JP5355768B2 - Manufacturing method of semiconductor laminated structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element which has high luminance and high output and is excellent in yield and reliability, by reducing variations in I-L characteristics of semiconductor light-emitting elements. <P>SOLUTION: In the semiconductor light-emitting element, a first conductivity type GaAs buffer layer 12 and a first conductivity type clad layer 13 are formed on a GaAs substrate 11 whose surface has a root-mean-square roughness of 0.8 nanometers or less, and an active layer 14 of a single structure (bulk structure) or a structure having a quantum well is formed on the first conductivity type clad layer, and the second conductivity type clad layer is formed thereon. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor stacked structure having a structure in which a plurality of semiconductor layers are stacked on a semiconductor substrate.

  Conventionally, a method of forming a semiconductor light emitting device by laminating a plurality of layers on a GaAs substrate used as a growth substrate by metal organic chemical vapor deposition (MOCVD) is known. For example, a plurality of layers are stacked on a GaAs substrate in the order of a first Al (Ga) InP cladding layer, an active layer, a second Al (Ga) InP cladding layer, and a current diffusion layer. In the first and second cladding layers, for example, Zn or Mg is used as a p-type dopant, and Si, Te, or Se is used as an n-type dopant. The active layer is composed of a bulk layer of Al (Ga) InP or GaInP or a quantum well layer using Al (Ga) InP or GaInP. The Al composition of the active layer is set lower than the Al composition of the cladding layer. The current spreading layer is made of GaP or AlGaAs. Furthermore, an appropriate electrode material such as Au—Zn is deposited on the side opposite to the surface on which the first cladding layer of the GaAs substrate is formed (that is, on the back side of the GaAs substrate) and on the current diffusion layer. Thus, an electrode is formed.

  In order to improve the performance of the semiconductor light emitting device as described above, it is necessary to grow a high-quality compound semiconductor epitaxial film on the GaAs substrate. In order to grow a high-quality compound semiconductor epitaxial film on a GaAs substrate, it is important that the GaAs substrate is cut out from a bulk crystal having good crystallinity, and that the optimal polishing and surface processing are performed on the surface of the GaAs substrate. Become. For example, it is known that when the dislocation density of a GaAs substrate is high or epitaxial growth is performed in the state where a surface oxide film or the like is present on the GaAs substrate, it is difficult to grow a film with good crystallinity. In addition, even when a good epitaxial film quality is obtained by such epitaxial growth, it is known that the device performance such as the lifetime or light output of the semiconductor light emitting device itself is affected.

FIG. 1 shows an example of current density-light output characteristics (IL characteristics) of a semiconductor light emitting device. The horizontal axis in FIG. 1 is current density (A / cm ² : Ampere / square centimeter), and the vertical axis is total luminous flux (mlm: millilumen). The driving current density of the semiconductor light emitting device when used for general display applications is about 40 A / cm ² (20 mA (milliampere) driving). As can be seen from FIG. 1, when the current density is 40 A / cm ² , the IL characteristic has a sufficient direct proportional relationship. For this reason, in such a conventional use, the problem in the use of a semiconductor light emitting element has not occurred.

However, recent semiconductor light emitting devices are not limited to display applications, but have been widely used in various environments such as in-vehicle use, signal lights, illumination, and liquid crystal backlights. Along with this, semiconductor light-emitting elements are required to have improved performance such as higher brightness and higher output. In order to increase the luminance and output of the semiconductor light emitting device, it is conceivable to increase the current density injected into the semiconductor light emitting device. However, the total luminous flux (that is, optical output) of the conventional semiconductor light emitting device having the IL characteristic as shown in FIG. 1 is lowered in the region where the injection current density is 120 A / cm ² or more. In other words, the conventional semiconductor light emitting device has not been able to sufficiently cope with the use state at a higher current density than the conventional one.

  In order to solve the above-described problems, various ideas have been applied to the structure of the semiconductor light emitting device. For example, there is a method for optimizing the number of wells in an active layer using quantum wells. There is also a method of suppressing carrier overflow by adding a quantum barrier structure to a cladding layer or the like. Patent Documents 1 and 2 disclose these methods.

However, the above-described method has been insufficient in improving the IL characteristics of the semiconductor light emitting device. Specifically, there has been a problem that variation in IL characteristics occurs for each semiconductor light emitting element as shown in FIG. FIG. 2 shows IL characteristics for each of two semiconductor light emitting devices having the same structure and growth lot. As can be seen from FIG. 2, the IL characteristic of sample A does not decrease the total luminous flux (that is, the light output) even when the current density is 120 A / cm ² or more. On the other hand, the IL characteristic of sample B shows almost no decrease in light output even when the current density is 120 A / cm ² or more, but compared with sample A, the light output is almost the same when the current density is 120 A / cm ² or more. Saturated. Such variations in the IL characteristics of each semiconductor light emitting element have led to problems of yield and reliability.

JP-A-6-181361 JP-A-6-104534

  The present invention has been made in view of the circumstances as described above, and provides a semiconductor light emitting device that reduces variations in IL characteristics of a semiconductor light emitting device, has high luminance and high output, and has excellent yield and reliability. The purpose is to do.

  In order to solve the above-described problem, the method for manufacturing a semiconductor laminated structure according to the present invention includes a first conductive type clad layer formed on a GaAs substrate having a surface mean square roughness of 0.8 nanometer or less. A mold clad layer step, an active layer step of forming an active layer on the first conductivity type clad layer, and a second conductivity type clad layer step of forming a second conductivity type clad layer on the active layer. Features.

  According to the semiconductor light emitting device of the present invention, since the root mean square roughness of the first conductivity type semiconductor substrate that is the growth substrate of the semiconductor light emitting device is 0.8 nanometer or less, the IL characteristic of each semiconductor light emitting device is improved. Variations can be reduced, and yield and reliability can be improved.

It is the graph which showed the IL characteristic of the conventional semiconductor light-emitting device. It is the graph which showed the IL characteristic of the conventional semiconductor light-emitting device. It is sectional drawing of the semiconductor light-emitting device which is the 1st Example of this invention. It is the graph which showed the IL characteristic in the semiconductor light-emitting device which is the 1st Example of this invention. It is the graph which showed the relationship between the total luminous flux and the surface roughness of an n-type GaAs substrate in the semiconductor light emitting element which is the 1st Example of this invention. It is a graph which shows the relationship between the dispersion | variation in the optical output in the semiconductor light-emitting device which is the 1st Example of this invention, and current density. 4 is a graph showing a relationship between an n-type GaAs substrate and an active layer in the semiconductor light emitting device according to the first embodiment of the present invention. It is sectional drawing in each manufacturing process of the semiconductor light-emitting device which is the 2nd Example of this invention. It is sectional drawing in each manufacturing process of the semiconductor light-emitting device which is the 2nd Example of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  First, the structure of a semiconductor light-emitting element that is an example of the present invention will be described with reference to FIG.

FIG. 3 is a cross-sectional view of the semiconductor light emitting device 10. As shown in FIG. 3, the semiconductor light emitting device 10 includes an n-type GaAs buffer layer 12 and an n-type cladding layer 13 on the surface (main surface) of an n-type GaAs substrate 11 which is a growth substrate (semiconductor substrate). The active layer 14, the p-type cladding layer 15, and the p-type current diffusion layer 16 are sequentially stacked. Each of these layers is formed by metal organic chemical vapor deposition (MOCVD). The growth conditions are, for example, a growth temperature of about 700 degrees Celsius and a growth pressure of about 10 kPa (kilopascal). As a raw material for the organic metal (MO) gas, for example, trimethylgallium (TMGa), trimethylaluminum (TMAl), or trimethylindium (TMI) is used. For example, arsine (AsH ₃ ) and phosphine (PH ₃ ) are used as the group V gas. For example, silane (SiH ₄ ) is used as an n-type impurity and dimethyl zinc (DMZn) is used as a p-type impurity. Furthermore, the semiconductor light emitting device 10 includes an n-side electrode 17 and a p-type current diffusion layer 16 on the entire surface of the n-type GaAs substrate 11 opposite to the surface on which the n-type GaAs buffer layer 12 is formed (that is, the back surface). A p-side electrode 18 is provided in the upper central portion.

  The n-type GaAs buffer layer 12 is a base layer obtained by growing GaAs on the n-type GaAs substrate 11 while adding impurities such as silicon. The film thickness of the n-type GaAs buffer layer 12 is, for example, about 0.2 μm (micrometer).

The n-type cladding layer 13 adds (Al _x Ga _1-x ) _y In to the n-type GaAs buffer layer 12 while adding silicon so that the silicon concentration is about 3.0 × 10 ¹⁷ cm ^−3. It is formed by growing _1-y P a (0 ≦ x ≦ 1,0 <y ≦ 1). For example, the n-type cladding layer 13 is (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P. Note that the film thickness of the n-type cladding layer 13 is, for example, about 1.0 μm.

The active layer 14 is formed, for example, by growing an undoped layer of (Al _x Ga _1-x ) _y In _1-y P (0 ≦ x ≦ 1, 0 <y <1) on the n-type cladding layer 13. Is done. Here, the values of x and y are set so that the band gap of the active layer 14 is smaller than the band gaps of the n-type cladding layer 13 and the p-type cladding layer 15. For example, the active layer 14 is a quantum in which the well layer is (Al _0.15 Ga _0.85 ) _0.5 In _0.5 P or (Al _0.1 Ga _0.9 ) _0.5 In _0.5 P and the barrier layer is (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P. It is a structure having a well. The active layer 14 may have a single structure (bulk structure). In addition, the film thickness of the active layer 14 is about 0.2-0.5 micrometer, for example.

The active layer 14 is not limited to the composition of this embodiment, and may be, for example, an InGaP-based layer that does not contain aluminum (that is, x = 0). For example, In _0.5 Ga _0.5 P is an InGaP-based active layer.

The p-type cladding layer 15 adds (Al _x Ga _1-x ) _y In to the active layer 14 while adding zinc so that the concentration of zinc (Zn) is about 5.0 × 10 ¹⁷ cm ^−3. It is formed by growing a _{1-y P (0 ≦ x} ≦ 1,0 <y ≦ 1). For example, the p-type cladding layer 15 is (Al _0.7 Ga _0.3 ) _0.5 In _0.5 P. The film thickness of the p-type cladding layer 15 is, for example, about 1.0 μm.

  Also, from the viewpoint of obtaining a high-power semiconductor light-emitting device without dislocation, a material that is substantially lattice-matched to the GaAs substrate is selected for the active layer and the cladding layer, or a material that is lattice-mismatched is less than the critical film thickness It is preferable to select the composition and film thickness as appropriate (such as a strained quantum well structure having a mismatched composition).

  The p-type current diffusion layer 16 is formed on the p-type cladding layer 15 by growing GaInP or GaP while adding zinc. The n-side electrode 17 may be formed by vacuum-depositing Au—Ge—Ni on the back surface of the n-type GaAs substrate 11. The p-side electrode 18 is formed by vacuum-depositing AuZn (gold-tin alloy) on the p-type current diffusion layer 16.

The configuration of the semiconductor light emitting element 10 described above is merely an example, and the configuration can be appropriately changed according to the characteristics of the semiconductor light emitting element 10. For example, the above-described methyl-based material may be changed to an ethyl-based material. Alternatively, silane (SiH ₄ ) used as the impurity gas may be changed to hydrogen selenide (H ₂ Se), and selenium (Se) may be added to the n-type GaAs buffer layer and the n-type cladding layer 12. A p-type intermediate layer may be provided between the p-type cladding layer 15 and the p-type current diffusion layer 16. This p-type intermediate layer is, for example, (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P. As the growth substrate, a GaAs substrate having an off angle of 4 degrees (4 °) is used, but another growth substrate having an off angle may be used. If epitaxial growth is possible on a GaAs substrate, film growth may be performed using a growth method other than MOCVD (for example, molecular beam epitaxy). Moreover, the structure which replaced the n-type and p-type mentioned above may be sufficient.

  Next, referring to FIGS. 4 to 6, it will be explained that the total luminous flux (that is, light output) of the semiconductor light emitting device 10 changes due to the difference in surface roughness of the n-type GaAs substrate 11, and n-type GaAs. The optimum surface roughness of the substrate 11 will be described in detail.

Conventionally, it has been known that the surface state of a GaAs substrate used as a growth substrate has an influence on the characteristics of a semiconductor light emitting device. However, the macro level (e.g., evaluated by X-rays such as surface treatment or polishing state of a GaAs substrate) Attention has been paid to defects with a root mean square (Rms) of several nanomails to several tens of nanometers. This is because the driving current density of the semiconductor light emitting element is 40 A / cm ² or less, and the current density-light output characteristic (IL characteristic) of the semiconductor light emitting element at this usage level is good. is there. That is, in order to improve the IL characteristics of the semiconductor light emitting device, it was considered sufficient to use a GaAs substrate evaluated as having no macro level defect as a growth substrate. However, even a GaAs substrate (e.g., one that is evaluated as a mirror surface by a differential interference microscope or the like) that has been determined to have a good surface state at the macro level, is at the nano level (Rms <1 nm (nanometer)). ), Irregularities are confirmed on the surface. As an evaluation method at the nano level, there is measurement of surface roughness using a scanning probe microscope. In the following, based on the measurement results of the light output of each semiconductor light emitting device using a GaAs substrate with a different surface roughness at the nano level as the growth substrate, the effect of the nano level surface roughness of the GaAs substrate on the light output will be explained. The effectiveness of the evaluation (management) of the nano-level surface roughness of the GaAs substrate will be described.

As evaluation contents for explaining the effectiveness described above, a plurality of n-type GaAs substrates 11 having different surface roughness at the nano level are prepared, and the semiconductor light emitting device 10 is manufactured using each n-type GaAs substrate 11. The IL characteristics of the manufactured semiconductor light emitting device 10 were evaluated. It is also possible to prepare the n-type GaAs substrate 11 adjusted to a predetermined surface roughness by polishing the n-type GaAs substrate 11 while changing the particle size of the polishing powder. In the present embodiment, in the region of 10 μm × 10 μm on the surface of the n-type GaAs substrate 11, Rms = 0.22, 0.35, 0.54, 0.72, 0.82, 0.93 nm in total 6 types N-type GaAs substrate 11 was used. Moreover, as evaluation of the IL characteristic of the semiconductor light emitting device 10, the injection current density into the semiconductor light emitting device 10 was set to ²⁰ , 40, 90, 125, 160, 180, and 200 A / cm ² . A semiconductor light emitting device is manufactured using the above six types of n-type GaAs substrates 11 having surface roughness, and each of the n-type GaAs substrates 11 is evaluated for IL characteristics using 40 semiconductor light emitting devices 10 as samples. Went.

FIG. 4 is a graph showing the relationship between the current density and the total luminous flux of the semiconductor light emitting element 10 for each semiconductor light emitting element 10 using the n-type GaAs substrate 11 having each surface roughness. The horizontal axis in FIG. 4 is current density (A / cm ² : Ampere / square centimeter), and the vertical axis is total luminous flux (mlm: millilumen). FIG. 4 is a plot of the average value of the total luminous flux for 40 samples (n = 40).

As shown in FIG. 4, the total luminous flux of the semiconductor light emitting element 10 (that is, the light intensity) is up to 40 A / cm ² (that is, current injection of about 20 mA), which is a conventional injection current density into the semiconductor light emitting element. There is almost no variation in output. However, as the current density increases, the light output of the semiconductor light emitting device 10 varies. The variation in light output increases as the current density increases. That is, it can be seen that there is no variation in IL characteristics due to the surface roughness of the n-type GaAs substrate 11 up to a current density of 40 A / cm ² .

In addition, the smaller the surface roughness of the n-type GaAs substrate 11, the higher the light output increase rate in a current density region of 100 A / cm ² or more (hereinafter referred to as a high current density region). Specifically, the light output of the semiconductor light emitting device 10 using the n-type GaAs substrate 11 having a surface roughness of Rms = 0.22 nm and 0.35 nm is increased in a current density region of 150 A / cm ² or more. It increases with or maintains a substantially constant value (that is, it is saturated). On the other hand, the light output of the semiconductor light emitting device 10 using the n-type GaAs substrate 11 having a surface roughness of Rms = 0.93 nm and 0.82 nm increases with an increase in current density in a current density region of 150 A / cm ² or more. Decrease.

Accordingly, it can be seen that the difference in nano-level surface roughness of the n-type GaAs substrate 11 affects the total luminous flux of the semiconductor light emitting device 10 in the high current density region. From this, in the use of the semiconductor light emitting device 10 in the high current density region, the dislocation and the small crystal distortion (negligible) of the n-type GaAs substrate 11 which were not affected by the current use of the current density of about 40 A / cm ^2. It can be seen that the nano-level surface state) leads to deterioration of the optical output characteristics in the high-density region of the semiconductor light emitting device 10.

  FIG. 5 shows the relationship between the total luminous flux of the semiconductor light emitting element 10 and the surface roughness of the n type GaAs substrate 11 when the current density is changed for each semiconductor light emitting element 10 using each n type GaAs substrate 11. It is the shown graph. The horizontal axis in FIG. 5 is the root mean square roughness (Rms), and the vertical axis is the total luminous flux (mlm: millilumen). 5 plots the average value of the total luminous flux for 40 samples (n = 40), as in FIG.

As shown in FIG. 5, when the current density is 20 and 40 A / cm ² , the total luminous flux of each semiconductor light emitting element 10 is substantially constant regardless of the surface roughness of the n-type GaAs substrate 11. . On the other hand, when the current density is 90 A / cm ² or more, it can be seen that the value of the total luminous flux varies depending on the surface roughness of the n-type GaAs substrate 11. Specifically, in the range of Rms> 0.8 nm, the total luminous flux of each semiconductor light emitting element 10 decreases. On the other hand, in the range of Rms <0.4 nm, the total luminous flux of each semiconductor light emitting element 10 increases. On the other hand, when the surface roughness of the n-type GaAs substrate 11 is in the range of 0.4 nm ≦ Rms ≦ 0.8 nm, no fluctuation of the total luminous flux depending on the surface roughness of the n-type GaAs substrate 11 is observed.

  Therefore, if the surface roughness of the n-type GaAs substrate 11 is reduced, the total luminous flux of the semiconductor light emitting device 10 increases even in a high current density region, and the IL characteristic can be improved. Further, by making the surface roughness of the n-type GaAs substrate 11 in the range of 0.4 nm ≦ Rms ≦ 0.8 nm, a constant light output independent of the surface roughness of the n-type GaAs substrate 11 can be obtained. Thereby, since the dispersion | variation in the characteristic for every semiconductor light-emitting device 10 can be suppressed, it becomes possible to provide a semiconductor light-emitting device of fixed quality.

FIG. 6 is a graph showing the relationship between the variation in light output for each semiconductor light emitting device 10 using each n-type GaAs substrate 11 and the current density. The horizontal axis in FIG. 6 is the current density (A / cm ² ), and the vertical axis is the standard deviation σ of the total luminous flux for each semiconductor light emitting device 10 using the n-type GaAs substrate 11 having different surface roughness. 6 shows the standard deviation σ of the total luminous flux of the semiconductor light emitting device in which the surface roughness of the n-type GaAs substrate varies at the nano level. In addition, each plot shown by FIG. 6 is a plot of the average value of 40 samples (n = 40) similarly to FIG.

  As shown in FIG. 6, the standard deviation σ of the conventional example increases in direct proportion as the current density increases. That is, the IL characteristic of the semiconductor light emitting device in which the surface roughness of the n-type GaAs substrate varies at the nano level varies in the high current density region. Therefore, when using an n-type GaAs substrate whose surface roughness varies at a nano level, it is difficult to manufacture a semiconductor light emitting device having good IL characteristics in a high current density region with a high yield. It can be seen that a semiconductor light emitting device having sufficient reliability cannot be obtained.

  Further, when the surface roughness of the n-type GaAs substrate 11 is Rms = 0.82, 0.93 nm (that is, Rms> 0.8 nm), the variation in each current density is smaller than that of the conventional example. Yes. However, the standard deviation σ of the semiconductor light emitting device 10 using the n-type GaAs substrate 11 having a surface roughness of Rms = 0.82 and 0.93 nm increases in direct proportion as the current density increases. Therefore, when the n-type GaAs substrate 11 having a surface roughness of Rms = 0.82 and 0.93 nm is used, the semiconductor light emitting device 10 having good IL characteristics in the high current density region is manufactured with a high yield. It is difficult to obtain the semiconductor light emitting device 10 having sufficient reliability.

On the other hand, when the surface roughness of the n-type GaAs substrate 11 is Rms = 0.22, 0.35, 0.54, 0.72 nm (that is, Rms ≦ 0.8 nm), the current density increases. The variation is also increasing. However, as compared with the semiconductor light emitting device 10 using the n-type GaAs substrate 11 with Rms> 0.8 nm, the variation is greatly reduced. In particular, when the current density is 100 A / cm ² or more, the standard deviation σ is almost saturated. That is, when the n-type GaAs substrate 11 having a surface roughness of Rms ≦ 0.8 nm is used, the semiconductor light emitting device 10 having a good IL characteristic in a high current density region can be manufactured with a high yield. The semiconductor light emitting device 10 having sufficient reliability can be obtained.

  From the contents described with reference to FIGS. 4 to 6, by setting the surface roughness range of the n-type GaAs substrate 11 at the nano level, semiconductor light emission with less variation in IL characteristics even in a high current density region. An element 10 can be provided. Specifically, the surface roughness of the n-type GaAs substrate 11 needs to be set to Rms ≦ 0.8 from the variation of the total luminous flux of the semiconductor light emitting device 10 shown in FIG. Thereby, in the semiconductor light emitting device 10 having the n-type GaAs substrate 11 having the same surface roughness, the variation of the total luminous flux in the high current density region is reduced. Furthermore, from the relationship between the surface roughness of the n-type GaAs substrate 11 and the total luminous flux shown in FIG. 5, the surface roughness of the n-type GaAs substrate 11 is set within a range of 0.4 ≦ Rms ≦ 0.8. It is preferable. As a result, the total luminous flux of the semiconductor light emitting device 10 is not changed depending on the surface roughness of the n-type GaAs substrate 11, and the yield of the semiconductor light emitting device 10 having good IL characteristics even in a high current density region is obtained. Can be manufactured well.

  FIG. 7 is a diagram illustrating a semiconductor light emitting device 10 using an n-type GaAs substrate 11 having a surface roughness Rms = 0.22, 0.35, 0.54, 0.72, 0.82, 0.93 nm. 3 is a graph showing the relationship between the type GaAs substrate 11 and each active layer 14. In FIG. 7, the horizontal axis represents the surface roughness Rms (nm) of the n-type GaAs substrate 11, and the vertical axis represents the surface roughness Rms (nm) of the active layer 14.

  As shown in FIG. 7, the surface roughness of the n-type GaAs substrate 11 is Rms = 0.22, 0.35, 0.54, 0.72 nm (that is, Rms ≦ 0.8). The surface roughness of the active layer 14 is substantially constant, and its value is as small as 2.0 nm or less. On the other hand, when the surface roughness of the n-type GaAs substrate 11 is Rms = 0.82, 0.93 nm (that is, Rms> 0.8), the surface roughness of the active layer 14 increases in direct proportion, The value is also as large as 3.0 nm or more.

  Therefore, when the surface roughness of the n-type GaAs substrate 11 is Rms ≦ 0.8, the surface roughness of the active layer 14 can be made constant, so that the IL characteristic due to the surface roughness of the active layer 14 can be obtained. Variations can be suppressed. This is because the variation (standard deviation σ) of the total luminous flux in the high current density region of the semiconductor light emitting device 10 using the n-type GaAs substrate 11 whose surface roughness is Rms ≦ 0.8, and the surface roughness is Rms> 0. This corresponds to the fact that the variation of the total luminous flux in the high current density region of the semiconductor light emitting device 10 using the .8 n-type GaAs substrate 11 is smaller (that is, the result shown in FIG. 6). Therefore, the surface roughness of the n-type GaAs substrate 11 is caused by the surface roughness of the active layer 14, and the surface roughness of the active layer 14 affects the variation in IL characteristics of the semiconductor light emitting device 10. Recognize.

  As described above in detail, the relationship between the nano-level surface roughness of the GaAs substrate and the light emission characteristics of the semiconductor light emitting device in the high current density region is investigated, and the brightness, output and emission characteristics of the semiconductor light emitting device are increased. The condition of the substrate surface roughness for reducing the variation of the substrate was found. According to the semiconductor light emitting device of the present invention, the n-type GaAs substrate, which is the growth substrate of the semiconductor light emitting device, has a root mean square roughness of 0.8 nanometers or less, thereby reducing variations in IL characteristics of the semiconductor light emitting device. In addition, the yield and reliability can be improved.

  The semiconductor light emitting device 10 of the first embodiment described above has the n-type GaAs substrate 11 used as a growth substrate as a permanent substrate, but the semiconductor light-emitting device of the present invention has an n-type GaAs substrate as the final substrate. Alternatively, the structure may be removed.

  Hereinafter, a method for manufacturing a semiconductor light emitting device that does not have an n-type GaAs substrate will be described with reference to FIG.

  First, an n-type GaAs substrate 81 having a surface root mean square roughness of 0.8 nanometer or less is prepared as a growth substrate (FIG. 8A). Note that the root mean square roughness of the surface of the n-type GaAs substrate 81 is more preferably not less than 0.4 nanometers and not more than 0.8 nanometers.

Next, an n-type cladding layer 82, an active layer 83, and a p-type cladding layer 84 are formed on the n-type GaAs substrate 81 using MOCVD (FIG. 8B). As a result, a semiconductor multilayer structure including the n-type GaAs substrate 81, the n-type cladding layer 82, the active layer 83, and the p-type cladding layer 84 is formed. The growth conditions are, for example, a growth temperature of about 700 degrees Celsius and a growth pressure of about 10 kPa (kilopascal). As a raw material for the organic metal (MO) gas, for example, trimethylgallium (TMGa), trimethylaluminum (TMAl), or trimethylindium (TMI) is used. For example, arsine (AsH ₃ ) and phosphine (PH ₃ ) are used as the group V gas. For example, silane (SiH ₄ ) is used as an n-type impurity and dimethyl zinc (DMZn) is used as a p-type impurity. Note that, as in the first embodiment, an n-type GaAs buffer layer may be formed between the n-type GaAs substrate 81 and the n-type cladding layer 82 in the semiconductor multilayer structure. A current diffusion layer may be formed.

  Next, a p-type electrode 85 is formed on the p-type cladding layer 84 by sputtering (FIG. 8C). An insulating reflective layer may be partially formed on the p-type cladding layer 84, and the p-type electrode 85 may be partially formed on the p-type cladding layer 84. Thereafter, a separately prepared support 86 is bonded to the p-type electrode 85 side via a bonding layer 87. (FIG. 8D). At this time, for example, the support 86 is composed of a conductive support substrate doped with boron (B) and made of silicon (Si), and various metal layers formed on both surfaces of the conductive support substrate. ing. The p-type electrode 85 and the support 86 are bonded together via a bonding layer 87 formed on at least one of the p-type electrode 85 and the support 86 and made of a eutectic alloy such as AuSn. Is called.

  Next, the n-type GaAs substrate 81 is removed by wet etching using a mixed solution of ammonia water and hydrogen peroxide water (FIG. 9A). An n-type electrode 88 is formed by sputtering on the n-type clad layer 82 exposed by removing the n-type GaAs substrate (FIG. 9B). The semiconductor light emitting device formed by such a manufacturing process can be used as the semiconductor light emitting device 80 of the second embodiment of the present invention.

  That is, a semiconductor multilayer structure including a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer, which is grown using a GaAs substrate having a surface mean square roughness of 0.8 nanometer or less as a growth substrate. If the semiconductor light-emitting element has, good electro-optical characteristics can be obtained even in a high current density region. A first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer grown using a GaAs substrate having a surface mean square roughness of 0.4 nanometers or more and 0.8 nanometers or less as a growth substrate. If the semiconductor light-emitting element has a semiconductor laminated structure including, electro-optical characteristics with good and little variation can be obtained even in a high current density region.

DESCRIPTION OF SYMBOLS 10 Semiconductor light-emitting device 11 n-type GaAs substrate 12 n-type GaAs buffer layer 13 n-type cladding layer 14 active layer 15 p-type cladding layer 16 p-type current diffusion layer 17 n-side electrode 18 p-type electrode

Claims (3)

A first conductivity type cladding layer step of forming a first conductivity type cladding layer on a GaAs substrate having a surface mean square roughness of 0.4 nanometers or more and 0.8 nanometers or less;
An active layer step of forming an active layer on the first conductivity type cladding layer;
And a second conductivity type cladding layer step of forming a second conductivity type cladding layer on the active layer. A second conductivity type electrode step of forming a second conductivity type electrode on the second conductivity type cladding layer;
The method for manufacturing a semiconductor multilayer structure according to claim 1, further comprising a bonding step of bonding the second conductivity type electrode to a support through a bonding layer.   The method for manufacturing a semiconductor multilayer structure according to claim 1, further comprising a removing step of removing the GaAs substrate.

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