JP6322059B2 - Manufacturing method of optical device - Google Patents

Description

  The present invention relates to an optical device manufacturing method, and more particularly to an optical device manufacturing method in which functional elements are integrated on the surface of a PLC.

  In recent years, with the spread of optical fiber transmission, a technique for integrating a large number of optical functional elements at a high density is required. As one of such techniques, a quartz-based planar optical waveguide circuit (hereinafter also referred to as PLC (Planar Lightwave Circuit)) is known. Quartz-based PLC has excellent features such as low loss, high reliability, and high design freedom, and is promising as a platform for integrating multiple functions.

  Actually, the optical receiver at the transmission terminal station includes an optical module including a light receiving element such as a photodiode (hereinafter also referred to as PD), a light emitting element such as a laser diode (hereinafter also referred to as LD), A PLC on which functional elements such as a coupler, a branching / coupling device, and an optical modulator are formed is mounted by optical coupling. Further, for example, in a node device in the wavelength division multiplexing transmission system, a large number of PDs are integrated and mounted in order to monitor the light intensity of a plurality of optical waveguides in the PLC.

  As a structure that enables optical coupling between the optical waveguide and the light receiving and emitting optical element, a reflection mirror that converts the optical path in a direction perpendicular to the substrate surface as shown in FIG. Proposed structures have been proposed. As shown in FIG. 1, light propagating through an optical waveguide composed of a lower clad 102, a core 103, and an upper clad 104 is reflected by a mirror 105 and coupled to a PD 106.

FIG. 2 is an enlarged view of a portion of PD 106 in FIG. The PD manufactured on the substrate 200 includes an insulating layer 201, an adhesive layer 202, a PIN layer 206 in which an N layer 203, an I layer 204, and a P layer 205 are sequentially stacked, and an electrode on the N layer 203. Layer 207-1, electrode layer 207-2 on PIN layer 206, adhesive layer 202, PIN layer 206, insulating layer 208 covering electrode layers 207-1 and 207-2, and wiring 209 on the insulating layer -1,209-2. The insulating layer 201 immediately above the substrate 200 is inserted when the substrate 200 is conductive, and specifically, is an SiO ₂ layer or a polyimide layer.

  FIG. 3 shows a manufacturing method. (A) After forming the optical waveguide 301, (b) an adhesive 304 is applied to the surface of the optical waveguide. Thereafter, the chip on which the epitaxial layer 303 is formed on the InP substrate 302 is bonded to the optical waveguide 301 with the epitaxial surface 302 facing down. (C) Thereafter, the InP chip substrate 302 is removed by grinding, polishing, and wet etching. (D) Then, the epitaxial film 303 on the optical waveguide is processed into a PD 305 through processes such as photolithography, etching, insulating film formation, and wiring formation. (E) Thereafter, the micromirror 306 is manufactured, and (f) a metal such as Al307 is deposited on the mirror surface. Among these, in the bonding process for bonding the InP chip onto the substrate, it is necessary to bond the InP chip of the minimum necessary size to the place where bonding is required.

Japanese Patent No. 4467544

Y. Kurata et al., “Heterogeneous Integration of High-Speed InP PDs on Silica-Based Planar Lightwave Circuit Platform”, Proc. ECOC2011, Th.12, LeSaleve.5, (2011)

  However, in order to arrange each chip with high positional accuracy, an expensive mounting device such as a chip bonder is required, which has been a problem in realizing a low-cost manufacturing process. Further, once the adhesive layer is formed, it is difficult to perform re-alignment because the adhesive adheres to the chip, which has been a problem in the process.

  The present invention has been made in view of these problems, and an object of the present invention is to provide an optical device manufacturing method capable of efficiently and accurately positioning functional elements represented by optical semiconductor chips on the upper surface of an optical waveguide. Is to provide.

In order to achieve the above object, a first aspect of the present invention is a light device fabrication method for fabricating an optical device arranged tip-like functional element on Shirikon'u Fine the optical waveguide is formed . The optical device manufacturing method includes the step of temporarily placing the chip-like functional element in the guide on the substrate for a surface on which the functional element of the guide substrate is temporarily placed, and the adhesive surface of the Shirikon'u Movement which an optical waveguide is formed the in opposition, placing the said guide substrate and those said Shirikon'u Fine, a step of contacting the Shirikon'u Movement and the functional element, the step of bonding the Shirikon'u Movement and the functional element, the It is characterized by providing.

  In one embodiment, the functional element is an optical semiconductor processing substrate on which an optical semiconductor epitaxial film is formed, or an optical semiconductor substrate that has been processed as an optical semiconductor circuit (having an optical semiconductor function mounted). It is characterized by. In one embodiment, the method includes the step of processing an optical semiconductor epitaxial film formed on a processing substrate for optical semiconductors.

  In one embodiment, the bonding step in the above method is a step of bonding at room temperature or a step of bonding with an organic material. In one embodiment, a marker representing a position where a chip-like functional element is to be disposed is formed on the guide substrate. In one embodiment, the marker is formed by a concave depression or a convex line or broken line formed on the surface of the guide substrate.

  As described above, according to the present invention, it is possible to provide an optical device manufacturing method in which functional elements represented by an optical semiconductor chip on the upper surface of an optical waveguide can be efficiently and accurately positioned.

It is a figure explaining the structure provided with the reflective mirror which reflects light and couple | bonds with PD based on a prior art. It is sectional drawing of the optical coupling circuit element PD based on a prior art. It is a figure explaining the manufacturing method of the optical device which integrated the functional element on the PLC surface based on a prior art. It is a figure explaining the method of arrange | positioning a functional element on the PLC surface based on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, as described with reference to FIG. 3, the functional element is an InP substrate on which an epitaxial layer is formed (the InP substrate is removed after bonding to the bonding surface of the optical waveguide substrate 420 and the epitaxial film is optical A member to be processed into a semiconductor circuit: an optical semiconductor processing substrate) is taken as an example, but the functional element may be an element that functions as a PD or LD in which an epitaxial film is formed with an insulating film or wiring.

FIG. 4 shows a method for arranging functional elements on the PLC surface according to an embodiment of the present invention.
In the method according to the present embodiment, as a first step, a guide substrate 401 on which a marker 402 representing a position where a functional element is to be arranged is prepared (see FIG. 4A). In consideration of the material and characteristics of the functional element 410, the required shape accuracy and position accuracy, and the subsequent bonding process, the guide substrate 401 is made of Si or SiO2 that transmits infrared rays, or a material such as epoxy, acrylic, or polyimide as a resin material. select. The marker 402 is preferably a concave depression formed on the surface of the guide substrate in order to arrange the functional element 410 with high accuracy. The recess has a positional accuracy necessary for bonding the functional element to the PLC surface, and has a depth equal to or less than the thickness of the functional element so that the adhesive contacts only the functional element in the subsequent bonding process. It is desirable. Needless to say, an appropriate depth is required because the step of the depression of the surface of the guide substrate 401 and the depression is too small to serve as a marker. In addition, when the optical waveguide chip or wafer to be bonded is not a perfect parallel plate due to warpage or the like, a step considering the shape deformation is required. The marker is not limited to a concave depression, but can be a convex line or a broken line formed on the surface of the guide substrate, as long as the marker can be prevented from moving in the horizontal direction on the surface of the guide substrate of the functional element 410 arranged. It may be.

  Next, as a second step, the functional element 410 composed of the epitaxial layer 404 and the InP substrate 403 is aligned with the marker 402 of the guide substrate 401 with the epitaxial layer 404 facing upward. Since the marker 402 has a hollow shape, the functional element 410 can be placed in the hollow with high accuracy (see FIGS. 4B and 4C).

  As a third step, an optical waveguide substrate 420 including a substrate 407 on which the optical waveguide 406 is formed is prepared. The substrate 420 may be a wafer on which one or more optical waveguide circuits are formed, or a substrate cut out in a chip shape. With the adhesive surface of the optical waveguide substrate 420 facing down, the optical waveguide substrate 420 is opposed to the surface of the guide substrate 401 on which the functional elements 410 are arranged. An adhesive 405 is uniformly applied in advance to the adhesive surface of the optical waveguide substrate 420 by a spin coater or the like. Examples of the adhesive 405 include thermosetting materials (organic materials) such as polyimide, BCB (benzocyclobutene), and epoxy. At this time, it is necessary to accurately align the guide substrate 401 and the optical waveguide substrate 420. As a method for this, first, the two are brought as close as possible, and the horizontal position is maintained while keeping the distance between the two. Align. In the horizontal alignment, it is desirable to use mounting markers formed on both, but in order to realize this, for example, the guide substrate 401 and the optical waveguide substrate 420 are made of Si, SiO2, or the like. The material that transmits the infrared light is selected, the infrared light is irradiated from below to above the guide substrate 401, and the mounting markers formed on the guide substrate 401 and the optical waveguide substrate 420 are aligned. Thus, the positional accuracy is ensured. (See FIG. 4 (d)).

  As a fourth step, the guide substrate 401 and the optical waveguide substrate 420 that ensure positional accuracy are brought into contact with each other, and the state is maintained until the adhesive 405 is cured (see FIG. 4E). After the adhesive 405 is cured, the guide substrate 401 and the optical waveguide substrate 420 are separated to obtain the optical waveguide substrate 420 on which the functional elements are arranged (see FIG. 4F). If the position of the functional element does not shift due to the adhesive force of the adhesive even in an uncured state, the adhesive may be cured in the state shown in FIG.

  After the adhesive is cured, as described with reference to FIG. 3, a step of removing the InP substrate 403 by grinding, polishing, wet etching or the like and a step of processing the epitaxial film into an optical semiconductor element are performed. An optical device having a function can be manufactured. As described above, in the case where the functional element is an element having a desired function because an insulating film or a wiring is formed by processing the epitaxial film, the functional element is formed on the optical waveguide substrate 420. There is no need to process the epitaxial layer after bonding to the adhesive surface.

  In this embodiment, the method of bonding the functional element and the optical waveguide substrate using an adhesive is described, but a bonding method called room temperature bonding without using an adhesive may be used. In the case of using room temperature bonding, it is often necessary to activate the adhesion surface by plasma treatment, and it is preferable to perform surface treatment of the epitaxial layer 404 in the state of FIG. Moreover, although the example of the InP substrate in which the epitaxial layer was formed was described as a functional element, the kind will not be limited if a new function can be provided to the optical waveguide which is a non-adhesion layer.

100 PLC
101 Substrate 102 Lower clad 103 Core 104 Upper clad 105 Mirror 106 PD
200 Substrate 201 Insulating layer 202 Adhesive layer 203 N layer 204 I layer 205 P layer 206 PIN layer 207-1, 207-2 Electrode layer 208 Insulating layer 209-1, 209-2 Wiring 301 Optical waveguide 302 InP substrate 303 Epitaxial layer 304 Adhesive 305 PD
306 Micromirror 307 Al
401 Guide substrate 402 Marker 403 InP substrate 404 Epitaxial layer 405 Adhesive 406 Optical waveguide 407 Substrate 410 Functional element 420 Optical waveguide substrate

Claims (7)

An optical device manufacturing method for producing an optical device placing the chip-like functional element on the optical waveguide is formed Shirikon'u Fine,
A step of temporarily disposing a chip-like functional element on a guide substrate;
A surface on which the functional element of the guide substrate is temporarily placed, the step of bonding surface and is opposed to the Shirikon'u Movement of the optical waveguide is formed, arranging the front Symbol Shirikon'u Movement and the guide substrate ,
And contacting the front Symbol Shirikon'u Movement and the functional element,
A step of bonding the pre-Symbol Shirikon'u Movement and the functional element,
An optical device manufacturing method characterized by comprising:   The optical device manufacturing method according to claim 1, wherein the functional element is an optical semiconductor processing substrate on which an optical semiconductor epitaxial film is formed.   The optical device manufacturing method according to claim 2, further comprising a step of processing the optical semiconductor epitaxial film. Process is characterized in that it comprises a step of bonding by the process or organic material room-temperature bonding, optical devices work made method according to any one of claims 1 to 3 for the bonding. The said guide substrate, characterized in that the marker indicating the position where the chip-like functional element is arranged is formed, the optical devices work steel according to any one of claims 1 to 4 Method. The guide substrate is made of a material that transmits infrared light,
A marker is formed on the silicon wafer,
The surface disposed temporarily and the bonding surface are opposed to each other, and infrared light is irradiated from the lower side to the upper side of the guide substrate to form the marker and the silicon wafer formed on the guide substrate. The optical device manufacturing method according to claim 5, wherein the guide substrate and the silicon wafer are arranged by combining the markers. The material that transmits infrared light is Si or SiO. ₂ The optical device manufacturing method according to claim 6, comprising:

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