JP2007157993A - Manufacturing method of optical semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture an electrode on an optical semiconductor element for controlling each of optical functional regions while suppressing current leakage between electrodes without damaging the regions with good yield, in the optical semiconductor element having the different optical functional regions formed adjacently on the same substrate. <P>SOLUTION: A non-doped clad layer and a non-doped cap layer are grown on the different optical functional layers formed on the same substrate. Thereafter, an electrode forming part in the cap layer is opened. Conductive dopant is thermally diffused through the opening into the clad layer, to make the clad layer selectively conductive. Then, a conductive contact layer is buried and grown in the opening, and the electrode is formed on the contact layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical semiconductor device used for optical fiber communication, and more particularly to a method for forming an electrode of a semiconductor device having a region having an optical function such as a plurality of optical amplifiers and optical modulators on an optical waveguide.

  In recent years, with the development of optical fiber communication, there has been an increasing demand for higher functionality and combination of optical elements used therefor. From some of them, for example, a plurality of optical amplifiers and optical modulators using semiconductors. Realization of an optical semiconductor device having a structure in which optical functions having different functions are integrated is becoming more and more important.

  In such an integrated optical semiconductor device, it is necessary to form a plurality of electrically separated electrodes on the surface of the device in order to control each mounted optical function. Various methods have been used to meet this requirement.

  For example, in the method shown by the schematic cross-sectional view of the optical semiconductor element in FIG. 8, the contact layer and the electrode at the boundary portion between the optical functional regions having different functions adjacent to each other are removed to electrically connect the optical functional regions. (For example, a cross-sectional view of the device shown in Patent Document 1). In the figure, a functional region layer 102 composed of a core layer 102-1 (for example, a non-doped semiconductor layer) and a cladding layer 102-2 (for example, a semi-insulator layer) is formed on a substrate 101 (for example, an n-type semiconductor substrate), In the functional region layer 102, an optical functional region A and an optical functional region B are formed adjacent to each other as illustrated. A cladding layer 103 (for example, a p-type semiconductor layer) is formed on the functional region layer 102 so as to cover the optical functional region A and the optical functional region B. In order to individually control the optical functional region A and the optical functional region B individually, it is necessary to form each electrode on the cladding layer 103. In this case, for example, the electrodes are uniformly formed on the cladding layer 103. After forming the contact layer 104 (for example, a p-type contact layer), a part of the contact layer 104 corresponding to the boundary of each predetermined optical functional region is partially removed to form the groove 107, so that the upper portion of the optical functional region A is formed. The contact layer 104A and the contact layer 104B are formed above the optical functional region B, respectively. Furthermore, electrodes 105A and 105B (for example, p-side electrode) are formed on each contact layer, and an electrode 106 (for example, n-side electrode) is formed below the substrate 101. As indicated by broken arrows a and b in FIG. It is possible to electrically apply each optical functional region between the electrodes. However, in such a configuration, for example, when there is a potential difference between the electrode 105A and the electrode 105B, current leakage is likely to occur between the electrodes through the cladding layer 103, as indicated by a dashed curve c in the figure.

  As a method for suppressing the occurrence of such current leakage, there is a method in which a high resistance region is formed above the boundary of each optical functional region in the cladding layer 103. The schematic cross-sectional view of the optical semiconductor device shown in FIG. 9 is basically the same structure as the structure shown in FIG. 8 except that each optical functional region is formed in the cladding layer 103 below the groove 107. The high resistance region 108 is formed so as to divide the clad layer.

  As a method of forming such a high resistance region 108, for example, there is an ion implantation method (for example, Patent Document 2). In this method, for example, in FIG. 9, using the contact layers 104A and 104B as a mask, protons are injected into the groove 107 between them to increase the resistance. Thereby, current leakage between the electrodes 105A and 105B can be reduced, but it is known that such an ion implantation method easily causes damage to the implantation region. In particular, there is a high possibility that damage to the optical functional area, for example, ion implantation to the active layer and the light receiving layer included in the optical functional area will damage those layers and degrade the optical function. In addition, the ion implantation method generally has a problem that the manufacturing cost increases.

  As another method of forming the high resistance region, there is a method of selectively embedding and growing a high resistance layer (for example, Patent Document 3). In this method, for example, in FIG. 9, an optical functional region A and an optical functional region B are formed adjacent to each other in the functional region layer 102 as shown in the figure, and the cladding layer 103 is formed on the entire surface, and then the entire surface is contacted. After the layer 104 is formed, a dielectric mask having an opening on the boundary region between the optical functional regions A and B is patterned thereon. Through this mask, the contact layer 104 and the cladding layer 103 in the boundary region are removed and the hole is opened until the functional region layer 102 is exposed, for example, by wet etching. Thereafter, a high resistance region is formed by embedding and growing a high resistance layer in the hole. In the case of such a method, the depth of the hole is normally relatively deep, about 2 to 3 μm or more, and burying growth is performed in this hole. However, the burying growth having a flat surface at the opening of the dielectric mask is performed. It is difficult to obtain a layer, and a growth layer having a protruding growth portion is usually easily formed near the opening edge of the dielectric mask. After that, the dielectric mask is removed by etching, and then, for example, a mesa stripe mask is formed to form a mesa stripe structure for the purpose of forming an optical semiconductor element of single mode operation. It is necessary to perform processing. There arises a problem that a part of the stripe mask formed in such a process is cut at the protruding growth portion, and the yield is lowered when the mesa stripe is formed.

  As another method for forming the high resistance region, contrary to the above two methods, after forming a semi-insulator cladding layer on the functional region layer, the semi-insulator cladding layer above the boundary of the different functional regions A method has been proposed in which the resistance of other cladding layers is reduced by, for example, impurity diffusion (Patent Document 4). The steps of the method performed by impurity diffusion will be described with reference to the cross-sectional view of the optical semiconductor element, using FIG. In FIG. 10A, a functional region layer 102 composed of a core layer 102-1 and a cladding layer 102-2 is formed on a substrate 101. The functional region layer 102 includes an optical functional region A and a light as shown in FIG. The functional region B is formed adjacent to each other. A semi-insulating clad layer 109 (for example, a Fe-doped semi-insulating layer) is formed on the functional region layer 102 so as to cover the optical functional region A and the optical functional region B. Next, as shown in FIG. 10B, a dielectric mask 110 (for example, SiO 2 film) is formed on the upper part of the boundary between different optical functional regions, and this is used as a mask for the p-type dopant in the semi-insulating cladding layer 109. For example, by selectively diffusing Zn, diffusion cladding layer regions 109A and 109B (conductive regions) and a semi-insulating region 109C (non-diffusion cladding region) are formed. Then, as shown in FIG. 10 (3), after removing the dielectric mask 110, a Zn-doped p-type contact layer 104 is grown on the entire device surface in order to make contact with the electrode. However, during this growth process, Zn in the contact layer diffuses on the surface of the semi-insulating region 109C, and a p-type region 109D is formed. As a result, as shown in FIG. 10 (4), the contact layer 104 is divided into functional regions A and B to form contact layers 104A and 104B, and electrodes 105A and 105B and a lower electrode 106 are formed thereon, When a voltage is applied to each electrode such that there is a potential difference between the electrodes, there is a problem that current leakage (indicated by a broken line curve c in the figure) occurs between the electrodes 105A and 105B.

In the above description, a functional region layer composed of a core layer and a cladding layer is formed on the substrate, and the optical functional region A and the optical functional region B are formed adjacent to each other in the functional region layer. With respect to a method for manufacturing a semiconductor element, in addition to a method of basically manufacturing various layers while being grown and stacked on the same substrate as shown in Patent Documents 1 to 4 above, Also, a method (referred to as a butt joint method) in which an end face of another semiconductor crystal layer is directly coupled to an end face of a semiconductor crystal layer grown on the substrate (but-joint) is also used. (For example, Patent Document 5).
JP-A-6-61473 JP-A 63-186488 JP-A-5-63179 JP-A-2-212804 JP 2001-189523 A

  As described above, in the method of increasing the resistance region so as to divide the cladding layer at the upper boundary between two adjacent optical functional regions, the conventional proton implantation method may cause damage to the optical functional region layer. In other conventional methods, in which the high resistance layer is embedded and grown, it is difficult to obtain a growth layer having a flat surface, and as a result, there is a high possibility that a defect will occur in mesa stripe formation. Further, in the conventional method of forming a selective diffusion layer in the semi-insulating clad layer, when the contact layer having a high impurity concentration is grown, the impurities in the contact layer are formed in the predetermined boundary portion. Both have problems such as current leakage due to diffusion into the surface region of the conductive cladding layer.

  Accordingly, an object of the present invention is to provide a method capable of manufacturing an optical semiconductor element capable of effectively suppressing the leakage current of an electrode application without causing damage to each optical functional region with a high yield. is there.

An object of the present invention is to form a plurality of semiconductor optical functional regions comprising a non-doped core layer and a first semi-insulating cladding layer on a semiconductor substrate having a first conductivity type;
A second semi-insulating cladding layer and then a first conductivity type or non-doped cap layer are formed on at least one set of semiconductor optical functional regions adjacent to each other in the plurality of semiconductor optical functional regions. And a process of
Forming a dielectric mask having an etching mask opening on each of the at least one set of semiconductor optical functional regions;
Removing the cap layer exposed in the etching mask opening to form at least one set of diffusion cap openings;
Selectively thermally diffusing a second conductivity type dopant from the diffusion cap opening into the second semi-insulating cladding layer and the first semi-insulating cladding layer;
Selectively growing a contact semiconductor layer having a second conductivity type in the diffusion cap opening to form at least one set of contacts;
It is possible by the manufacturing method of the optical semiconductor element characterized by having.

Further, a step of forming a mesa stripe forming dielectric mask on the at least one set of semiconductor optical functional regions, and etching the at least one set of semiconductor optical functional regions into a mesa stripe structure;
Embedding a semi-insulating semiconductor layer on both sides of the mesa stripe structure;
It is characterized by having.

Further, the step of removing the cap layer between the at least one set of contacts of the mesa stripe structure;
It is characterized by having.

Then, following the step of forming the at least one set of diffusion cap openings, a predetermined depth of the second semi-insulating clad layer is etched from the diffusion cap openings to form a cladding layer opening Forming a step;
Selectively thermally diffusing a dopant of the second conductivity type from the opening of the cladding layer into the second semi-insulating cladding layer and the first semi-insulating cladding layer;
Selectively growing a cladding layer having a second conductivity type in the opening of the cladding layer;
Selectively growing a contact semiconductor layer having a second conductivity type in the diffusion cap opening to form at least one set of contacts;
It is characterized by having.

  The first conductivity type is n-type, and the second conductivity type is p-type.

  When manufacturing an optical semiconductor element in which optical functions are integrated such that different optical functional areas are formed adjacent to each other on the same substrate, in forming electrodes for controlling each optical functional area on the element, By applying the method of the invention, the current leakage between the electrodes (between the p-side electrodes on the element) is greatly reduced without damaging the core layer, which is the functional layer of each optical functional region, and In particular, when the mesa stripe structure is used, an effect that it can be manufactured with a high yield can be obtained.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
(Embodiment serving as a reference of the present invention)
First, an embodiment serving as a reference of the present invention will be described. 1 to 2 are schematic views showing cross sections of respective steps for explaining the manufacturing method. In this example of the manufacturing process, the above-described process of forming optical functional elements having different optical functional areas adjacent to each other using the butt joint method is employed. However, the manufacturing method of the present invention is not limited to this. I can't.

  In FIG. 1 (1), an optical functional region A composed of a core layer 2A (for example, a non-doped layer) and a clad layer 3-1A (for example, a semi-insulating layer) is formed on a substrate 1 (for example, an n-type substrate). A dielectric mask 4 (for example, a semiconductor oxide film) is formed so as to cover it. Next, the core layer 2B (for example, a non-doped layer) and the cladding layer 3-1B (for example, a semi-insulating layer) are different from each other so as to be butt-joined to the core layer 2A and the cladding layer 3-1A by a butt joint method. An optical functional region B having an optical function is grown and formed. In such a configuration, the core layer 2A and the core layer 2B constitute the core layer 2 which is a continuous light propagation region, and the clad layer 3-1A and the clad layer 3-1B are clad layers 3 which are continuous light clad regions. Make one.

  Next, in FIG. 1B, after the dielectric mask 4 is removed, a cladding layer 3-2 (for example, a semi-insulating layer) having the same composition as this is further grown on the cladding layer 3-1, and then the cladding is formed. The layer 3-1 and the clad layer 3-2 constitute the clad layer 3 which is a continuous clad region, and thus an optical semiconductor element having different optical functional regions A and B is formed.

  Then, a cap layer 5 (for example, an n-type layer) is continuously grown on the cladding layer 3. The composition of the cap layer 5 may be a composition different from that of the cladding layer 3.

  Then, as shown in FIG. 1 (3), a dielectric mask 6 (for example, a semiconductor oxide film) having an opening at a portion where the electrodes above the optical functional regions A and B are provided is formed on the cap layer 5. .

  Next, as shown in FIG. 2 (4), the opening groove 7 is formed by etching the cap layer 5 using the dielectric mask 6.

  Thereafter, as shown in FIG. 2 (5), an impurity diffusion region 8 is formed by selectively thermally diffusing an impurity (for example, p-type dopant Zn) from the opening groove 7 into the cladding layer 3. The impurity non-diffusion region 9 remains in the cladding layer 3 above the boundary between B and B.

  Finally, selective buried growth of the contact layer 10 (for example, p-type layer) is performed in the portion of the opening groove 7. At this time, by setting the depth of the opening groove 7 of the cap layer 5 to be buried to 1 μm or less, the surface of the contact layer 10 to be buried and grown can be grown flat. The flat growth of the contact layer is important, thereby ensuring the flatness of the surface including the cap layer 5, and in the mesa stripe forming process of the optical semiconductor element described later, the mask for forming the mesa stripe is flat. This is an indispensable condition for ensuring a high yield because it can be formed on a smooth surface with high accuracy and stability.

  Thereafter, the dielectric mask 6 is removed, an electrode (p-side electrode) is formed on the contact layer 10, and an electrode (n-side electrode) is formed on the lower portion of the substrate 1, thereby forming an optical semiconductor device.

  In the manufacturing method of the present invention as described above, the contact layer 10 is not grown on the upper portion of the non-diffusion region 9, and therefore, as discussed with respect to the above-mentioned Patent Document 4, the contact layer is moved to the upper layer of the non-diffusion region. Problems such as diffusion of impurities (Zn) and current leakage between the electrodes can be avoided.

  In FIG. 2 (4), only the cap layer 5 is etched to form the opening groove 7, but the opening groove 7 may be formed by further etching to a partial depth of the cladding layer 3. In this case, after the impurity (for example, p-type dopant Zn) is selectively thermally diffused from the opening groove 7 to form the impurity diffusion region 8, first, the impurity (for example, A cladding layer containing a p-type impurity) is embedded, and then a contact layer (for example, a p-type layer) is embedded and grown. This method has an advantage that it is easy to control the impurity concentration distribution of the clad layer containing impurities (for example, p-type impurities) in order to obtain a good electrode contact and to further reduce the leakage current between the electrodes.

  Further, in order to further reduce the leakage current between the electrodes, the optical semiconductor element formed by the above method is formed into a mesa stripe for the purpose of, for example, carrying out single mode propagation of light, and then the mesa side surface portion is half-finished. It is preferable to use a method of embedding with an insulating layer.

  FIG. 3 is a perspective view of an optical semiconductor element for explaining a process when forming the mesa stripe of the optical semiconductor element of the present invention. In FIG. 3A, the mesa stripe dielectric mask 11 is used to form an optical semiconductor element having a mesa stripe structure in which the optical functional regions A and B are formed adjacent to each other and long in the light propagation direction. FIG. 6 is a perspective view when each layer on the side surface of the element is etched to the substrate 1. Optical functional regions A and B are formed on a substrate 1, and each has a core layer 2 and a cladding layer 3. The cladding layer 3 on the boundary between the optical functional region A and the optical functional region B has a non-diffusing region. 9, and the other region of the cladding layer 3 is an impurity diffusion region in which impurities are diffused. A contact layer 10 is formed on each of the regions, and a cap layer 5 is formed on the non-diffusion region 9. On the plane composed of the contact layer 10 and the cap layer 5, a mesa stripe dielectric mask 11 is formed.

  Next, as shown in FIG. 3B, the mesa side surface portion is embedded with the semi-insulating layer 12.

  Then, as shown in FIG. 3C, the mesa stripe dielectric mask 11 is removed. Thereafter, before the electrode is formed on the contact layer 10, the cap layer 5 between the contact layers 10 may be removed. The cap layer 5 normally uses an n-type layer. After that, a p-type electrode is formed in the contact layer, so that a pnp junction exists between the electrodes, and a current may flow. Because. After removing the cap layer 5 in this manner, an electrode is formed to obtain a mesa stripe type optical semiconductor element that is used in the method of the present invention.

  Thus, by using the manufacturing method of the present invention, the surface can be grown flat without damaging the core layer, which is the active layer of the optical functional region, and the vicinity thereof, and the current leakage between the electrodes Can be greatly reduced.

Examples specifically carried out by the above-described manufacturing method serving as a reference of the present invention will be described below.
(First embodiment)
4 to 6 are element sectional views and perspective views for explaining the steps of the first embodiment of the present invention. In this embodiment, in a process of manufacturing an optical semiconductor element which is a TDA-DFB laser (Tunable Distributed Amplification-Distributed Feed Back Laser), a manufacturing process of forming a p-side electrode which is an upper part of the element is shown.

  As shown in FIG. 4A, on the n-type InP substrate 11, an active layer region X that emits light by current injection and a tuning region Y in which the refractive index changes are alternately formed by, for example, the butt joint method. The core layer 12 (for example, X: a 1.55 μm band strain quantum well made of non-doped InGaAsP and Y: a non-doped 1.38 μm composition InGaAsP) is formed by bonding. On top of this, first, a clad layer 13 made of semi-insulating InP, for example, has a thickness of 2.5 μm, and a cap layer 14 made of n-type InGaAsP, for example, has a thickness of 0.3 μm, MOCVD (organic). Growing using metal chemical vapor deposition.

  Next, as shown in FIG. 4B, a mask 16 made of a SiO 2 film having an opening 15 only in a portion where the p-side electrode is provided above each region is formed.

  Next, as shown in FIG. 4 (3), only the cap layer 14 is wet-etched using, for example, a mixed solution of sulfuric acid, hydrogen peroxide, and water through a mask 16, and an opening groove is formed in the cap layer 14. 17 is formed.

  Next, as shown in FIG. 5 (4), the diffusion region 18 is formed by diffusing Zn as a p-type dopant from the opening groove 17, and only the cladding layer under the p-side electrode is made p-type. In this diffusion step, for example, vapor phase diffusion in which a Zn compound serving as a diffusion source and the present element are placed in a closed tube and heat treatment is performed is used.

  Then, as shown in FIG. 5 (5), in the opening groove 17 portion of the cap layer 14, Zn is used as a p-type dopant, and the buried growth of the contact layer 19 made of InGaAs is performed by the MOCVD method. Here, since the depth for performing the burying growth is about 0.3 μm which is the depth of the opening groove, it is possible to grow the surface into a film having sufficient flatness.

  Thereafter, the mask 16 is removed with hydrogen fluoride water or the like, and in order to make this element into a mesa stripe, the perspective view of FIG. 5 (6) (the optical functional regions other than the two adjacent optical functional regions). As shown in FIG. 7, the mesa stripe mask 20 made of the SiO 2 film is patterned. Then, using the mesa stripe mask 20, for example, a mesa stripe having a width of 1 to 2 μm is formed so as to propagate light in a single mode by dry etching using a reactive ion etching apparatus.

  Next, as shown in FIG. 6 (7), a semi-insulating layer 21 made of semi-insulating InP is embedded on the side of the mesa stripe by using MOCVD.

Then, as shown in FIG. 6 (8), the mesa stripe mask 20 is removed with hydrogen fluoride water or the like, and a p-side electrode made of, for example, Au / Zn / Au is formed on the contact layer 19 made of InGaAs. . In order to further reduce current leakage between the upper p-side electrodes, it is desirable to remove the cap layer 14 between the electrodes.
(Second embodiment)
FIG. 7 shows an element cross-sectional view for explaining the process of the second embodiment of the present invention. In this embodiment, similarly to the first embodiment, in the process of manufacturing an optical semiconductor element that is a TDA-DFB laser, a p-side electrode that forms the upper portion of this element is shown.

  In the present embodiment, the process up to the step of forming the mask 16 made of the SiO 2 film having the opening 15 only in the portion where the p-side electrode is provided in the upper part of each region shown in FIG. Are carried out in the same way.

  Next, as shown in FIG. 7A, the cap layer 14 (0.3 μm thickness) and a part of the semi-insulating cladding layer 13 (for example, a depth of 0.2 μm) are passed through the mask 16, for example. Wet etching is performed to form an opening groove 17 having a depth of 0.5 μm.

  Next, as shown in FIG. 7B, the diffusion region 18 is formed by diffusing Zn as a p-type dopant from the opening groove 17 portion, and only the cladding layer under the p-side electrode is made p-type.

  Then, a buried cladding layer 22 made of InP using Zn as a p-type dopant is buried in the opening groove 17, and then a contact layer 19 made of InGaAs using Zn as a p-type dopant is buried and grown. In this embodiment, since the depth of the buried growth is about 0.5 μm which is the depth of the opening groove, this surface is grown into a film having sufficient flatness as in the first embodiment. It is possible.

  Thereafter, an optical semiconductor element having a mesa stripe structure is formed in the same manner as the process performed in the first embodiment.

  In the above embodiment, InGaAsP is used as the composition of the cap layer 14. However, the composition is not limited to this, and any composition different from that of the cladding layer 13 may be used. For example, InGaAs may be used. Further, the semi-insulating clad layer 13 may be an undoped type having a very low background concentration, or may be one using Fe or Ru as semi-insulating dopants as the dopant of this cladding layer.

  By such a method of the present invention, the optical function is integrated, which significantly reduces current leakage between electrodes (between the p-side electrodes) without damaging the functional layer that is the core layer of each optical functional region. The optical semiconductor device could be manufactured with good yield.

  The following supplementary notes are further disclosed with respect to the embodiments including the above examples.

(Appendix 1)
Forming a plurality of semiconductor optical functional regions comprising a non-doped core layer and a first semi-insulating cladding layer on a semiconductor substrate having a first conductivity type;
A second semi-insulating cladding layer and then a first conductivity type or non-doped cap layer are formed on at least one set of semiconductor optical functional regions adjacent to each other in the plurality of semiconductor optical functional regions. And a process of
Forming a dielectric mask having an etching mask opening on each of the at least one set of semiconductor optical functional regions;
Removing the cap layer exposed in the etching mask opening to form at least one set of diffusion cap openings;
Selectively thermally diffusing a second conductivity type dopant from the diffusion cap opening into the second semi-insulating cladding layer and the first semi-insulating cladding layer;
Selectively growing a contact semiconductor layer having a second conductivity type in the diffusion cap opening to form at least one set of contacts;
A method for producing an optical semiconductor element, comprising:

(Appendix 2)
A step of forming a mesa stripe forming dielectric mask on the at least one set of semiconductor optical functional regions, and etching the at least one set of semiconductor optical functional regions into a mesa stripe structure;
Embedding a semi-insulating semiconductor layer on both sides of the mesa stripe structure;
The method for producing an optical semiconductor element according to appendix 1, wherein:

(Appendix 3)
And removing the cap layer between the at least one set of contacts of the mesa stripe structure;
The method for producing an optical semiconductor element according to appendix 2, wherein:

(Appendix 4)
Following the step of forming the at least one set of diffusion cap openings, a predetermined depth of the second semi-insulating cladding layer is etched from the diffusion cap openings to form a cladding layer opening. And a process of
Selectively thermally diffusing a dopant of the second conductivity type from the opening of the cladding layer into the second semi-insulating cladding layer and the first semi-insulating cladding layer;
Selectively growing a cladding layer having a second conductivity type in the opening of the cladding layer;
Selectively growing a contact semiconductor layer having a second conductivity type in the diffusion cap opening to form at least one set of contacts;
The method for producing an optical semiconductor element according to any one of appendices 1 to 3, wherein:

(Appendix 5)
5. The method of manufacturing an optical semiconductor element according to any one of appendices 1 to 4, wherein the first conductivity type is n-type and the second conductivity type is p-type.

(Appendix 6)
6. The method of manufacturing an optical semiconductor element according to any one of appendices 1 to 5, wherein the semi-insulating cladding layer is a non-doped cladding layer.

(Appendix 7)
6. The method of manufacturing an optical semiconductor element according to any one of appendices 1 to 5, wherein the dopant of the semi-insulating cladding layer is Fe or Ru.

(Appendix 8)
8. The method of manufacturing an optical semiconductor element according to any one of appendices 1 to 7, wherein the semiconductor substrate and the cladding layer are made of InP, and the core layer and the cap layer are made of InGaAsP or InGaAs.

(Appendix 9)
9. The method of manufacturing an optical semiconductor element according to any one of appendices 1 to 8, wherein the second conductivity type dopant for the selective thermal diffusion is Zn.

The figure for demonstrating embodiment used as the reference | standard of this invention (the 1) The figure for demonstrating embodiment used as the reference | standard of this invention (the 2) The figure for demonstrating embodiment used as the reference | standard of this invention (the 3) The figure for demonstrating the 1st Example of this invention (the 1) The figure for demonstrating 1st Example of this invention (the 2) The figure for demonstrating 1st Example of this invention (the 3) The figure for demonstrating the 2nd Example of this invention Diagram for explaining a conventional example Diagram for explaining a conventional example Diagram for explaining a conventional example

Explanation of symbols

1, 11 Substrate 2, 12 Core layer 3, 13 Clad layer 4, 6, 16 Dielectric mask 5, 14 Cap layer 7, 17 Open groove 8, 18 Impurity diffusion region 9 Non-diffusion region 10, 19 Contact layer 11, 20 Mesa stripe dielectric mask 12, 21 Semi-insulating layer 15 Opening 22 Embedded cladding layer

Claims (5)

Forming a plurality of semiconductor optical functional regions comprising a non-doped core layer and a first semi-insulating cladding layer on a semiconductor substrate having a first conductivity type;
A second semi-insulating cladding layer and then a first conductivity type or non-doped cap layer are formed on at least one set of semiconductor optical functional regions adjacent to each other in the plurality of semiconductor optical functional regions. And a process of
Forming a dielectric mask having an etching mask opening on each of the at least one set of semiconductor optical functional regions;
Removing the cap layer exposed in the etching mask opening to form at least one set of diffusion cap openings;
Selectively thermally diffusing a second conductivity type dopant from the diffusion cap opening into the second semi-insulating cladding layer and the first semi-insulating cladding layer;
Selectively growing a contact semiconductor layer having a second conductivity type in the diffusion cap opening to form at least one set of contacts;
A method for producing an optical semiconductor element, comprising: A step of forming a mesa stripe forming dielectric mask on the at least one set of semiconductor optical functional regions, and etching the at least one set of semiconductor optical functional regions into a mesa stripe structure;
Embedding a semi-insulating semiconductor layer on both sides of the mesa stripe structure;
The method of manufacturing an optical semiconductor element according to claim 1, wherein: And removing the cap layer between the at least one set of contacts of the mesa stripe structure;
The method of manufacturing an optical semiconductor element according to claim 2, wherein: Following the step of forming the at least one set of diffusion cap openings, a predetermined depth of the second semi-insulating cladding layer is etched from the diffusion cap openings to form a cladding layer opening. And a process of
Selectively thermally diffusing a dopant of the second conductivity type from the opening of the cladding layer into the second semi-insulating cladding layer and the first semi-insulating cladding layer;
Selectively growing a cladding layer having a second conductivity type in the opening of the cladding layer;
Selectively growing a contact semiconductor layer having a second conductivity type in the diffusion cap opening to form at least one set of contacts;
The method for producing an optical semiconductor element according to claim 1, wherein:   5. The method of manufacturing an optical semiconductor element according to claim 1, wherein the first conductivity type is n-type and the second conductivity type is p-type.

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