JP5290928B2 - Method for manufacturing optical semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical semiconductor device, for manufacturing an optical integrated circuit smaller than a high-mesa structure and having no problem in characteristics of a waveguide, strong in mechanical strength by using a group III-V semiconductor to form an optical waveguide having the same refractive index difference as a silicon thin line. <P>SOLUTION: The optical semiconductor device has a substrate 1, and a second etching stop layer 4 and a core layer 2, and an organic material clad layer 3 having a lower refractive index than the core layer 2, formed on the substrate 1. In the optical semiconductor device, the organic material clad layer 3 is formed on the second etching stop layer 4, and the whole outer peripheral face of the core layer 2 is covered with the organic material clad layer 3. In addition, the structure is formed by etching a layered structure formed by sequentially stacking the second etching stop layer, the clad layer, a first etching stop layer, and the core layer on the substrate 1, for one side and the other side in a width direction, separately. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to a method for manufacturing an optical semiconductor equipment.

  Due to the explosive spread of the current Internet, the necessary communication capacity is increasing year by year. In order to meet such demands, in addition to conventional time division multiplexing that modulates an optical signal to 0 and 1 in the time domain, and space division multiplexing that increases the number of channels in the space, the wavelength at which the signal is placed on the color (wavelength) of light Division multiplex (WDM) communication has been developed. WDM communication is mainly used for long-distance trunk line communication, and uses a wavelength in the 1.55 μm band with the smallest optical fiber loss. The interval between adjacent wavelengths is determined by the standard. For example, in DWDM (Dense WDM), it is determined that signals are placed on light wavelengths at intervals of 0.8 nm. In WDM communication, it is necessary to have a laser that emits each color and a light receiver that receives them, but in addition to this, the output destination varies depending on the color of the light, and conversely various colors. An optical multiplexer / demultiplexer that bundles the light into one is required.

  Such an optical multiplexer / demultiplexer has been realized with various materials and shapes. However, an optical waveguide having a core having a large refractive index and a cladding layer having a smaller refractive index on a planar substrate is used. Of the planar optical integrated circuits (PLCs) that form integrated circuits, glass is the most common, and various optical multiplexers / demultiplexers such as optical waveguide diffraction gratings (AWG) are realized. It has been. In particular, an optical multiplexer / demultiplexer based on a PLC using glass has a very good demultiplexing characteristic even in a DWDM having a very narrow wavelength interval. However, with the recent increase in communication capacity, As the number of channels processed by a chip has increased, the size and power consumption of the chip are starting to become a problem.

  The size of the chip in the PLC is determined by the bending loss of the optical waveguide used there. In an optical integrated circuit such as an optical multiplexer / demultiplexer, it is indispensable to bend an optical waveguide in order to draw light on a plane. At that time, light may radiate to an area outside the bending. This is known and is called bending loss. This loss is smaller as it is gently bent (larger bend radius) and larger as it is bent more rapidly (smaller bend radius). The magnitude of this loss is determined by the difference between the refractive index of the core portion of the optical waveguide and the refractive index of the cladding portion surrounding it. The greater the difference in the refractive index, the better the light is confined in the core part. However, if the refractive index is small, the light leaks to the clad part and the bending loss increases.

  In the case of PLC using glass, the refractive index is increased by doping impurities in the core, but the difference in refractive index from the clad is usually as small as 0.1% to 3%. The size is about several cm square at most.

  For this reason, attempts have been made to construct an optical integrated circuit using a group III V semiconductor waveguide having a larger refractive index difference. When using III-V semiconductors, a waveguide layer with a high refractive index is formed on the substrate, an overclad layer with a low refractive index is formed on the substrate, and etching is performed on both sides of the waveguide to a depth that penetrates the waveguide layer. A waveguide is formed by shaving and filling the portion with, for example, an organic material having a low refractive index (high mesa structure). In this case, the optical confinement is not so much in the vertical direction of the waveguide because of the semiconductors, but the lateral direction is due to the semiconductor (refractive index is usually about 3.4) and the organic material (refractive index is about 1.5 to 2). A huge refractive index difference of several tens of percent can be obtained. At this time, for example, when an AWG is created, the chip size is several mm square, and the light leakage in the vertical direction determines the minimum size of the chip. Another major advantage of using a Group III V semiconductor is that it can be integrated with a semiconductor laser (transmitter) and a light receiver. By integrating on the same substrate as the transmitter / receiver, the transmitter / receiver module can be made smaller and reduced in insertion loss. This is a feature not found in glass-based materials.

  Recently, with the aim of further miniaturization of optical integrated circuits, research on ultra-compact optical integrated circuits using a waveguide (silicon thin-wire waveguide) with a silicon core and glass cladding on a silicon substrate has been actively conducted. ing. The refractive index of silicon is about 3.5 and the refractive index of glass is about 1.5, so that a refractive index difference equivalent to that of III-V semiconductors can be obtained, and silicon can be deposited on the glass film. Therefore, since the waveguide structure is surrounded by glass in any direction in the upper, lower, left and right directions of the silicon core, the refractive index difference in any direction is very large, and the size can be further reduced as compared with the case of III-V semiconductors. Further, the size of the core in the cross section at this time is about several hundreds of nanometers for the communication wavelength of 1.55 μm, which is about the wavelength of light in the medium. For example, when an AWG is created, its chip size is several tens of μm square, which is 1/1000 of that when glass is used. The biggest problem with this structure is the coupling with the transceiver. When a transmission / reception module is configured using a silicon waveguide, it is difficult to integrate it on a single chip like a III-V semiconductor, so the semiconductor laser is coupled with a lens or the like. Efficient coupling is difficult due to the condensing limit of the lens.

  Although attempts have been made to fabricate ultra-compact optical waveguides such as silicon wire waveguides using III-V semiconductors, it is difficult to deposit semiconductors on films with a low refractive index as in the case of silicon. For this reason, it is fabricated by melting to the lower side of the waveguide by wet etching. At that time, it is necessary to connect the waveguide and the outside non-etched portion with a thin semiconductor rod so that the waveguide portion is not flowed. Therefore, this waveguide has no support on the lower side and is suspended mechanically by a thin rod, so it is mechanically weak, and there are periodically thin rods in the direction of light travel, and that part is a discontinuous part Therefore, it adversely affects the characteristics of the waveguide, for example, the transmission characteristic of light of a certain wavelength is deteriorated. In addition, since the surroundings are air, the waveguide is almost thermally insulated, and the influence of heat, which is often a problem in semiconductor optical devices, is received.

K. Okamoto, K. Shuto, H. Takahashi, and H. Ohmori, "Fabrication of 128-channel arrayed waveguide grating multiplexer with 25GHz channel spacing," Electronics Letters, Vol. 32, No. 16, pp. 1474-1476, Aug. 1996. N. Kikuchi, Y. Shibata, H. Okamoto, Y. Kawaguchi, S. Oku, H. Ishii, Y. Yoshikuni, and Y. Tohmori, "Monolithically integrated 64-channel WDM channel selector with novel configuration," Electronics Letters, Vol. 38, No. 7, pp. 331-332, Mar. 2002. K. Sasaki, F. Ohno, A. Motegi, and T. Baba, "Arrayed waveguide grating of 7060 μm2 size based on Si photonic wire waveguides," Electronics Letters, Vol. 41, No. 14, pp. 801-801, July 2005. TH Stievater, WS Rabinovich, D. Park, JB Khurgin, S. Kanakaraju, and CJK Richardson, "Low-loss suspended quantum well waveguides," Optics Express, Vol. 16, No. 4, pp. 2621-2627, Feb. 2008.

  As described above, when the silicon thin wire waveguide is used, the chip size of the optical integrated circuit is remarkably reduced, but it is difficult to integrate it with a semiconductor laser or a light receiver. However, since the optical confinement in the vertical direction is small in an optical integrated circuit using a high-mesa waveguide of a group III V semiconductor, the size of the chip is determined there. There are also problems with the mechanical strength and waveguide characteristics of thin wire waveguides using III-V semiconductors due to their structure.

  Therefore, the present invention has been made in view of such a problem, and using an IIIV group semiconductor, an optical waveguide having a refractive index difference equivalent to that of a silicon thin wire is formed, which is further smaller than a high mesa structure, It is an object of the present invention to provide a method for manufacturing an optical semiconductor device capable of realizing an optical integrated circuit having high mechanical strength and no problem with the characteristics of a waveguide. That is, an optical component having an optical waveguide having a core layer whose size is approximately equal to the wavelength of light in a medium (semiconductor optical waveguide structure on the substrate) is formed on a group III V semiconductor mixed crystal substrate. It is an object to realize downsizing of the system.

A method of manufacturing an optical semiconductor device according to a first aspect of the present invention that solves the above problem includes a substrate, a second etching stop layer formed on the substrate, a core layer that is a light waveguide layer, and a refractive index that is higher than that of the core layer. The organic material cladding layer is formed on the second etching stop layer, and the organic material cladding layer covers the entire outer peripheral surface of the core layer. A method of manufacturing the optical semiconductor device of
The first etching stop layer is made of a material that does not etch the first etching stop layer when the core layer is etched, and the core layer and the cladding layer are made of the core layer when the first etching stop layer is etched. And the core layer, the first etching stop layer, and the second etching stop layer using a material that is not etched, and the core layer, the first etching stop layer, and the second etching stop layer when the cladding layer is etched. By using a material in which the second etching stop layer is not etched,
Sequentially laminating the second etching stop layer, the cladding layer, the first etching stop layer, and the core layer on the substrate;
Etching one side of the core layer in the width direction;
Etching one side of the first etching stop layer in the width direction;
Etching one side of the cladding layer in the width direction;
Covering the upper surface, one side surface and the lower surface of the core layer with the organic material cladding layer;
Etching the other side in the width direction of the organic material cladding layer covering the upper surface of the core layer;
Etching the other side in the width direction of the core layer;
Etching the other side in the width direction of the first etching stop layer;
Etching the other side in the width direction of the cladding layer;
Covering the other side surface and lower surface of the core layer with the organic material cladding layer;
It is characterized by implementing.

A method for manufacturing an optical semiconductor device according to a second aspect of the present invention is the method for manufacturing an optical semiconductor device according to the first aspect of the present invention.
The band gap wavelength of the semiconductor mixed crystal used for the core layer is smaller than the band gap wavelength of the semiconductor mixed crystal used for the first etching stop layer, and the band gap wavelength of the semiconductor mixed crystal used for the first etching stop layer is The semiconductor mixed crystal used for the cladding layer is larger than the band gap wavelength.
Further, a method for manufacturing an optical semiconductor device of the third invention is a method for manufacturing an optical semiconductor device of the first or second invention,
The height from the upper surface of the second etching stop layer to the lower surface of the core layer is 1 μm or more.
Further, a method for manufacturing an optical semiconductor device of the fourth invention is a manufacturing method of any one of the optical semiconductor device of the first to third invention,
The core layer includes a bulk semiconductor or a quantum well structure using a semiconductor.

  By implementing the present invention, the refractive index difference between the core layer and the surrounding organic material clad layer is large, and the bending loss is small, so that it can be integrated on the same substrate as the semiconductor laser or the light receiver. It is possible to realize a configuration of an ultra-compact optical integrated circuit using the.

1 is a structural diagram of a semiconductor thin wire waveguide using a group III V semiconductor in an optical semiconductor device according to Embodiment 1 of the present invention. It is a laminated structure figure for producing the said semiconductor fine wire waveguide. 1B is a structural diagram of a high mesa waveguide in a conventional optical semiconductor device shown for comparison with FIG. 1A. FIG. It is a figure which shows the manufacturing method of the semiconductor fine wire waveguide in the optical semiconductor device which concerns on Embodiment 1 of this invention, Comprising: A 2nd etching stop layer, a clad layer, a 1st etching stop layer, and a core layer are laminated | stacked on a board | substrate. It is a figure which shows the process to do. It is a figure which shows the manufacturing method of the said semiconductor wire waveguide, Comprising: It is a figure which shows the process of etching the one side of the width direction of the said core layer. It is a figure which shows the manufacturing method of the said semiconductor fine wire waveguide, Comprising: It is a figure which shows the process of etching the one side of the width direction of a said 1st etching stop layer. It is a figure which shows the manufacturing method of the said semiconductor wire waveguide, Comprising: It is a figure which shows the process of etching the one side of the width direction of the said cladding layer. It is a figure which shows the manufacturing method of the said semiconductor wire waveguide, Comprising: It is a figure which shows the process of etching the one side of the width direction of the said cladding layer. It is a figure which shows the preparation methods of the said semiconductor wire waveguide, Comprising: It is a figure which shows the process of covering the whole one side of the width direction of the outer periphery of the said core layer with an organic material clad layer. It is a figure which shows the manufacturing method of the said semiconductor fine wire waveguide, Comprising: It is a figure which shows the process of etching the other side of the width direction of the said organic material clad layer. It is a figure which shows the manufacturing method of the said semiconductor fine wire waveguide, Comprising: It is a figure which shows the process of etching the other side of the width direction of the said core layer. It is a figure which shows the manufacturing method of the said semiconductor fine wire waveguide with a support | pillar, Comprising: It is a figure which shows the process of etching the other side of the width direction of a said 1st etching stop layer. It is a figure which shows the manufacturing method of the said semiconductor fine wire waveguide, Comprising: It is a figure which shows the process of etching the other side of the width direction of the said cladding layer. It is a figure which shows the preparation methods of the said semiconductor wire waveguide, Comprising: It is a figure which shows the process of covering the other side whole side of the outer periphery of the said core layer with the said organic material clad layer. It is a figure which shows the bending radius dependence of the bending loss per 90 degree | times of the said semiconductor fine wire waveguide. It is a figure which shows the bending radius dependence of the bending loss per 90 degree | times of the conventional high mesa waveguide.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

<Embodiment 1>
As shown in FIG. 1A, an optical semiconductor device according to Embodiment 1 of the present invention includes a semiconductor mixed crystal substrate 1, a second etching stop layer 4 formed on the substrate 1, and an optical waveguide layer. And an optical waveguide core layer 2 made of a semiconductor mixed crystal, and an organic material cladding layer 3 having a refractive index lower than that of the core layer 2. An organic material cladding layer 3 is formed on the second etching stop layer 4, and the organic material cladding layer 3 covers the entire outer peripheral surface of the core layer 2. That is, the upper surface 2a, both side surfaces 2a, 2c, and the lower surface 2d, which are the outer peripheral surfaces of the cross section perpendicular to the light traveling direction of the core layer 2 (direction perpendicular to the paper surface of FIG. 1A), are covered with the organic material cladding layer 3. ing. In the core layer 2, the size of the cross section (transverse cross section) perpendicular to the light traveling direction is as large as the wavelength of light in the medium (semiconductor wire waveguide structure on the substrate).

  A laminated structure for producing a thin wire waveguide using the group III V semiconductor is as shown in FIG. 1B. That is, the second etching stop layer 4, the cladding layer 5, the first etching stop layer 6, and the core layer 2 are sequentially stacked on the substrate 1. Then, as will be described in detail later, this laminated structure is etched twice in one direction and the other side in the width direction (left and right direction in FIG. 1B), so that a semiconductor fine wire waveguide structure as shown in FIG. 1A is obtained. Form.

  In addition, in order to be able to form the semiconductor thin wire waveguide having the above structure by sequentially etching from the core layer 2 to the lower layers 6 and 5, the core layer 2, the first etching stop layer 6, the cladding layer 5 and The material of the second etching stop layer 4 is that the first etching stop layer 6 is not etched when the core layer 2 is etched, and the core layer 2 and the cladding layer 5 are etched when the first etching stop layer 6 is etched. The core layer 2, the first etching stop layer 6, and the second etching stop layer 4 are made of a material that is not etched when the cladding layer 5 is etched.

At this time, for example, the band gap wavelength of the semiconductor mixed crystal used for the core layer 2 is made smaller than the band gap wavelength of the semiconductor mixed crystal used for the first etching stop layer 6, and further, the semiconductor mixed crystal used for the first etching stop layer 6 is further reduced. The band gap wavelength of the crystal is made larger than the band gap wavelength of the semiconductor mixed crystal used for the cladding layer 5.
The height H from the upper surface 4a of the second etching stop layer 4 to the lower surface 2d of the core layer (that is, the thickness of the organic material cladding layer 3 between the core layer 4 and the second etching stop layer 4) is 1 μm or more. It is.

  As shown in FIG. 1C, a conventional high-mesa waveguide is formed by sequentially laminating a lower cladding layer 5, a core layer 2, and an upper cladding layer 5 on a substrate 1, as shown in FIG. 1C. Only the structure is covered with the clad layer 3 using an organic material.

  Next, a method for manufacturing a thin wire waveguide using a group III V semiconductor according to the first embodiment will be described. The semiconductor thin wire waveguide is manufactured in the order of FIGS. 2A to 2K. The etching process from the core layer 2 to the cladding layer 5 is characterized by being performed in two steps.

  First, as shown in FIG. 2A, a second etching stop layer 4, an InP clad layer 5, a first etching stop layer 6 and a core layer 2 are sequentially grown on an InP substrate 1 which is a group III V semiconductor mixed crystal substrate. .

  At this time, the second etching stop layer 4 may be made of the same material as that of the core layer 2 and may have a thickness of about several tens of nm. The InP clad layer 5 needs to have a thickness of about 1 μm in order to sufficiently separate the core layer 2 from the substrate 1. The first etching stop layer 4 is made of a material capable of selective wet etching with the material of the core layer 5. That is, the first etching stop layer 6 may be made of a material that does not etch the first etching stop layer 6 when the core layer 2 is etched. When the core layer 2 is InGaAsP, for example, the first etching stop layer 6 is made of InGaAs, thereby enabling selective etching by wet etching. The thickness of the first etching stop layer 6 may be about several tens of nm. The core layer 5 is grown to a desired thickness. Here, the core layer 2, the second etching stop layer 4 are InGaAsP, and the first etching stop layer is InGaAs.

Next, a mask (not shown) is attached to a part of the core layer 2 (only on the right side in FIG. 2B), and one side in the width direction of the core layer 2 (FIG. 2B) is formed by dry etching up to the upper surface of the first etching stop layer 6. Etch the left side of As a result, the state shown in FIG. 2B is obtained. More specifically, reactive ion etching (RIE) using CH ₄ and H ₂ , reactive RIE using halogen gas (ICP-RIE: Inductive Coupled Plasma-RIE), reactive ion beam etching The core layer 2 is etched using (RIBE: Reactive Ion Beam Etching) or the like.

  Then, using a solution in which the first etching stop layer 6 is etched earlier than the core layer 2, that is, using a solution for etching only the first etching stop layer 6, the width direction of the first etching stop layer 6 Wet etching is performed on one side (left side in FIG. 2C). For example, when a solution in which sulfuric acid, water, and hydrogen peroxide are mixed at a ratio of 3: 1: 1 is used, the etching rate of InGaAs is faster than InGaAsP, and InP is not etched. Etching is performed, but the InGaAsP core layer 2 and the InP cladding layer 5 are not etched. That is, the core layer 2 and the cladding layer 5 are made of a material that does not etch the core layer 2 and the cladding layer 5 when the first etching stop layer 6 is etched. As a result of this etching, the state shown in FIG. 2C is obtained.

  Further, from this state of FIG. 2C, one side of the InP cladding layer 5 in the width direction (left side of FIG. 2D) is etched by dry etching to obtain a state as shown in FIG. 2D, and then a solution that dissolves only InP. For example, when wet etching is performed on one side in the width direction of the InP cladding layer 5 (left side in FIG. 2E) using a solution in which hydrochloric acid and phosphoric acid are mixed at a ratio of 1: 3, the state shown in FIG. 2E is obtained. That is, when the cladding layer 5 is etched, the core layer 2, the first etching stop layer 6, and the second etching stop layer 4 are not etched, and the core layer 2, the first etching stop layer 6, and the second etching stop layer 4 are used. Used for. Here, the mixing ratio of hydrochloric acid and phosphoric acid in the solution is 1: 3, but other mixing ratios may be used. If the first etching stop layer 6 is not present and the core layer 2 is etched and then the InP cladding layer 5 is etched directly, depending on the crystal plane orientation, the core layer 2 serves as a mask and the etching in the lateral direction proceeds. The semiconductor under the core layer 2 cannot be removed.

  From the state of FIG. 2E, the mask on the core layer 2 is removed, and an organic material (here, BCB (benzocyclobutene)) is applied, whereby the upper surface 2a of the core layer 2, one side surface 2b, The organic material cladding layer 3 covers the lower surface 2d (that is, one side surface 2b formed by etching the core layer 2 and one side of the lower surface 5d exposed by etching the first etching stop layer 6 and the cladding layer 5). As a result, the state shown in FIG. 2F is obtained. Here, the first etching process is completed.

  In the steps of FIGS. 2B to 2D, there is no problem even if the order of the steps of FIGS. 2C and 2D is reversed. That is, the first etching stop layer 6 may be etched by wet etching after first etching the cladding layer 5 by dry etching. Also, the dry etching (FIG. 2D) of the cladding layer 5 after the first etching stop layer 6 is etched by wet etching may be omitted, and the wet etching of the cladding layer 5 of FIG. 2E may be performed.

  In the second etching process, first, as shown in FIG. 2G, a mask (not shown) is attached to the organic material clad layer 3 so as to leave the core layer 2 with a desired width, and the organic material clad layer in the other part. 3 is etched. That is, the other side in the width direction of the organic material cladding layer 6 covering the upper surface 2a of the core layer 2 (the right side in FIG. 2G) is etched. After that, the same etching process is repeated in the same procedure as the first etching process.

  That is, first, the other side in the width direction of the core layer 2 (the right side in FIG. 2H) is etched and etched to the upper surface of the first etching stop layer 6 by dry etching. As a result, the state shown in FIG. 2H is obtained.

  Then, using a solution in which the first etching stop layer 6 is etched earlier than the core layer 2, that is, using a solution for etching only the first etching stop layer 6, the width direction of the first etching stop layer 6 Wet etching is performed on the other side (right side in FIG. 2I). As a result, all the first etching stop layers 6 are deleted, and a state as shown in FIG. 2I is obtained.

  Further, from the state of FIG. 2I, wet etching is performed on the other side in the width direction of the InP cladding layer 5 (right side in FIG. 2J) using a solution that dissolves only InP. As a result, all of the InP cladding layer 5 is deleted, and a state as shown in FIG. 2J is obtained. Even if all of the first etching stop layer 6 and the cladding layer 5 are deleted, since the shell side of the organic material cladding layer 3 is formed at the time of the first etching, the core layer 2 is formed by the organic material cladding layer 3 on one side. Can be supported.

  Finally, an organic material (BCB) is applied once more, whereby the other side surface 5c and the lower surface 5d of the core layer 5 (that is, the other side surface 2c formed by etching the core layer 2) and the first etching stop layer 6 And the other side of the lower surface 5 d exposed by etching of the cladding layer 5 is covered with the organic material cladding layer 6. Thus, the entire outer peripheral surface (upper and lower surfaces 2a, 2d, both side surfaces 2b, 2c) of the core layer 2 is covered with the organic material cladding layer 3. That is, the state as shown in FIG. 4K is obtained, and the structure of the semiconductor thin wire waveguide is completed.

  In the structure of this semiconductor thin wire waveguide, since the entire periphery of the waveguide is filled with the clad layer 3 made of an organic material, there is no problem with respect to mechanical strength, and light is strongly confined in all directions. Can do. In addition, since no discontinuity occurs in the light traveling direction, the characteristics of the waveguide are normal. Furthermore, since the material that fills the surroundings is not air, heat dissipation is better than a waveguide exposed to air. Although the organic material filling the periphery of the waveguide is BCB here, other organic materials such as polyimide may be used as long as the refractive index thereof is smaller than that of the semiconductor.

  FIG. 3A and FIG. 3B show the bending radius dependence of the 90-degree bending loss of the thin wire waveguide and the high mesa waveguide with respect to the light wavelength of 1.55 μm, respectively. Here, the waveguide width of the high mesa waveguide is 1.5 μm, the thickness of the core layer 2 is 0.4 μm, the height of the upper cladding layer 5 is 2 μm, and the height of the entire mesa is 3 μm. For the thin wire waveguide, the width W and thickness of the core layer 2 are both 0.4 μm. The widths of the waveguides both satisfy the condition that the waveguide mode is single with respect to the thickness of the core layer 2 of 0.4 μm. In both waveguides, the cladding layer 3 is an organic material BCB, and the core layer 2 is InGaAsP. The core layer 2 is assumed to be lattice-matched to the substrate 1 and its composition is specified by the band gap wavelength. For example, when the band gap wavelength is 1.1 μm, 1.1Q is written.

  From FIG. 3A and FIG. 3B, in the case of the high mesa waveguide, even if 1.3Q is used for the core layer 2, the bend radius must be 100 μm or more to achieve a bend loss of 0.01 dB per 90 degrees. On the other hand, it can be seen that the thin wire waveguide can be achieved with a bending radius of 2 μm even if the core layer is 1.2Q. At this time, the length of the waveguide at one bent portion can be reduced to 1/50, that is, 628 μm for the high-mesa waveguide and 13 μm for the thin wire waveguide. Therefore, even when an optical integrated circuit including a large number of bent portions is used, the same size reduction can be achieved.

<Embodiment 2>
In the optical semiconductor device according to the second embodiment of the present invention, the structure and the manufacturing method of the semiconductor thin wire waveguide are the same as those in the first embodiment (see FIGS. 1A and 2A to 2K), but the first etching stop is performed. The layer 6 is characterized by being InGaAlAs. In general, since a semiconductor mixed crystal mixed with aluminum has a property of being more easily dissolved in an acid, InGaAlAs can be used for the first etching stop layer 4 for forming the semiconductor fine wire waveguide of the present invention. The same effect as in Embodiment 1 can be obtained.

<Embodiment 3>
In the optical semiconductor device according to the third embodiment of the present invention, the structure and manufacturing method of the semiconductor thin wire waveguide are the same as those of the first and second embodiments, but the core layer 2 and the first etching stop layer 6 are made of InGaAlAs. There is a feature in doing. By changing the band gap wavelengths of the core layer 2 and the first etching stop layer 6, a semiconductor fine wire waveguide can be created as in the first embodiment, and the same effect can be obtained.

In the first to third embodiments, InP, InGaAsP, and InGaAlAs are used for the waveguide layer. However, the wavelength of light used is longer than the band gap wavelength, and the above-described material conditions, that is, the core layer 5 are used. The material of the first etching stop layer 4, the cladding layer 3 and the second etching stop layer 2 is not etched when the core layer 5 is etched, but the first etching stop layer 4 is etched. If the condition that the core layer 5 and the cladding layer 3 are not etched sometimes and the core layer 5, the first etching stop layer 4 and the second etching stop layer 2 are made of a material that is not etched when the cladding layer 3 is etched is satisfied. For example, other semiconductor materials such as GaAs, AlGaAs, GaInNAs, ZnSe, and GaN may be used.
In the first to fourth embodiments, InP is used as the substrate, but a GaAs, Si, sapphire substrate, or the like may be used.
The core layer may be a bulk semiconductor or a quantum well structure using a semiconductor.

The present invention relates to a method for manufacturing an optical semiconductor equipment, it is useful to apply such a semiconductor laser or a semiconductor light receiving device optical semiconductor transceiver device, such as a.

DESCRIPTION OF SYMBOLS 1 Semiconductor mixed crystal substrate 2 Semiconductor waveguide core layer 2a Upper surface 2b, 2c Side surface 2d Lower surface 3 Organic material cladding layer 4 Second etching stop layer 5 Semiconductor cladding layer 6 First etching stop layer

Claims (4)

A second etching stop layer formed on the substrate, a core layer that is an optical waveguide layer, and an organic material cladding layer having a refractive index lower than that of the core layer. A method of manufacturing an optical semiconductor device having a configuration in which the organic material cladding layer is formed on a stop layer, and the entire outer peripheral surface of the core layer is covered with the organic material cladding layer ,
The first etching stop layer is made of a material that does not etch the first etching stop layer when the core layer is etched, and the core layer and the cladding layer are made of the core layer when the first etching stop layer is etched. And the core layer, the first etching stop layer, and the second etching stop layer using a material that is not etched, and the core layer, the first etching stop layer, and the second etching stop layer when the cladding layer is etched. By using a material in which the second etching stop layer is not etched,
Sequentially laminating the second etching stop layer, the cladding layer, the first etching stop layer, and the core layer on the substrate;
Etching one side of the core layer in the width direction;
Etching one side of the first etching stop layer in the width direction;
Etching one side of the cladding layer in the width direction;
Covering the upper surface, one side surface and the lower surface of the core layer with the organic material cladding layer;
Etching the other side in the width direction of the organic material cladding layer covering the upper surface of the core layer;
Etching the other side in the width direction of the core layer;
Etching the other side in the width direction of the first etching stop layer;
Etching the other side in the width direction of the cladding layer;
Covering the other side surface and lower surface of the core layer with the organic material cladding layer;
The manufacturing method of the optical semiconductor device characterized by implementing. The method for manufacturing an optical semiconductor device according to claim 1 ,
The band gap wavelength of the semiconductor mixed crystal used for the core layer is smaller than the band gap wavelength of the semiconductor mixed crystal used for the first etching stop layer, and the band gap wavelength of the semiconductor mixed crystal used for the first etching stop layer is A method for producing an optical semiconductor device, wherein the semiconductor mixed crystal used for the clad layer is larger than a band gap wavelength. In the manufacturing method of the optical semiconductor device according to claim 1 or 2 ,
A method of manufacturing an optical semiconductor device , wherein a height from an upper surface of the second etching stop layer to a lower surface of the core layer is 1 μm or more. In the manufacturing method of the optical semiconductor device according to any one of claims 1 to 3 ,
The method for manufacturing an optical semiconductor device , wherein the core layer includes a bulk semiconductor or a quantum well structure using a semiconductor.

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