JP2010067775A - Vapor phase growth method and vapor phase growth device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor phase growth method and a vapor phase growth device capable of unifying the composition of a film to be formed. <P>SOLUTION: The vapor phase growth method includes: a step of preparing a substrate 20 having a main surface 20a; and a step of forming a film on the main surface 20a by supplying source gas in a direction along the main surface 20a and heating a substrate 20. In the step of forming a film, source gas G1 containing first source gas containing a group V element and second source gas containing a group III element is supplied from a first gas supply section 11a positioned at a side close to the main surface 20a onto the main surface 20a in a direction D vertical to the main surface 20a of the substrate 20. At the same time, source gas G2 containing third source gas containing a group III element is supplied onto the main surface 20a from a second gas supply section 11b positioned at a side farther from the main surface 20a than the first gas supply section 11a in the direction D vertical to the main surface 20a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vapor phase growth method and a vapor phase growth apparatus, and more particularly to a vapor phase growth method and a vapor phase growth apparatus for forming a III-V compound semiconductor film by a metal organic vapor phase growth method.

  The metal organic chemical vapor deposition (MOCVD) method is one of typical vapor deposition methods. For example, a group III organic metal is vaporized and thermally decomposed on the substrate surface. This is a method of forming a film by reacting with a group V gas. Since this method can control the film thickness and composition and is excellent in productivity, it is widely used as a film forming technique when manufacturing a semiconductor device.

  An MOCVD apparatus used for the MOCVD method includes a chamber, a susceptor disposed in the chamber, and a passage for flowing a reaction gas to the surface of the substrate. In the MOCVD apparatus, a substrate is placed on a susceptor, the substrate is heated to an appropriate temperature, and an organic metal gas is introduced into the substrate surface through a passage to form a film. Here, in order to make the thickness of the film to be formed uniform, the MOCVD apparatus is required to flow the reaction gas uniformly along the substrate surface. In the MOCVD apparatus, various passage shapes have been proposed in order to flow the reaction gas uniformly along the substrate surface.

As a conventional MOCVD apparatus, for example, Japanese Unexamined Patent Application Publication No. 2008-16609 (Patent Document 1) discloses a MOCVD apparatus including a susceptor for placing a substrate and a passage for introducing a reaction gas into the substrate. ing. The passage is a horizontal three-layer flow system and extends in parallel to the mounting surface of the susceptor. A purge gas such as H ₂ (hydrogen) gas or N ₂ (nitrogen) gas is used at a position farthest from the substrate in the passage, and trimethylgallium (TMG), trimethylindium (TMI), trimethylaluminum is positioned closer to the substrate. A mixed gas of an organometallic gas containing a group III element such as (TMA) and a carrier gas such as H ₂ gas or N ₂ gas is used, and NH ₃ is positioned closer to the substrate, that is, closer to the substrate. A mixed gas of a gas containing a group V element such as (ammonia) and a carrier gas such as H ₂ gas or N ₂ gas is used. When these gases are introduced into the MOCVD apparatus, the reaction gases mixed with each other are introduced and diffused parallel to the mounting surface in the susceptor and heated by the susceptor. Organometallic gas contained in the mixed gas becomes decomposed by heating the intermediate reaction member, a nitride semiconductor react with NH ₃ gas. As a result, a nitride semiconductor layer is formed on the surface of the substrate.
JP 2008-16609 A

  However, in the MOCVD apparatus disclosed in Patent Document 1, the conditions of the reaction gas supplied on the upstream side and the downstream side of the susceptor are different. For this reason, the problem that the composition of the film | membrane formed into a film is not uniform has arisen.

  Accordingly, an object of the present invention is to provide a vapor phase growth method and a vapor phase growth apparatus that can make the composition of a film to be formed uniform.

  As a result of diligent research, the inventor has found that the composition of the conventional film formed is not uniform so that the source gas containing a group III element such as an organometallic gas increases monotonously from upstream to downstream. I found out that it was due to being supplied. That is, since the source gas containing a group III element cannot sufficiently diffuse the source gas containing a group V element on the upstream side, the source gas containing a group III element cannot sufficiently reach the substrate. For this reason, the group III element is not sufficiently supplied on the upstream side and is supplied excessively on the downstream side. As a result, there is a large difference in the amount of group III element incorporated into the film to be formed, that is, the composition of the group III element between the upstream side and the downstream side.

  Therefore, the vapor phase growth method of the present invention includes a step of preparing a substrate having a main surface and a film on the main surface of the substrate by heating the substrate while supplying a source gas in a direction along the main surface of the substrate. Forming a step. In the step of forming the film, the first source gas containing the group V element and the second source gas containing the group III element from the first gas supply unit located on the side close to the main surface in the direction perpendicular to the main surface of the substrate. From the second gas supply unit located on the side farther from the main surface than the first gas supply unit in the direction perpendicular to the main surface of the substrate A source gas containing a third source gas containing an element is supplied onto the main surface of the substrate.

  The vapor phase growth apparatus of the present invention includes a reaction chamber, a susceptor on which a substrate having a main surface disposed inside the reaction chamber is placed, a heater that heats the substrate via the susceptor, And a source gas supply unit that supplies source gas from a direction along the main surface. The source gas supply unit is located on the side close to the main surface in a direction perpendicular to the main surface of the substrate, and reacts a source gas containing a first source gas containing a group V element and a second source gas containing a group III element. A first gas supply unit that supplies the chamber, and a source gas that includes a third source gas that includes a group III element and is located farther from the main surface than the first gas supply unit in a direction perpendicular to the main surface of the substrate And a second gas supply part for supplying the reaction chamber to the reaction chamber.

  According to the vapor phase growth method and the vapor phase growth apparatus of the present invention, the first source gas including the group V element and the group III element including the group III element are supplied from the first gas supply unit located on the side close to the main surface of the substrate. A source gas containing two source gases is supplied onto the main surface of the substrate, from a second gas supply unit located on a side farther from the main surface than the first gas supply unit in a direction perpendicular to the main surface of the substrate; A third source gas containing a group III element is supplied. Thereby, the distance which the 2nd source gas containing a group III element diffuses to the main surface of the substrate located in the upper stream side can be shortened. For this reason, the second source gas containing the group III element can be sufficiently supplied also to the main surface of the substrate located on the upstream side. In addition, since the third source gas containing the group III element is also supplied from the second gas supply unit, the third source gas containing the group III element is sufficiently supplied also to the main surface of the substrate located on the downstream side. be able to. Therefore, the concentration of the group III element in the film formed from the upstream to the downstream can be made uniform. As a result, the composition of the film to be formed can be made uniform.

  Preferably, in the vapor phase growth method, in the step of forming the film, the source gas is supplied from the first and second gas supply units, and from the second gas supply unit in a direction perpendicular to the main surface of the substrate. A gas that does not contain a raw material is further supplied from a third gas supply unit located on the side far from the main surface.

  A gas that does not contain the raw material supplied from the third gas supply unit is supplied to the farthest side from the main surface of the substrate. Thereby, it can suppress that 1st and 2nd source gas is supplied to the opposing surface of a susceptor in a reaction chamber. For this reason, it can suppress that a film | membrane accumulates on the opposing surface of the susceptor of a reaction chamber.

Preferably, in the vapor phase growth method, in the step of forming the film, Al _x Ga _y In _(1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) is used as the film. Form.

  Conventionally, a film containing at least one of Al (aluminum), Ga (gallium), and In (indium) is likely to have a difference in the amount of group III element incorporated. However, according to the present invention, the composition of the nitride compound semiconductor is improved by supplying a gas containing at least one of Al, Ga, and In from the first gas supply unit as the second source gas. Thus, a film can be formed.

Preferably in the vapor phase growth method, in the step of forming the film, Al _x Ga _y N as film (0 <x <1,0 <y <1, x + y = 1), Ga y In (1-y) N (0 <y <1) and Al _x In _(1-x) N (0 <x <1) are formed.

  Thus, by supplying a gas containing at least one of Al, Ga and In as the second source gas from the first gas supply unit, the composition of the ternary nitride-based compound semiconductor can be improved. A film can be formed.

Preferably, in the above vapor deposition method, in the step of forming the film, forming a _{Ga y In (1-y)} N (0 <y <1) as a film.

  Conventionally, when forming a film containing In, it has been particularly difficult to control the amount of In taken in. However, according to the present invention, a film containing In uniformly can be formed by supplying a gas containing In as the second source gas from the first supply unit.

  Preferably, in the vapor phase growth method, in the step of forming the film, the group III element contained in the second source gas and the group III element contained in the third source gas are the same.

  Thereby, when forming the film incorporating the same group III element, the second source gas can be supplied mainly to the upstream side, and the third source gas can be supplied mainly to the downstream side. Thereby, a film having a more uniform composition can be formed.

  In the vapor phase growth method, preferably, in the step of forming the film, the number of group III elements contained in the second source gas is less than the type of group III elements contained in the third source gas.

  When a film containing two or more group III elements is grown, the composition distribution of the film to be formed can be adjusted even if there is a difference in thermal decomposition depending on the type of group III element.

  Preferably, in the vapor phase growth method, in the step of forming the film, the second source gas is more easily pyrolyzed than the third source gas.

  The second source gas has a shorter distance to be heated by the susceptor than the third source gas. Therefore, when the second source gas is more easily pyrolyzed than the third source gas, the second source gas can easily supply the group III element upstream, and the third source gas can supply the group III element downstream. It becomes easy. Thereby, a film having a more uniform composition can be formed.

  Preferably, in the vapor phase growth method, in the forming step, the second raw material gas includes trimethylindium, and the third raw material gas includes trimethylgallium and trimethylindium.

Thereby, Ga and In composition of (1-y) to the more uniform _{y In (1-y) N} (0 <y <1) can be formed.

  Preferably, in the vapor phase growth apparatus, the source gas supply unit is a branch pipe for supplying a source containing a group III element as the second and third source gases to the first and second gas supply units, respectively. And a switching unit that is provided in the branch pipe and for selecting supply to the first and second gas supply units.

  Thereby, it can supply to the 1st and 2nd gas supply part from one raw material container. For this reason, since the number of raw material containers can be reduced, a more simplified vapor phase growth apparatus can be realized.

  Preferably, the vapor phase growth apparatus further includes a rotation mechanism for rotating the susceptor.

  By forming the film while rotating the susceptor by the rotation mechanism, the difference in the supply amount of the first and second source gases supplied to the upstream side and the downstream side can be further alleviated. For this reason, a film having a more uniform composition can be formed.

  As described above, according to the vapor phase growth method and vapor phase growth apparatus of the present invention, the composition of the film to be formed can be made uniform.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a cross-sectional view showing a configuration of an MOCVD apparatus as a vapor phase growth apparatus according to an embodiment of the present invention. FIG. 2 is a schematic view of the vicinity of the source gas supply unit of FIG. Referring to FIGS. 1 and 2, MOCVD apparatus 1 a in the present embodiment includes chamber 3 as a reaction chamber, susceptor 5, heater 9, and source gas supply unit 11. A susceptor 5, a heater 9, and a source gas supply unit 11 are disposed in the chamber 3. The source gas supply unit 11 extends in the horizontal direction in FIG. 1, and the placement surface (upper surface in FIG. 1) of the susceptor 5 faces inside the source gas supply unit 11.

  The susceptor 5 is disposed inside the chamber 3. The susceptor 5 has a disk shape and is disposed on a heater 9 having a disk shape. A rotating shaft 13 serving as a rotating mechanism is attached to the lower part of the susceptor 5, so that the susceptor 5 can rotate with the mounting surface facing the inside of the source gas supply unit 11. A plurality of grooves 7 having a circular shape when viewed in plan are formed on the mounting surface of the susceptor 5. Each of the substrates 20 having the main surface 20a is placed in each of the grooves 7, whereby the substrate 20 is heated. For example, seven grooves 7 are formed on the mounting surface of the susceptor 5, and a circular substrate 20 is mounted in each of these grooves 7. The heater 9 heats the substrate 20 via the susceptor 5.

  The source gas supply unit 11 supplies source gases G 1 and G 2 to the chamber 3 from the direction along the main surface 20 a of the substrate 20. That is, the source gas supply unit 11 is a passage for flowing a reaction gas composed of the source gases G1, G2 and the gas G3 to the main surface 20a of the substrate 20. The source gas supply unit 11 of the present embodiment extends parallel to the mounting surface of the susceptor 5 and is rectangular when viewed in a plane perpendicular to the source gas flow direction (the direction from the left side to the right side in FIG. 1). The cross-sectional shape is as follows. The source gas supply unit 11 is a horizontal three-layer flow system, and the first gas supply unit 11a, the second gas supply unit 11b, and the third gas supply unit 11c are arranged upstream (left side in FIG. 1). Including.

  The first gas supply unit 11 a is located on the side close to the main surface 20 a in the direction D perpendicular to the main surface 20 a of the substrate 20. The second gas supply unit 11b is located on the side farther from the main surface 20a than the first gas supply unit 11a in the direction D perpendicular to the main surface 20a of the substrate 20. The third gas supply unit 11 c is located on the side farther from the main surface 20 a than the second gas supply unit 11 b in the direction D perpendicular to the main surface 20 a of the substrate 20. That is, in the direction D perpendicular to the mounting surface of the susceptor 5, the first gas supply unit 11a, the second gas supply unit 11b, and the third gas supply unit 11c are closer to the mounting surface of the susceptor 5 in this order. Note that the positions of the outlets of the source gases G1, G2 and the gas G3 of the first to third gas supply units 11a to 11c are the directions along the main surface 20a of the substrate 20, that is, the source gases G1, G2 and the gas G3. As shown in FIG. 1, the flow directions may be different or the same.

The first gas supply unit 11a supplies the chamber 3 with a source gas G1 containing a first source gas containing a group V element and a second source gas containing a group III element. As the raw material gas G1, it is possible to use a gas containing a Group V element such as NH ₃ gas, H ₂ gas, a mixed gas of a carrier gas such as N ₂ gas. The second gas supply unit 11b supplies the chamber 3 with a source gas G2 containing a third source gas containing a group III element. As a source gas G2, a mixed gas of trimethyl gallium (TMG), an organometallic gas containing a group III element such as trimethyl indium (TMI), or trimethylaluminum (TMA), H ₂ gas, a carrier gas such as N ₂ gas Can be used. The 3rd gas supply part 11c supplies gas G3 which does not contain a raw material. As the gas G3, a purge gas that suppresses the reaction of the source gases G1 and G2 is preferably used. As the gas G3, a carrier gas such as H ₂ gas or N ₂ gas can be used.

As shown in FIG. 2, the source gas supply unit 11 includes containers 101 to 107 that accommodate various gases therein. The container 101 is a first source gas containing a group V element such as NH ₃ . The containers 102 and 103 are carrier gases such as N ₂ and H ₂ . Vessels 104 to 106 are second and third source gases containing group V elements such as TMG, TMI, and TMA, respectively. The container 107 is a gas serving as a dopant, such as cyclopentadienyl magnesium (Cp ₂ Mg). A mass flow controller for controlling the flow rate is installed in each raw material gas, carrier gas, and dopant gas pipe, but is omitted in the figure.

  The source gas supply unit 11 is provided with pipes 111 to 113 for supplying the gas accommodated in the containers 101 to 103 to the first to third gas supply units 11a to 11c, respectively.

  Connected to containers 104 to 106 to supply second and third source gases containing group III elements contained in containers 104 to 106 to first and second gas supply units 11a and 11b, respectively. Branched pipes 114 to 116 are provided. Further, a branch pipe 117 connected to the container 107 is provided in order to supply the dopant gas accommodated in the container 107 to the first or second gas supply unit 11a, 11b, respectively. The branch pipes 114 to 117 are connected to pipes 111 and 112 for supplying gas to the first and second gas supply units 11a and 11b. The branch pipes 114 to 117 include first and second gas supply parts 11a and 11b, and switching parts 134a to 134c, 135a to 135c, and 136a to 136c for arbitrarily selecting supply to the vent pipe 120, 137a to 137c are provided. The organometallic raw material is supplied by bubbling the carrier gas to the container, but in order to keep the container temperature constant, a pressure control mechanism is installed to keep the container pressure constant. Is done. These are omitted in the figure.

  FIG. 3 is a cross-sectional view showing the configuration of the MOCVD apparatus in a modification of the present embodiment. As shown in FIG. 3, in the MOCVD apparatus 1b, the third gas supply unit 11c may be omitted. In this case, the film is deposited by supplying the source gases G1 and G2 to the surface (upper wall in FIG. 1) facing the main surface 20a of the substrate 20 of the chamber 3 (the mounting surface of the susceptor 5). It is preferable to provide means such as a purge mechanism for suppression.

  In the MOCVD apparatuses 1a and 1b according to the present embodiment and the modification, the susceptor 5 is a face-up type in which the susceptor 5 is disposed below the chamber 3. However, the present invention is not limited to this. The MOCVD apparatus may be a face-down type in which the susceptor 5 is disposed above the chamber 3.

  Next, the MOCVD method as the vapor phase growth method in this embodiment will be described. In the present embodiment, a group III-V compound semiconductor film is formed by MOCVD using the MOCVD apparatus 1a shown in FIGS.

  First, the substrate 20 having the main surface 20a is prepared. In this step, for example, in the MOCVD apparatus 1a, the substrate 20 is placed on the placement surface of the susceptor 5, and the substrate 20 is held by the susceptor 5. The substrate 20 to be prepared is not particularly limited. For example, a GaN (gallium nitride) substrate can be used.

  Next, a film is formed on the main surface 20 a of the substrate 20 by heating the substrate 20 while supplying the source gas in a direction along the main surface 20 a of the substrate 20. In the step of forming this film, the first source gas containing the group V element and the group III element from the first gas supply unit 11a located on the side close to the main surface 20a in the direction D perpendicular to the main surface 20a of the substrate 20 A source gas G1 containing a second source gas containing oxygen is supplied onto the main surface 20a of the substrate 20, and is farther from the main surface 20a than the first gas supply part 11a in a direction D perpendicular to the main surface 20a of the substrate 20. A source gas G2 containing a third source gas containing a group III element is supplied onto the main surface 20a of the substrate 20 from the second gas supply part 11b located on the side. Further, a gas G3 that does not include a raw material is supplied from a third gas supply unit 11c that is located farther from the main surface 20a than the second gas supply unit 11b in the direction D perpendicular to the main surface 20a of the substrate 20.

  Specifically, in the MOCVD apparatus 1 a, the susceptor 5 is heated by the heater 9 while the substrate 20 is placed on the placement surface of the susceptor 5, and the susceptor 5 is rotated by the rotation shaft 13. And source gas G1, G2 and gas G3 which constitute source gas are introduced from each of the 1st-3rd gas supply parts 11a-11c. The source gas flows from the upstream side to the downstream side (right direction in FIG. 1). For example, when forming a group III-V compound semiconductor layer, the above-described source gases G1 and G2 are used. When each of these source gases G1, G2 and G3 is introduced into each of the first to third gas supply parts 11a to 11c, they are introduced and diffused in parallel to the mounting surface on the susceptor 5 and heated. The susceptor 5 is heated. A gas having a group III element contained in the second and third source gases is decomposed by heating to become an intermediate reactant, and an intermediate reactant of a gas having a group V element contained in the first source gas similarly decomposed by heating; It reacts to form a III-V compound semiconductor. As a result, a III-V compound semiconductor is formed on the main surface 20 a of the substrate 20.

  In the step of forming this film, the group III element contained in the second source gas and the group III element contained in the third source gas are preferably the same. For example, a gas containing In as a group III element is contained in the second and third source gases. In this case, the gas containing In may be the same or different. If they are different, TMI and triethylindium (TEI) can be used as the gas containing In. Further, the second and third source gases can be supplied by the branch pipes 114 to 116 and the switching units 134a, 134b, 135a, 135b, 136a, and 136b as shown in FIG.

  In the step of forming the film, the number of group III elements contained in the second source gas may be smaller than the type of group III elements contained in the third source gas. For example, a second source gas containing one group III element is supplied from the first gas supply unit 11a, and a third source gas containing two or more group III elements is supplied from the second gas supply unit 11b. . In this case, for example, the switching units 134a, 134b, 135a, 136b, 137a, and 137b shown in FIG. 2 supply TMG contained in the container 104 out of the source gas to only the second gas supply unit 11b. The TMI accommodated in 105 is supplied to the first and second gas supply units 11a and 11b.

In the step of forming a film, it is preferable that the second source gas is more easily pyrolyzed than the third source gas. Here, it is easy to thermally decompose, for example, the activation energy required for decomposing into a group III element (active group III element) having a dangling bond can be determined from the value. For example, TMG (Ga (CH ₃ ) ₃ ) and triethylgallium (TEG: Ga (C ₂ H ₅ ) ₃ ) are compared. The activation energy required for the reaction of Ga (CH ₃ ) ₃ → Ga (CH ₃ ) ₂ + CH ₃ is 59.5 kcal, Ga (C ₂ H ₅ ) ₃ → Ga (C ₂ H ₅ ) ₂ + C ₂ H ₅ The activation energy required for this reaction is 47 kcal. For this reason, TEG is easier to thermally decompose than TMG. The _{TMA (Al (CH 3) 3} ) and triethylaluminum _{(TEA: Al (C 2 H} 5) 3) is compared with. The activation energy required for the reaction of Al (CH ₃ ) ₃ → Al (CH ₃ ) ₂ + CH ₃ is 37.9 kcal, and Al (C ₂ H ₅ ) ₃ → Al (C ₂ H ₅ ) ₂ + C ₂ H ₅ The activation energy required for this reaction is 29 kcal. For this reason, TEA is easier to thermally decompose than TMA. Therefore, when forming a film containing Ga or Al, TEG and TEA are supplied from the first gas supply unit 11a, and TMG and TMA are supplied from the second gas supply unit 11b. When a film containing In is formed, TEI (triethylindium) is supplied from the first gas supply unit 11a and TMI is supplied from the second gas supply unit 11b.

  In addition, as described above, when the number of group III elements contained in the second source gas is smaller than the type of group III elements contained in the third source gas, the second and third source gases are pyrolyzed. It is preferable to determine the second and third source gases in consideration of ease. In this case, the distribution of the composition of the group III element of the film to be formed can be controlled.

It is preferable to form Al _x Ga _y In _(1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) as the film, and Al _x Ga _y N (0 <x <1). , 0 <y <1, x + y = 1), Ga _y In _(1-y) N (0 <y <1) and Al _x In _(1-x) N (0 <x <1) it is more preferable to, it is most preferable to form the _{Ga y In (1-y)} N (0 <y <1). When forming a _{Ga y In (1-y)} N (0 <y <1) supplies the TMI from the first gas supply unit 11a, supplying TMG and TMI from the second gas supply unit 11b It is preferable to do. Further, by supplying the dopant gas to the main surface 20a of the substrate 20 simultaneously with the source gases G1 and G2, a film containing the dopant can be formed.

  By performing the above steps, a film can be formed. In the present embodiment, the first raw material containing the group V element from the first gas supply unit 11a located on the side close to the main surface 20a in the direction D perpendicular to the main surface 20a of the substrate 20 placed on the susceptor 5 is used. A source gas G1 containing a gas and a second source gas containing a group III element is supplied onto the main surface 20a of the substrate 20. Thereby, the third source gas containing the group III element diffuses the source gas G1 supplied from the first gas supply unit 11a and reaches the main surface 20a of the substrate 20 as compared with the conventional case. The distance by which the second source gas containing the element diffuses to the main surface 20a of the substrate 20 located on the upstream side can be shortened. Therefore, the concentration of the second source gas containing the group III element on the upstream side can be increased, and the second source gas can be sufficiently supplied to the main surface 20a of the substrate 20 located on the upstream side. Further, since the third source gas containing the group III element is also supplied from the second gas supply unit 11b, the third source gas containing the group III element is also sufficient on the main surface 20a of the substrate 20 located on the downstream side. Can be supplied to. Therefore, the concentration of the group III material supplied to the main surface 20a of the substrate 20 from the upstream to the downstream can be supplied uniformly. As a result, when a film is formed, particularly when a film is formed on the plurality of substrates 20, the difference in the composition (composition ratio, molar ratio) of the group III element between the plurality of films can be reduced. Therefore, the composition of the film to be formed can be made uniform.

If the composition of the film thus formed can be made uniform, the composition of the group III element incorporated as an average can be ensured. For this reason, it is possible to prevent the group III element from being excessively taken in on the downstream side (the outer peripheral side when the susceptor 5 is rotated). Thereby, it is possible to suppress the deterioration of the crystallinity of the film due to an unnecessarily large group III element composition value. Particularly when forming Ga _y In _(1-y) N (0 <y <1) having a large In composition (1-y), the film is formed on the downstream side (the outer peripheral side when the susceptor 5 is rotated). It is possible to prevent the In composition (1-y) value from becoming larger than the target value. Therefore, there is a tendency that the crystallinity of Ga _y In _(1-y) N to be formed can be improved.

  Further, a group V element, particularly an N source, is supplied from the first gas supply unit 11a on the side close to the substrate 20. For this reason, the quality of the film to be formed is improved.

  Furthermore, since a sufficient amount of group III element and group V element can be supplied to the substrate 20 from the upstream side, film formation is promoted more than before. As a result, the deposition rate can be improved.

  Note that in this embodiment mode, a III-V compound semiconductor film is formed by MOCVD using an MOCVD apparatus, but the present invention is not limited to this. For example, a vapor phase growth method such as HVPE (Hydride Vapor Phase Epitaxy) method may be employed.

  In this embodiment, a source gas G1 containing a first source gas containing a group V element and a second source gas containing a group III element from the first gas supply unit 11a located on the side close to the main surface 20a of the substrate 20. The effect of supplying the liquid crystal on the main surface 20a of the substrate 20 was examined.

(Invention Example 1)
In the present invention Example 1 to form a _{Ga y In (1-y)} N (0 <y <1) with a MOCVD device 1a shown in FIG. 1 essentially above.

  Specifically, first, the substrate 20 was placed on the placement surface of the susceptor 5 of the MOCVD apparatus 1a shown in FIG. 1 on the upstream side of the center and on the downstream side of the center. As the substrate 20, an epitaxial substrate in which a GaN film having a thickness of 1.5 μm was formed on a sapphire substrate was prepared in advance.

Next, while the source gases G1, G2 and G3 were supplied in order from the side close to the main surface 20a of the substrate 20 under the conditions shown in Table 1 below, the susceptor 5 was heated by the heater 9 so as to reach 750 ° C. The susceptor 5 was not rotated by the rotating shaft 13. The growth pressure as 100 kPa, to form a _{Ga y In (1-y)} N on the main surface 20a of the substrate 20.

The source gas G1 supplied from the first gas supply unit 11a was NH ₃ as the first source gas, TMI as the second source gas, and N ₂ as the carrier gas. The source gas G2 supplied from the second gas supply unit 11b was TMG and TMI as the third source gas and N ₂ as the carrier gas. Gas G3 supplied from the third gas supply unit 11c, was N _2. The flow rate of the source gas G1 supplied from the first gas supply unit 11a was 30 slm, and the flow rate of the source gas G2 supplied from the second gas supply unit 11b was 15 slm. The flow rate of the gas G3 supplied from the third gas supply unit 11c was 35 slm.

  The supply amount of TMI in the source gas G1 supplied from the first gas supply unit 11a with respect to the total supply amount of TMI in the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b. {TMI of source gas G1 / (TMI of source gas G1 + TMI of source gas G2)} was 22%. The total TMI supply amount {TMI / (TMI + TMG)} in the raw material gases G1 and G2 with respect to the total supply amount of the total TMI in the raw material gases G1 and G2 and the TMG in the raw material gas G2 is 54 %Met. In the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b, the ratio of group V elements to group III elements (V / III) was 12300.

(Comparative Example 1)
Comparative Example 1 was basically formed in the same manner as Example 1 of the present invention, but the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b were different. That is, no source gas containing a group III element was supplied from the first gas supply unit 11a.

Specifically, the source gases supplied from the first gas supply unit 11a were NH ₃ and N ₂ . Raw material gas supplied from the second gas supply unit 11b, met TMG, and TMI, and N _2. Gas supplied from the third gas supply unit 11c, was N _2. The flow rate of the source gas supplied from the first gas supply unit 11a was 30 slm, and the flow rate of the source gas supplied from the second gas supply unit 11b was 15 slm. The flow rate of the gas supplied from the third gas supply unit 11c was 35 slm. In the source gas supplied from the second gas supply unit 11b, the TMI supply amount {TMI / (TMI + TMG)} relative to the total supply amount of TMI and TMG was 54%. In the source gas supplied from the first and second gas supply units 11a and 11b, the ratio of the group V element to the group III element (V / III) was 16000.

(Evaluation methods)
The distance from the center of the susceptor 5 was measured for the upstream and downstream substrates of Invention Example 1 and Comparative Example 1. In addition, the In composition (1-y) of the film formed on each substrate was measured by X-ray diffraction. The result is shown in FIG. FIG. 4 is a diagram showing the relationship between the position of the substrate and the composition of In in Example 1. In FIG. 4, the vertical axis represents the composition of indium (unit: none), and the horizontal axis represents a negative value from the center of the susceptor 5 toward the upstream side, and a positive value from the center of the susceptor 5 toward the downstream side. The distance (unit: mm) from the center of the susceptor 5 is shown.

(Evaluation results)
As shown in FIG. 4, in Inventive Example 1 in which the source gas G1 containing the second source gas containing the group III element is supplied from the first gas supply part 11a, the composition of In in the film on the substrate on the upstream side The difference between (1-y) and the In composition (1-y) of the film on the downstream substrate was smaller than that of Comparative Example 1. For this reason, the uniformity of the film composition on the upstream side and the downstream side can be improved.

  Further, in the film on the upstream substrate, the difference between the In composition (1-y) in the region located upstream and the In composition (1-y) in the region located downstream is Comparative Example 1. It was smaller than. For this reason, the difference in the composition distribution of In in the plane of the film could be reduced.

  In this embodiment, a source gas G1 containing a first source gas containing a group V element and a second source gas containing a group III element from the first gas supply unit 11a located on the side close to the main surface 20a of the substrate 20. The effect of supplying the liquid crystal on the main surface 20a of the substrate 20 was examined.

(Invention Example 2)
In the present invention example 2, a single substrate was placed on the upstream side of the susceptor 5 and a film was formed in the same manner as in the present invention example 1, but the film was formed while rotating the susceptor 5 by the rotating shaft 13, and the susceptor The only difference was that the temperature was 800 ° C.

(Invention Example 3)
In Invention Example 3, a single substrate is placed on the upstream side of the susceptor 5 and is basically formed in the same manner as in Invention Example 2, but in the source gas G1 supplied from the first gas supply unit. As shown in Table 2 below, the supply amount of TMI was different.

  Specifically, in the source gas G1 supplied from the first gas supply unit 11a with respect to the total supply amount of TMI in the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b. The TMI supply amount {TMI of source gas G1 / (TMI of source gas G1 + TMI of source gas G2)} was 28%. As a result, the total TMI supply amount {TMI / (TMI + TMG)} in the raw material gases G1 and G2 with respect to the total supply amount of the total TMI in the raw material gases G1 and G2 and the TMG in the raw material gas G2 is 60 %Met. In the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b, the ratio of the group V element to the group III element (V / III) was 14700.

(Comparative Example 2)
In Comparative Example 2, one substrate was placed on the upstream side of the susceptor 5 and was basically formed in the same manner as in Comparative Example 1, but the film was formed while rotating the susceptor 5 by the rotating shaft 13, In addition, the temperature of the susceptor was 800 ° C., and the ratio of the group V element to the group III element (V / III) in the source gas supplied from the first and second gas supply units 11a and 11b was 12800. It differed only in the points.

(Comparative Example 3)
In Comparative Example 3, a single substrate was placed on the upstream side of the susceptor 5 and was basically formed in the same manner as in Comparative Example 2, but the TMI in the source gas supplied from the first gas supply unit was The feed rate was different as shown in Table 2 below. Specifically, the TMI supply amount {TMI / (TMI + TMG)} relative to the total supply amount of TMI and TMG in the source gas supplied from the second gas supply unit 11b was 60%. The ratio of the group V element to the group III element (V / III) in the source gas supplied from the first and second gas supply units 11a and 11b was 14700.

  The total supply amount of In in Comparative Examples 2 and 3 was the same as the total supply amount of In in Invention Examples 2 and 3.

(Evaluation methods)
For each of the films formed on the substrates of Invention Examples 2 and 3 and Comparative Examples 2 and 3, the In composition (1-y) was measured in the same manner as in Example 1. The result is shown in FIG. FIG. 5 is a diagram showing the relationship between the TMI in the Group III element raw material and the In composition of the film in Example 2. In FIG. 5, the vertical axis represents the composition of indium (unit: none), and the horizontal axis represents the ratio (unit:%) of TMI to the total of TMI and TMG, which are raw materials of group III elements in the raw material.

(Evaluation results)
As shown in FIG. 5, Inventive Examples 2 and 3 have a composition of In (1-y) in comparison with Comparative Examples 2 and 3, even though the supply amount of TMI as an In supply source is the same. We were able to deposit a high _{Ga y In (1-y)} N. That is, the source gas G1 containing the first source gas containing the group V element and the second source gas containing the group III element from the first gas supply part 11a located on the side close to the main surface 20a of the substrate 20 is used as the substrate 20. It was found that the amount of In taken in can be increased by supplying the main surface 20a of In.

  In this embodiment, a source gas G1 containing a first source gas containing a group V element and a second source gas containing a group III element from the first gas supply unit 11a located on the side close to the main surface 20a of the substrate 20. The effect of supplying the substrate on the main surface of the substrate was investigated.

(Invention Example 4)
In Example 4 of the present invention, a single substrate was placed on the upstream side of the susceptor 5, and film formation was basically performed in the same manner as Example 1 of the present invention, but the following points were different.

Specifically, a GaN layer having a thickness of 1.5 μm was formed on the sapphire substrate. Next, to form a _{Ga y In (1-y)} N (0 <y <1) under the conditions shown in Table 3 below. That is, the TMI in the source gas G1 supplied from the first gas supply unit 11a with respect to the total supply amount of TMI in the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b. The supply amount {TMI of source gas G1 / (TMI of source gas G1 + TMI of source gas G2)} was 8.3%. As a result, the total TMI supply amount {TMI / (TMI + TMG)} in the raw material gases G1 and G2 with respect to the total supply amount of the total TMI in the raw material gases G1 and G2 and TMG in the raw material gas G2 is 56. %Met. In the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b, the ratio of the group V element to the group III element (V / III) was 14000.

(Comparative Example 4)
In Comparative Example 4, a single substrate was placed on the upstream side of the susceptor 5 and was basically formed in the same manner as in Comparative Example 1, but the TMI in the source gas supplied from the first gas supply unit was The feed rate was different as shown in Table 3 below. Specifically, the TMI supply amount {TMI / (TMI + TMG)} with respect to the total supply amount of TMI and TMG in the source gas supplied from the second gas supply unit 11b was 54%. In the source gases G1 and G2 supplied from the first and second gas supply units 11a and 11b, the ratio of the group V element to the group III element (V / III) was 13100.

(Evaluation methods)
For the films formed on the substrates of Invention Example 4 and Comparative Example 4, the In composition (1-y), film thickness, X-ray diffraction peak intensity, and X-ray diffraction half width were measured. The In composition (1-y) was measured in the same manner as in Example 1.

  In the ω-2θ scan, measurement was performed by synchronizing ω (sample angle) and 2θ (detector angle). In the ω scan, 2θ was fixed at the InGaN crystal peak position, and ω was scanned for measurement. The results are shown in FIGS. 6 and 7 are diagrams showing diffraction intensities in Example 3. FIG. 6 and 7, the vertical axis represents diffraction intensity (unit: count / second), and the horizontal axis represents ω (unit: second). In FIG. 6, an angular position where ω is 0 (second) indicates a GaN crystal, and an angular position where −1500 (second) indicates an InGaN crystal. In FIG. 6, it is shown that the larger the value of ω that indicates the peak value of diffraction intensity, the greater the amount of In incorporated. The peak value on the vertical axis in FIG. 6 was determined as the X-ray diffraction peak intensity. Further, the X-ray diffraction half width was obtained from the peak width of FIG. The results are shown in Table 3 below.

(Evaluation results)
As shown in FIG. 6, Example 4 of the present invention in which the source gas G1 containing the second source gas containing the group III element is supplied from the first gas supply unit 11a uses the source gas containing the group III element as the second gas. The intake amount of In was larger than that of Comparative Example 4 supplied from the supply unit 11b. As a result, it was found that Example 4 of the present invention was able to sufficiently capture In on the upstream side of Comparative Example 4, so that the average composition when the substrate was rotated could be improved.

  As shown in FIG. 6 and Table 3, Example 4 of the present invention had higher X-ray diffraction peak intensity than Comparative Example 4. As a result, it was found that Inventive Example 4 had less variation in In composition than Comparative Example 4. Further, as shown in FIG. 7 and Table 3, Example 4 of the present invention had a peak value higher than that of Comparative Example 4 and a narrow X-ray diffraction half width. Thus, it was found that the inventive example 4 had better crystallinity than the comparative example 4. For this reason, it turned out that the crystallinity of a film | membrane can be improved by supplying the source gas G1 containing the 2nd source gas containing a III group element from the 1st gas supply part 11a.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

It is sectional drawing which shows the structure of the MOCVD apparatus in embodiment of this invention. FIG. 2 is a schematic diagram in the vicinity of a source gas supply unit in FIG. 1. It is sectional drawing which shows the structure of the MOCVD apparatus in the modification of embodiment of this invention. In Example 1, it is a figure which shows the relationship between the position of a board | substrate, and the composition of In. It is a figure which shows the relationship between TMI in the raw material of the group III element in Example 2, and the composition of In of a film | membrane. FIG. 6 is a diagram showing diffraction intensity in Example 3. FIG. 6 is a diagram showing diffraction intensity in Example 3.

Explanation of symbols

  1a, 1b MOCVD apparatus, 3 chamber, 5 susceptor, 7 groove, 9 heater, 11 source gas supply unit, 11a first gas supply unit, 11b second gas supply unit, 11c third gas supply unit, 13 rotations Axis, 20 substrate, 20a main surface, 101-107 container, 111-113 piping, 114-117 branch piping, 120 vent piping, 134a-134c, 135a-135c, 136a-136c, 137a-137c switching part, D direction, G1, G2 source gas, G3 gas.

Claims (12)

Preparing a substrate having a main surface;
Forming a film on the main surface of the substrate by heating the substrate while supplying a source gas in a direction along the main surface of the substrate,
In the step of forming the film,
A source material including a first source gas containing a group V element and a second source gas containing a group III element from a first gas supply unit located on the side close to the main surface in a direction perpendicular to the main surface of the substrate Supplying gas onto the main surface of the substrate;
A source gas containing a third source gas containing a group III element from a second gas supply unit located on a side farther from the main surface than the first gas supply unit in a direction perpendicular to the main surface of the substrate. A vapor phase growth method for supplying the main surface of the substrate. In the step of forming the film,
The source gas is supplied from the first and second gas supply units, and a third position is located farther from the main surface than the second gas supply unit in a direction perpendicular to the main surface of the substrate. The vapor phase growth method according to claim 1, wherein a gas not containing a raw material is further supplied from a gas supply unit. The step of forming the film forms Al _x Ga _y In _(1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) as the film. The vapor phase growth method described in 1. In the step of forming the film, the film as _{Al x Ga y N (0 <} x <1,0 <y <1, x + y = 1), Ga y In (1-y) N (0 <y <1) 4. The vapor phase growth method according to claim 3, wherein any one of Al 2 and Al _x In _(1-x) N (0 <x <1) is formed. In the step of forming the film, to form the film as a _{Ga y In (1-y)} N (0 <y <1), vapor deposition method according to claim 4.   6. The gas according to claim 1, wherein in the step of forming the film, the group III element contained in the second source gas and the group III element contained in the third source gas are the same. Phase growth method.   7. The vapor phase growth method according to claim 6, wherein in the step of forming the film, the number of group III elements contained in the second source gas is less than the type of group III elements contained in the third source gas. .   The vapor deposition method according to claim 6, wherein in the step of forming the film, the second source gas is more easily pyrolyzed than the third source gas.   9. The vapor phase growth method according to claim 1, wherein, in the step of forming the film, the second source gas includes trimethylindium, and the third source gas includes trimethylgallium and trimethylindium. A reaction chamber;
A susceptor on which a substrate having a main surface disposed inside the reaction chamber is placed;
A heater for heating the substrate via the susceptor;
A source gas supply unit that supplies source gas from a direction along the main surface of the substrate in the reaction chamber,
The source gas supply unit
A source gas, which is located near the main surface in a direction perpendicular to the main surface of the substrate and includes a first source gas containing a group V element and a second source gas containing a group III element, is supplied to the reaction chamber. A first gas supply section for supplying;
A source gas containing a third source gas containing a group III element and located at a position farther from the main surface than the first gas supply unit in a direction perpendicular to the main surface of the substrate is supplied to the reaction chamber. And a gas supply unit. The source gas supply unit
Branch pipes for supplying a raw material containing a group III element as the second and third raw material gases to the first and second gas supply parts, respectively;
The vapor phase growth apparatus according to claim 10, further comprising: a switching unit provided in the branch pipe for selecting supply to the first and second gas supply units.   The vapor phase growth apparatus according to claim 10 or 11, further comprising a rotation mechanism for rotating the susceptor.

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