JP5479765B2 - One-dimensional array element manufacturing method and one-dimensional array element - Google Patents

Description

  The present invention relates to a method for manufacturing a one-dimensional array element including a single element arranged one-dimensionally on a substrate, and a one-dimensional array element.

  Vertical Cavity Surface Emitting Laser (VCSEL) is used for various optical communication light sources such as optical interconnection or other various applications. It is used as a device (see, for example, Patent Document 1). Since the surface emitting laser element emits laser light in a direction perpendicular to the substrate, a plurality of elements can be easily arranged one-dimensionally on the same substrate as compared with the conventional edge-emitting laser element. Can be formed. Further, since the volume of the active layer is very small, there are many advantages such that laser oscillation is possible with extremely low threshold current and low power consumption.

  In general, a surface-emitting laser element is composed of a resonant structure composed of a lower reflecting mirror, an active layer, and an upper reflecting mirror disposed on the same plane as the crystal substrate surface, and a structure that excites the active layer. The active layer is excited by implantation. Since the active layer is usually made of a semiconductor, the lower reflecting mirror located between the substrate and the active layer is also generally made of a semiconductor. Therefore, a semiconductor multilayer film reflecting mirror in which a pair of a material having a large refractive index and a layer of a material having a small refractive index are stacked is widely used. Since the surface emitting laser element has a cavity length shorter than that of a general semiconductor laser, a reflector having a high reflectivity of 99% or more is required for low threshold operation. A mirror is usually formed by stacking 20-60 pairs of the above layers. As a result, the film thickness becomes a relatively thick layer of several μm to 15 μm. In addition, the layer thickness varies depending on the refractive index difference of the material to be combined, the design of the wavelength to be reflected, and the like. In general, the lower reflector is epitaxially grown by metal organic chemical vapor deposition (MOCVD) or molecular beam growth (MBE). On the other hand, the upper reflecting mirror is selected from a semiconductor multilayer reflecting mirror, a dielectric multilayer reflecting mirror, or a combination of these and a metal depending on the combination with the current injection structure and the emitting direction.

In the case of a surface emitting laser element that emits light in the wavelength band from 650 nm to 1300 nm centering around the 850 nm band, an epitaxial layer is grown on a GaAs substrate that is a III-V group semiconductor material, _{Al x Ga 1-x As /} Al y Ga 1-y As (0 <x ≦ 1,0 ≦ y <1, x <y) AlGaAs -based semiconductor multilayer reflector with a combination of widely used. The AlGaAs-based semiconductor multilayer film reflector has a characteristic that it has a lattice constant almost the same as that of a GaAs substrate and can be laminated in multiple layers.

  A one-dimensional surface-emitting laser array element is configured by arranging a single surface-emitting laser element that is electrically independent from each other in a line, and is usually formed from the same substrate using semiconductor microfabrication techniques such as lithography and etching. A large number of array elements are manufactured together. For example, it is usually desirable to form elements regularly and two-dimensionally on a substrate and use dicing or scribing with a rotary saw along the pattern of the array elements (a method of scratching the surface and scratching and pressing). A one-dimensional array element is manufactured by cutting out a set of single elements. A two-dimensional array element is manufactured in the same manner.

  Note that an orientation flat is formed on the substrate used in the above manufacturing in order to identify the direction. FIG. 11 is a diagram showing a relationship between a (100) substrate whose main surface made of a III-V group semiconductor crystal has a plane orientation (100) and the plane orientation. Symbols D1 and D2 indicate plane orientations of the III-V group semiconductor crystal, and symbols F1 and F2 indicate a group V element (As, P, etc.) plane and a group III element (Ga, In, etc.), respectively. Shows the surface. Symbols W, W1, and W2 indicate a substrate (wafer), an orientation flat (Orientation Flat, OF) according to US standards, and an index flat (Index Flat, IF), respectively. As shown in FIG. 11, according to the US standard, OF is formed on the (01-1) plane, and IF is formed on the (011) plane. According to the EJ standard, OF is formed on the (0-1-1) plane, and IF is formed on (0-11).

JP 2008-117899 A

  However, in order for one array element to satisfy the required performance and become a non-defective product, all the single elements in the array element must satisfy the required performance. That is, if even one single element in the array element does not satisfy the required performance, the array element becomes a defective product. Therefore, compared with the case of a single element, it is much more difficult to achieve a desired high manufacturing yield of array elements. Therefore, when manufacturing the array element, it is necessary to carefully remove factors that reduce the manufacturing yield.

  In general, factors that reduce the manufacturing yield include deviation from the epitaxial growth and design of the substrate processing process and defects. On the other hand, the manufacturing yield is improved by strictly controlling the manufacturing conditions by optimizing the manufacturing process. Specifically, as a defect during epitaxial growth, the composition of the semiconductor layer of the manufactured substrate deviates from the design, resulting in lattice mismatch with the substrate crystal and the accumulation of strain in the layer, resulting in slip dislocations. Such a dislocation occurs. This dislocation is usually observed as a cross hatch and has a serious influence on the operating characteristics of the semiconductor element. In order to prevent these problems, it is necessary to reduce and avoid lattice mismatch by improving the accuracy of composition control during epitaxial growth.

  In addition, as defects during epitaxial growth, there are defects due to the influence of particles adhering during epitaxial growth. That is, in the case of manufacturing a surface emitting laser element including an array element, if particles exist around the light emitting portion, specifically in the mesa, the epitaxial layer structure is disturbed or leakage current is generated. This may cause a device failure. Further, in the case of a surface emitting laser element using an oxidation type current confinement structure, if particles exist in the mesa, the oxidation shape is disturbed during the oxidation process. Therefore, it is necessary to reduce the number of particles during epitaxial growth by careful handling. In addition, as a particle in the case of using a III-V group semiconductor, when using MOCVD method, there are many As clusters and semiconductor polycrystals which fly from the wall of a reaction furnace. On the other hand, when the MBE method is used, there are many particles due to As clusters and semiconductor polycrystals and metallic droplets such as Ga called oval defects.

  The present invention has been made in view of the above, and an object thereof is to provide a method for manufacturing a one-dimensional array element having a high manufacturing yield and a one-dimensional array element having high reliability.

  In order to solve the above-described problems and achieve the object, a method for manufacturing a one-dimensional array device according to the present invention is a method for manufacturing a one-dimensional array device made of a III-V semiconductor material, using epitaxial growth. A single element having an active region in a part of the element region is arranged on the main surface of the substrate having the (100) plane as the main surface in an arrangement direction that forms an angle larger than zero with respect to the <011> direction. A plurality of one-dimensional array elements configured by arranging a plurality are formed, and the formed one-dimensional array elements are separated.

Further, in the method of manufacturing a one-dimensional array element according to the present invention, in the above invention, when the element spacing of the single elements is a in the arrangement direction and b in the width direction perpendicular to the arrangement direction, the array The angle formed by the direction is tan ⁻¹ (a / b) or more.

  The method for manufacturing a one-dimensional array element according to the present invention is characterized in that, in the above invention, the arrangement direction is substantially parallel to the <01-1> direction.

The method for manufacturing a one-dimensional array element according to the present invention is characterized in that, in the above invention, an average particle density in the substrate surface after the end of the epitaxial growth is 1000 cm ⁻² or less.

  The method for manufacturing a one-dimensional array element according to the present invention is characterized in that, in the above invention, the single element is a vertical cavity surface emitting laser element.

  The one-dimensional array element according to the present invention is a one-dimensional array element made of a III-V group semiconductor material, and has a <011> direction on the main surface of a substrate having a (100) plane as the main surface. A plurality of single elements having an active region in a part of the element region, which are arranged in an arrangement direction having an angle larger than zero with respect to the element region, are provided.

Further, the one-dimensional array element according to the present invention is the above-described invention, wherein the element spacing of the single elements is a in the arrangement direction, and the width of the one-dimensional array element perpendicular to the arrangement direction is b. The angle formed by the arrangement direction is tan ⁻¹ (a / b) or more.

  In the one-dimensional array element according to the present invention as set forth in the invention described above, the arrangement direction is substantially parallel to the <01-1> direction.

The one-dimensional array element according to the present invention is characterized in that, in the above invention, an average particle density in the substrate surface is 1000 cm ⁻² or less.

  The one-dimensional array element according to the present invention is characterized in that, in the above invention, the single element is a vertical cavity surface emitting laser element.

  According to the present invention, it is possible to realize a method for manufacturing a one-dimensional array element having a high manufacturing yield and a one-dimensional array element having high reliability.

FIG. 1 is a schematic plan view of the array element according to the first embodiment. 2 is a cross-sectional view taken along line AA of the array element shown in FIG. FIG. 3 is a diagram for explaining dislocations occurring in the semiconductor multilayer structure on the substrate. FIG. 4 is a diagram showing the relationship between the particle density in the substrate surface and the total number of linear dislocations in the 3-inch substrate surface in the <01-1> direction and the <011> direction. FIG. 5 is a diagram schematically showing a state where a large number of array elements are formed on a substrate in the first embodiment. FIG. 6 is a diagram schematically showing a state in which a large number of array elements are formed on a substrate. FIG. 7 is a diagram for explaining the definition of the angle between the arrangement direction of the surface emitting lasers in the array element and the <011> direction. FIG. 8 is a diagram showing the relationship between the angle θ1 and the number of defective arrays. FIG. 9 is a diagram for explaining the definition of the angle between the arrangement direction of the surface emitting lasers in the array element and the <011> direction. FIG. 10 is a diagram showing the relationship between the angle θ2 (in radians) and the number of defective arrays. FIG. 11 is a diagram showing a relationship between a (100) substrate made of a group III-V semiconductor crystal and a plane orientation.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a method for manufacturing a one-dimensional array element and an embodiment of a one-dimensional array element according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic plan view of a one-dimensional surface-emitting laser array element (hereinafter, abbreviated as an array element as appropriate) according to Embodiment 1 of the present invention, and FIG. 2 is an array element 1000 shown in FIG. It is an AA sectional view taken on the line. As shown in FIG. 1, the array element 1000 includes a surface emitting laser element 100 as a single element having a mesa post M1 serving as an active region in a part of the element region in a one-dimensional manner in the direction of the arrangement direction Ar1. This is a so-called 10-channel array element configured by arranging 10 elements. In FIG. 1, the electrode structure and the like are not shown.

Further, as shown in FIG. 2, the surface emitting laser element 100 has a thickness of each layer on a substrate 2 made of n-type GaAs having a main surface of (100) surface and an n-side electrode 1 formed on the back surface. A lower DBR mirror 3 composed of 35 pairs of n-type Al _0.9 Ga _0.1 As / n-type GaAs having a length of λ / (4n) (λ is an oscillation wavelength and n is a refractive index), a lower cladding layer 4 composed of n-type GaAs, The active layer 5 made of multiple quantum wells with a GaInNAs / GaAs structure, the upper cladding layer 6 made of p-type GaAs, and the thickness of each layer is λ / (4n) (where λ is the oscillation wavelength and n is the refractive index). A laminated structure including an upper DBR mirror 7 composed of 25 pairs of p-type Al _0.9 Ga _0.1 As / p-type GaAs and a contact layer 8 composed of high-concentration p-type GaAs doped with carbon at about 2 × 10 ¹⁹ cm ^−3. I have. The n-type GaAs layer and the p-type GaAs layer constitute a high refractive index layer of the DBR mirror, and the n-type Al _0.9 Ga _0.1 As layer and the p-type Al _0.9 Ga _0.1 As layer constitute a low refractive index layer of the DBR mirror. Here, the reflection band center wavelength of the lower DBR mirror 3 and the upper DBR mirror 7 is 1270 nm.

In the upper DBR mirror 7, an oxidized constricting layer 9 is formed instead of the single p-type Al _0.9 Ga _0.1 As layer on the side close to the active layer 5. This oxidized constriction layer 9 is composed of a current confinement region 9a which is selectively thermally oxidized from the surroundings to make Al ₂ O ₃ Al, and a current injection region 9b made of AlAs left in the center. The oxidized constricting layer 9 constitutes a current confinement structure and an optical confinement structure in the surface emitting laser element 100.

  Further, in the entire resonator structure, the portion from the upper DBR mirror 7 to the lower surface of the lower cladding layer 4 is processed into a cylindrical mesa post M1 having a diameter of 30 μm, for example.

  At the upper end of the mesa post M1, a ring-shaped (annular) p-side electrode 10 having a width of about 5 μm to 10 μm on the outer periphery is provided. The mesa post M1 is embedded with a dielectric layer (polyimide layer) 11 such as polyimide. Further, on the polyimide layer 11, a p-side electrode pad 12 for connecting to an external terminal with a wire is formed and electrically connected to the p-side electrode 10.

  In the array element 1000, the arrangement direction Ar1 of the surface emitting laser elements 100 is at an angle of π / 2 radians (rad) with respect to the <011> direction of the crystal direction, and is substantially parallel to the <01-1> direction. It has become. As a result, this array element 1000 has reduced failures and defects due to dislocation, and has high reliability. The reason will be described in detail later.

  When manufacturing the array element 1000, first, for example, the lower DBR mirror 3, the lower cladding layer 4, the active layer 5, the AlAs are formed on the substrate 2 having a diameter of 3 inches (76.2 mm) by using, for example, the MBE method. The upper DBR mirror 7 including the layers and the contact layer 8 are epitaxially grown sequentially.

  Thereafter, the mesa post M1 is patterned by photolithography, and etched to a predetermined depth from the contact layer 8 by etching to form the mesa post M1. Since many array elements 1000 are collectively formed on the substrate 2, the number of mesa posts M1 corresponding to the surface emitting laser elements 100 included in each array element 1000 is also formed. Here, the arrangement direction Ar1 of the surface emitting laser elements 100 in the array element 1000 is determined.

  Thereafter, the laminated structure processed into the mesa post M1 is oxidized at a temperature of about 400 ° C. in a water vapor atmosphere to selectively oxidize the outer peripheral region of the AlAs layer in the mesa post M1. By this selective oxidation, for example, an outer peripheral side region having a width of 10 μm is oxidized to become a current confinement region 9a, a current injection region 9b made of AlAs left in the center is formed, and an oxidation constriction layer 9 is formed. Thereafter, the p-side electrode 10 is formed on the contact layer 8, the mesa post M1 is embedded with the polyimide layer 11, the p-side electrode pad 12 is formed, and the back surface of the substrate 2 is appropriately polished to adjust the substrate thickness to, for example, 200 μm. After that, the n-side electrode 1 is formed. Furthermore, element separation is performed for each array element 1000 to complete a plurality of array elements 1000.

  Here, in the manufacturing method according to the first embodiment, in the photolithography and etching processes described above, the arrangement direction Ar1 of the surface emitting laser element 100 has an angle of π / 2 rad with respect to the <011> direction of the crystal direction. None, patterning and etching are performed so as to be substantially parallel to the <01-1> direction. As a result, defects in the array element 1000 due to linear dislocations oriented in the <01-1> direction are reduced, so that the manufacturing yield of the array element 1000 is increased.

  This will be specifically described below. As described above, the AlGaAs-based semiconductor multilayer mirror has the same lattice constant as that of the GaAs substrate and can be laminated in multiple layers. As a result, it has a feature that high reflectivity is easily obtained. In general, it has been considered that these multilayer reflectors hardly generate cross hatching due to lattice mismatch with a GaAs substrate.

  However, in order to improve the manufacturing yield of the array element, the present inventors have examined the cross hatch generated in the array element, and found that particles adhering to the substrate during the epitaxial growth cause the cross hatch. I found it.

That is, when the present inventors observed the epitaxial substrate grown up to the contact layer in the above manufacturing method with a Nomarski microscope, the particles originating from As clusters and the particles considered to be Ga droplets were combined in a total of 25 cm. ^It was present in the substrate plane at a density of ^-2 . The total number was about 950 for the area excluding 6 mm from the outer peripheral edge of the substrate. In addition, linear dislocations starting from the particles were observed, and the dislocations extended to the edge of the substrate. Further, five similar dislocations were found in the substrate surface. Furthermore, it has been found that all of these linear dislocations are oriented in the <01-1> direction. This linear dislocation is almost identical in shape to the cross hatch due to lattice mismatch, but the cross hatch due to lattice mismatch is oriented not only in the <01-1> direction but also in the <011> direction. In contrast, the linear dislocations are differently oriented in one direction.

  This linear dislocation is considered to have occurred as follows. FIG. 3 is a diagram for explaining dislocations occurring in the semiconductor multilayer structure on the substrate. As shown in FIG. 3, on the substrate 2, particles P having the above-mentioned size up to about several μm are attached to the surface. Here, when the semiconductor layer 13 including the lower DBR mirror 3 or the like of about several μm to 15 μm is epitaxially grown, the semiconductor layer 13 grows so as to embed the particles P therein. However, local strain occurs in the semiconductor layer 13 due to the difference in thermal expansion coefficient between the particles P and the semiconductor layer 13 during the epitaxial growth or at the time of temperature reduction after the end of the growth, and the linear dislocation DL is generated from the particles P as a starting point. It is formed in the plane. Here, since the dislocation formation rate (dislocation rate) is faster in the <01-1> direction than in the <011> direction, more dislocations oriented in the <01-1> direction are considered to occur.

FIG. 4 is a diagram showing the relationship between the particle density in the substrate plane and the total number of linear dislocations in the 3-inch substrate plane in the above-described experiment in the <01-1> direction and the <011> direction. It is. Note that the particle density is intentionally changed by changing manufacturing conditions and the like. As shown in FIG. 4, in the case of a very high defect density with a particle density of 1000 cm ⁻² or more, many linear dislocations are observed not only in the <01-1> direction but also in the <011> direction. As a result, aggregated states of cross-hatched linear dislocations were observed. However, when the particle density is decreased, anisotropy occurs in the <01-1> direction and the <011> direction, and at a particle density of 1000 cm ⁻² or less, the number of linear dislocations in the <011> direction is almost zero. Only 01-1> direction.

  Based on the knowledge obtained as described above, the present inventors can arrange <01-1> if the arrangement direction Ar1 of the surface emitting laser element 100 is arranged at an angle with respect to the <011> direction. The present invention has been completed by conceiving that defects in the array element 1000 due to linear dislocations oriented in the direction are reduced and the manufacturing yield of the array element 1000 is increased. This will be further described below.

  FIG. 5 is a diagram schematically showing a state in which a large number of array elements 1000 are formed on the substrate 2 in the first embodiment. The code base 2a is OF. As shown in FIG. 5, it is assumed that the linear dislocation DL oriented in the <01-1> direction penetrates the mesa post M1 of a plurality of surface-emitting laser elements and makes these elements defective. At this time, if the number of defects as a surface emitting laser element is A and the number of arrangements of surface emitting lasers in the array element 1000 is N (= 10), as is apparent from FIG. The number is A / N. The reason is that all the surface emitting laser elements included in the defective array element 1000 are defective.

  On the other hand, FIG. 6 is a diagram schematically showing a state in which a large number of array elements 2000 are formed on the substrate 2. This array element 2000 has the same structure as the array element 1000 shown in FIGS. 1 and 2 except that the arrangement direction Ar2 of the surface emitting laser elements therein is the <011> direction. Similarly to FIG. 5, it is assumed that the linear dislocation DL in the <01-1> direction penetrates the mesa posts M1 of a plurality of surface emitting laser elements, and these elements are defective. At this time, assuming that the number of defects as the surface emitting laser element is A and the number of arrangements of the surface emitting laser elements in the array element 2000 is N (= 10), as is apparent from FIG. Is A. The reason is that the defective surface emitting laser elements belong to different array elements 2000, and therefore the number of defects of the surface emitting laser elements is equal to the number of defects of the array element 2000.

  As is clear from the description using FIGS. 5 and 6, according to the manufacturing method according to the first embodiment, the number of array elements to which the surface emitting laser element that becomes defective due to linear dislocations belongs is determined. Therefore, the array element can be manufactured with a high production yield, and the manufactured array element is less affected by linear dislocations, has high reliability, and is low in cost.

(Examples and comparative examples)
As an example of the present invention, the manufacturing method according to the first embodiment was performed in order to manufacture the array element having the structure shown in FIGS. In addition, about the element of the single surface emitting laser element and the geometry between elements, the diameter of the mesa post was 30 μm. The element interval, that is, the mesa post interval was 250 μm in each of the arrangement direction and the width direction. Then, when the operation of all elements before arraying was tested in a state where the elements were not separated, 270 elements could not satisfy the required performance with respect to a total of 72,000 elements for a single surface emitting laser element. It was a defective element. That is, the manufacturing yield as a single surface emitting laser element was 99.6%.

  Next, in consideration of the address of each element, when manufacturing the 10-channel array element by separating the element from the substrate, the manufacturing yield is estimated. As a result, the defective elements are included in all 7000 array elements. It was confirmed that the number of defective array elements was 27, and the manufacturing yield was maintained at a high value of 99.6%. As a result of analyzing the arrangement of the defective elements, all of the surface emitting laser elements in the defective array element were in the same straight line and were defective elements.

  On the other hand, as a comparison, in order to manufacture an array element having the structure shown in FIGS. I did it. The element of the single surface emitting laser element and the geometry between the elements were the same as those in the example. Then, when the operation of all elements before arraying was tested in a state where the elements were not separated, 270 elements could not satisfy the required performance with respect to a total of 72,000 elements for a single surface emitting laser element. It was a defective element. That is, the production yield as a single surface emitting laser element was 99.6% as in the example.

  Next, in consideration of the address of each element, when manufacturing the 10-channel array element by separating the element from the substrate, the manufacturing yield is estimated. As a result, the defective elements are included in all 7000 array elements. The number of defective array elements was 261, and the manufacturing yield was greatly reduced to 96.2%.

In the comparative example, when the epitaxial substrate grown up to the contact layer was observed with a Nomarski microscope, the particles originating from As clusters and the particles considered to be Ga droplets were combined at a density of 25 cm ^−2. Randomly present in the plane. In addition, five linear dislocations oriented in the <01-1> direction starting from the particles were found in the substrate surface.

  And as a result of analyzing the cause of the defect in the comparative example, one of the five linear defects discovered by the above-mentioned microscope observation crosses all the mesa posts in one row on the substrate, and each It passed through the light emitting part of the mesa post, and it was found that these elements deteriorated rapidly during the operation test, resulting in insufficient light emission characteristics. Furthermore, when arbitrary two were extracted from the series of elements and a planar TEM (transmission electron microscope) image was observed, a linear dislocation and a dislocation loop derived therefrom were found. This dislocation loop was the same as the dark line defect reported in the surface emitting laser in the 850 nm band. Further, when a cross-sectional TEM image of the light emitting portion in the vicinity of the active layer was observed, slip dislocations were observed from the lower DBR mirror in parallel to the surface seen on the (111) plane, and the slip dislocations were observed in the active layer. Dark line defects were concentrated around the part that crossed.

  That is, in the above element, since the slip dislocation crosses the active layer where carriers recombine, starting from the slip dislocation, the dislocation rises and descends, and the dislocation loop proliferates near the slip dislocation. Therefore, it is considered that the luminous efficiency has rapidly deteriorated during the operation test.

  However, regarding the growth rate of dislocations, not only the semiconductor material system, wavelength band, and device structure, but also the positional relationship between the location where the dislocation crosses the mesa post and the light emitting portion are different, the speed is different from the above case. Therefore, a defect does not always appear during the initial measurement, and there is a possibility that a reliability problem such as a failure of the user during use is induced. Therefore, it goes without saying that an appropriate screening process such as burn-in is required.

  The decrease in the manufacturing yield of the array element is due to the fact that only one of the 10 surface emitting laser elements in the array element overlaps with the linear dislocation and becomes defective. In other words, the other nine elements in the same array element satisfy the characteristics, but as an array element, if there is usually one defective element, the array element cannot be used. Therefore, it becomes a defective product.

  Here, the defective element means an element that does not satisfy the required performance. The required performance is diverse, such as threshold value, light output, differential quantum efficiency, current and voltage for obtaining constant light output, light output at constant current and voltage, differential resistance, and response characteristics at high speed operation. However, the physical factors that do not satisfy these required performances are mainly due to one factor: non-radiative recombination caused by dark line defects because the slip dislocation crosses the active layer in the mesa post. It is considered that the ratio is higher than that of a normal element having no slip dislocation, resulting in a decrease in internal quantum efficiency.

(Angle dependence)
In the first embodiment, the array direction Ar1 of the surface emitting laser elements 100 in the array element 1000 is at an angle of π / 2 rad with respect to the <011> direction of the crystal direction, and substantially in the <01-1> direction. Although it is made parallel, this invention is not limited to this. Hereinafter, the relationship between the angle between the arrangement direction of the surface emitting laser elements and the <011> direction and the number of defective array elements will be described.

  FIG. 7 is a diagram for explaining the definition of the angle between the arrangement direction of the surface emitting lasers in the array element and the <011> direction. In the following, the (100) plane substrate 2 having the OF 2a has the same structure as the array element 1000 shown in FIGS. 1 and 2, but the arrangement direction Ar3 forms an angle θ1 with respect to the <011> direction. The change in the number of defects (number of defective arrays) when the angle of the array element 3000 is changed will be examined. The symbol DL indicates a linear dislocation oriented in the <01-1> direction. In addition, between the adjacent array elements 3000 on the substrate 2 or in the array element 3000, the surface emitting laser element intervals are the same in the arrangement direction and the width direction perpendicular thereto. The element spacing in the width direction is substantially equal to the width of the array element 3000. However, when the array element 3000 on the substrate 2 is actually separated, dicing or scribing is used as described above. Therefore, it is usual to provide “cutting margins” of about 10 to 100 μm (usually 20 to 50 μm) between the array elements 3000. Therefore, there is a difference of about “cutting” between the element spacing in the width direction and the width of the array element 3000.

  FIG. 8 is a diagram showing the relationship between the angle θ1 (in radians) and the number of defective arrays. In FIG. 8, A is the number of defects as the surface emitting laser element as described above, and N is the number of arrangements of the surface emitting lasers. As shown in FIG. 8, when the angle θ1 is 0, the arrangement direction Ar3 is the <011> direction. Therefore, the number of defective arrays is A as in the case of FIG. Next, when θ1 is increased from zero, the number of defective arrays gradually decreases. When θ1 = π / 4, the number of defective arrays becomes A / √2. In addition, the number of defective arrays suddenly decreases substantially from θ1 = π / 4, and when θ1 = π / 2, the arrangement direction Ar3 becomes the <01-1> direction. Therefore, the number of defective arrays becomes minimum at A / N as in the case of the first embodiment shown in FIG.

  As shown in FIG. 8, in the present invention, when the surface emitting laser element interval is the same in the arrangement direction and the width direction, the arrangement direction of the surface emitting laser elements in the array element is π / 2 rad with respect to the <011> direction. However, it is sufficient that it is larger than 0 rad, and π / 4 rad or more is preferable.

  Next, the case where the surface emitting laser element interval is different between the arrangement direction and the width direction will be described. FIG. 9 is a diagram for explaining the definition of the angle between the arrangement direction of the surface emitting lasers in the array element and the <011> direction. In the following, on the (100) plane substrate 2 having the OF 2a, it has the same cross-sectional structure as the array element 1000 shown in FIG. 2, but the surface emitting laser element interval is different in the arrangement direction and the width direction, and the arrangement direction Ar4 is In the array element 4000 having an angle θ2 with respect to the <011> direction, the change in the number of defects (number of defective arrays) when the angle is changed will be examined. The interval between the surface emitting laser elements, that is, the interval between the mesa posts M2, is a in the arrangement direction Ar4 and b in the width direction. The interval between the mesa posts M2 in the width direction is substantially equal to the width of the array element 4000, but there is a difference of “cutting” as described above. In FIG. 9, the linear dislocation DL crosses the mesa post M2a of the surface emitting laser element included in the array element 4000a, and therefore the array element 4000a is defective.

FIG. 10 is a diagram showing the relationship between the angle θ2 (in radians) and the number of defective arrays. In FIG. 10, A is the number of defects as the surface emitting laser element as described above, and N is the number of arrangements of the surface emitting lasers. As shown in FIG. 10, when the angle θ2 is 0, the number of defective arrays is A. Next, when θ2 is increased from zero, the number of defective arrays gradually decreases. When θ2 = α = tan ⁻¹ (a / b), the number of defective arrays becomes A / cos α. In addition, the number of defective arrays suddenly decreases substantially from θ2 = α, and becomes minimum at A / N when θ2 = π / 2.

As shown in FIG. 10, in the present invention, when the surface emitting laser element interval is a in the arrangement direction and b in the width direction, the arrangement direction of the surface emitting laser elements in the array element only needs to be larger than 0 rad, α = tan ⁻¹ (a / b) or more is preferable.

As shown in FIG. 4, when the average particle density in the substrate surface is set to 1000 cm ⁻² or less, the ratio of linear dislocations oriented in the <01-1> direction becomes almost the same, and the effect of the present invention is achieved. Although it becomes particularly remarkable, it is preferable, but even if it is larger than 1000 cm ⁻² , the linear dislocations are more oriented in the <01-1> direction than in the <011> direction. To play.

  In the first embodiment, the substrate 2 has the (100) plane as the main surface, but the main surface is not limited to the (100) plane just. For example, even when a substrate having a main surface inclined by about ± 10 degrees from the (100) plane is used, it is considered to be substantially the same as the (100) substrate and linear dislocations oriented in the <01-1> direction. Therefore, the effect of the present invention is achieved.

  In the first embodiment, a GaAs-based semiconductor material is used. However, even when another III-V group semiconductor material such as InP is used, the alignment is similarly oriented in the <01-1> direction. Since the linear dislocation occurs, the effect of the present invention is exhibited.

  In the first embodiment, the array element is a surface emitting laser array element. However, if the array element has an active region in part, the effect of the present invention is achieved.

1 n-side electrode 2 substrate 2a OF
DESCRIPTION OF SYMBOLS 3 Lower DBR mirror 4 Lower clad layer 5 Active layer 6 Upper clad layer 7 Upper DBR mirror 8 Contact layer 9 Oxide constriction layer 9a Current confinement region 9b Current injection region 10 P side electrode 11 Polyimide layer 12 P side electrode pad 13 Semiconductor layer 100 Surface emitting laser element 1000-4000, 4000a Array element Ar1-Ar4 Arrangement direction D1, D2 Plane orientation DL Linear dislocation F1 Group V element surface F2 Group III element surface M1, M2, M2a Mesa post P Particle W Substrate W1 OF
W2 IF

Claims (2)

A manufacturing method of a one-dimensional array element made of a III-V semiconductor material,
A single element which is a vertical cavity surface emitting laser element having an active region in a part of the element region is formed on the main surface of a substrate having a (100) plane as a main surface by using epitaxial growth. one-dimensional array 1> a one-dimensional array element constituted by arranging a plurality to a flat row direction form a plurality, characterized in that parallel to the isolation of one-dimensional array element in which the formed <01-1> direction Device manufacturing method. A one-dimensional array element made of a III-V semiconductor material,
On the major surface of the substrate having a (100) plane as a main surface, comprises a plurality of single elements having the <01-1> are arranged in a flat row direction, the active region in part of the device region,
The one-dimensional array element, wherein the single element is a vertical cavity surface emitting laser element.

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