JP2011023453A - Method for manufacturing semiconductor device - Google Patents

Abstract

When a semiconductor material of the same type as a semiconductor layer is used as a substrate for growing a semiconductor layer constituting a semiconductor element structure, an alignment mark that can be recognized at the time of exposure after the semiconductor layer is grown can be formed. .
A second alignment mark 120 made of a material having a refractive index different from that of the substrate 101 is formed on a substrate 101 made of a material transparent to an alignment mark detection light source. Subsequently, a GaN-based epitaxial layer including the active layer 105 is grown on the substrate 101 so as to bury the second alignment mark 120. Subsequently, with reference to the second alignment mark 120, exposure alignment for the GaN-based epitaxial layer is performed.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a group III nitride (GaN) -based semiconductor device.

  A GaN-based semiconductor laser device is an indispensable device as a light source for reading and writing of a high-density optical disk device and a light source of a laser display device. As a light source of an optical disk device, a light output of several hundred mW is required, and as a light source of a laser display device, a light output of several W class is required. In order to realize such a high output operation, the end face structure at the cavity end face of the laser device is an important technical problem.

  Usually, the end face of the resonator is constituted by a cleavage plane by cleavage. Since the cleavage plane is a plane in which crystals are discontinuously discontinuous, a large number of dangling bonds (dangling bonds) are formed on this surface. Dangling bonds act as non-radiative recombination centers. Thereby, the carriers (electron-hole pairs) injected from the electrodes recombine via these non-radiative recombination centers, and energy is converted into heat. Further, since there are high-density non-radiative recombination centers in the vicinity of the cleavage plane, the effective energy band gap is smaller than that inside the crystal. For this reason, light reciprocating in the resonator (recombined light) is easily absorbed in the vicinity of the cleavage plane. The absorbed light energy generates carriers, and heat is also generated by recombination through non-radiative recombination centers. Heat generation at the cleavage plane (resonator end face) causes a reduction in energy and band gap. As a result, further light absorption and local heat generation are promoted at the end face of the resonator, and eventually melting occurs at the end of the resonator. This is a well-known phenomenon called catastrophic optical damage (COD).

  In order to avoid this COD, a method is generally adopted in which the energy band gap at the end of the resonator is made larger than that inside the resonator. This structure is called an end window structure. In the end face window structure, since light absorption at the resonator end can be suppressed, local heat generation that causes COD can be suppressed. For this reason, a high output operation is possible.

  As a method for forming the end face window structure, a technique is known in which the vicinity of the resonator end face in the active layer is disordered by an ion implantation method or an impurity diffusion method to form a wide band gap (see, for example, Patent Document 1). reference.). However, in the GaN-based material, since the bonds between atoms are strong, this disordering method cannot be applied.

  In view of this, a method has been developed in which a stepped portion or a selective growth mask is formed in advance on a substrate, and then a layer structure (heterostructure) necessary for the laser structure is epitaxially grown. In the vicinity of the stepped portion or the selective growth mask, a laser resonator is fabricated by using the phenomenon that the energy and band gap of the active layer that has been epitaxially grown is enlarged so that the portion with the enlarged energy and band gap becomes the end face. . As a result, an end face window structure can be realized without using an ion implantation method and an impurity diffusion method.

JP-A 63-196088 JP 2007-123781 A

  By the way, in order to realize the end face window structure using the stepped portion or the selective growth mask, after the epitaxial growth of the layer structure necessary for the laser structure, the laser resonator (in the vicinity of the stepped portion or the selective growth mask) It is necessary to fabricate an optical waveguide.

  The size of the energy band gap in the active layer largely depends on the distance from the stepped portion or the selective growth mask. Therefore, in order to realize a desired end face window structure, it is necessary to precisely control the position of the optical waveguide. For this purpose, alignment of the mask by a reduction projection type exposure apparatus (hereinafter referred to as a stepper apparatus) is effective. In a general stepper apparatus, it is necessary to provide a predetermined alignment mark on the wafer in order to control the exposure position. The stepper device irradiates the alignment mark with laser light and detects the diffracted light. The position of the alignment mark is detected with reference to the signal from the detected diffracted light, and exposure is performed at a predetermined position. In a normal manufacturing process of a GaN-based laser device, a plurality of stepped portions (uneven portions) are generally used as alignment marks.

  For example, conventionally, an alignment mark 10a formed on the GaN substrate 10 as shown in FIG. Here, when the periphery of each alignment mark 10a is dry-etched, an alignment mark 10a composed of convex portions as shown in FIG. 8B is obtained. Further, when each alignment mark 10a portion is dry-etched, an alignment mark 10b composed of a concave portion as shown in FIG. 8C is obtained. In either case, diffracted light can be obtained by utilizing the optical path difference generated by the uneven stepped portion.

  In the manufacturing process of the semiconductor laser device, resist coating and stripping, dielectric film (for example, silicon oxide film) deposition and removal, and the like are repeated. However, since the GaN-based semiconductor material is insoluble in most wet etchants, the step shape due to the alignment mark 10a or the like does not change. For this reason, the alignment mark 10a and the like produced by dry etching can be used from the beginning to the end of the wafer process.

  The manufacturing process of the laser device having the end face window structure using the stepped portion or the selective growth mask described above requires a process of forming the stepped portion or the selective growth mask before the epitaxial growth. Therefore, it is necessary to form the alignment mark 10a and the like before epitaxial growth. However, since the alignment mark 10a shown in FIG. 8A is almost buried by epitaxial growth as shown in the micrograph of FIG. 9B, the alignment mark 10a after epitaxial growth cannot be recognized. is there. Here, FIG. 9A is a micrograph of the upper surface of the GaN substrate 10 on which a plurality of alignment marks 10a are formed, and FIG. 9B is a GaN-based semiconductor formed on the GaN substrate 10. 2 is a micrograph of an epitaxial layer 11 made of

  The present invention solves the above-mentioned conventional problems and grows a semiconductor layer when a semiconductor material of the same type as the semiconductor layer is used as a growth substrate (including a thin film for growth) of the semiconductor layer constituting the semiconductor element structure. It is an object of the present invention to be able to form an alignment mark that can be recognized at the time of subsequent exposure.

  In order to achieve the above object, the present invention provides a method for manufacturing a semiconductor light emitting device, in which an alignment mark made of a material having a refractive index different from that of the substrate is formed on the main surface of the growth substrate. .

  Specifically, the method for manufacturing a semiconductor device according to the present invention includes a step of growing a first crystal layer made of a material transparent to an alignment mark detection light source, and a step of growing the first crystal layer on the first crystal layer. Forming a first mark made of a material having a refractive index different from that of the first crystal layer, and growing a second crystal layer on the first crystal layer so as to embed the first mark; And a step of aligning exposure of the second crystal layer with reference to the first mark.

  According to the method for manufacturing a semiconductor device of the present invention, the first crystal layer made of a material transparent to the alignment mark detection light source is grown, and then the first crystal layer is formed on the first crystal layer. A first mark made of a material having a different refractive index is formed. Subsequently, since the second crystal layer is grown on the first crystal layer so as to embed the first mark, the first mark can be detected by the exposure apparatus. Therefore, it is possible to accurately control the alignment with respect to the stepped portion or the selective growth mask formed before the growth of the second crystal layer.

  In the method for manufacturing a semiconductor device of the present invention, a group III nitride semiconductor can be used for the first crystal layer.

  In the method for manufacturing a semiconductor device of the present invention, a substrate made of a group III nitride semiconductor can be used for the first crystal layer.

  Most of group III nitride semiconductors are transparent to an alignment mark detection light source provided in an exposure apparatus such as a stepper apparatus. Therefore, the first alignment mark embedded in the first crystal layer and the second crystal layer and made of a material having a refractive index different from that of the first crystal layer can be read reliably.

  In the method of manufacturing a semiconductor device of the present invention, in the step of growing the first crystal layer, the first crystal layer is formed by growing on a substrate made of a material different from the group III nitride semiconductor. May be.

  In the method for manufacturing a semiconductor device of the present invention, a dielectric or a refractory metal can be used for the first mark.

  Thus, the shape of the first mark formed before the growth of the second crystal layer can be maintained even after the high temperature process of crystal growth, and the function as the alignment mark can be maintained.

  In the method for manufacturing a semiconductor device of the present invention, the width of the first mark is preferably not more than twice the thickness of the second crystal layer.

  In this way, the upper surface of the second crystal layer grown by embedding the first mark can be reliably flattened.

  In the method for manufacturing a semiconductor device of the present invention, the thickness of the first mark is set to a thickness at which the diffracted light intensity obtained by being embedded by the second crystal layer becomes a maximum point or a thickness in the vicinity thereof. It is preferable.

  In this way, since the diffraction intensity from the first mark embedded in the second crystal layer can be increased, the recognition rate of the first mark in the exposure apparatus can be increased.

  In the method for manufacturing a semiconductor device of the present invention, a region different from the first mark in the first crystal layer is formed between the step of growing the first crystal layer and the step of forming the first mark. The first mark and the second mark in the first crystal growth layer differ from each other by forming a second mark formed of a concave portion or a convex portion and performing alignment with reference to the second mark. A step of forming a stepped portion in the region, and a step of forming a ridge stripe portion in the vicinity of the stepped portion in the second growth layer after the alignment step of exposing the second crystal layer. Good.

  Thus, a semiconductor laser device having an end face window structure can be formed.

  According to the semiconductor device manufacturing method of the present invention, when the same type of first crystal layer is used as the second crystal layer growth substrate, it can be recognized at the time of exposure after growing the second crystal layer. Alignment marks can be formed.

(A) is a top view which shows the GaN-type semiconductor laser apparatus which has an end surface window structure concerning one Embodiment of this invention. (B) is sectional drawing in the Ib-Ib line | wire of (a). (C) is a left view of (a). It is typical sectional drawing which shows the alignment mark formed in the board | substrate which concerns on one Embodiment of this invention. (A) is a top view which shows the 1st alignment mark which concerns on one Embodiment of this invention. (B) is sectional drawing in the IIIb-IIIb line | wire of (a). (C) is a graph which shows the calculation result of the diffracted light intensity by the 1st alignment mark. (A) is the microscope picture before embedding the 2nd alignment mark which concerns on one Embodiment of this invention. (B) is a photomicrograph after the second alignment mark is embedded. It is a graph which shows the calculation result of the diffracted light intensity by the 2nd alignment mark concerning one embodiment of the present invention. It is a modification of one embodiment of the present invention, and is a typical sectional view showing an alignment mark on a semiconductor layer formed on a heterogeneous substrate. FIG. 4A is a scanning electron micrograph of a step portion for forming an end face window structure of a GaN-based semiconductor laser device according to an embodiment of the present invention. (B) is a graph which shows the measurement result of the energy band gap in the peripheral region of a level | step-difference part. (C) is the graph which expanded the positive area | region. (A) is a typical top view which shows the conventional alignment mark. (B) is sectional drawing in the VIIIb-VIIIb line | wire of (a). (C) is typical sectional drawing which shows the other example of the conventional alignment mark. (A) is the microscope picture before embedding the conventional alignment mark. (B) is a photomicrograph after the conventional alignment mark is embedded.

(One embodiment)
A method of manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a GaN semiconductor laser device having an end face window structure will be described as an example of a semiconductor device.

  As shown in FIGS. 1A to 1C, in the semiconductor laser device according to the present embodiment, an end face window structure is formed by providing a stepped portion 101a on a substrate 101 in advance. 1A to 1C, the crystal plane orientations of the substrate 101 and the epitaxial layer thereon are represented by symbols c, a, and m. Symbol c represents a plane whose plane orientation is equivalent to the {0001} plane or its normal vector (c axis), and symbol a represents a plane whose plane orientation is equivalent to the {11-20} plane or its normal vector (a axis) The symbol m represents a plane whose plane orientation is equivalent to the {1-100} plane or its normal vector (m-axis). Further, the minus sign (−) attached to the index of each plane orientation represents the inversion of one index following the minus sign for convenience.

  As shown in FIG. 1, the laser structure according to the present embodiment is characterized in that a step portion 101a is formed in a side portion of the ridge stripe waveguide at the end of the resonator. In the vicinity of the stepped portion 101a, regions 105a in which the energy and band gap of the active layer 105 are selectively and self-alignedly increased are formed at both ends of the resonator. As a result, an end face window structure is realized. The reason why the energy / band gap of the active layer 105 is selectively increased by providing the stepped portion 101a in the substrate and the epitaxial layer will be described later.

  Details of the structure of the substrate 101 and the epitaxial layer thereon will be described below together with the manufacturing method.

  As shown in FIG. 2, first, a step-shaped first alignment mark 115 is placed at a predetermined position on a main surface of a substrate 101 made of n-type gallium nitride (GaN) whose main surface has a (0001) plane orientation. To form. Specifically, as shown in FIG. 3A, each mark 115 has a width of 4 μm and a pattern period of 8 μm.

  First, a method for forming the first alignment mark 115 will be described.

That is, a first silicon oxide (SiO ₂ ) film having a thickness of 200 nm is formed on the main surface of the substrate 101 by thermal chemical vapor deposition (hereinafter abbreviated as thermal CVD). Deposit (not shown). Subsequently, a resist pattern having an opening pattern that opens the formation position of each first alignment mark 115 is formed on the first SiO ₂ film by lithography using a stepper apparatus.

Next, using the resist pattern as a _mask, CF 4 / CHF ₃ gas mixture a reactive ion etching using: a (Reactive Ion Etching RIE), by etching the first SiO ₂ film, said first SiO ₂ The opening pattern is transferred to the film. Subsequently, after removing the resist pattern, an inductively coupled plasma (ICP) dry etching apparatus using chlorine (Cl ₂ ) gas as an etching gas is used as a mask with the SiO ₂ film having an opening pattern as a mask. Is etched to form a first alignment mark 115 on the upper portion of the substrate. Thereafter, the first SiO ₂ film is removed by buffered hydrofluoric acid (BHF). Here, the etching depth d of the first alignment mark 115 is 0.8 μm. Thereby, the first alignment mark 115 having the cross-sectional profile shown in FIG. 3B is formed.

  The optimum etching depth (mark depth) d varies depending on the width and period of each mark 115. For example, as in this embodiment, when the width of each mark 115 is 4 μm and the period is 8 μm, the reflectance of the obtained first-order diffracted light is calculated as shown in FIG. Here, it is assumed that a He—Ne laser beam (wavelength 633 nm) is used as a light source for laser alignment. Therefore, in the present embodiment, the mark depth d is selected to be 0.8 μm at which the intensity of the first-order diffracted light is maximized.

Next, a second SiO ₂ film having a thickness of 600 nm is formed on the substrate 101 by thermal CVD (not shown). Subsequently, by a lithography method and a wet etching method using hydrofluoric acid (HF), the second SiO ₂ film has a planar square shape in which each side is parallel to the a-axis direction and the m-axis direction and one side is 30 μm × 30 μm. An opening pattern is formed. At this time, mask alignment is performed by referring to the first alignment mark 115 in the stepper apparatus. Thereafter, a stepped portion 101a having a depth of 2 μm is formed on the substrate 101 by an ICP dry etching apparatus using Cl ₂ as an etching gas, as shown in FIG. Thereafter, the second SiO ₂ film used as an etching mask is removed by BHF.

Next, as shown in FIG. 2, a second alignment mark 120 is formed on the main surface of the substrate 101 on which the stepped portion 101a is formed. Specifically, a third SiO ₂ film having a thickness of 140 nm is formed in a region different from the first alignment mark 115 on the substrate 101 by a thermal CVD method. Thereafter, a resist pattern having a second alignment mark formation pattern is formed by lithography using a stepper apparatus. At this time, mask alignment by the stepper device is performed with reference to the first alignment mark 115. Subsequently, the third SiO ₂ film is etched by RIE using a mixed gas of CF ₄ / CHF ₃ . Thereby, the second alignment mark 120 having a width of 4 μm and a period of 8 μm is formed from the third SiO ₂ film. Note that the second alignment mark 120 is not limited to SiO _2, and silicon nitride (SiN) can be used as long as it is a dielectric. Further, a high melting point metal such as titanium (Ti) or molybdenum (Mo) can be used instead of the dielectric.

Thereafter, a laminated structure (GaN-based epitaxial layer) necessary for the laser structure is epitaxially grown on the substrate 101. Here, as will be described later, the thickness of the laminated structure is about 2.8 μm. Since the stacked structure grows laterally on the upper surface of the second alignment mark 120 as well as in the thickness direction, the second alignment mark 120 made of SiO ₂ is embedded in the stacked structure.

  4A is a surface micrograph of the second alignment mark 120 on the substrate 101 before the growth of the GaN-based epitaxial layer, and FIG. 4B is a surface micrograph after the epitaxial growth. As shown in FIG. 4B, it can be seen that each second alignment mark 120 is buried by a GaN-based epitaxial layer.

FIG. 5 shows the diffraction intensity of the second alignment mark 120 embedded in the GaN-based epitaxial layer. Assuming the case where He—Ne laser light (wavelength 633 nm) is used as the light source for laser alignment, the GaN-based epitaxial layer is transparent to the alignment light source. Therefore, the second alignment mark 120 made of SiO ₂ embedded in the GaN-based epitaxial layer can be detected. The diffraction intensity from the arranged second alignment marks 120 strongly depends on the film thickness d. As shown in FIG. 5, the diffraction intensity in the second alignment mark 120 has an initial maximum value when the film thickness d is 0.14 μm, that is, the signal intensity from the second alignment mark 120 is maximum. If this is utilized, mask alignment by a stepper apparatus can be performed even after epitaxial growth.

  On the other hand, since the step-shaped first alignment mark 115 formed on the substrate 101 made of GaN shown in FIG. 3B is buried by the GaN-based epitaxial layer, the growth of the GaN-based epitaxial layer is performed. After that, it cannot be used as an alignment mark as shown in FIG.

  Next, the laser structure shown in FIG. 1 is formed by crystal growth on the substrate 101 on which the step portion 101a and the second alignment mark 120 are formed. For the crystal growth, for example, a metalorganic chemical vapor deposition (MOCVD) method is used.

First, on the main surface of the substrate 101, for example, an n-type cladding layer 103 made of n-type Al _x Ga _1-x N (x = 0.03) having a thickness of 2 μm and an n-type having a thickness of 0.1 μm. An n-type light guide layer 104 made of Al _x Ga _1-x N (x = 0.003), a barrier layer made of In _y Ga _1-y N (y = 0.02) with a thickness of 8 nm, and a thickness of A multiple quantum well active layer 105 composed of a well layer composed of 3 nm of In _y Ga _1-y N (y = 0.12), a p-type light guide layer 106 composed of p-type GaN having a thickness of 0.1 μm, A p-type cladding layer 107 made of p-type Al _x Ga _1-x N (x = 0.03) having a thickness of 0.5 μm and a p _- type contact layer 108 made of p-type GaN having a thickness of 60 nm are successively grown. To do.

As a crystal growth method for the GaN-based epitaxial layer, a growth method capable of growing a GaN-based semiconductor laser structure such as a molecular beam epitaxy (MBE) method may be used in addition to the MOCVD method. Further, as raw materials in the case of using the MOCVD method, for example, trimethyl gallium (TMG) is used as a Ga raw material, trimethyl indium (TMI) is used as an In raw material, and trimethyl aluminum (TMA) is used as an Al raw material, and ammonia (NH is used as an N raw material. ₃ ) may be used. Further, silane (SiH ₄ ) gas may be used for the Si raw material that is an n-type impurity, and biscyclopentadienyl magnesium (Cp ₂ Mg) may be used for the Mg raw material that is a p-type impurity.

Next, a mask layer (not shown) made of SiO ₂ having a thickness of 0.2 μm is formed on the p-type contact layer 108 by thermal CVD. Subsequently, the mask layer is patterned by a lithography method and an etching method so as to have a stripe shape with a width of 1.5 μm and to extend in parallel with the m-axis direction. At this time, in the stepper apparatus, the mask alignment of the ridge stripe pattern is performed while referring to the second alignment mark 120. As a result, the distance between the stepped portion 101a formed before epitaxial growth and the ridge stripe portion formed after epitaxial growth can be precisely controlled with an accuracy of about 0.1 μm. Subsequently, the p-type contact layer 108 and the upper part of the p-type cladding layer 107 are etched by an ICP dry etching apparatus using Cl ₂ as an etching gas, and ridge stripes are formed on the p-type contact layer 108 and the p-type cladding layer 107. Forming a waveguide of the mold. Thereafter, the mask layer is removed. The formation position of the ridge stripe portion is an important parameter for forming the end face window structure. Details thereof will be described later.

Next, a light confinement insulating film 109 made of SiO ₂ having a thickness of 400 nm is deposited by thermal CVD. Note that the light confinement insulating film 109 can be made of SiN or the like in addition to SiO ₂ . Subsequently, an opening that exposes the top of the ridge stripe portion is formed in the optical confinement insulating film 109 by lithography and wet etching. Thereafter, the p-side ohmic electrode 110 is formed so as to be in contact with the top of the ridge stripe portion by a lift-off method. Here, the p-side ohmic electrode 110 is composed of palladium (Pd) having a thickness of 40 nm and platinum (Pt) having a thickness of 35 nm.

  Thereafter, as shown in FIGS. 1A and 1B, titanium (Ti) having a thickness of 50 nm and 35 nm having a thickness of 35 nm are formed on the optical confinement insulating film 109 so as to cover the p-side ohmic electrode 110. A p-side pad electrode 111 made of platinum (Pt) and gold (Au) having a thickness of 500 nm is formed by a lift-off method, and the processing on the surface side in the laser structure is completed.

  Next, the surface (back surface) opposite to the n-type cladding layer 103 in the substrate 101 is ground and polished so that the thickness of the substrate 103 including the epitaxial layer is about 100 μm. Subsequently, an n-side ohmic electrode 112 made of Ti having a thickness of 5 nm, Pt having a thickness of 100 nm and Au having a thickness of 1 μm is formed on the back surface of the polished substrate 101 to complete the wafer process.

  Next, a primary cleavage process for cleaving the wafer into a plurality of strip-shaped laser bars is performed. In the present embodiment, the width of each laser bar is cleaved to 600 μm so that the resonator length is 600 μm. After that, the laser is passed through an end face coating process for the purpose of reflectance control and end face protection on the primary cleavage plane (resonator end face), a secondary cleavage process for separating the laser bar into individual chips, and a packaging process for packaging each chip. The device is completed.

The GaN semiconductor laser device according to the present embodiment is not limited to the configuration using GaN for the substrate 101. For example, as shown in FIG. 6, a GaN-based semiconductor layer 202 is formed on a heterogeneous substrate 201 made of sapphire (Al ₂ O ₃ ), spinel (MgAl ₂ O ₄ ), silicon carbide (SiC), silicon (Si), or the like. The first alignment mark 115 and the second alignment mark 120 are formed on the upper surface of the grown GaN-based semiconductor layer 202 by crystal growth. Thereafter, a GaN-based epitaxial layer may be grown on the GaN-based semiconductor layer 202 so as to cover the alignment marks 115 and 120.

  Hereinafter, in the present embodiment, the step portion 101a provided on the substrate 101 causes a phenomenon in which the energy band gap of the multiple quantum well active layer 105 changes in a region near the step portion 101a, that is, the energy band gap increases. A phenomenon in which the end face window structure is formed by the region 105a will be described.

  FIG. 7A is a scanning electron microscope (SEM) photograph of the surface grown up to the multiple quantum well active layer 105 on the substrate 101. The waveguide (resonator) is formed along the m-axis direction (lateral direction in FIG. 7A). FIG. 7B shows the result of evaluating the energy band gap Eg of the multiple quantum well active layer 105 by cathodoluminescence (CL) along the broken line direction shown in FIG. As shown in FIG. 7B, it can be seen that there are regions where Eg increases on both sides of the stepped portion 101a along the a-axis. Therefore, if the position of the optical waveguide (ridge stripe portion) is set so that the end face of the resonator is formed in the vicinity of the stepped portion 101a, an end face window structure in which the energy band gap Eg is increased near the end face of the resonator. realizable.

  FIG.7 (c) is the graph which expanded the right half of FIG.7 (b). The region of ± 15 μm at the position is the end of the step 101a. As can be seen from FIG. 7C, the energy band gap Eg is the largest at a position of 5 μm from the end of the stepped portion 101a. If it deviates from this position, Eg becomes small rapidly. Therefore, it is necessary to perform high-precision mask alignment by the stepper device so that the optical waveguide (ridge stripe portion) is formed at a position of 5 μm from the end of the stepped portion 101a. At that time, the second alignment mark 120 embedded with the above-described GaN-based epitaxial layer is effective.

  As described above, the second alignment mark 120 embedded with the GaN-based epitaxial layer is not limited to the formation of the end face window structure of the semiconductor laser device as in the present embodiment, and a device process in which epitaxial growth is performed during the process. It is effective in general.

  In addition, the present invention is not limited to a GaN-based (Group III nitride) semiconductor as long as it is a semiconductor that makes it impossible to refer to mask alignment after epitaxial growth, such as the first alignment mark 115.

  In the method for manufacturing a semiconductor device according to the present invention, when a first crystal layer of the same kind is used as a growth substrate for a second crystal layer including an active layer, the exposure is performed after growing the second crystal layer. A recognizable alignment mark can be formed, which is particularly useful in a method for manufacturing a GaN-based semiconductor device.

101 substrate (first crystal layer)
101a Step 103 n-type cladding layer 104 n-type light guide layer 105 multiple quantum well active layer 105a region where the forbidden band width increases 106 p-type light guide layer 107 p-type cladding layer 108 p-type contact layer 109 light confinement insulating film 110 p-side ohmic electrode 111 p-side pad electrode 112 n-side ohmic electrode 115 first alignment mark (second mark)
120 Second alignment mark (first mark)
201 heterogeneous substrate 202 GaN-based semiconductor layer

Claims (8)

Growing a first crystal layer made of a material transparent to the alignment mark detection light source;
Forming a first mark made of a material having a refractive index different from that of the first crystal layer on the first crystal layer;
Growing a second crystal layer on the first crystal layer so as to embed the first mark;
And a step of aligning exposure of the second crystal layer with reference to the first mark.   The method of manufacturing a semiconductor device according to claim 1, wherein the first crystal layer is made of a group III nitride semiconductor.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the first crystal layer is a substrate made of a group III nitride semiconductor.   3. The method according to claim 1, wherein in the step of growing the first crystal layer, the first crystal layer is grown on a substrate made of a material different from the group III nitride semiconductor. A method for manufacturing a semiconductor device.   The method of manufacturing a semiconductor device according to claim 1, wherein the first mark is made of a dielectric or a refractory metal.   6. The method of manufacturing a semiconductor device according to claim 1, wherein the width of the first mark is not more than twice the thickness of the second crystal layer.   2. The thickness of the first mark is set to a thickness at which a diffracted light intensity obtained by being embedded by the second crystal layer becomes a maximum point or a thickness in the vicinity thereof. The manufacturing method of the semiconductor device of any one of -6. Between the step of growing the first crystal layer and the step of forming the first mark,
Forming a second mark consisting of a concave portion or a convex portion in a region different from the first mark in the first crystal layer;
Forming a stepped portion in a region different from the first mark and the second mark in the first crystal growth layer by performing alignment with reference to the second mark;
2. The method of claim 1, further comprising a step of forming a ridge stripe portion in the vicinity of the step portion in the second growth layer after the exposure alignment step for the second crystal layer. The manufacturing method of the semiconductor device as described in any one of.