JP2010103254A - GaAs SUBSTRATE, MULTILAYER SUBSTRATE AND ELECTRONIC DEVICE USING THE SAME, DUMMY GaAs SUBSTRATE, AND GaAs SUBSTRATE FOR REUSE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GaAs substrate, along with a multilayer substrate and an electronic device using the same, a dummy GaAs substrate, and a GaAs substrate for reuse, of which warping is reduced. <P>SOLUTION: The GaAs substrate 12 is such GaAs substrate 12 where an epitaxial layer 13 is film-formed. Here, the concentration of Si that is added (C[Si] cm<SP>-3</SP>) and the concentration of B(C[B] cm<SP>-3</SP>) satisfy two equations: equation (1) 4.0×10<SP>17</SP>≤C[Si]≤1.0×10<SP>19</SP>, and equation (2) C[B]≥4.8×10<SP>5</SP>×C[Si]<SP>0.7</SP>. In other words, inventors newly found that warping of a substrate 10 is reduced if the epitaxial layer 13 is film-formed on such GaAs substrate 12 as satisfies the two equations, or the equation (1) and the equation (2). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a GaAs substrate, a laminated substrate, an electronic device using the same, a GaAs substrate for dummy use, and a GaAs substrate for reuse.

  2. Description of the Related Art Conventionally, a substrate made of a III-V group semiconductor such as GaAs has been used to manufacture an electronic device such as a light emitting diode (LED) or a laser diode (LD). When this GaAs substrate is used for an LED or LD, it is generally used as an n-type conductivity substrate. In this case, Si is added to the GaAs substrate as impurity atoms.

  In order to actually manufacture an electronic device, an epitaxial layer made of various materials is formed on a GaAs substrate. However, it is known that when an epitaxial layer is formed on a GaAs substrate, the laminated substrate (epitaxial substrate) is warped due to a difference in lattice constant or thermal expansion coefficient. Regarding the coefficient of thermal expansion, the epitaxial layer is formed in the temperature range of 500 to 750 ° C., whereas the device process is performed at a low temperature of about 200 to 300 ° C. It has become. In addition, regarding the point of the lattice constant, in order to adjust the device characteristics, it is one factor of the warp to stack an epitaxial layer having a lattice constant different from the lattice constant of the GaAs substrate.

  In particular, high output is required for laser diodes, and high brightness is required for light-emitting diodes. To meet this requirement, it is necessary to increase the thickness of the epitaxial layer formed on the GaAs substrate. In such a case, the above-described warpage has been a big problem.

Accordingly, development of a technique for reducing the warpage by changing the material of the epitaxial layer and the film formation conditions is underway (see, for example, Patent Document 1 below).
JP-A-8-241896

  The inventors paid attention to the additive of the GaAs substrate, not the material of the epitaxial layer and the film formation conditions, and discovered a new technique capable of reducing the warp after intensive research.

  The present invention has been made to solve the above-described problems. A GaAs substrate, a laminated substrate, an electronic device using the same, a GaAs substrate for dummy use, and a GaAs substrate for reuse are designed to reduce warpage. The purpose is to provide.

The GaAs substrate according to the present invention is a GaAs substrate on which an epitaxial layer is to be formed, and the concentration of added Si (C [Si] cm ⁻³ ) and the concentration of B (C [B] cm ^−3). ) Is the following two formulas (1) and (2)
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
Meet.

  That is, the inventors have newly found that when an epitaxial layer is formed on a GaAs substrate satisfying the above two formulas (1) and (2), the warpage of the substrate can be reduced.

When the lattice constant of the GaAs substrate is a ₁ and the lattice constant of the epitaxial layer is a ₂ , the difference in lattice constant Δa (= | (a ₂ −a ₁ ) / a ₁ |) is expressed by the following formula (3)
Δa ≧ 4.0 × 10 ⁻⁴ (3)
In which the thickness of the epitaxial layer is 1 μm or more.

Further, when the radius is R (mm) and the thickness is d (μm), the following formula (4)
1.5 ≦ (d / 2R) ≦ 15 (4)
The aspect which satisfy | fills may be sufficient.

The multilayer substrate according to the present invention is a multilayer substrate including a GaAs substrate and an epitaxial layer formed on the GaAs substrate, and the concentration of Si added to the GaAs substrate (C [Si] cm ⁻³ ). And the concentration of B (C [B] cm ⁻³ ) are the following two formulas (1) and (2)
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
Meet.

  That is, the inventors have newly found that when an epitaxial layer is formed on a GaAs substrate satisfying the above two formulas (1) and (2), the warpage of the substrate can be reduced.

When the lattice constant of the GaAs substrate is a ₁ and the lattice constant of the epitaxial layer is a ₂ , the difference in lattice constant Δa (= | (a ₂ −a ₁ ) / a ₁ |) is expressed by the following formula (3)
Δa ≧ 4.0 × 10 ⁻⁴ (3)
In which the thickness of the epitaxial layer is 1 μm or more.

Further, when the GaAs substrate is substantially disk-shaped, the radius of the GaAs substrate is R (mm), and the thickness of the GaAs substrate is d (μm), the following formula (4)
1.5 ≦ (d / 2R) ≦ 15 (4)
The aspect which satisfy | fills may be sufficient.

An electronic device according to the present invention is an electronic device manufactured using a laminated substrate including a GaAs substrate and an epitaxial layer formed on the GaAs substrate, and the concentration of Si added to the GaAs substrate ( C [Si] cm ⁻³ ) and B concentration (C [B] cm ⁻³ ) are expressed by the following two formulas (1) and (2):
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
Meet.

  That is, the inventors have newly found that when an epitaxial layer is formed on a GaAs substrate satisfying the above two formulas (1) and (2), the warpage of the substrate can be reduced. A characteristic electronic device was fabricated.

The dummy use GaAs substrate according to the present invention is a dummy use GaAs substrate on which an epitaxial layer is to be formed, and the concentration of added Si (C [Si] cm ⁻³ ) and the concentration of B (C [B ] Cm ⁻³ ) and the following two formulas (1) and (2)
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
Meet.

  That is, the inventors have newly found that, when an epitaxial layer is formed on a dummy GaAs substrate satisfying the above two formulas (1) and (2), the warpage of the substrate can be reduced. The dummy application substrate in the present invention refers to a substrate that is installed in an epitaxial growth apparatus and does not have a primary purpose of epitaxial growth. Such a dummy application substrate is installed in a substrate installation region in the apparatus in the same manner as a normal substrate for the purpose of covering empty pockets in the apparatus or maintaining predetermined epitaxial growth conditions, for example.

When the lattice constant of the GaAs substrate is a ₁ and the lattice constant of the epitaxial layer is a ₂ , the difference in lattice constant Δa (= | (a ₂ −a ₁ ) / a ₁ |) is expressed by the following formula (3)
Δa ≧ 4.0 × 10 ⁻⁴ (3)
In which the thickness of the epitaxial layer is 1 μm or more.

Further, when the radius is R (mm) and the thickness is d (μm), the following formula (4)
1.5 ≦ (d / 2R) ≦ 15 (4)
The aspect which satisfy | fills may be sufficient.

Furthermore, the reusable GaAs substrate according to the present invention is a reusable GaAs substrate on which an epitaxial layer is to be formed, and the concentration of added Si (C [Si] cm ⁻³ ) and B The concentration (C [B] cm ⁻³ ) of the following two formulas (1) and (2)
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
Meet.

  That is, the inventors have newly found that when an epitaxial layer is formed on a GaAs substrate for reuse that satisfies the above two formulas (1) and (2), the warpage of the substrate can be reduced.

  Further, the inventors have found that the warpage of the multilayer substrate can be reduced according to the multilayer substrate including the GaAs substrate for reuse described above and the epitaxial layer formed on the GaAs substrate.

  According to the present invention, there are provided a GaAs substrate, a laminated substrate, an electronic device using the same, a GaAs substrate for dummy use, and a GaAs substrate for reuse purpose, in which warpage is reduced.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments that are considered to be the best in carrying out the invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

  As shown in FIG. 1, the laminated substrate 10 includes an n-type GaAs substrate 12 and an epitaxial layer 13.

  The GaAs substrate 12 is a disk-shaped substrate (VB method, Vertical boat method, for details, refer to Chapter 9 of “Bulk Crystal Growth Technology (Advanced Electronics Series) Baifukan (1994/05)”). For example, it has a diameter of 75 mm), and contains GaAs as a main material and Si and B as impurities.

  The epitaxial layer 13 is made of, for example, GaInP, AlInP, AlGaInP, or the like. When a QW structure is formed on the GaAs substrate 12, InGaAs / (Al) GaAs, InGaP / AlGaInP, or the like may be used as a constituent material of the epitaxial layer 13.

When the concentration of Si added as an impurity to the GaAs substrate 12 is C [Si] cm ⁻³ and the concentration of B is C [B] cm ⁻³ , C [Si] and C [B] Satisfies the following two formulas (1) and (2).
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)

  These equations (1) and (2) are shown in a graph as shown in FIG. Here, in the graph of FIG. 2, the horizontal axis indicates the Si concentration C [Si], and the vertical axis indicates the B concentration C [B].

When a conventional n-type GaAs substrate is manufactured by a vertical manufacturing method, the relational expression between C [Si] cm ⁻³ and C [B] cm ⁻³ is an approximate expression such as the following expression (10). Indicated by
C [B] ≈3.5 × 10 ⁵ × C [Si] ^0.7 (10)
This equation (10) is shown in a graph as shown in FIG.

  The inventors have formed a laminated substrate 10 by forming an epitaxial layer 13 on a GaAs substrate 12 satisfying the above two formulas (1) and (2), and in the case of a GaAs substrate satisfying the above formula (10). In comparison, the knowledge that the warpage of the laminated substrate 10 can be effectively reduced was obtained and verified as follows.

Here, a stylus-type thickness measuring device was used to measure the warpage generated in the laminated substrate. Then, a laminated substrate of GaAs substrates satisfying the above two formulas (1) and (2) is sample A (C [Si] = 1.3 × 10 ¹⁸ cm ⁻³ , C [B] = 2.5 × 10 ¹⁸ cm ^{−. 3} ) A laminated substrate of a GaAs substrate that satisfies the above formula (10) is designated as sample B (C [Si] = 1.3 × 10 ¹⁸ cm ⁻³ , C [B] = 1.7 × 10 ¹⁸ cm ⁻³ ). For each sample A and B, the maximum height position and the minimum height position of the substrate surface were determined. Thereafter, (maximum height position of substrate surface−minimum height position) / (diameter of substrate) was calculated as the amount of warpage. Note that other measurement devices (for example, an optical wavelength interference measurement device) may be used for measuring warpage as appropriate.

  As a result, a large warpage of about 5.3 μm / 10 mm was detected for the sample B as a comparative example. On the other hand, Sample A as an example had a small warpage amount of about 2.6 um / 10 mm.

  Considering that the general warpage amount of the GaAs substrate on which no epitaxial layer is formed is 0.13 um / 10 mm or less, the warpage amount is about 40 times in the comparative example, In the examples, it was found that the amount of warpage was suppressed to about 20 times.

Note that the inventors have a lattice constant difference Δa (= | (a ₂ −a ₁ ) / a ₁ | where the lattice constant of the GaAs substrate 12 is a ₁ and the lattice constant of the epitaxial layer 13 is a _2. ) Satisfies the following formula (3), and the thickness (d ₂ ) of the epitaxial layer is 1 μm or more, the amount of warpage was found to be significantly reduced.
Δa ≧ 4.0 × 10 ⁻⁴ (3)
Regarding the thickness d ₂ of the epitaxial layer, when the epitaxial layer is composed of a plurality of layers, the total thickness is preferably 1 μm or more.

However, the epitaxial layer on the GaAs substrate is used as the light emitting layer of the quantum well structure (QW) and the multiple quantum well structure (MQW), and the difference Δa in lattice constant between the epitaxial layer and the GaAs substrate is
Δa ≧ 7.0 × 10 ⁻³
In this case, the total thickness d ₂ is not 1 μm or more, but may be 20 nm or less. This is because, in a bulk crystal, dislocations are introduced due to a difference in lattice constant when the film is made thick, so that a large lattice constant difference cannot be realized, but an epitaxial layer having a QW structure or MQW structure has a thin large lattice constant difference. This is because the thickness can be realized.

Further, when the radius of the GaAs substrate 12 is R (mm) and the thickness of the GaAs substrate 12 is d ₁ (μm), when the following formula (4) is satisfied, the warping amount is as follows. A significant reduction was also found. The radius R of the GaAs substrate 12 is typically 50 mm to 200 mm.
1.5 ≦ (d ₁ / 2R) ≦ 15 (4)

  The multilayer substrate 10 described above can be applied to an electronic device such as a CD, a DVD laser diode, a light emitting diode, and a mobile phone electronic device (HBT, HEMT). Hereinafter, as an example of an electronic device using the multilayer substrate 10, a light emitting diode will be described with reference to FIG.

  FIG. 4 is a schematic cross-sectional view showing the light emitting diode 100 according to the embodiment of the present invention. The light emitting diode 100 includes a lower cladding layer 13, a light absorption layer 14, a separation layer 15, a lower guide layer 16, an active layer 17, an upper guide layer 18, and an upper cladding layer 19 that are sequentially stacked on the upper surface of the GaAs substrate 12. Have. Each of these layers is made of a compound semiconductor.

  A circular anode 20 is provided on the upper cladding layer 19. The entire lower surface of the substrate 12 is covered with the cathode 22. By injecting current into the active layer 17 through the anode 20 and the cathode 22, the light emitting diode 100 emits light, and light can be extracted from the upper surface and side surfaces as light output.

  The active layer (light emitting layer) 17 has a higher refractive index than each of the lower guide layer 16 and the upper guide layer 18. Both the guide layers 16 and 18 have a higher refractive index than each of the lower cladding layer 13 and the upper cladding layer 19. These layers have a role of confining light and hole-electrons generated in the active layer 17.

  In this light emitting diode 100, since the GaAs substrate 12 satisfying the above two formulas (1) and (2) is employed, the amount of warpage is effectively reduced, thereby improving the element characteristics (for example, luminance). Is planned.

  The GaAs substrate 12 described above can also be used as a dummy application substrate. Hereinafter, the dummy application GaAs substrate 12 having the same characteristics as the GaAs substrate 12 described above will be described.

  When manufacturing the electronic device described above, GaAs-based epi-growth is performed on a GaAs substrate using, for example, OMVPE method, MBE method, GSMBE method, or LPE method. The epi-growth apparatus used in these methods is usually provided with a plurality of pockets so that a plurality of GaAs substrates can be charged at the same time. Various types of epitaxial film formation can be performed efficiently in the same growth run.

  Thus, although the apparatus is provided with a plurality of pockets for installing substrates, the same number of substrates as the number of pockets is not always processed. For example, when starting up after maintenance, checking the condition and conditions of the furnace, checking after replacing the raw materials, checking the prototype of a product, etc., there are cases where epi-growth is performed on a substrate having a number less than the installable number.

  In such a case, it is desirable to set a dummy substrate (hereinafter referred to as a dummy substrate) in an empty pocket where no substrate is set. Because, when the dummy substrate is not set, epi material is deposited on the pocket surface and the surface is contaminated, and the thermal, chemical and physical surface states of the pocket after the deposition are changed, As a result, it is not suitable for subsequent epi growth. In addition, the deposited pockets need to be chemically, thermally and physically cleaned, which causes time, cost and quality losses.

  It is desirable to use a GaAs substrate as the dummy substrate to be used. This is because when a substrate of a material different from the material to be grown is set, the thermal, physical, and chemical states in the growth furnace change and adversely affect the subsequent epitaxial growth. .

  Even with the dummy substrate of the GaAs substrate as described above, the above-described warpage occurs when the epi material is deposited. In particular, when the same dummy substrate is used over a plurality of growth runs, the accumulated film thickness to be deposited increases according to the number of runs, so that the influence of warpage becomes more prominent.

  In order to form an electronic device structure such as a light-emitting diode, six substrates are set in a growth furnace having eight pockets, and a dummy substrate is set in the remaining two pockets. When growing the epi film, the six substrates are replaced with new substrates every growth run, and the two dummy substrates are continuously used while being installed over a plurality of growth runs. In this case, for example, if the epitaxial growth is performed five times, an epitaxial film having a thickness of 15 μm is grown on the dummy substrate. Normally, when an epi film having a thickness of several tens of μm is deposited on a substrate having a thickness of about 200 to 800 μm, the substrate is very easily warped. In addition, as described above, the growth that requires dummy growth is often aimed at confirming conditions and conditions, so the degree of lattice matching of epi may be shifted from that of the substrate, which also contributes to warpage. Yes.

  When the dummy substrate is warped, in the case of a high-speed rotary furnace, the dummy substrate is scattered due to the centrifugal force and damages the furnace. Also in the case of the auto-revolution furnace, the dummy substrate is detached from the pocket and damages other substrates, and the epitaxial film is deposited in the pocket from which the dummy substrate is detached, thereby greatly hindering the productivity. Even if they do not scatter, the warpage of the substrate inhibits the flow of gas in the growth furnace, and the physical, chemical, electrical, and optical uniformity of the epi characteristics deteriorates.

  Therefore, by applying the above-described GaAs substrate 12 to a dummy application substrate, warpage of the dummy substrate is suppressed, and as a result, the problems described above are eliminated.

  Furthermore, the GaAs substrate 12 described above can be used as a substrate for reuse as described below. Hereinafter, a reusable GaAs substrate 12 having the same characteristics as the GaAs substrate 12 described above will be described.

  Among electronic devices, especially in devices such as high-frequency electronic devices, power application devices, light-emitting LEDs, and solar cells, an epitaxial layer grown on a substrate is attached to another substrate, and the epitaxial layer is peeled off from the original substrate. A pasted electronic device of the type to be manufactured is known. In such a device, as shown in FIG. 5, the GaAs substrate 12 on which the epitaxial layer 13 is formed is opposed to a predetermined support substrate 30 (see FIG. 5A), and bonded to each other. After bonding (see FIG. 5B), only the GaAs substrate 12 is peeled from the epitaxial layer 13 (see FIG. 5C), and the epitaxial layer 13 is transferred to the support substrate 30 side (FIG. 5D). ))).

  The epitaxial layer can be attached to the support substrate by 1) anodic bonding by forming a chemical bond of the bonding material, 2) metal bonding by bonding with a eutectic alloy, etc. 3) UV curable epoxy, thermosetting epoxy, adhesive Resin bonding that joins with an agent, etc. 4) Surface bonding has a high surface flatness to form a hydroxyl group on the surface, and this is a method of joining via heating, pressure bonding, etc. Is possible.

Specific examples of the pasted electronic device are shown below.
1) A transistor for power use having high heat dissipation, manufactured by peeling the original substrate 12 after attaching the epitaxial layer 13 to the support substrate 30 having high thermal conductivity. 2) The epitaxial layer 13 is replaced with the original substrate 12. A high-frequency electronic device manufactured by pasting on a substrate 30 having a smaller parasitic capacitance 3) A high-intensity light-emitting diode (LED) fabricated by pasting the epitaxial layer 13 on a substrate 30 having a higher reflectance than that of the original substrate 12 )
4) Solar cell with increased cost efficiency and weight efficiency, produced by attaching the epitaxial layer 13 to a substrate 30 that is cheaper or lighter than the original substrate 12

  The process for manufacturing these electronic devices includes the process of peeling the epitaxial layer from the GaAs substrate as described above. In this process, if the GaAs substrate is greatly warped and the substrate material is plastically or elastically deformed, poor bonding with the support substrate occurs. Hereinafter, this bonding failure will be described with reference to FIG.

  FIG. 6A is a diagram showing a state in which a warp occurs such that the GaAs substrate 112 side is convex and the epitaxial layer 113 side is concave. In this case, it becomes difficult to firmly join the central portion of the GaAs substrate 112 to the support substrate 30, and if a strong force is applied to forcibly join the peripheral portion of the GaAs substrate 112 may be damaged. is there. On the other hand, FIG. 6B is a diagram showing a state in which a warp in which the GaAs substrate 112 side is concave and the epitaxial layer 113 side is convex occurs throughout. In this case, although the central portion of the GaAs substrate 112 can be firmly bonded to the support substrate 30, it is difficult to bond the peripheral portion of the GaAs substrate 112. The part may be damaged. In addition, not only the board | substrate with which curvature generate | occur | produced over the whole but the board | substrate with which curvature generate | occur | produced partially in the peripheral part and the center part has the problem of the same joining failure.

  Due to the above-described bonding failure, there is a problem that the epitaxial layer cannot be uniformly peeled or there are problems in manufacturing and cost. Although measures to reduce the warpage by increasing the thickness of the substrate to be used can be considered, there are various problems such as an increase in cost.

  As described above, in the process of peeling the epitaxial layer from the GaAs substrate, it is effective to apply the above-described GaAs substrate 12 in which the warpage is suppressed in order to avoid the above-described problems.

  In addition, as for the situation where the substrate is reused, when manufacturing electronic devices, such as an epitaxial layered substrate that has not achieved characteristics, an epitaxial layered substrate whose surface morphology has become defective, or an epitaxial layered substrate that has become unnecessary after condition confirmation growth In some cases, only the epitaxial layer is removed from the substrate to reuse the substrate.

  In order to remove the epitaxial layer from the epitaxial laminated substrate, a re-polishing step for performing at least one of an etching process and a polishing process is required. In this process, when the GaAs substrate is greatly warped and the substrate material is plastically or elastically deformed, uniform polishing becomes difficult. Hereinafter, the state in which polishing becomes non-uniform will be described with reference to FIG.

  FIG. 7A is a diagram showing a state in which a warp in which the GaAs substrate 112 side is convex and the epitaxial layer 113 side is concave occurs throughout. The substrate 112 attached to the polishing surface plate 32 is preferentially polished at the peripheral portion in contact with the polishing buff 34, so that the epitaxial layer 113 is not uniformly polished, and the thickness of the epitaxial layer 113 at the peripheral portion is the central portion. It will be thinner than the thickness at. On the other hand, FIG. 7B is a diagram showing a state in which a warp occurs in which the GaAs substrate 112 side is concave and the epitaxial layer 113 side is convex. The substrate 112 attached to the polishing surface plate 32 is preferentially polished at the central portion in contact with the polishing buff 34, contrary to the case of FIG. It becomes thin compared with the thickness in a peripheral part.

  As described above, when a large warp occurs, the epitaxial layer cannot be uniformly polished, and the substrate from which the epitaxial layer is removed cannot maintain the original shape. Therefore, it is difficult to reuse the substrate, and there are problems in terms of environment and cost. Although measures to reduce the warpage by increasing the thickness of the substrate to be used can be considered, there are various problems such as an increase in cost.

  Therefore, the inventors have developed a technique for returning to the same shape as the substrate before the epitaxial layer is formed even after the epitaxial layer is removed. As a result of intensive research, it was found that the B shape of the GaAs substrate can be returned to a substantially same shape as before the film formation by increasing the B concentration to a predetermined concentration or more. Specifically, the inventors have confirmed that an InGaP epitaxial layer has been grown on each GaAs substrate having a diameter of 2 to 6 inches, and in either substrate, the shape returns to substantially the same as before film formation. Was confirmed.

  As described above, in the step of repolishing the epitaxial layer of the GaAs substrate, it is effective to apply the above-described GaAs substrate 12 in which warpage is suppressed in order to avoid the above problems.

It is the schematic sectional drawing which showed the laminated substrate which concerns on embodiment of this invention. It is the graph which showed the relationship between Si density | concentration and B density | concentration in this invention. It is the graph which showed the relationship between Si density | concentration and B density | concentration in the past. 1 is a schematic cross-sectional view showing a semiconductor laser device according to an embodiment of the present invention. It is the figure which showed the procedure which peels an epitaxial layer from the laminated substrate which concerns on embodiment of this invention. It is the figure which showed the malfunction at the time of peeling an epitaxial layer. It is the figure which showed the malfunction at the time of re-polishing an epitaxial layer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Laminated substrate, 12 ... GaAs substrate, 13 ... Epitaxial layer, 100 ... Semiconductor laser element.

Claims (12)

A GaAs substrate on which an epitaxial layer is to be deposited,
The concentration of added Si (C [Si] cm ⁻³ ) and the concentration of B (C [B] cm ⁻³ ) are the following two formulas (1) and (2):
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
A GaAs substrate that meets the requirements. When the lattice constant of the GaAs substrate is a ₁ and the lattice constant of the epitaxial layer is a ₂ , the difference in lattice constant Δa (= | (a ₂ −a ₁ ) / a ₁ |) is expressed by the following formula (3)
Δa ≧ 4.0 × 10 ⁻⁴ (3)
The filling,
The GaAs substrate according to claim 1, wherein the epitaxial layer has a thickness of 1 μm or more. A substantially disk-shaped GaAs substrate,
When the radius is R (mm) and the thickness is d (μm), the following formula (4)
1.5 ≦ (d / 2R) ≦ 15 (4)
The GaAs substrate according to claim 1, wherein the GaAs substrate satisfies the following conditions. A laminated substrate comprising a GaAs substrate and an epitaxial layer formed on the GaAs substrate,
The concentration of Si added to the GaAs substrate (C [Si] cm ⁻³ ) and the concentration of B (C [B] cm ⁻³ ) are the following two formulas (1) and (2):
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
Meeting the laminated substrate. When the lattice constant of the GaAs substrate is a ₁ and the lattice constant of the epitaxial layer is a ₂ , the difference in lattice constant Δa (= | (a ₂ −a ₁ ) / a ₁ |) is expressed by the following formula (3)
Δa ≧ 4.0 × 10 ⁻⁴ (3)
The filling,
The multilayer substrate according to claim 4, wherein the epitaxial layer has a thickness of 1 μm or more. The GaAs substrate is substantially disc-shaped,
When the radius of the GaAs substrate is R (mm) and the thickness of the GaAs substrate is d (μm), the following formula (4)
1.5 ≦ (d / 2R) ≦ 15 (4)
The multilayer substrate according to claim 4 or 5, which satisfies the following conditions. An electronic device manufactured using a multilayer substrate comprising a GaAs substrate and an epitaxial layer formed on the GaAs substrate,
The concentration of Si added to the GaAs substrate (C [Si] cm ⁻³ ) and the concentration of B (C [B] cm ⁻³ ) are the following two formulas (1) and (2):
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
Meet the electronic device. A dummy GaAs substrate on which an epitaxial layer is to be deposited,
The concentration of added Si (C [Si] cm ⁻³ ) and the concentration of B (C [B] cm ⁻³ ) are the following two formulas (1) and (2):
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
A GaAs substrate for dummy applications that meets the requirements. When the lattice constant of the GaAs substrate is a ₁ and the lattice constant of the epitaxial layer is a ₂ , the difference in lattice constant Δa (= | (a ₂ −a ₁ ) / a ₁ |) is expressed by the following formula (3)
Δa ≧ 4.0 × 10 ⁻⁴ (3)
The filling,
The dummy use GaAs substrate according to claim 8, wherein the epitaxial layer has a thickness of 1 μm or more. A substantially disk-shaped GaAs substrate,
When the radius is R (mm) and the thickness is d (μm), the following formula (4)
1.5 ≦ (d / 2R) ≦ 15 (4)
The dummy application GaAs substrate according to claim 8 or 9, wherein A reusable GaAs substrate on which an epitaxial layer is to be deposited,
The concentration of added Si (C [Si] cm ⁻³ ) and the concentration of B (C [B] cm ⁻³ ) are the following two formulas (1) and (2):
4.0 × 10 ¹⁷ ≦ C [Si] ≦ 1.0 × 10 ¹⁹ (1)
C [B] ≧ 4.8 × 10 ⁵ × C [Si] ^0.7 (2)
A reusable GaAs substrate that meets the requirements.   A multilayer substrate comprising the GaAs substrate for reuse according to claim 11 and an epitaxial layer formed on the GaAs substrate.

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