present embodiment, a reactive gas is supplied to a substrate 133, and a deposit (eg, GaN layer 160) is formed on the substrate 133 by hydride vapor phase epitaxy. Process. In this step, the airflow changing member 170 that changes the flow of the reactive gas is positioned more than the peripheral portion of the substrate 133 or the region in the vicinity thereof so as to face the peripheral portion of the substrate 133 or the region in the vicinity of the peripheral portion of the substrate 133. A deposit is formed in a state of being disposed upstream of the reaction gas. Thereby, a GaN substrate 180 as a semiconductor device is manufactured.

  This manufacturing method is performed using, for example, an HVPE apparatus 120 as shown in FIG. The HVPE apparatus 120 according to the present embodiment includes a holding unit (substrate holder 123) that holds the substrate 133 so that a deposit (for example, the GaN layer 160) can be formed on the substrate 133 by a hydride vapor phase growth method, and a holding unit. A gas supply unit that supplies the reaction gas to the substrate 133 held by the gas flow, and an airflow changing member 170 that changes the flow of the reaction gas. The airflow changing member 170 is arranged on the upstream side of the reaction gas with respect to the peripheral portion of the substrate 133 or the region in the vicinity thereof so as to face the peripheral portion of the substrate 133 or the region in the vicinity of the peripheral portion of the substrate 133. The gas supply unit includes, for example, a group III source gas supply unit 139 and a nitrogen source gas supply unit 137.

  The HVPE apparatus 120 includes a reaction tube 121 having a growth region 122 therein, a substrate holder 123 provided in the reaction tube 121, a group III source gas supply unit 139 for supplying a group III source gas to the growth region 122, A nitrogen source gas supply unit 137 for supplying nitrogen source gas to the growth region 122, a gas supply pipe 125 for supplying doping gas to the growth region 122, a gas exhaust pipe 135 for exhausting gas from the reaction tube 121 to the outside, Heaters 129 and 130.

  The reaction gas includes a group III source gas, a nitrogen source gas, and a doping gas. The reaction gas flows from the left side to the right side in FIG. Hereinafter, the upstream side in the reaction gas flow is simply referred to as the upstream side, and the downstream side in the reaction gas flow is simply referred to as the downstream side.

  The growth region 122 is located on the downstream side in the reaction tube 121, that is, on the right side portion in FIG. The substrate holder 123 is rotatably provided by a rotating shaft 132 in a downstream portion (hereinafter simply referred to as a downstream portion) in the reaction tube 121. The rotating shaft 132 is rotationally driven around a shaft by a rotary actuator such as a motor (not shown), and the substrate holder 123 rotates together with the rotating shaft 132. The substrate holder 123 holds the substrate 133 on the upstream surface of the substrate holder 123. Therefore, the direction of the reactive gas flow supplied to the substrate 133 includes a perpendicular direction component with respect to the substrate 133. Specifically, if the influence of the airflow changing member 170 is excluded, the reaction gas is supplied substantially perpendicular to the substrate 133. The substrate 133 held by the substrate holder 123 is located in the growth region 122. As the substrate holder 123 rotates, the substrate 133 rotates in the plate surface direction.

  The gas discharge pipe 135 is disposed on the downstream side of the substrate holder 123 and discharges the gas from the reaction pipe 121 to the outside.

  The upstream portion (hereinafter simply referred to as the upstream portion) in the reaction tube 121 is divided into two layers by a partition plate 136.

  The group III source gas supply unit 139 is disposed in the gas supply pipe 126, a group III source gas supply pipe 139a that is a lower layer than the partition plate 136 in the reaction pipe 121, and a group III source gas supply pipe 139a. The source boat 128 and the Ga material 127 are included. The source boat 128 contains a Ga raw material 127.

  The gas supply pipe 126 supplies a halogen-containing gas such as HCl gas to the group III source gas supply pipe 139a. The supply port (downstream end) of the gas supply pipe 126 is disposed upstream of the source boat 128.

  The halogen-containing gas supplied from the gas supply pipe 126 comes into contact with the surface of the Ga raw material 127 in the source boat 128 or volatilized Ga in the group III raw material gas supply unit 139, and chlorinates Ga to form Ga chloride. A group III source gas (such as GaCl) is generated. A heater 129 is disposed around the group III source gas supply unit 139, and the group III source gas supply unit 139 is maintained at a temperature of, for example, about 800 to 900 ° C. during hydride vapor phase growth.

  The group III source gas supply unit 139 supplies the group III source gas such as GaCl thus generated to the growth region 122. That is, the group III source gas is supplied to the surface of the substrate 133 held by the substrate holder 123.

  The nitrogen source gas supply unit 137 includes a gas supply tube 124 and a nitrogen source gas supply unit tube 137a that is a layer (excluding the gas supply tube 125 and its interior) above the partition plate 136 in the reaction tube 121. Including.

  The gas supply pipe 124 supplies ammonia gas to the nitrogen source gas supply section pipe 137a. This ammonia gas is decomposed by heat in the process of passing through the nitrogen source gas supply pipe 137a. A heater 129 is disposed around the nitrogen source gas supply unit 137, and the nitrogen source gas supply unit 137 is maintained at a temperature of, for example, about 800 to 900 ° C. during hydride vapor phase growth.

  The nitrogen source gas supply unit 137 supplies ammonia to the growth region 122. That is, ammonia is supplied to the surface of the substrate 133 held by the substrate holder 123.

The gas supply pipe 125 supplies a doping gas such as dichlorosilane (SiH ₂ Cl ₂ ) gas to the growth region 122. That is, the doping gas is supplied to the surface of the substrate 133 held by the substrate holder 123.

  In the growth region 122, GaN is grown on the surface of the substrate 133 (the left surface in FIG. 1). A heater 130 is disposed around the growth region 122, and the inside of the growth region 122 is maintained at a temperature of, for example, about 1000 to 1200 ° C. during hydride vapor phase growth.

  As shown in FIG. 2, the HVPE apparatus 120 according to the present embodiment includes an airflow changing member 170 that changes the flow of the reaction gas. The airflow changing member 170 is arranged on the upstream side of the peripheral edge portion of the substrate 133 or the vicinity thereof so as to face the peripheral portion of the substrate 133 or the vicinity thereof. The airflow changing member 170 is, for example, a plate-like member, and is arranged so that the plate surface is orthogonal to the flow of the reaction gas.

  3A and 3B are views showing the airflow changing member 170, in which FIG. 3A is a view of the airflow changing member 170 in a direction perpendicular to the substrate 133, and FIG. 3B is parallel to the surface direction of the substrate 133. It is the figure which looked at the airflow change member 170 in various directions.

  For example, the airflow changing member 170 is integrally provided with a fixing member 173 for fixing the airflow changing member 170 to the reaction tube 121. The airflow changing member 170 is fixed to the inner surface of the reaction tube 121 via a fixing member 173. 1 and 2, the illustration of the fixing member 173 is omitted.

  Compared with the case where the airflow changing member 170 is not used, the airflow changing member 170 changes the airflow of the reaction gas supplied to the substrate 133 so that the supply amount of the reaction gas to the peripheral portion of the substrate 133 is suppressed. . In other words, the airflow changing member 170 functions as a shielding member (or shielding plate) that shields the peripheral portion of the substrate 133 from the reactive gas flow. In the left half of FIG. 1, an example of how airflow is changed by the airflow changing member 170 is schematically indicated by arrows.

  Each of FIGS. 4 to 7 is a diagram illustrating an example of a positional relationship between the airflow change member 170 and the substrate 133 when the airflow change member 170 and the substrate 133 are viewed in a direction perpendicular to the substrate 133. In FIGS. 4, 5, and 7, the airflow changing member 170 is hatched to make the shape of the airflow changing member 170 easier to understand. 4 to 7, the illustration of the fixing member 173 is omitted.

  The substrate 133 is held by the substrate holder 123 by being fixed to one surface (the left surface in FIG. 2) of the substrate holder 123 by an adhesive 123a.

  The airflow changing member 170 is formed in, for example, a frame shape (such as a donut shape) along the peripheral edge of the substrate 133. That is, an opening 170 a is formed at the center of the airflow changing member 170.

  The substrate 133 may be configured, for example, by arranging a plurality of pieces 133a adjacent to each other in a matrix as shown in FIG. 4, or a single substrate as shown in FIGS. It may be. Further, the shape (planar shape) of the substrate 133 may be rectangular as shown in FIGS. 4 and 5, or may be circular as shown in FIGS.

For example, as shown in FIGS. 4 to 6, the airflow changing member 170 is disposed in a region facing the peripheral portion of the substrate 133.
In this case, when the airflow change member 170 and the substrate 133 are viewed in a direction perpendicular to the substrate 133, the radial direction of the substrate 133 is a region where the airflow change member 170 and the substrate 133 overlap (overlap) each other. The dimension L in FIG. 6 (FIG. 6) is preferably 20% or less of the diameter of the substrate 133 (or the outer dimension of the substrate 133). As an example, the dimension L can be about 4 mm.

  However, as shown in FIG. 7, the airflow changing member 170 may be disposed in a region facing a region near the peripheral portion of the substrate 133 (a region facing a region near the outside of the substrate 133). In this case, the airflow changing member 170 is preferably arranged in a region facing the region adjacent to the outer periphery of the substrate 133.

  However, when the airflow change member 170 and the substrate 133 are viewed in the direction perpendicular to the substrate 133, a gap may exist between the airflow change member 170 and the substrate 133. That is, when the airflow change member 170 and the substrate 133 are viewed in the direction perpendicular to the substrate 133, the airflow change member 170 and the substrate 133 do not need to overlap. That is, the inner diameter of the airflow changing member 170 may be larger than the outer diameter of the substrate 133. In this case, the dimension of the gap between the airflow changing member 170 and the substrate 133 in the radial direction of the substrate 133 is preferably, for example, 10% or less of the diameter of the substrate 133 (or the outer dimension of the substrate 133).

  The distance d1 (FIG. 1) between the airflow changing member 170 and the substrate 133 is preferably, for example, about 0 mm to 10 mm. Further, the distance d2 (FIG. 1) between the airflow changing member 170 and the GaN layer 160 (deposit) formed on the substrate 133 is preferably about 0 mm or more and 10 mm or less, for example. Therefore, the airflow changing member 170 may be disposed so as to be in contact with the substrate 133 or the GaN layer 160 or may be disposed apart from the substrate 133 or the GaN layer 160.

  Hereinafter, the steps of the semiconductor device manufacturing method according to the present embodiment will be described in detail.

  First, the substrate 133 is prepared. The substrate is, for example, a heterogeneous substrate such as a GaN substrate or sapphire on which a GaN layer is formed. When a GaN substrate is used as the substrate, a plurality of small pieces of the GaN substrate may be used.

  Next, the substrate 133 is set on the substrate holder 123 in the reaction tube 121.

Then, the inside of the reaction tube 121 is sufficiently purged by supplying N ₂ gas as a purge gas from the gas supply tubes 125 and 126. Thereafter, the gas introduced from the gas supply pipes 125 and 126 is switched to H ₂ gas (carrier gas), and the temperature of the reaction tube 121 is increased by the heater 129 and the heater 130.

When the temperature of the growth region 122 reaches a predetermined temperature (for example, 500 ° C.), NH ₃ gas is added to the gas supplied from the gas supply pipe 125. Subsequently, the temperature rise is continued until the temperature of the Ga material 127 reaches a predetermined temperature (for example, 850 ° C.) and the temperature of the growth region 122 reaches a predetermined temperature (for example, 1040 ° C.). After each temperature is stabilized, HCl gas is added to the gas supplied from the gas supply pipe 126, this gas is reacted with the Ga raw material 127, gallium chloride (GaCl) is generated, and transported to the growth region 122.

At this time, SiH ₂ Cl ₂ gas (doping gas) is supplied from the gas supply pipe 126. In the growth region 122, NH ₃ gas, GaCl, and SiH ₂ Cl ₂ gas react to grow a Si-doped GaN layer 160 (FIG. 1) on the substrate 133.

When the thickness of the GaN layer 160 reaches a predetermined thickness, the supply of SiH ₂ Cl ₂ gas from the gas supply pipe 126 and the supply of HCl gas from the gas supply pipe 126 are stopped, and the heater 129 is stopped. , 130 and the temperature of the reaction tube 121 is lowered.

Then, the NH ₃ gas is continuously supplied from the gas supply pipe 124 until the temperature of the growth region 122 decreases to around 500 ° C., and after the temperature decreases to around 200 ° C., the gas supplied from the gas supply pipe 124 is changed from NH ₃ gas to N Switch to purge gas such as ₂ gas.

  Thus, the GaN substrate 180 in which the GaN layer 160 is formed on the substrate 133 can be obtained by hydride vapor phase epitaxy. Note that the substrate 133 rotates in the plate surface direction during hydride vapor phase growth.

  In the initial stage of hydride vapor phase growth, mask growth may be performed as necessary.

  FIG. 13 is a schematic side view of a GaN substrate manufactured by the semiconductor device manufacturing method according to the comparative embodiment. The manufacturing method according to the comparative embodiment is different from the manufacturing method of the semiconductor device according to the present embodiment only in that the airflow changing member 170 is not used, and is otherwise the same as the manufacturing method of the semiconductor device according to the present embodiment. It is.

  According to the knowledge of the present inventor, when deposits such as the GaN layer 160 are formed on the substrate 133 by the hydride vapor phase growth method without using the airflow changing member 170, as shown in FIG. In some cases, the film thickness of the deposit in the portion becomes thicker than the film thickness of the deposit in the other region. That is, a doughnut-shaped ridge along the peripheral edge of the substrate 133 may be generated in the deposit. The occurrence of the raised portions means that the film thickness of the deposit on the substrate 133 is not uniform, that is, the flatness of the deposit is deteriorated. Further, in this raised portion, a growth failure such as the growth of polycrystals or polarity inversion crystals may occur, and the film quality of the deposit may become non-uniform.

  In view of such circumstances, in the present embodiment, the hydride vapor phase growth method is performed in a state where the airflow changing member 170 that changes the flow of the reaction gas is disposed so as to face the peripheral portion of the substrate 133 or a region in the vicinity thereof. I do. For this reason, it is possible to moderately suppress the growth of deposits such as the GaN layer 160 in the peripheral portion of the substrate 133. As a result, for example, as shown in FIG. 8, the film thickness of the deposit such as the GaN layer 160 on the substrate 133 can be made uniform over the entire surface. As a result, the flatness of the deposit can be improved, and the occurrence of growth failure such as the occurrence of polycrystals or polarity reversal crystals in the deposit can be suppressed, so that the film quality of the deposit can be made uniform.

  According to the first embodiment as described above, the airflow changing member 170 that changes the flow of the reaction gas is a region facing the peripheral portion of the substrate 133 or a region facing the peripheral portion of the substrate 133. A deposit is formed in the state of being arranged in the above. Thereby, the growth of the deposit on the peripheral portion of the substrate 133 can be moderately suppressed, and as a result, the thickness of the deposit on the substrate 133 can be made uniform over the entire surface.

  By using the airflow changing member 170 formed in a frame shape along the peripheral edge of the substrate 133, the growth of deposits on the peripheral edge of the substrate 133 can be more reliably suppressed.

  FIG. 11 is a diagram showing a first modification of the airflow changing member 170, and FIG. 12 is a diagram showing a second modification of the airflow changing member 170. 11 and 12 show the positional relationship between the airflow change member 170 and the substrate 133 when the airflow change member 170 and the substrate 133 are viewed in the direction perpendicular to the substrate 133, respectively.

  As shown in FIG. 11, in the first modification, the airflow changing member 170 is not an integral frame-shaped member, but has a divided structure including a plurality of portions 171. The plurality of portions 171 are each formed in an arc shape, for example. For example, the plurality of portions 171 are arranged along a region facing the peripheral portion of the substrate 133 or a region in the vicinity thereof. The portions 171 are individually fixed to the inner surface of the reaction tube 121 via a fixing member 173 (see FIG. 3; not shown in FIG. 11). Even when the airflow changing member 170 according to Modification 1 is used, the same effect as described above can be obtained. In particular, substantially the same effect as described above can be obtained by rotating the substrate 133 in the plate surface direction during hydride vapor phase growth.

  As shown in FIG. 12, in the second modification, the airflow changing member 170 is not a frame-shaped member, but is arranged in at least a part of a region facing the peripheral portion of the substrate or a region in the vicinity thereof. The airflow changing member 170 can be, for example, a single arc-shaped portion as shown in FIG. However, the shape of the airflow changing member 170 is arbitrary, and may be, for example, a rectangular shape or a circular shape. In FIG. 12, the illustration of the fixing member 173 (see FIG. 3) is omitted. Even when the airflow changing member 170 according to Modification 2 is used, substantially the same effect as described above can be obtained by rotating the substrate 133 in the plate surface direction during hydride vapor phase growth.

[Second Embodiment]
FIG. 9A and FIG. 9B are schematic cross-sectional views for explaining the method for manufacturing a semiconductor device according to the second embodiment. This manufacturing method differs from the manufacturing method of the semiconductor device according to the first embodiment in the points described below, and is otherwise the same as the manufacturing method of the semiconductor device according to the first embodiment. It is configured. In FIG. 9, illustration of the fixing member 173 (see FIG. 3) is omitted.

  In the present embodiment, the step of forming a deposit such as the GaN layer 160 on the substrate 133 includes a step of changing the distance d1 between the peripheral edge of the substrate 133 and the airflow changing member 170.

  In the step of changing the distance d1 between the peripheral edge of the substrate 133 and the airflow changing member 170, for example, as shown in FIGS. 9A and 9B, the film thickness of the GaN layer 160 on the substrate 133 is increased. As the distance increases, the distance d1 between the substrate 133 and the airflow changing member 170 is increased.

  More specifically, for example, as shown in FIGS. 9A and 9B, the distance d2 between the surface of the GaN layer 160 on the substrate 133 and the airflow changing member 170 is kept constant. As described above, the step of changing the distance d1 between the peripheral portion of the substrate 133 and the airflow changing member 170 is performed. That is, from the state where the film thickness of the GaN layer 160 on the substrate 133 is T1 (FIG. 9A) to the state where the film thickness is increased by ΔT to T2 (in the process of becoming the state of FIG. 9B). ) Increase the distance d1 between the surface of the substrate 133 and the airflow changing member 170 by ΔT.

  FIG. 10 is a schematic cross-sectional view showing an HVPE apparatus 220 according to the second embodiment. The HVPE device 220 differs from the HVPE device 120 according to the first embodiment in the points described below, and is otherwise configured in the same manner as the HVPE device 120 according to the first embodiment. Yes. In FIG. 10, the illustration of the fixing member 173 (see FIG. 3) is omitted.

  As shown in FIG. 10, the HVPE apparatus 220 includes a distance changing mechanism 150 that changes the distance d1 between the airflow changing member 170 and the peripheral portion of the substrate 133, and a control unit 155 that controls the operation of the distance changing mechanism 150. Have.

  The distance changing mechanism 150 changes the distance d1 by moving the substrate holder 123 (holding unit) relative to the airflow changing member 170, for example. The distance changing mechanism 150 has an actuator (not shown) such as a motor. The control unit 155 changes the distance d1 between the peripheral portion of the substrate 133 and the operation of the actuator. That is, for example, from the state where the film thickness of the GaN layer 160 on the substrate 133 is T1 (FIG. 9A) to the state where the film thickness is increased by ΔT and becomes T2 (state of FIG. 9B). In the process), the substrate holder 123 is moved away from the airflow changing member 170 by ΔT. The distance changing mechanism 150 is supported by the rotating shaft 132 and the rotating shaft 132 by, for example, holding the protruding portion 132a protruding to the outside of the reaction tube 121 on the rotating shaft 132 and moving the protruding portion 132a in the axial direction. The substrate holder 123 thus moved and the substrate 133 held by the substrate holder 123 are moved relative to the airflow changing member 170. In FIG. 10, the illustration of a rotation mechanism (including a rotation actuator) that rotates the rotation shaft 132 is omitted.

  Note that the distance changing mechanism 150 may change the distance d1 gradually and gradually, or may change it stepwise.

  According to the second embodiment as described above, the step of forming the deposit such as the GaN layer 160 on the substrate 133 includes the step of changing the distance d1 between the peripheral portion of the substrate 133 and the airflow changing member 170. . Thereby, the distance d1 can be set to an appropriate distance, and the deposit such as the GaN layer 160 can be favorably formed on the substrate 133.

  More specifically, for example, the amount of change in the distance d2 can be suppressed by increasing the distance d1 as the thickness of the deposit on the substrate 133 increases. Therefore, since the change with time of the state of the reactive gas flow on the surface of the deposit can be suppressed, the deposit such as the GaN layer 160 can be favorably formed on the substrate 133.

  More specifically, for example, by performing the step of changing the distance d1 so that the distance d2 is kept constant, it is possible to further suppress the temporal change in the state of the reactive gas flow on the surface of the deposit. Therefore, a deposit such as the GaN layer 160 can be formed on the substrate 133 more satisfactorily.

  In the above description, the HVPE apparatus is a horizontal type, but the HVPE apparatus may be a vertical type.

  Further, in the above description, an example in which the GaN layer 160 is grown on the substrate 133 by the hydride vapor phase growth method has been described. However, a GaN-based semiconductor layer (AlGaN layer, InGaN layer, etc.) other than the GaN layer may be grown. .

  In the above description, the substrate 133 and the airflow change member 170 are arranged so that the substrate 133 and the opening 170a are concentric with each other when the airflow change member 170 and the substrate 133 are viewed in a direction perpendicular to the substrate 133. An example of arranging the above has been described. However, the centers of the substrate 133 and the airflow change member 170 may be offset from each other, and the arrangement of the substrate 133 and the airflow change member 170 may be adjusted so that only a part of the substrate 133 in the circumferential direction overlaps the airflow change member 170. .

  In the above description, an example in which the number of substrate holders 123 is one has been described. However, the number of substrate holders 123 is two or more. Each substrate holder 123 holds a substrate 133, and a hydride vapor phase is formed on each substrate 133. A deposit may be formed by a growth method. An airflow changing member 170 is provided for each substrate 133 (each substrate holder 123).

  In the second embodiment, the distance d1 may be changed by moving the airflow changing member 170 instead of moving the substrate holder 123. Further, the distance d1 may be changed by moving both the substrate holder 123 and the airflow changing member 170.

In the second embodiment, the distance d1 is changed in accordance with a change in outer shape such as an apparent thickness increase due to polycrystalline deposition on the airflow change member 170 or an apparent diameter reduction of the opening 170a. You may let them. The change of the distance d1 in this case may be performed gradually and gradually as in the second embodiment.
Specifically, for example, the distance d1 is maintained so that the distance between the deposit attached to the surface of the airflow change member 170 on the substrate 133 side and the surface of the GaN layer 160 on the substrate 133 is kept constant. Can be changed.

A GaN substrate having a diameter of 54 mm was prepared as the substrate 133. The substrate 133 was attached to the substrate holder 123 using an alumina-based adhesive, and was naturally dried and dried in an electric furnace at 150 ° C. for 1 hour.
Next, the substrate 133 affixed to the substrate holder 123 and the airflow changing member 170 having an inner diameter of various set values (described later), an outer diameter of 67 mm, and a thickness of 3 mm are connected to the substrate 133 and the airflow changing member 170. It arrange | positioned in the HVPE apparatus 120 so that a space | interval might become predetermined distance (after-mentioned).
The growth conditions are a growth temperature of 1075 ° C., a carrier gas flow rate ratio (N ₂ / (N ₂ + H ₂ )) supplied with dichlorosilane as a doping gas via a gas supply pipe 125 0.25, and a gas supply pipe 126. The flow rate of HCl supplied onto the Ga raw material 127 via 200 was 200 cc / min, and the flow rate of NH ₃ supplied via the gas supply pipe 124 was 3000 cc / min.

  Each growth condition is as follows.

  Comparative Example 1: No airflow change member 170, growth time 15 min

  Example 1: Inner diameter 54 mm (L = 0 mm, overlap area ratio 0%) of airflow changing member 170, distance from substrate 133 (distance d1): 5 mm, growth time 15 min

  Example 2: The inner diameter of the airflow changing member 170 is 54 mm (L = 0 mm, the overlap area ratio is 0%), the distance from the substrate 133 (distance d1): 2 mm, and the growth time is 15 min.

  Example 3: The inner diameter of the airflow changing member 170 is 54 mm (L = 0 mm, the overlap area ratio is 0%), the distance from the substrate 133 (distance d1): 1 mm, and the growth time is 15 min.

  Example 4: The inner diameter of the airflow changing member 170 is 50 mm (L = 2 mm, the overlap area ratio is 14.3%), the distance from the substrate 133 (distance d1): 5 mm, and the growth time is 15 min.

  Example 5: The inner diameter of the airflow changing member 170 is 50 mm (L = 2 mm, the overlap area ratio is 14.3%), the distance from the substrate 133 (distance d1): 2 mm, and the growth time is 15 min.

  Example 6: The inner diameter of the airflow changing member 170 is 50 mm (L = 2 mm, the overlap area ratio is 14.3%), the distance from the substrate 133 (distance d1): 1 mm, and the growth time is 15 min.

  Comparative Example 2: No airflow change member 170, growth time 5h, position of substrate 133 is constant

  Example 7: Internal diameter of airflow changing member 170 50 mm (L = 2 mm, overlap area ratio 14.3%), initial value of distance (distance d1) from substrate 133: 2.5 mm, growth time 18 h, d1 is 0 Increased at a rate of 5 mm / h

  The overlap area ratio is the area of the region where the airflow change member 170 and the substrate 133 overlap (overlap) each other when the airflow change member 170 and the substrate 133 are viewed in a direction perpendicular to the substrate 133. When the area of the substrate 133 is S1, the ratio is obtained by (S2 / S1) × 100 (%).

For Comparative Example 1 and Examples 1 to 3, the film thickness of the deposit (GaN layer 160) grown on the substrate 133 was measured, and the growth rate near the center of the substrate 133 was used as a reference. The growth rate ratio (growth rate at each location / growth rate near the center) at each location was determined. The result is shown in FIG. That is, FIG. 14 is a graph showing the growth rate ratio of the deposit between the vicinity of the center of the substrate 133 and each position on the substrate 133 in each of Comparative Example 1 and Examples 1 to 3. In FIG. 14, the horizontal axis is the distance (mm) from the outer peripheral edge of the substrate 133, and the vertical axis is the growth rate ratio.
As shown in FIG. 14, in the case of Comparative Example 1 (when there is no airflow changing member 170), the growth rate at the outer peripheral edge of the substrate 133 protrudes faster and the growth rate at the outer peripheral edge of the substrate 133 is higher than that of the substrate 133. It is 2.3 times the growth rate near the center.
On the other hand, in Examples 1 to 3 using the airflow changing member 170 having an inner diameter of 54 mm, the rapid growth rate increase near the outer peripheral edge of the substrate 133 is suppressed, and the growth speed at the outer peripheral edge of the substrate 133 is It can be seen that the growth rate is in the range of 0.7 to 1.7 times the growth rate in the vicinity of the center.
Further, when the distance d1 between the substrate 133 and the airflow changing member 170 is reduced, the growth rate near the outer peripheral edge of the substrate 133 decreases, and when the distance is increased, the growth rate near the outer peripheral edge of the substrate 133 tends to increase. I understand. For this reason, it was found that the growth rate distribution can be optimized by appropriately adjusting the distance d1.

For Examples 4 to 6 using the airflow changing member 170 having an inner diameter of 50 mm, the film thickness of the deposit (GaN layer 160) grown on the substrate 133 was measured in the same manner as in Examples 1 to 3, and the vicinity of the center of the substrate 133 was measured. A reference growth rate ratio (growth rate at each position / growth rate near the center) was determined. The result is shown in FIG. That is, FIG. 15 is a diagram showing the growth rate ratio of the deposit between the vicinity of the center of the substrate 133 and each position on the substrate 133 in each of Examples 4 to 6. In FIG. 15, the horizontal axis represents the distance (mm) from the outer peripheral edge of the substrate 133, and the vertical axis represents the growth rate ratio.
As shown in FIG. 15, when the airflow changing member 170 having an inner diameter of 50 mm is used, the growth rate near the outer peripheral edge of the substrate 133 is compared with the case where the airflow changing member 170 having an inner diameter of 54 mm is used (Examples 1 to 3). The increase is further suppressed, and it can be seen that the growth rate at the outer peripheral edge of the substrate 133 is in the range of 0.5 to 1.4 times the growth rate near the center of the substrate 133.
In the case where the inner diameter of the airflow changing member 170 is 50 mm, as in the case where the inner diameter of the airflow changing member 170 is 54 mm, if the distance d1 between the substrate 133 and the airflow changing member 170 is reduced, the growth near the outer peripheral edge of the substrate 133 is performed. It was confirmed that the growth rate in the vicinity of the outer peripheral edge of the substrate 133 increased as the rate decreased and moved away.

  From the results of FIGS. 14 and 15, the growth rate distribution becomes convex (in the periphery of the substrate 133) by reducing the inner diameter of the airflow changing member 170 or shortening the distance d1 between the airflow changing member 170 and the substrate 133. It was confirmed that this led to a slowdown in growth rate.

FIG. 16 is a diagram illustrating the relationship between the distance from the outer peripheral edge of the substrate 133 and the growth thickness of the deposit in each of Comparative Example 2 and Example 7. In FIG. 16, the horizontal axis is the distance (mm) from the outer peripheral edge of the substrate 133, and the vertical axis is the growth thickness (growth film thickness).
In Comparative Example 2, the substrate 133 was grown at a constant position without using the airflow changing member 170. As shown in FIG. 16, in Comparative Example 2, the GaN layer 160 grows flat near the center of the substrate 133, but the peripheral portion of the substrate 133 (the portion along the outer peripheral arc of the substrate 133) has a width of about 1 mm. A sharpened GaN layer 160 having a height of about 1 mm (having a sharpened tip in the height direction) was formed. Moreover, the location where the polycrystal was produced | generated at the front-end | tip of the sharpened GaN layer 160 was also confirmed. When the growth thickness of the GaN layer 160 was measured, the growth thickness near the center was 0.89 mm, the maximum growth thickness at the peripheral edge (height from the interface to the apex of the sharp edge) was 1.85 mm, and the substrate The maximum value of the growth rate ratio between the vicinity of the center of 133 and the peripheral portion was 1.85 / 0.89 = 2.08.
On the other hand, in Example 7, there was no sharp shape in the outer peripheral edge part of the growth surface, and it grew flat. When the growth thickness was measured, the growth thickness near the center was 3.21 mm, the growth thickness at the outer peripheral edge was 3.27 mm, and the growth rate ratio was 3.27 / 3.21 = 1.02. It was. Further, even at the thickest growth thickness, it is 3.53 mm, and the maximum value of the growth rate ratio is 3.53 / 3.21 = 1.10. That is, it was confirmed that the GaN layer 160 is substantially flat.
As the thickness of the GaN layer 160 on the substrate 133 increases, not only the distance d1 between the airflow changing member 170 and the substrate 133 decreases, but also the appearance of the airflow changing member 170 due to the deposition of GaN polycrystals on the airflow changing member 170. The upper inner diameter is also smaller. As in Example 7, the flat GaN layer 160 could be grown by increasing the distance d1 between the airflow changing member 170 and the substrate 133 at a rate of 0.5 mm / h.

120 Hydride vapor phase growth equipment (HVPE equipment)
121 Reaction tube 122 Growth region 123 Substrate holder 123a Adhesive 124 Gas supply tube 125 Gas supply tube 126 Gas supply tube 127 Ga raw material 128 Source boat 129 Heater 130 Heater 132 Rotating shaft 132a Protrusion 133 Substrate 133a Piece 135 Gas discharge tube 136 Partition plate 137 Nitrogen source gas supply unit 137a Nitrogen source gas supply unit tube 139 Group III source gas supply unit 139a Group III source gas supply tube 150 Distance change mechanism 155 Control unit 160 GaN layer 170 Airflow change member 170a Opening 171 Portion 173 Fixed member 180 GaN substrate 220 Hydride vapor phase growth equipment (HVPE equipment)

Claims (11)

Supplying a reaction gas to the substrate, and forming a deposit on the substrate by a hydride vapor phase growth method;
In the step of forming the deposit, the air flow changing member that changes the flow of the reaction gas is more reactive than the peripheral portion or the region near the peripheral portion or the region near the peripheral portion of the substrate. A method for manufacturing a semiconductor device, wherein the deposit is formed in a state of being disposed upstream of a gas.   The method of manufacturing a semiconductor device according to claim 1, wherein the airflow change member is formed in a frame shape along a peripheral edge portion of the substrate.   The method of manufacturing a semiconductor device according to claim 1, wherein the step of forming the deposit includes a step of changing a distance between a peripheral edge portion of the substrate and the airflow change member.   The step of changing the distance between the peripheral portion of the substrate and the airflow changing member increases the distance between the substrate and the airflow changing member as the film thickness of the deposit on the substrate increases. Item 4. A method for manufacturing a semiconductor device according to Item 3.   5. The step of changing the distance between the peripheral portion of the substrate and the airflow change member so that the distance between the surface of the deposit on the substrate and the airflow change member is kept constant. The manufacturing method of the semiconductor device as described in any one of.   6. The method of manufacturing a semiconductor device according to claim 1, wherein a direction of an air flow of a reactive gas supplied to the substrate includes a perpendicular direction component with respect to the substrate. A holding unit for holding the substrate so that a deposit can be formed on the substrate by a hydride vapor phase growth method;
A gas supply unit for supplying a reactive gas to the substrate held by the holding unit;
An airflow changing member for changing the flow of the reaction gas;
Have
The hydride vapor phase growth apparatus, wherein the airflow changing member is disposed on the upstream side of the reactive gas with respect to the peripheral edge or the vicinity thereof so as to face the peripheral edge of the substrate or the vicinity thereof.   The hydride vapor phase growth apparatus according to claim 7, wherein the airflow changing member is formed in a frame shape along the peripheral edge of the substrate.   The hydride vapor phase growth apparatus according to claim 7 or 8, further comprising a distance changing mechanism that changes a distance between the airflow changing member and a peripheral portion of the substrate.   The hydride vapor phase growth apparatus according to claim 9, wherein the distance changing mechanism changes the distance by moving the airflow changing member relative to the holding unit.   The hydride vapor phase growth apparatus according to any one of claims 7 to 10, wherein a direction of a flow of a reactive gas supplied to the substrate by the gas supply unit includes a perpendicular direction component with respect to the substrate.

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