JP5046182B2 - Method for producing compound semiconductor epitaxial wafer - Google Patents

Description

  The present invention relates to a method for manufacturing a compound semiconductor epitaxial wafer.

US Patent No. 5,008,718 JP 2004-128452 A

The light-emitting layer portion is formed of (Al _x Ga _1-x ) _y In _1-y P mixed crystal (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1; hereinafter also referred to as AlGaInP mixed crystal or simply AlGaInP). The light emitting device has a high brightness by adopting a double hetero structure in which a thin AlGaInP active layer is sandwiched between an n-type AlGaInP cladding layer and a p-type AlGaInP cladding layer having a larger band gap. An element can be realized.

  For example, taking an AlGaInP light emitting device as an example, an n-type GaAs buffer layer, an n-type AlGaInP cladding layer, an AlGaInP active layer, and a p-type AlGaInP cladding layer are formed in this order in a heterogeneous form on an n-type GaAs substrate. The light emitting layer part which laminates | stacks and makes a double hetero structure is formed. Energization of the light emitting layer portion is performed through a metal electrode formed on the element surface. Here, since the metal electrode acts as a light shield, it is formed, for example, so as to cover only the central portion of the main surface of the light emitting layer portion, and light is extracted from the surrounding electrode non-formation region.

  In this case, reducing the area of the metal electrode as much as possible can increase the area of the light leakage region formed around the electrode, which is advantageous from the viewpoint of improving the light extraction efficiency. Conventionally, attempts have been made to increase the light extraction amount by effectively spreading the current in the element by devising the electrode shape, but in this case also the increase in the electrode area is unavoidable anyway, the light leakage area On the contrary, it falls into a dilemma where the amount of light extraction is limited by the decrease. In addition, the carrier concentration of the dopant in the clad layer, and thus the conductivity, is kept somewhat low in order to optimize the light emission recombination of carriers in the active layer, and the current tends not to spread in the in-plane direction. . This leads to concentration of current density in the electrode coating region, and a substantial light extraction amount in the light leakage region is reduced.

Therefore, a method is known in which a current density is minimized by providing a thick and conductive transparent window layer (current diffusion layer) between the light emitting layer portion and the electrode (Patent Document 1). ).
In order to efficiently form a current spreading layer, a thin light emitting layer is formed by metal organic vapor phase epitaxy (hereinafter also referred to as MOVPE method), while a thick current spreading layer is formed by hydride gas. A method of forming by the phase growth method (Hydride Vapor Phase Epitaxial Growth Method: hereinafter also referred to as HVPE method) is known (Patent Document 2).

  However, when the current diffusion layer is formed using the hydride vapor phase epitaxy method, a hole (hereinafter sometimes referred to as “back surface hole”) is easily formed on the back surface of the GaAs substrate. Since the GaAs substrate is thin in the region where the back hole is formed, it cannot be processed to a desired chip thickness when forming the LED chip. Further, in a region where the back surface hole penetrates the GaAs substrate and reaches the light emitting layer portion, light is not emitted during energization, so the yield is lowered.

  An object of the present invention is to provide a compound semiconductor epitaxial wafer manufacturing method capable of suppressing a back hole or removing a generated back hole when a current diffusion layer is formed using a hydride vapor phase growth method. Is to provide.

Means for Solving the Problems and Effects of the Invention

The first method for producing a compound semiconductor epitaxial wafer of the present invention is (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 <y ≦ 1) on a GaAs single crystal substrate. A metal-organic vapor phase growth process for vapor-phase epitaxy layer, an InP-containing particle removal process for removing InP-containing particles attached to the back surface of the GaAs single crystal substrate, and gallium chloride as a source gas And a hydride vapor phase growth step in which a GaP layer is vapor-grown on the epitaxial layer in a hydrogen atmosphere in this order.

In the method for producing a compound semiconductor epitaxial wafer of the present invention, for example, (Al _x Ga _1-x ) _y In _1-y P containing two or more group III elements (where 0 ≦ x ≦ 1, 0 <y ≦ In order to grow the light emitting layer portion constructed in 1) on the GaAs substrate by using the metal organic vapor phase epitaxy (MOVPE method) (metal organic vapor phase epitaxy process), on the susceptor on which the GaAs substrate is placed. InP-containing particles are interspersed. Then, when a GaAs substrate is placed on a susceptor in which InP-containing particles are scattered and an organic metal vapor phase growth process is performed, the InP-containing particles adhere to the back surface of the GaAs substrate.

Next, in order to form a current diffusion layer using a hydride vapor phase growth method, when a GaP layer is vapor-phase grown in a hydrogen atmosphere using gallium chloride (GaCl) and, for example, phosphine (PH ₃ ) as a source gas, HCl is generated in the vapor phase growth atmosphere. Then, a part of HCl goes around to the back surface side of the GaAs substrate, and InAs formed in the boundary region between the GaAs substrate and the InP-containing particles is etched by HCl to form a back surface hole. InP and GaP are also etched by HCl.

  Etching is continuously performed during hydride vapor phase growth for several hours, so that a back hole of about 20 μm to 300 μm is formed in the GaAs substrate. When the back surface hole penetrates the GaAs single crystal substrate and reaches the light emitting layer portion composed of AlGaInP, the region cannot emit light when energized.

  Therefore, the InP-containing particles attached to the back surface of the GaAs single crystal substrate are removed between the metal organic vapor phase growth step and the hydride vapor phase growth step (InP-containing particle removal step). The InP-containing particle removal step may be performed by partially removing the back surface of the GaAs single crystal substrate on which the InP-containing particles are adhered using, for example, a pen grinder, or polishing process or ammonia / peroxidation, for example. You may perform by performing wet etching using hydrogen water etc. and removing the whole back surface of a GaAs single crystal substrate 1 micrometer or more and 10 micrometers or less.

The second method for producing a compound semiconductor epitaxial wafer of the present invention is (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 1, 0 <y ≦ 1) on a GaAs single crystal substrate. A metal-organic vapor phase growth step for vapor-growing an epitaxial layer comprising: an InP adhesion amount observing step for observing an adhesion amount of InP-containing particles attached to the back surface of the GaAs single crystal substrate; and the InP-containing particles A GaAs single crystal substrate having a larger adhesion amount is arranged on the upstream side of a source gas supply containing gallium chloride, and a hydride vapor phase growth step in which a GaP layer is vapor-grown on the epitaxial layer in a hydrogen atmosphere in this order. It is characterized by performing.

  As described above, when hydride vapor phase growth is performed with InP-containing particles attached to the back surface of the GaAs single crystal substrate, a part of HCl generated during the vapor phase growth passes to the back surface side of the GaAs single crystal substrate. At the same time, the InP-containing particles are etched, and at the same time, the GaAs where the InP-containing particles are attached is also etched to form a back hole. The HCl concentration is relatively small on the upstream side of the source gas supply, but the HCl concentration is higher on the downstream side.

  Therefore, after the metal organic chemical vapor deposition process, the amount of InP-containing particles adhering to the back surface of the GaAs single crystal substrate is observed (InP adhesion amount monitoring step). Hydride vapor phase growth of the GaP layer is performed in a hydrogen atmosphere by being arranged upstream of the source gas supply containing gallium chloride. Then, since the HCl concentration is lower on the upstream side of the source gas supply than on the downstream side, it is difficult to form a back hole even if the amount of InP-containing particles attached is large.

A third method for producing a compound semiconductor epitaxial wafer according to the present invention is an epitaxial structure composed of (AlxGa1-x) yIn1-yP (where 0≤x≤1, 0 <y≤1) on a GaAs single crystal substrate. A metal-organic vapor phase growth process for vapor-depositing a layer; a hydride vapor phase growth process for vapor-depositing a GaP layer on the epitaxial layer in a hydrogen atmosphere using gallium chloride as a source gas; and the GaAs single crystal substrate rows that have a back hole removal step of removing the backside hole formed on the back surface in this order,
After the backside hole removing step, after the hydride vapor phase growth step, the backside hole detection step of detecting the backside hole by irradiating light on the backside of the GaAs single crystal substrate identifies the position of the backside hole. and wherein the line of Ukoto.

  When the hydride vapor phase growth process of the GaP layer is performed in a state where the InP-containing particles are attached to the back surface of the GaAs single crystal substrate in the metal organic vapor phase growth process, a back hole is easily formed in the GaAs single crystal substrate. In the region where the back hole penetrates the GaAs substrate and reaches the light emitting layer portion, no light is emitted when energized. Therefore, the back hole is preferably removed before the compound semiconductor epitaxial wafer is chipped. However, a crushed layer formed by free As is also formed on the back surface of the GaAs single crystal substrate after the hydride vapor phase growth step, and it is often difficult to specify the back surface hole.

  Therefore, after the hydride vapor phase growth step, the back surface hole is detected by irradiating the back surface of the GaAs single crystal substrate to detect the back surface hole (back surface hole detection step), and then the position of the back surface hole is specified. desirable. Usually, the GaAs single crystal substrate does not transmit the condensed light, so it looks gray or black. On the other hand, in the area where the back hole is formed, the GaAs single crystal substrate is locally thinned or completely removed by etching, and the back hole glows red when irradiated with condensed light. Can be detected. Alternatively, after the hydride vapor phase growth process, if the polishing process is performed on the back surface of the GaAs single crystal substrate, the crushed layer is removed and the back surface hole can be easily identified. May be performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual diagram showing an example of a compound semiconductor epitaxial wafer 100 that can be manufactured by the manufacturing method of the present invention. In the compound semiconductor epitaxial wafer 100, a light emitting layer portion 24 is formed on a first main surface MP1 of an n-type GaAs single crystal substrate (hereinafter also simply referred to as a GaAs substrate) 1, and the first main surface MP1 of the GaAs substrate 1 and An n-type GaAs buffer layer 2 is formed in contact therewith, a light emitting layer portion 24 is formed on the buffer layer 2, and a p-type GaP current diffusion layer 7 is formed on the light emitting layer portion 24.

The light emitting layer portion 24 includes the active layer 5 made of a non-doped (Al _x Ga _1-x ) _y In _1-y P (where 0 ≦ x ≦ 0.55, 0.45 ≦ y ≦ 0.55) mixed crystal. , p-type _{(Al z Ga 1-z)} y In 1-y P ( except x <z ≦ 1) p-type cladding layer 6 and the n-type composed of _{(Al z Ga 1-z)} y In 1-y P ( However, it has a structure sandwiched between n-type cladding layers 4 made of x <z ≦ 1). The term “non-doped” as used herein means “does not actively add dopant”, and contains a dopant component inevitably mixed in a normal manufacturing process (for example, 10 ¹³ to 10 ¹⁶ / cm 3). It is not excluded that the upper limit is about ³ ).

  The formation thickness of the p-type GaP current diffusion layer 7 is, for example, 30 μm or more and 300 μm or less. The p-type GaP current diffusion layer 7 is formed by laminating a first GaP layer 7a formed by metal organic vapor phase epitaxy and a second GaP layer 7b formed by hydride vapor phase epitaxy in this order.

  A first electrode 9 for applying a light emission driving voltage to the light emitting layer portion 24 is formed on the p-type GaP current diffusion layer 7, and the second electrode 20 is formed on the second main surface MP2 side of the substrate 1 in the same manner. When it is formed, the light emitting element 200 is obtained (FIG. 2). The first electrode 9 is formed substantially at the center of the first main surface PF, and a region around the first electrode 9 is a light extraction region from the light emitting layer portion 24. A bonding pad 16 made of Au or the like for bonding the electrode wire 17 is disposed at the center of the first electrode 9. In the light emitting element 200, the p-type AlGaInP clad layer 6 is disposed on the first electrode 9 side, and the n-type AlGaInP clad layer 4 is disposed on the second electrode 20 side. Therefore, the energization polarity is positive on the first electrode 9 side.

  Hereinafter, a method for manufacturing the compound semiconductor epitaxial wafer 100 and the light emitting element 200 will be described. First, as shown in Step 1 of FIG. 3, a GaAs substrate 1 having a main axis with an off angle of 10 ° or more and 20 ° or less with a <100> direction as a reference direction is prepared and provided in a metal organic chemical vapor deposition apparatus. Placed on the susceptor. Since there are many InP-containing particles on the susceptor of the metal organic vapor phase epitaxy apparatus for forming the AlGaInP layer, the InP-containing particles D1, D2, and D3 also adhere to the back surface MP2 of the GaAs substrate 1 placed on the susceptor. .

Next, as shown in step 2, the n-type GaAs buffer layer 2 is, for example, 0.5 μm on the first main surface MP1 of the GaAs substrate 1, and then the light emitting layer portion 24 is (Al _x Ga _1-x ). ₁ μm n-type clad layer 4 (n-type dopant is Si), 0.6 μm active layer (non-doped) 5, 1 μm p-type clad layer 6, p-type first GaP layer made of _y In _1-y P 7a (p-type dopant is Mg: C from organometallic molecules can also contribute as p-type dopant) is epitaxially grown in this order to obtain an MO epitaxial wafer 50 (organometallic vapor phase growth step). Epitaxial growth of each of these layers is performed by a known MOVPE method. The following materials can be used as source gases for the source components of Al, Ga, In (indium), and P (phosphorus);
Al source gas; trimethylaluminum (TMAl), triethylaluminum (TEAl), etc .;
Ga source gas; trimethylgallium (TMGa), triethylgallium (TEGa), etc .;
In source gas; trimethylindium (TMIn), triethylindium (TEIn), etc.
P source gas: trimethyl phosphorus (TMP), triethyl phosphorus (TEP), phosphine (PH ₃ ), etc.

  After the step 2 is completed, the MO epitaxial wafer 50 is taken out from the metal organic vapor phase epitaxy apparatus, and the adhesion amounts of InP-containing particles D1, D2, and D3 adhering to the back surface MP2 of the GaAs substrate 1 (hereinafter also referred to as InP adhesion amount) are obtained. For example, visual observation is performed under a fluorescent lamp (Step 3, InP adhesion amount observation step). In the InP adhesion amount observing step, the back surface MP2 of the GaAs substrate 1 is image-processed, the adhesion portions of the InP-containing particles D1, D2, and D3 are discriminated and the total area is calculated to obtain the InP adhesion amount. . When the amount of InP attached is relatively small, the InP-containing particles attached to the back surface MP2 are removed by partially removing the back surface MP2 of the GaAs substrate 1 using a pen grinder or the like (Step 4, InP-containing particle removal). Process). For convenience of the following description, it is assumed that the InP-containing particles D1 are removed in the InP-containing particle removal step, and the InP-containing particles D2 and D3 remain on the back surface MP2 of the GaAs substrate 1.

  When the amount of InP deposited is relatively large or when the number of MO epitaxial wafers 50 subjected to the removal process is large, the entire back surface of the GaAs substrate 1 is obtained by polishing or wet etching the back surface of the GaAs substrate 1. It is more efficient to remove

  Proceeding to step 5, the MO epitaxial wafer 50 is placed on a susceptor provided in the HVPE vapor phase growth apparatus, and hydrogen is used directly on the p-type first GaP layer 7a using gallium chloride (GaCl) as a source gas. The p-type second GaP layer 7b is vapor-phase grown by HVPE in an atmosphere (hydride vapor-phase growth step). FIG. 5 is a schematic diagram showing an example of an HVPE vapor phase growth apparatus. The apparatus 201 accommodates a first chamber 204 in which a crucible 208 for accommodating a Ga melt 209 is disposed, and a susceptor 210 (for example, but not limited to, made of carbon) that holds an MO epitaxial wafer 50. A growth vessel having a second chamber 205;

Specifically, in the HVPE method, GaCl, which is a group III element, is heated and held at a predetermined temperature in a container, and hydrogen chloride is introduced onto the Ga, thereby causing GaCl by the reaction of the following formula (1). And is supplied onto the MO epitaxial wafer 50 together with H ₂ gas as a carrier gas.
Ga (liquid) + HCl (gas) → GaCl (gas) + 1 / 2H ₂ (1)
The first chamber 204 and the second chamber 205 are made of quartz together with the crucible 208, and are heated to an appropriate growth temperature by the heaters 202 and 203 so that the HVPE reaction proceeds sufficiently. In the case of GaP, the growth temperature is set to, for example, 640 ° C. or more and 860 ° C. or less. In the first chamber 204 in which the crucible 208 is disposed, HCl gas, H ₂ gas as a carrier gas, PH ₃ as a P source gas, and DMZn (dimethyl zinc) as a dopant gas are introduced from an introduction port 206. be introduced.

GaCl is excellent in reactivity with PH _3, and as shown in Step 5 of FIG. 4, a p-type second GaP layer 7 b that forms a main part of the p-type GaP current diffusion layer 7 is grown by the reaction of the following equation (2). Can be:
GaCl (gas) + PH ₃ (gas)
→ GaP (solid) + HCl (gas) + H ₂ (gas) (2)
In FIG. 5, a plurality of MO epitaxial wafers 50 are disposed in the growth vessel in the flow direction of the source gas, and the p-type second GaP layer 7 b is epitaxially grown collectively on the plurality of MO epitaxial wafers 50.

As shown in the equation (2), HCl gas is generated as the reaction proceeds. As shown in step 5 of FIG. 4, at this time, a part of HCl circulates to the back surface (MP1) side of the GaAs substrate 1 and etches InAs formed in the boundary region between the GaAs substrate 1 and the InP-containing particles D2 and D3. As a result, back holes H2 and H3 are generated at the positions where the InP-containing particles D2 and D3 are attached. The concentration of HCl gas is relatively low on the upstream side of the source gas supply where the concentrations of the raw material GaCl and PH ₃ are high, and the concentration increases toward the downstream side after the reaction of formula (2) is exhausted. On the other hand, the back holes H2 and H3 are more likely to be generated as the adhesion amount of the InP-containing particles is larger.

  Therefore, as shown in FIG. 5, the MO epitaxial wafer 50 having the GaAs substrate 1 with a large amount of InP-containing particles D attached is disposed on the upstream side of the source gas supply containing gallium chloride, and conversely the one with a small amount of attachment. When the second GaP layer 7b is vapor-phase grown in a hydrogen atmosphere by being arranged on the downstream side, the back hole is less likely to occur throughout the batch.

  Returning to FIG. 4, after completion of the hydride vapor phase growth process in step 5, the compound semiconductor wafer 60 on which the p-type second GaP layer 7 b is formed is taken out from the HVPE vapor phase growth apparatus and focused on the back surface MP <b> 2 of the GaAs substrate 1. , And the back holes H2 and H3 are detected (back hole detection step). Under the fluorescent lamp, the back holes H2 and H3 appear to be almost the same gray as the GaAs substrate 1 on which the crushed layer is formed, but are difficult to detect. Can be easily identified.

  Therefore, if the back surface MP2 of the GaAs substrate 1 after the hydride vapor phase growth step is irradiated with light, the positions where the back surface holes H2 and H3 are generated can be specified easily and reliably, and then the back surface hole removing step (step 6) is performed. It becomes possible to carry out in a short time without waste. The back hole removal step may be performed, for example, by removing the generation site of the back holes H2 and H3 by cleaving, or grinding the peripheral part of the GaAs substrate 1 with a grinder or the like around the back hole H3 generated in the peripheral part. You may implement by removing.

  Since a crushed layer is formed on the back surface MP2 of the GaAs substrate 1 immediately after the hydride vapor phase growth process is completed, it is difficult to detect the back surface holes H2 and H3. However, if the back surface MP2 of the GaAs substrate 1 is subjected to a polishing process. Since the crushed layer is removed, the back holes H2 and H3 can be easily detected even under a fluorescent lamp. Further, the back hole H2 in which the hole is formed relatively shallow can be removed only by performing a polishing process. Therefore, the back hole removal step may be performed after the polishing step is performed on the back surface MP2 of the GaAs substrate 1 after the hydride vapor phase growth step. In this case, the step of removing the back hole H3 remaining after the polishing step can be removed by cleaving or grinding, as described above.

  In addition, the specific means for aiming at suppression of a back surface hole is InP content particle | grains D in an InP containing particle removal process (process 4) and a hydride vapor phase growth process (process 5) according to the generation | occurrence | production degree of a back surface hole. The MO epitaxial wafer 50 having a GaAs substrate 1 with a large amount of adhesion of either one of the method of arranging the GaAs substrate 1 on the upstream side of the source gas supply containing gallium chloride and the back surface hole removing step (step 6) alone. It is possible to carry out and do nothing particularly, or conversely, it is possible to carry out a combination of two or more.

  After obtaining the compound semiconductor wafer 100 of FIG. 1 having no back holes H2 and H3 by the above steps, as shown in FIG. 2, the first electrode 9 and the second electrode 20 are formed by vacuum deposition, A bonding pad 16 is disposed on the first electrode 9 and baking for electrode fixing is performed at an appropriate temperature. Then, the second electrode 20 is fixed to a terminal electrode (not shown) that also serves as a support using a conductive paste such as an Ag paste, while an Au wire 17 is formed so as to straddle the bonding pad 16 and another terminal electrode. The light emitting device 200 is obtained by bonding and further forming a resin mold.

The schematic diagram which shows an example of the compound semiconductor wafer of this invention by laminated structure. The schematic diagram which shows an example of the light emitting element obtained from the compound semiconductor wafer of this invention by laminated structure. Explanatory drawing which shows the manufacturing process of the compound semiconductor wafer of FIG. 1, and the light emitting element of FIG. Explanatory drawing following FIG. The schematic diagram which shows an example of the growth apparatus of HVPE.

Explanation of symbols

1 GaAs single crystal substrate 4 n-type cladding layer 5 active layer 6 p-type cladding layer 7 p-type GaP current diffusion layer 7a first GaP layer 7b second GaP layer 9 first electrode 24 light emitting layer part 100 compound semiconductor wafer 200 light emitting element

Claims (8)

  A metal organic vapor phase growth step of vapor-phase-growing an epitaxial layer composed of (AlxGa1-x) yIn1-yP (where 0 ≦ x ≦ 1, 0 <y ≦ 1) on a GaAs single crystal substrate; An InP-containing particle removing process for removing InP-containing particles attached to the back surface of the GaAs single crystal substrate, and hydride vapor phase growth in which a GaP layer is vapor-phase grown on the epitaxial layer in a hydrogen atmosphere using gallium chloride as a source gas. A method for producing a compound semiconductor epitaxial wafer, wherein the steps are performed in this order.   2. The method of manufacturing a compound semiconductor epitaxial wafer according to claim 1, wherein the InP-containing particle removing step is performed by partially removing a back surface of the GaAs single crystal substrate.   2. The method of manufacturing a compound semiconductor epitaxial wafer according to claim 1, wherein the InP-containing particle removing step is performed by removing the entire back surface of the GaAs single crystal substrate.   4. The method for producing a compound semiconductor epitaxial wafer according to claim 3, wherein the entire back surface of the GaAs single crystal substrate is removed by polishing the back surface of the GaAs single crystal substrate.   4. The method of manufacturing a compound semiconductor epitaxial wafer according to claim 3, wherein the entire back surface of the GaAs single crystal substrate is removed by performing wet etching on the back surface of the GaAs single crystal substrate.   A metal organic vapor phase growth step of vapor-phase-growing an epitaxial layer composed of (AlxGa1-x) yIn1-yP (where 0 ≦ x ≦ 1, 0 <y ≦ 1) on a GaAs single crystal substrate; An InP adhesion amount observing step for observing the adhesion amount of InP-containing particles attached to the back surface of the GaAs single crystal substrate, and a GaAs single crystal substrate having a larger adhesion amount of the InP-containing particles, the upstream side of the source gas supply containing gallium chloride And a hydride vapor phase growth step in which a GaP layer is vapor-phase grown on the epitaxial layer in a hydrogen atmosphere in this order. A metal-organic vapor phase growth step of vapor-phase-growing an epitaxial layer composed of (AlxGa1-x) yIn1-yP (where 0 ≦ x ≦ 1, 0 <y ≦ 1) on a GaAs single crystal substrate; A hydride vapor phase growth process in which gallium is used as a source gas and a GaP layer is vapor-grown on the epitaxial layer in a hydrogen atmosphere, and a back hole removal process in which a back hole formed on the back surface of the GaAs single crystal substrate is removed. bet the line stomach in this order,
After the backside hole removing step, after the hydride vapor phase growth step, the backside hole detection step of detecting the backside hole by irradiating light on the backside of the GaAs single crystal substrate identifies the position of the backside hole. method of manufacturing a compound semiconductor epitaxial wafer, comprising a row of Ukoto.   After the backside hole removing step, after the hydride vapor phase growth step, the backside hole detection step of detecting the backside hole by irradiating light on the backside of the GaAs single crystal substrate identifies the position of the backside hole. 8. The method for producing a compound semiconductor epitaxial wafer according to claim 7, wherein the method is performed.

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