JP2005322786A - Nitride semiconductor element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride semiconductor element capable of preventing a crack from occurring and forming a nitride semiconductor growth layer with good surface flatness, and to provide its manufacturing method. <P>SOLUTION: The nitride semiconductor element is constituted by laminating a nitride semiconductor film on a processing substrate including an embedded region consisting of a recess such that a ratio in a cross-sectional area occupied by the nitride semiconductor film embedded in the recess is ≤0.8 of a cross-sectional area of the recess. Thus, the semiconductor growth layer can be formed for preventing the crack with good surface flatness. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a nitride semiconductor device such as a nitride semiconductor laser device and a method for manufacturing the same, and more particularly to a nitride semiconductor device using a nitride semiconductor substrate as a substrate.

  Nitride semiconductors such as GaN, AlGaN, GaInN, AlGaInN, and mixed crystals thereof are characterized by having a large band gap Eg and a direct transition semiconductor material compared to AlGaInAs semiconductors and AlGaInP semiconductors. ing. Therefore, these nitride semiconductors are used as materials for semiconductor light-emitting elements such as semiconductor lasers capable of emitting short-wavelength light from ultraviolet to green and light-emitting diodes capable of covering a wide emission wavelength range from ultraviolet to red. It is attracting attention and is widely considered for high-density optical discs, full-color displays, and environmental and medical fields.

In addition, this nitride semiconductor has higher thermal conductivity than GaAs-based semiconductors and the like, and is expected to be applied to devices operating at high temperature and high output. Furthermore, since a material corresponding to arsenic (As) in an AlGaAs-based semiconductor, cadmium (Cd) in a ZnCdSSe-based semiconductor, and its raw material (arsine (AsH ₃ )) are not used, the compound semiconductor material has a low environmental impact. Be expected.

  However, conventionally, in the manufacture of a nitride semiconductor laser element, which is one of the nitride semiconductor elements, the ratio of the number of non-defective elements obtained to the number of nitride semiconductor laser elements manufactured on one wafer is shown. There is a problem that the yield value is very low. This yield is affected by whether or not the cleavage direction to be divided becomes a desired direction when dividing a single wafer to form a plurality of nitride semiconductor laser elements.

  That is, in order to divide a nitride semiconductor laser element fabricated on a wafer into individual nitride semiconductor laser elements, first, the wafer is moved along a direction perpendicular to the cavity direction of the nitride semiconductor laser element. Cleave to form the resonator end face and make it a bar shape. Thereafter, in order to further divide the nitride semiconductor laser element on the nitride semiconductor substrate that has been cleaved into a bar shape, the bar manufactured as described above along the direction parallel to the resonator direction is used. Need to be split. At this time, in the case of dividing the wafer into a bar shape, if a nitride semiconductor substrate such as an n-type GaN substrate is used, the nitride semiconductor substrate and the nitride semiconductor growth layer stacked on the surface thereof are arranged in the resonator direction. Has a cleavage plane in a direction perpendicular to the surface, and can be easily cleaved.

  However, the crystal structure of a nitride semiconductor substrate such as an n-type GaN substrate is hexagonal and does not have a cleavage plane in a direction parallel to the cavity direction, so the bar is divided into individual nitride semiconductor laser elements. Difficult to do. Therefore, in this division, not only chipping and cracks, which are minute chips, occur, but also break in an unintended direction, resulting in a decrease in yield.

  To solve this problem, after laminating the nitride semiconductor growth layer on the substrate, a dicing device is used to cut a groove from the surface of the nitride semiconductor growth layer to the middle of the substrate, and the thickness of the substrate is reduced by polishing. Furthermore, a method of dividing a nitride semiconductor laser element or the like with a high yield by inserting a scribe line on the surface of a groove formed by a dicing apparatus and applying a load to the substrate has been proposed (see Patent Document 1).

  Another cause of the decrease in yield is the occurrence of cracks. This crack may occur due to a nitride semiconductor growth layer stacked on the substrate. That is, when a nitride semiconductor laser device is manufactured, a nitride semiconductor growth layer is stacked on a substrate, and the nitride semiconductor growth layer is composed of different types of films such as GaN, AlGaN, and InGaN. At this time, the films constituting the nitride semiconductor growth layer have different lattice constants and cause lattice mismatch, and thus cracks are generated. Therefore, a method of reducing cracks by forming a recess without using a processed substrate to grow a nitride semiconductor growth layer and then flattening the surface of the nitride semiconductor growth layer has been proposed (patented). Reference 2). For example, by using the method described in Patent Document 2, it is possible to suppress cracks that are generated due to lattice mismatch of each film constituting the nitride semiconductor growth layer formed on the substrate.

  When a nitride semiconductor laser device is manufactured using the technique described in Patent Document 2 described above, for example, the nitride semiconductor growth layer is configured as shown in FIG.

That is, the nitride semiconductor growth layer 11 formed on the surface of the processed substrate 10 made of etched n-type GaN or the like has, for example, an n-type GaN layer 120 having a layer thickness of 1.0 μm on the surface of the processed substrate 10. The n-type Al _0.062 Ga _0.938 N first cladding layer 121 having a layer thickness of 1.5 μm, the n-type Al _0.1 Ga _0.9 N second cladding layer 122 having a layer thickness of 0.2 μm, and the n-type Al having a layer thickness of 0.1 μm Multiple quantum consisting of _0.062 Ga _0.938 N third cladding layer 123, n-type GaN guide layer 124 having a thickness of 0.1 μm, three InGaN well layers having a thickness of 4 nm and four GaN barrier layers having a thickness of 8 nm. The well active layer 125, the p-type Al _0.3 Ga _0.7 N evaporation preventing layer 126 having a thickness of 20 nm, the p-type GaN guide layer 127 having a thickness of 0.05 μm, and the p-type Al _0.062 Ga _0.938 N having a thickness of 0.5 μm. Cladding layer 128 and layer thickness 0 A 1 μm p-type GaN contact layer 129 is sequentially stacked. The multiple quantum well active layer 125 is formed in the order of barrier layer / well layer / barrier layer / well layer / barrier layer / well layer / barrier layer.

  In this manner, the nitride semiconductor growth layer 11 is laminated on the processed substrate 10 surface by using the MOCVD (Metal Organic Chemical Vapor Deposition) method, thereby forming the nitride semiconductor growth layer 11 as shown in FIG. A nitride semiconductor wafer having depressions on the surface is formed. In FIG. 11, the drawing orientation is also displayed.

  In addition, when the index indicating the crystal plane or orientation is negative, it is a rule of crystallography to indicate the absolute value with a horizontal line, but in the following, since such notation is not possible, the absolute value A negative sign “−” is added in front of to indicate a negative index.

The “processed substrate” is assumed to be a nitride semiconductor substrate or a substrate in which a dug region and a hill are formed on the surface of a nitride semiconductor thin film laminated on the surface of the nitride semiconductor substrate. Further, a p-type Al _0.3 Ga _0.7 N evaporation prevention layer 126 doped with Mg, a p-type GaN guide layer 127, a p-type Al _0.062 Ga _0.938 N clad layer 128, and a p-type GaN contact layer 129 are obtained. Hereinafter, the nitride semiconductor layer is referred to as a “p layer”.

An n-type GaN substrate is used as the processed substrate 10 shown in FIG. 11 and is dug in a stripe shape using a dry etching technique such as RIE (Reactive Ion Etching) in the [1-100] direction. Region 16 is formed. The width of the dug area is 5 μm, the depth is 3 μm, and the period between adjacent dug areas is 15 μm. A nitride semiconductor growth layer 11 having a laminated structure as shown in FIG. 12 is formed on the processed substrate 10 subjected to such etching by a growth method such as MOCVD.
JP-A-5-315646 JP 2002-246698 A

  However, with the technique according to Patent Document 2 described above, a nitride semiconductor laser is obtained by using an n-type GaN substrate as the processing substrate 10 and epitaxially growing the nitride semiconductor growth layer 11 on the n-type GaN substrate using the MOCVD method or the like. Fabrication of the element was effective in reducing cracks, but the yield was not significantly improved. This is because if the recess is left on the nitride semiconductor growth layer 11, the remaining recess causes the film flatness to deteriorate. If the flatness deteriorates, the thickness of each layer varies within the nitride semiconductor growth layer 11, the characteristics of each nitride semiconductor laser element differ, and the number of elements that satisfy the characteristics within the standard range decreases. Therefore, in order to improve the yield, it is necessary not only to reduce the generation of cracks but also to improve the flatness of the film.

  Moreover, when the surface flatness in the nitride semiconductor wafer surface formed as shown in FIGS. 11 and 12 was measured, the measurement result of the surface flatness measured in the [1-100] direction is as shown in FIG. The measurement was performed under the measurement conditions of a measurement length of 600 μm, a measurement time of 3 s, a stylus pressure of 30 mg, and a horizontal resolution of 1 μm / sample. At this time, the step difference between the highest part and the lowest part of the surface in the measured 600 μm wide region was 200 nm from the graph of FIG.

The difference in flatness is because the film thickness of each layer of the nitride semiconductor growth layer 11 stacked on the surface of the processed substrate 10 varies depending on the position of the wafer, as shown in FIG. It is. Therefore, the characteristics of the nitride semiconductor laser element vary greatly depending on the in-plane position of the wafer on which the element is manufactured, and the thickness of the p layer doped with Mg that greatly affects the characteristics of the nitride semiconductor laser element (FIG. 12). (Corresponding to the sum of the layer thicknesses of the p layers stacked from the p-type Al _0.3 Ga _0.7 N evaporation preventing layer 126 to the p-type GaN contact layer 129) greatly varies depending on the in-plane position of the substrate.

  Also, when a ridge structure that is a current confinement structure is formed, the ridge portion is left in a stripe shape having a width of 2 μm, and the other portions are etched using a dry etching technique using an ICP (Inductively Coupled Plasma) apparatus or the like. . Therefore, if the p-layer thickness before etching varies depending on the in-plane position of the wafer, the remaining thickness of the p-layer after etching that most affects the characteristics of the nitride semiconductor laser device also varies greatly depending on the in-plane position of the wafer. It becomes. For these reasons, the nitride semiconductor laser elements have different layer thicknesses, and even within a single nitride semiconductor laser element, the p-layer has almost no remaining film thickness and remains significantly. Will be mixed. Thus, when the remaining film thickness of the p layer varies, it affects the characteristics such as the lifetime of the nitride semiconductor laser element.

  In addition, such a large layer thickness distribution exists in the wafer surface because the growth rate of the film epitaxially growing on the hill portion of the processed substrate including the nitride semiconductor substrate changes due to the influence of the digging region. This is probably because the uniformity in the wafer plane deteriorated.

  That is, when the epitaxial growth is started on the processed substrate 10 in which the digging region 16 is formed as shown in FIG. 14A, the digging is performed as shown in FIG. 14A in the initial stage of the growth. The bottom growth portion 142 made of a nitride semiconductor thin film grown on the bottom portion 144 of the recessed region 16 fills only a part of the digging region 16. At this time, the growth of the upper surface growth portion 141 made of the nitride semiconductor thin film growing on the surface of the upper surface portion 143 of the hill proceeds while the surface of the nitride semiconductor thin film is flat.

  When the epitaxial growth of the nitride semiconductor thin film proceeds from the state of FIG. 14A described above, the nitride semiconductor thin film grown on the bottom surface portion 144 of the digging region 16 as shown in FIG. The bottom growth portion 142 formed almost fills the digging region 16 and is connected via the growth portion 145 and the top growth portion 141 made of a nitride semiconductor thin film grown on the surface of the top surface portion 143 of the hill. In such a state, the atoms / molecules that are the raw materials attached to the surface of the nitride semiconductor thin film grown on the top surface portion 143 of the hill cause migration or the like and move to the growth portion 145 or the bottom surface growth portion 142. . The movement of atoms / molecules due to this migration or the like occurs very unevenly within the wafer surface, and the distance of movement differs within the wafer surface. As a result, as shown in FIG. 14B, the flatness of the surface of the upper surface growth portion 141 is deteriorated.

  The flatness of such a nitride semiconductor thin film is due to the non-uniformity of the nitride semiconductor substrate itself such as the off-angle wafer in-plane distribution and the substrate curvature in-wafer distribution, or the epitaxial growth rate in-plane non-uniformity. Also, the non-uniformity in the substrate surface of the digging process affects the [1-100] direction. In other words, the time until the digging region 16 is filled differs depending on the [1-100] direction, and the portion that has been buried quickly is the atoms / materials used as the raw material of the nitride semiconductor thin film by migration or the like from the upper surface growth portion 141 of the hill. The molecules move to the growth part 145 or the bottom growth part 142. As a result, the time for forming the nitride semiconductor thin film becomes longer when moved, and as a result, the thickness of the nitride semiconductor thin film formed in the digging region 16 increases. On the other hand, in the portion where the digging region 16 is not completely filled, the atoms / molecules that are the raw material of the nitride semiconductor thin film do not move from the top surface growth portion 141 of the hill to the digging region 16 or even if moved, the nitride semiconductor thin film. The time to form is short. Therefore, the film thickness of the nitride semiconductor thin film formed in the digging region 16 is thinner than the portion where the digging region 16 is buried early.

  Also, when the growth rate of the nitride semiconductor thin film is controlled by the flux of atoms / molecules supplied to the wafer surface, the so-called supply-controlled state, the atoms / molecules that are the raw materials for the nitride semiconductor thin film migrate When flowing into the digging region 16 by a method such as the above, since the flux of atoms / molecules as the raw material supplied to the entire wafer surface is constant, the upper surface growth portion where the nitride semiconductor thin film grows on the upper surface portion 143 of the hill The film thickness of 141 part becomes thin. In the reverse case, that is, when atoms / molecules that are the raw material of the nitride semiconductor thin film do not flow into the digging region 16 due to migration or the like, the upper surface growth portion 141 where the nitride semiconductor thin film grows on the upper surface portion 143 of the hill The film thickness increases.

  As described above, the layer thickness of the upper surface growth portion 141 on the upper surface portion 143 of the hill differs within the wafer surface, and as a result, the flatness of the nitride semiconductor thin film surface is deteriorated. That is, in order to improve the flatness, the atoms / molecules as the raw material of the nitride semiconductor thin film move to the growth portion 145 or the bottom growth portion 142 by migration or the like from the upper surface growth portion 141 of the hill, and the nitride semiconductor thin film is removed. It is necessary to suppress the formation.

Furthermore, when a nitride semiconductor laser element is manufactured by the technique according to Patent Document 2 described above, if an electrode is formed in a recessed portion on the surface of the nitride semiconductor growth layer 11, a current leakage path is generated in the recessed portion, and normal. As a result, it was found that the IV characteristics could not be obtained. Usually, an insulating film such as SiO ₂ is formed on the depression, and an electrode is formed thereon. However, since the depression exists, the insulating film is not uniformly formed on the surface. There are many small cracks, very thin areas, and small holes (pits). For this reason, current leakage occurs through the uneven insulating film portion.

  In addition, when a nitride semiconductor laser device manufactured on a nitride semiconductor substrate using the technique according to Patent Document 1 described above is divided into individual devices, dicing is performed after a nitride semiconductor growth layer is stacked on the nitride semiconductor substrate. It has been found that since the grooves are formed using the apparatus, damage occurs in the nitride semiconductor growth layer, and the characteristics of the nitride semiconductor laser device may be deteriorated.

  In view of such problems, the present invention prevents the generation of cracks when a nitride semiconductor growth layer is laminated on a nitride semiconductor substrate to produce a nitride semiconductor device such as a nitride semiconductor laser device. Therefore, the surface flatness is reduced by suppressing the formation of the nitride semiconductor thin film by migration of atoms / molecules that are the raw material of the nitride semiconductor thin film to the digging region due to migration or the like from the upper surface growth portion of the hill surface. It is an object of the present invention to propose a nitride semiconductor device which forms a good nitride semiconductor growth layer and has no current leakage path or damage, and a method for manufacturing the same.

  In order to achieve the above object, the present invention comprises at least one recess on a nitride semiconductor substrate in which at least a part of the surface is a nitride semiconductor or a substrate in which a nitride semiconductor thin film is laminated on the nitride semiconductor substrate. A first step of forming a processed substrate by forming a hill portion that is a digging region and a non-digged region, and a plurality of nitride semiconductor thin films on both the digging region and the hill surface provided in the processed substrate In the method for manufacturing a nitride semiconductor device, comprising: a second step of laminating a nitride semiconductor multilayer portion comprising: a surface perpendicular to a direction in which the recess extends in the first step and the second step A cross-sectional area of a region surrounded by a cross-sectional portion of the concave portion cut out in the above and a line parallel to the hill surface extending from the hill surface is defined as A, and laminated in the concave portion. The nitride sectional area occupied by the semiconductor thin film is B, the embedding degree B / A of the recess by the nitride semiconductor thin film, characterized by 0.8 or less were.

  Further, in such a method of manufacturing a nitride semiconductor device, in the first step, the recess having an opening width larger than 100 μm is formed in the digging region, and in the second step, the recess is formed from the hill surface. The total film thickness, which is the thickness up to the surface of the nitride semiconductor multilayer portion, is 0.8 times or less the depth of the recess. Further, the concave portions constituting the digging region may be formed in a stripe shape or in a grid shape.

  According to such a method, since the opening width of the concave portion is large, the growth rate of the nitride semiconductor thin film grown on both the digging region and the hill surface is substantially equal, so that the film thickness is substantially equal. Therefore, when the above-described conditions are satisfied, the embedding condition B / A is suppressed to 0.8 or less.

  Further, in such a method of manufacturing a nitride semiconductor device, in the first step, in the digging region, the recess having an opening width of greater than 30 μm and not more than 100 μm is formed, and in the second step, The total film thickness that is the thickness from the hill surface to the nitride semiconductor multilayer surface is set to be twice or less the depth of the recess.

  According to such a method, since the opening width of the concave portion is larger than 30 μm and equal to or smaller than 100 μm and the opening width is narrow, atoms / molecules serving as a material for the nitride semiconductor thin film are sufficiently contained in the digging region. I can't get in. For this reason, the growth rate of the nitride semiconductor thin film in the digging region is smaller than the growth rate of the nitride semiconductor thin film on the hill surface, and the film thickness is also on the hill surface. It becomes smaller. Therefore, when the above-described conditions are satisfied, the embedding condition B / A is suppressed to 0.8 or less.

  In such a method of manufacturing a nitride semiconductor device, in the first step, in the digging region, the recess having an opening width of 2 μm or more and 30 μm or less is formed, and in the second step, the hill The total film thickness, which is the thickness from the surface of the part to the surface of the nitride semiconductor multilayer part, is set to 3 times or less the depth of the recess.

  According to such a method, the opening width of the recess is 30 μm or less, and the opening width of the recess is narrower than that of the above-described case where the opening width is 100 μm or less. The atoms / molecules that can not enter further into the digging area. For this reason, the growth rate of the nitride semiconductor thin film in the digging region is further smaller than the growth rate of the nitride semiconductor thin film on the hill surface, and the film thickness is also on the hill surface. Even smaller than a semiconductor thin film. Therefore, when the above-described conditions are satisfied, the embedding condition B / A is suppressed to 0.8 or less. Further, when the width of the opening of the recess is smaller than 2 μm, the nitride semiconductor thin film associates above the digging region, and a cavity is formed in the digging region. As a result, the nitride semiconductor thin film The flatness is poor and the effect of reducing cracks is reduced. Therefore, the opening width of the recess is preferably 2 μm or more.

  Further, in such a method for manufacturing a nitride semiconductor device, wire bonding is performed for electrical connection to the outside on the nitride semiconductor laminated portion laminated on the processed substrate surface in the second step. In the method for manufacturing a nitride semiconductor device comprising a third step of forming an electrode pad and forming a plurality of nitride semiconductor devices on the substrate, in the third step, the electrode pad is formed above the digging region. Does not form.

  In such a method for manufacturing a nitride semiconductor device, in the third step, the electrode pad may be formed at a distance of 5 μm or more from the end of the digging region.

  Further, in such a method for manufacturing a nitride semiconductor device, in the first step, the width of the hill portion may be 92 μm or more and 4 mm or less.

  According to such a method, when wire bonding is performed on the electrode pad, the diameter (80 μm or more) of the ball portion at the tip of the wire, the opening width of the concave portion (2 μm or more) in the digging region, and the electrode described above Considering the distance (5 μm or more × 2) between the both ends of the pad and the digging region, the width of the hill portion needs to be 92 μm or more. Moreover, in order to prevent the nitride semiconductor thin film to be laminated from cracking, the width of the hill portion is preferably 4 mm or less.

  Further, in such a method of manufacturing a nitride semiconductor device, one nitride semiconductor device may be formed on the hill portion sandwiched between two adjacent digging regions, and a plurality of the nitride semiconductor devices may be formed. A physical semiconductor element may be formed.

  Further, in such a method of manufacturing a nitride semiconductor device, chip division is performed by scribing the back surface side or the front surface side of the nitride semiconductor substrate which is a portion immediately below the digging region of the processed substrate. I do not care.

  In such a method of manufacturing a nitride semiconductor device, the processed substrate is cleaved in a direction perpendicular to the first direction in which the digging region of the nitride semiconductor device extends, and a plurality of the nitride semiconductor devices are mounted. A fourth step of forming a formed bar, and a fifth step of dividing the nitride semiconductor element on the bar into individual chips by dividing the manufactured bar in a direction parallel to the first direction. In the fifth step, scribing the surface of the nitride semiconductor multilayer stacked in the digging region or the back side of the nitride semiconductor substrate that is directly below the digging region, After forming a scribe line parallel to the resonator direction, the chip division may be performed.

  Further, in such a method of manufacturing a nitride semiconductor device, the method includes the fourth step and the fifth step, and in the fifth step, the surface of the nitride semiconductor stacked portion stacked in the digging region or the A back surface side of the nitride semiconductor substrate which is a portion directly under the digging region, and a back surface side of the nitride semiconductor substrate which is a surface of the nitride semiconductor multilayer portion stacked on the hill portion or a portion directly below the hill portion; The chip division may be performed by scribing.

  In addition, the nitride semiconductor device manufacturing method includes the fourth step and the fifth step. In the fifth step, the scribe line is formed as a solid scribe line from the end of the bar. It does not matter if they are formed.

  In the method of manufacturing a nitride semiconductor device, the fourth step and the fifth step are provided. In the fifth step, the scribe line is formed as a solid scribe line in a part of the bar. It does n’t matter what you do.

  In addition, the nitride semiconductor device manufacturing method includes the fourth step and the fifth step. In the fifth step, the scribe line is formed as a broken-line scribe line from the end of the bar. It does not matter if they are formed.

  In the method for manufacturing a nitride semiconductor device, the fourth step and the fifth step are provided, and in the fifth step, the scribe line is formed in a direction perpendicular to the first direction. It does not matter even if it is formed at the end portion which becomes the end face side.

  Furthermore, the nitride semiconductor device of the present invention is manufactured by any one of the above-described nitride semiconductor device manufacturing methods.

  According to the present invention, when a nitride semiconductor growth layer is stacked on a processed substrate to produce a nitride semiconductor device, the recess filling level B / A in the digging region of the nitride semiconductor thin film is set to 0.8 or less. Prevents the occurrence of cracks. In addition, by setting the degree of embedding in this way, atoms / molecules that are the raw material of the nitride semiconductor thin film move to the digging region by migration etc. from the top surface growth part where the nitride semiconductor thin film is laminated on the hill surface. Thus, formation of the nitride semiconductor thin film can be suppressed. As described above, a nitride semiconductor growth layer with good surface flatness can be formed on the nitride semiconductor substrate.

In addition, according to the present invention, the electrode pad is not formed on the upper portion of the digging region, and the distance from the end of the digging region to the electrode pad is set to 5 μm or more, so that the non-planar nitride in the digging region is obtained. Not only the influence of cracks, threading dislocations, holes, and partially thin parts that occur when an insulating film such as SiO ₂ is formed on the surface of the semiconductor growth layer, but the digging region is filled with the nitride semiconductor thin film. It is not affected by defects, dislocations, cracks, etc. in the nitride semiconductor thin film generated in the process. As a result, a nitride semiconductor element free from current leakage paths and damage can be manufactured.

  Further, according to the present invention, the surface of the nitride semiconductor laminated portion laminated in the digging region or the back side of the nitride semiconductor substrate that is directly below the digging region is scribed, and the direction in which the digging region extends is obtained. After forming parallel scribe lines, chip division is performed. For this reason, since the digging region is not completely filled, a groove can be formed in the digging region. And since this groove | channel can be used as a guide at the time of chip | tip division | segmentation, generation | occurrence | production of the chipping or the division | segmentation to the direction which is not intended can be prevented. Also, when the scribe line is off the digging area, when the chip is divided, even if the cracking direction is away from the scribe line and the crack progresses in an unintended direction, the digging line will reach the adjacent digging area. Cracks can be advanced along the grooves in the intrusion region. Therefore, even when a crack occurs in this unintended direction, the adjacent nitride semiconductor element is not destroyed.

  First, in this specification, the meaning of some terms will be clarified in advance. First, the “digging region” means, for example, a recess processed into a stripe shape on the surface of the nitride semiconductor substrate as shown in FIG. FIG. 2 is a schematic cross-sectional view of the substrate after performing the digging process. The cross-sectional shape of the digging region does not necessarily have to be a rectangular shape, and may be a Δ shape or a trapezoidal shape as shown in FIG. Further, the digging region is not necessarily a single concave portion, but may be composed of a plurality of concave portions and narrow flat portions sandwiched between the concave portions as will be described later (see FIG. 10).

  The “hill” is a convex portion that is similarly processed into a stripe shape. The digging regions and hills shown in FIG. 2 are stripe arrangements processed along one direction, but may be a grid arrangement in which the digging regions or hills cross each other. In addition, digging regions having different shapes, digging depths, and digging regions having different shapes may exist on one substrate. Further, the period in which the digging region is formed on one substrate may be different.

“Nitride semiconductor substrate” means a substrate made of Al _x Ga _y In _z N (0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z ≦ 1; x + y + z = 1). However, about 10% or less of the nitrogen element of the nitride semiconductor substrate may be substituted with an element of As, P, or Sb (however, the hexagonal system of the substrate is maintained). The nitride semiconductor substrate may be doped with Si, O, Cl, S, C, Ge, Zn, Cd, Mg, or Be. Furthermore, as these n-type nitride semiconductors, Si, O, and Cl are particularly preferable among these doping materials. The principal plane orientation of the nitride semiconductor substrate is preferably C plane {0001}, A plane {11-20}, R plane {1-102}, M plane {1-100}, or {1-101} plane. Can be used. Further, if the substrate main surface has an off angle within 2 ° from these crystal plane orientations, the surface morphology can be good.

  Next, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a nitride semiconductor laser element will be described as an example of a nitride semiconductor element, but the present invention can also be applied to other nitride semiconductor elements. FIG. 1A is a schematic cross-sectional view of the nitride semiconductor laser device according to this embodiment, and FIG. 1B is a top view of FIG. FIG. 3B is a schematic cross-sectional view of the processed substrate 10 before growing the nitride semiconductor thin film according to the embodiment of the present invention, and FIG. 3A is a top view of FIG. The plane orientation is also displayed. For example, the nitride semiconductor growth layer 11 having the structure shown in FIG. 12 is stacked on the processed substrate 10 shown in FIG. 3 to obtain the nitride semiconductor laser device shown in FIG.

The nitride semiconductor laser device of the present embodiment is manufactured by growing the nitride semiconductor growth layer 11 on the processed substrate 10 made of a nitride semiconductor substrate having the digging region 16 serving as a recess. In such a nitride semiconductor laser device, first, a method for manufacturing the processed substrate 10 will be described with reference to the drawings. In this embodiment, an n-type GaN substrate is used as the processed substrate 10. First, SiO ₂ or the like having a thickness of 1 μm is sputter-deposited on the entire surface of the n-type GaN substrate. Subsequently, in a general photolithography process, a stripe-shaped photoresist pattern is formed with a resist opening width of 5 μm and a stripe center portion. It is formed in the [1-100] direction so that the distance (hereinafter referred to as the period) in the direction parallel to the [11-20] direction between the adjacent stripe center portions is 400 μm. Next, by using a dry etching technique such as an RIE (Reactive Ion Etching) technique, the SiO ₂ and n-type GaN substrates are etched to make the digging region 16 having a digging depth Y of 5 μm and an opening width X of 5 μm. Form. Thereafter, SiO ₂ is removed using HF (hydrofluoric acid) or the like as an etchant to obtain a processed substrate 10 before the nitride semiconductor growth layer 11 is laminated on the surface thereof as shown in FIG. Note that the SiO ₂ deposition method described above is not limited to sputtering deposition, and methods such as an electron beam deposition method and a plasma CVD method may be used. Also, the period of the resist pattern is not limited to the above-mentioned 400 μm, and may be changed depending on the width of the nitride semiconductor laser element to be manufactured.

  As described above, a dry etching technique or a wet etching technique may be used as an etching method for producing the digging region 16 in the processed substrate 10. Further, the processed substrate 10 may be formed by digging the digging region 16 directly on the surface of the n-type GaN substrate as described above. GaN, InGaN, AlGaN, InAlGaN may be formed on the surface of the n-type GaN substrate. After growing a nitride semiconductor thin film such as, it may be formed by digging.

  The nitride semiconductor growth layer 11 as shown in FIG. 12 is epitaxially grown on the processed substrate 10 obtained as described above by appropriately using a well-known technique such as MOCVD, as shown in FIG. A nitride semiconductor laser device is manufactured.

The nitride semiconductor laser device of FIG. 1 has a nitride semiconductor growth layer in which a plurality of nitride semiconductor thin films shown in FIG. 12 are stacked on a processing substrate 10 having a dug region 16 manufactured as described above. 11 is formed. Further, on the surface of the nitride semiconductor growth layer 11, a laser stripe 12 which is a laser optical waveguide and an SiO ₂ film 13 which is disposed so as to sandwich the laser stripe 12 and for the purpose of current confinement are formed. A p-side electrode 14 is formed on the surface of each of the laser stripe 12 and the SiO ₂ film 13, and an n-side electrode 15 is formed on the back surface of the processed substrate 10. A convex portion on the surface of the p-side electrode 14 immediately above the laser stripe 12 is defined as a stripe 17.

  Such a nitride semiconductor laser element having a ridge structure is manufactured by appropriately using a well-known technique after the nitride semiconductor growth layer 11 is laminated on the processed substrate 10, and its detailed manufacturing method and the like. Description of is omitted. Then, by stacking the nitride semiconductor growth layer 11, a plurality of nitride semiconductor laser elements formed on the processed substrate 10 (wafer) are divided into individual elements. That is, first, the wafer is cleaved along a direction parallel to the [11-20] direction (see FIG. 1) to form a bar having a plurality of nitride semiconductor laser elements as shown in FIG. . At this time, in this embodiment, the resonator length, which is the length in the resonator direction ([1-100] direction), is 600 μm, but is not limited to this value, and preferably the resonator length is 300 μm. To 1200 μm. Then, individual nitride semiconductor laser elements are obtained by dividing the bar obtained by the division into chips. Details of the chip division will be described later.

  The nitride semiconductor laser device of FIG. 1 is obtained as described above. Here, the distance between the center of the laser stripe 12 and the end of the digging region 16 is d. In this embodiment, d = 40 μm. FIG. 1 is a cross-sectional view of a nitride semiconductor laser device obtained by performing chip division at a location different from a digging region which is a position where the chip is actually divided, which will be described later, in order to make the sectional structure easy to understand. It is set as the figure which shows.

In the nitride semiconductor laser device as shown in FIG. 1, the p-side electrode 14 is only Mo / Au, Mo / Pt / Au, or Au single layer from the side close to the nitride semiconductor growth layer 11. Formed from. In this embodiment, the SiO ₂ film 13 is used as an insulating film for current confinement. However, ZrO, TiO ₂ or the like may be used as an insulating film material.

In such a nitride semiconductor laser device, the correlation between the growth process of the nitride semiconductor thin film in the digging region 16 and the flatness of the nitride semiconductor thin film grown on the hill will be described below.

  When epitaxial growth is started with respect to the processed substrate 40 in which the digging region 16 is formed, as shown in FIG. 4A, the top surface portion 43 of the hill, the side surface portion 44 and the bottom surface portion in the digging region 16 45, the nitride semiconductor thin film grows as an upper surface growth portion 41 and a digging region growth portion 42, respectively. The opening width of the digging region 16 formed in the processed substrate 40 before growing the nitride semiconductor thin film is X, and the depth is Y. Further, a line extending in parallel with the surface from the surface of the upper surface portion 43 of the hill is set as a digging region boundary line 46. At this time, in the digging region 16, A is a cross-sectional area of a portion surrounded by the side surface portion 44, the bottom surface portion 45, and the digging region boundary line 46. That is, the value of the cross-sectional area A is the same value as X × Y.

  At the initial stage when the epitaxial growth is started, as shown in FIG. 4A, a top surface growth portion 41 in which a nitride semiconductor thin film is grown on the surface of the top surface portion 43 of the hill, a side surface portion 44 and a bottom surface portion in the digging region 16. 45 is separated from the growth portion 42 in the digging region where the nitride semiconductor thin film is grown. Further, as the growth of the nitride semiconductor thin film proceeds, as shown in FIG. 4B, the upper surface growth portion 41 grown on the upper surface portion 43 of the hill and the digging region grown in the digging region 16. The inner growth part 42 is coupled via the growth part 47. It is to be noted that the cross-sectional area of the in-digging region growing portion 42 that grows from the dug region 16 is B, the ratio (%) of the cross-sectional area B to the cross-sectional area A is C, and the nitriding in the dug region 16 It represents the degree of embedding of the semiconductor thin film.

  For example, in the case where the digging region 16 is laminated with a nitride semiconductor thin film and buried by the in-digging region growing portion 42 as shown in FIG. Regardless of whether the surface of the thin film is flat or not, it is 100%. Further, as shown in FIG. 6B, when the digging region 16 is not completely filled with the stacked nitride semiconductor thin film (growing portion 42 in the digging region), C is calculated by the calculation method described above. And (B / A) × 100. Further, as shown in FIG. 6C, the lateral growth rate of the upper surface growth portion 41 is high, and as a result, the nitride semiconductor thin film is formed above the cavity 61 in a state where the cavity 61 is formed in the digging region 16. When (upper surface growth portion 41) is associated, the flatness of the surface of the nitride semiconductor thin film is deteriorated. Therefore, since the effect of reducing cracks is low, it is not included in this embodiment.

  A method for evaluating the flatness will be described below. A wafer obtained by laminating a nitride semiconductor growth layer 11 made of a plurality of nitride semiconductor thin films on a processed substrate 10 having a digging region 16 shown in FIG. 1 is formed into a ridge structure using an optical interference microscope. The p layer thickness before etching to form the film was measured. The variation of the p layer thickness in the wafer plane was used as an index of flatness. That is, the design value of the p-layer thickness at this time was set to 0.670 μm, 20 points were measured on the wafer surface, and σ was obtained as the average deviation. The average deviation σ indicates the degree of variation in the film thickness at the 20 locations measured. If the average deviation σ is large, variations in various characteristics of the nitride semiconductor laser element such as FFP (Far Field Pattern), threshold current, and slope efficiency may occur. growing. The value of this average deviation σ needs to be suppressed to 0.01 or less in order to suppress variations in characteristics of the nitride semiconductor laser element. The average deviation σ is the result of dividing the sum of the absolute values of the differences between the measured values of the layer thickness at the 20 locations and the average value of the layer thickness at the 20 locations by 20.

  FIG. 5 shows the relationship between the degree of burying of the nitride semiconductor thin film C in the digging region 16 and the average deviation σ indicating the degree of variation in the p-layer thickness before etching for forming the ridge structure. From the graph of FIG. 5, the average deviation σ of the p layer thickness suddenly increases when the embedding degree C is greater than 80%, and the average deviation σ of the p layer thickness is reduced to a small value when the embedding degree C is 80% or less. It turns out that it can be suppressed. Also, for example, when a nitride semiconductor laser device with a filling degree C of 70% was fabricated, the average deviation of the p layer thickness was 0.0034 μm, which was a very good value.

As a method for suppressing the burying degree C of the digging region 16 to 80% or less, a method for controlling the total thickness of the nitride semiconductor thin film, a method for controlling the opening width X and the depth Y of the digging region 16, and the like. is there. The total film thickness of the nitride semiconductor thin film (hereinafter referred to as the total film thickness) is various nitride semiconductors from the surface of the portion where the digging region 16 is not formed in the processed substrate 10 where the digging region 16 is formed. It refers to the layer thickness up to the surface of the nitride semiconductor growth layer 11 formed by stacking thin films. That is, after the laser stripe 12 (see FIG. 1) is formed, from the surface of the processed substrate 10 where the digging region 16 is not formed to the surface of the laser stripe portion 12 of the nitride semiconductor growth layer 11. Refers to the layer thickness. The SiO ₂ film 13 and the p-side electrode 14 are not included.

  In order to obtain such good film flatness, when the opening width X of the digging region 16 is larger than 100 μm, the digging region growing portion 42 that grows on the bottom surface 45 of the digging region 16 is The upper surface growth part 41 that grows on the surface of the upper surface part 43 of the hill where the digging region 16 is not formed grows at the same growth rate and has the same film thickness. Therefore, if the total film thickness is 0.8 times or less the depth Y of the digging region 16, the burying degree C of the digging region 16 is 80% or less.

  When the opening width X of the digging region 16 is 2 μm or more and 30 μm or less, since the opening of the digging region 16 is narrow, atoms / molecules that are the raw material of the nitride semiconductor thin film are in the digging region 16. I can't get enough. For this reason, the growth rate of the in-digging region growth portion 42 in the bottom surface portion 45 of the digging region 16 is smaller than the growth rate of the top surface growth portion 41 on the surface of the upper surface portion 43 of the hill where the digging region 16 is not formed. The film thickness is also smaller than that of the upper surface growing portion 41 on the surface of the upper surface portion 43 of the hill. Therefore, if the total film thickness is three times or less the depth Y of the digging region 16, the burying degree C of the digging region 16 is 80% or less.

  When the opening width X of the digging region 16 is greater than 30 μm and 100 μm or less, X takes a value between the two regions described above, and the total film thickness is twice the depth Y of the digging region 16. If it is below, the embedding degree C of the digging area | region 16 will be 80% or less. If the opening width X of the digging region 16 is smaller than 2 μm, the state shown in FIG. Therefore, in this embodiment, the opening width X of the digging region 16 is 2 μm or more.

Further, when a nitride semiconductor growth layer 11 made of various nitride semiconductor thin films is laminated on the processed substrate 10 in which the digging region 16 is formed and evaluated for cracks, the burying degree C is 80% or less. to the crack density in the film 0 present / cm ^2, the embedding degree C is 3 to 4 with 80% / cm ^2, and embedding the degree C is approximately 100% ten / cm ^2. That is, by setting the filling degree C to 80% or less as described above, the nitride semiconductor thin film in which the variation in p layer thickness is suppressed, the flatness of the nitride semiconductor thin film is good, and the occurrence of cracks is further suppressed. A laser element can be manufactured.

  The nitride semiconductor laser device thus manufactured is divided into individual chips. Prior to chip division, the wafer is first cleaved to form the resonator end face. This will be described below with reference to the drawings. FIG. 7 (b) is a part of a schematic cross-sectional view of a resonator end face formed by cleaving the wafer in a direction parallel to the [11-20] direction (see FIG. 1), and having a bar shape. FIG. 7A is a top view thereof.

A nitride semiconductor growth layer 11 is laminated on the processed substrate 10 in which the digging region 16 is formed, and further, a p-side comprising an insulating film such as a SiO ₂ film 13 and a p-side electrode 14 (see FIG. 1) on the surface thereof. An electrode pad 70 is formed. Wire bonding is performed on the p-side electrode pad 70, and the thickness of the p-side electrode pad 70 is usually about 100 nm to 1 μm. In the “embedded current confinement laser” that has a current confinement layer in the nitride semiconductor growth layer 11 and performs current confinement in this layer, only the p-side electrode 14 becomes the p-side electrode pad 70. Further, a convex stripe 17 is provided on the surface of the p-side electrode pad 70, and an n-side electrode 15 is formed on the back surface of the processed substrate 10. As shown in FIG. 7, the distances from both ends of the p-side electrode pad 70 to the ends of the digging region 16 adjacent to both ends are M and N, respectively.

Further, the p-side electrode pad 70 is not formed on the digging region 16 as shown in FIG. This is because, since the surface of the nitride semiconductor growth layer 11 is not flat on the digging region 16, when an insulating film such as SiO ₂ is formed on the surface, there are cracks, threading dislocations, holes, and a partial thickness. This is because there are thin portions and the like, and the insulating property is low as compared with other regions other than the digging region 16, and a leak current flows.

Further, in the state where the digging region 16 is buried, the digging region 16 is buried by stacking the nitride semiconductor thin film even if the groove or the depression is not visually confirmed. Defects, dislocations, cracks and the like are generated in the nitride semiconductor thin film in the digging region 16. For this reason, when SiO ₂ or the like is formed on the surface of the nitride semiconductor growth layer 11 in the digging region 16, the insulating property is lowered. Therefore, when the p-side electrode pad 70 is formed on the digging region 16 or the depression, spontaneous emission light may be confirmed in that region. The spontaneous emission light is generated when a leak current flows in the nitride semiconductor laser element. Then, when the p-side electrode pad 70 was formed at a distance of 5 μm or more from the end of the digging region 16, the spontaneous emission light was not emitted from other than the region of the laser stripe 12 (see FIG. 1). Therefore, the distances M and N from the end of the digging region 16 to both ends of the p-side electrode pad 70 are preferably 5 μm or more, respectively.

Further, in the present embodiment, the ridge stripe type laser that performs current confinement using an insulating film such as SiO ₂ on the nitride semiconductor growth layer 11 has been described. However, the present invention is not limited to this. A VSIS (V-channeled Substrate Inner Stripe) type laser having a current confinement layer inside the growth layer 11 may be used. Such a laser does not have an insulating film for current confinement on the surface of the nitride semiconductor growth layer 11, and the p-side electrode pad 70 comprises only the p-side electrode 14. In this specification, an electrode pad refers to an electrode pad on an insulating film or the electrode itself. Even in such a laser, when the p-side electrode pad 70 is formed in the digging region 16, a large leak current is generated as in the ridge stripe type laser, the characteristics of the nitride semiconductor laser device deteriorate, and laser oscillation occurs. I couldn't. This is presumably because the crystallinity of the current confinement layer above the digging region 16 has deteriorated. Therefore, even in a laser such as a VSIS type laser, the distances M and N from the end of the digging region 16 to both ends of the p-side electrode pad 70 are preferably 5 μm or more.

  In this embodiment, n-type GaN is used as the processed substrate 10 and the electrode pad formed on the surface of the nitride semiconductor growth layer 11 is the p-side electrode pad. However, the present invention is not limited to this, and the processed substrate 10 Also, a nitride semiconductor laser device having a structure in which a p-type semiconductor material is used, the surface of the nitride semiconductor growth layer 11 is composed of an n-type nitride semiconductor thin film, and an electrode pad formed on the surface is an n-side electrode pad. I do not care.

  Although depending on the structure of the nitride semiconductor laser element and the like, when wire bonding is performed, the diameter of the ball portion at the tip of the wire is approximately 80 μm, so the width of the p-side electrode pad 70 is required to be 80 μm or more. . Therefore, the period T of the digging region 16 is T ≧ {the opening width X of the digging region 16 (2 μm or more) + the width of the p-side electrode pad 70 (80 μm or more) +10 μm (both ends of the p electrode pad 70 and the digging region 16 The minimum value of the sum of the distances M and N at the end of Further, if the value of T is larger than 4 mm, cracks are likely to occur in the laminated nitride semiconductor thin film. Therefore, the value of the period T of the digging region 16 is preferably 4 mm or less. T is preferably 92 μm or more and 4 mm or less.

  Further, as shown in FIG. 7, a plurality of nitride semiconductor laser elements fabricated on the processed substrate 10 divided into bar shapes are divided into individual chips. Hereinafter, chip division will be described with reference to the drawings.

  FIG. 7 shows chip division locations 71 and 72. Scribing is performed at the chip division locations 71 and 72 from the n-side electrode 15 side or the nitride semiconductor growth layer 11 side using a diamond pen or the like. A sharp blade with a sharp tip shape is applied to the scribed line (hereinafter referred to as a scribe line), and the pressure is applied using a braking device to be cracked. The position of the scribe line is preferably at the center of the digging region 16. However, in the present embodiment, as described above, the burying degree C of the digging region 16 is 80% or less, the digging region 16 is not completely buried, and a groove is formed. It becomes a guide when dividing. For this reason, even if the position of the scribe line is deviated from the center of the digging region 16, chipping or division in an unintended direction does not occur within the digging region 16.

  Further, even when the position of the scribe line is deviated from the digging area 16, even when the chip is divided, the breaking direction is away from the scribe line, and even if the crack progresses in an unintended direction, the adjacent digging area 16 When it reaches, the crack advances along the groove in the digging region 16, so that the adjacent nitride semiconductor laser element is not broken. The reason why the divided portions do not spread outward from the digging region 16 is that the crystallinity and the plane orientation of the nitride semiconductor thin film stacked in the digging region 16 are flat on the undigged region. This is considered to be because it is different from the nitride semiconductor thin film grown on the portion.

  In the present embodiment, as shown in FIG. 7, it is preferable to manufacture one nitride semiconductor laser element on a hill that is an unexcavated region sandwiched between two adjacent excavation regions. However, the present invention is not limited to this, and two or more nitride semiconductor laser elements may be fabricated on a hill that is an undigged region sandwiched between two adjacent dug regions. .

  As for the scribing method, as shown in FIG. 8, at the chip division points 82 and 83, only the end portion of the digging region 16 formed in the bar on the resonator end face side is scribed, and only the end portion is scribed. The line 80 may be formed, or the scribe line 81 may be formed by making the scribe line a broken line. Even if scribing is performed in this manner, chips can be divided with a high yield. The scribe line may be a solid line (not shown).

  When chip division is performed in this manner, individual nitride semiconductor laser elements are obtained as shown in FIG. The chip dividing method according to the present embodiment uses the grooves formed in the digging region 16 because the digging region 16 is not completely embedded even after the nitride semiconductor thin film is stacked, and the chip dividing step is performed. Compared with the conventional method of newly forming a groove for division, the damage to the nitride semiconductor thin film is suppressed, and the chip can be divided with high yield without deteriorating the characteristics of the nitride semiconductor laser device.

  Further, as shown in FIG. 10, two stripe-shaped recesses 106 are formed, and in the flat region sandwiched between the two stripes, the rear surface side of the wafer or the nitride semiconductor growth layer 11 (see FIG. 1). ) Side may be divided by scribing. With such a structure, even when the chip is divided in an unintended direction, the adjacent portions of the nitride semiconductor laser element can be separated from each other by the concave portions 106 on both sides without being separated from the outside. There is no damage. That is, even if scribing is not performed in the concave portion 106, chip division can be performed with high yield by scribing in a flat region sandwiched between the concave portions 106 as in the chip dividing portions 100 and 101 shown in FIG. In addition, the scribe line formed is a scribe line 102 shown in FIG. 10, a scribe line 103 in which only the end on the resonator end face side is scribed, a solid scribe line 104, and a part is scribed. Any solid line scribe line 105 may be used.

It is the schematic of the nitride semiconductor laser element in embodiment of this invention. It is a schematic sectional drawing of the process board | substrate with which the digging area | region of various shapes was formed. It is the schematic of the process board | substrate in embodiment of this invention. It is explanatory drawing of the embedding condition C of the digging area | region in embodiment of this invention. FIG. 5 is a correlation diagram between an embedding condition C and an average deviation σ of p layer thickness. It is explanatory drawing of the embedding condition of the embedding area. It is the schematic of the nitride semiconductor substrate divided | segmented into the bar shape in embodiment of this invention. It is explanatory drawing of the chip | tip division | segmentation of the nitride semiconductor laser element in embodiment of this invention. 1 is a schematic cross-sectional view of a nitride semiconductor laser element divided into chips according to an embodiment of the present invention. It is explanatory drawing of the chip | tip division | segmentation of the nitride semiconductor laser element in embodiment of this invention. It is the schematic of the wafer which laminated | stacked the nitride semiconductor growth layer on the conventional process board | substrate. It is a schematic sectional drawing of a nitride semiconductor growth layer. It is the surface level | step difference plot figure of the wafer which laminated | stacked the nitride semiconductor growth layer on the conventional process board | substrate. It is explanatory drawing explaining the model of flatness deterioration.

Explanation of symbols

10 processed substrate 11 nitride semiconductor growth layer 12 the laser stripe 13 SiO ₂ film 14 p-side electrode 15 n-side electrode 16 engraved regions 40 working substrate 41 upper surface growth portions 42 dug in the region growing portion 43 upper surface 44 side of the hill 45 bottom surface portion 46 digging region boundary line 47 growth portion 61 cavity 70 p-side electrode pad 71 chip division location 72 chip division location 80 scribe line 81 scribe line 82 chip division location 83 chip division location 100 chip division location 101 chip division location 102 Scribe line 103 Scribe line 104 Scribe line 105 Scribe line 106 _Recess 120 N-type GaN layer 121 n-type Al _0.062 Ga _0.938 N first cladding layer 122 n-type Al _0.1 Ga _0.9 N second cladding layer 123 n-type Al _0.062 G a _0.938 N third clad layer 124 n-type GaN guide layer 125 multiple quantum well active layer 126 p-type Al _0.3 Ga _0.7 N evaporation prevention layer 127 p-type GaN guide layer 128 p-type Al _0.062 Ga _0.938 N clad layer 129 p-type GaN Contact layer 141 Top surface growth part 142 Bottom surface growth part 143 Hill top surface part 144 Bottom surface part 145 Growth part

Claims (17)

In a non-excavated region and an unexcavated region consisting of at least one recess in a nitride semiconductor substrate in which at least a part of the surface is a nitride semiconductor or a substrate in which a nitride semiconductor thin film is laminated on the nitride semiconductor substrate A first step of forming a certain hill portion to produce a processed substrate; and a step of laminating a nitride semiconductor multilayer portion composed of a plurality of nitride semiconductor thin films on both the digging region provided on the processed substrate and the hill surface. In a method for manufacturing a nitride semiconductor device comprising two steps,
In the first step and the second step,
A is a cross-sectional area of a region surrounded by a cross-sectional portion of the concave portion cut by a plane perpendicular to the extending direction of the concave portion and a line parallel to the hill surface extending from the hill surface. ,
The cross-sectional area occupied by the nitride semiconductor thin film stacked in the recess is B,
A method of manufacturing a nitride semiconductor device, wherein a degree B / A of embedding the recess by the nitride semiconductor thin film is 0.8 or less. In the first step,
In the digging region, forming the concave portion having an opening width larger than 100 μm,
In the second step,
2. The nitride semiconductor according to claim 1, wherein a total film thickness that is a thickness from the hill surface to the nitride semiconductor multilayer surface is 0.8 times or less of a depth of the concave portion. Device manufacturing method. In the first step,
In the digging region, forming the concave portion whose opening width is larger than 30 μm and not larger than 100 μm,
In the second step,
2. The nitride semiconductor element according to claim 1, wherein a total film thickness that is a thickness from the hill surface to the nitride semiconductor multilayer surface is not more than twice the depth of the concave portion. Production method. In the first step,
In the digging region, forming the concave portion having an opening width of 2 μm or more and 30 μm or less,
In the second step,
2. The nitride semiconductor element according to claim 1, wherein a total film thickness that is a thickness from the surface of the hill portion to the surface of the nitride semiconductor stacked portion is not more than three times the depth of the concave portion. Production method. A plurality of nitrides are formed on the substrate by forming electrode pads for performing wire bonding for electrical connection with the outside on the nitride semiconductor laminated portion laminated on the processed substrate surface in the second step. In a method for manufacturing a nitride semiconductor device comprising a third step of forming a semiconductor device,
5. The method for manufacturing a nitride semiconductor device according to claim 1, wherein, in the third step, the electrode pad is not formed above the digging region. 6.   6. The method of manufacturing a nitride semiconductor device according to claim 5, wherein, in the third step, the electrode pad is formed at a distance of 5 [mu] m or more from an end of the digging region. In the first step,
The method for manufacturing a nitride semiconductor device according to any one of claims 1 to 6, wherein a width of the hill portion is set to 92 µm or more and 4 mm or less.   The nitride semiconductor element according to claim 1, wherein one nitride semiconductor element is formed in the hill portion sandwiched between two adjacent digging regions. Production method.   The nitride semiconductor element according to any one of claims 1 to 7, wherein a plurality of the nitride semiconductor elements are formed in the hill portion sandwiched between two adjacent digging regions. Production method.   9. The chip division is performed by scribing the back surface side or the front surface side of the nitride semiconductor substrate which is a portion immediately below the digging region of the processed substrate. The manufacturing method of the nitride semiconductor element of description. A fourth step of cleaving the processed substrate in a direction perpendicular to the first direction in which the digging region of the nitride semiconductor element extends to form a bar on which the plurality of nitride semiconductor elements are mounted; A fifth step of dividing the nitride semiconductor device on the bar into individual chips by dividing the bar in a direction parallel to the first direction;
Prepared,
In the fifth step,
A scribe line parallel to the first direction was formed by scribing the surface of the nitride semiconductor laminated portion laminated in the digging region or the back side of the nitride semiconductor substrate that is directly below the digging region. 9. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the chip division is performed later. While comprising the fourth step and the fifth step,
In the fifth step,
A surface of the nitride semiconductor laminated portion laminated in the digging region or a back surface side of the nitride semiconductor substrate which is a portion immediately below the digging region; and a surface of the nitride semiconductor laminated portion laminated in the hill portion or The method for manufacturing a nitride semiconductor device according to claim 9, wherein the chip division is performed by scribing a back surface side of the nitride semiconductor substrate that is directly below the hill portion. While comprising the fourth step and the fifth step,
In the fifth step,
13. The method for manufacturing a nitride semiconductor device according to claim 10, wherein the scribe line is formed as a solid line scribe line from end to end of the bar. While comprising the fourth step and the fifth step,
In the fifth step,
13. The method for manufacturing a nitride semiconductor device according to claim 10, wherein the scribe line is formed as a solid line scribe line in a part of the bar. While comprising the fourth step and the fifth step,
In the fifth step,
The method of manufacturing a nitride semiconductor device according to any one of claims 10 to 12, wherein the scribe line is formed as a broken-line scribe line from end to end of the bar. While comprising the fourth step and the fifth step,
In the fifth step,
13. The nitride semiconductor device according to claim 10, wherein the scribe line is formed at an end portion on an end face side formed in a direction perpendicular to the first direction. Method.   A nitride semiconductor device manufactured by the method for manufacturing a nitride semiconductor device according to any one of claims 1 to 16.

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