JP5563618B2 - Optical modulator and mounting method thereof - Google Patents

Description

  The present invention relates to an optical modulator and a mounting method thereof.

  FIG. 1 shows a conventional PLC-LN optical modulator. In the conventional PLC-LN optical modulator 100 shown in FIG. 1, the LN optical modulation element 103 is fixed to the wiring substrate 102 of the package 101 with the element surface facing upward, and the PLCs 104 and 105 are facing the element surface upward. It is connected to the LN light modulation element 103. The PLC-LN optical modulator 100 is created by providing high-frequency electrical wiring with wires and connecting optical fibers 106 and 107 to the PLCs 104 and 105, respectively.

  However, in the conventional PLC-LN optical modulator 100, the number of high-frequency electrical wirings to be provided by wires is large, and it takes time and cost to manufacture, and furthermore, the high-frequency electrical wirings are routed on a plane, so a space is necessary. It was difficult to reduce the size of the element.

  Further, in the conventional PLC-LN optical modulator 100, an adhesive is used at the connection portion between the LN optical modulation element 103 and the PLCs 104 and 105. In order to prevent the adhesive from being deteriorated by heat, the element is fixed or the wire is fixed. There is a limit to the temperature applied during the connection process.

  For the LN optical modulator, flip chip mounting with the element surface facing downward (face down) has been proposed (see Patent Document 1). FIG. 2 shows a conventional PLC-LN optical modulator using flip chip mounting. In the conventional PLC-LN optical modulator 200 shown in FIG. 2, bumps 208 serving as electrodes are provided on the multilayer substrate 202 of the package 201. In the conventional PLC-LN optical modulator 200, the LN light modulation element 203 is fixed to the bump 208 with the element surface facing downward and flip-chip mounted, and the PLCs 204 and 205 are mounted on the LN light modulation element 203 with the element surface facing downward. It is connected.

  The PLC-LN optical modulator 200 can perform electrode connection in a lump by providing wiring in the package 201 by three-dimensional wiring using the multilayer substrate 202, and can reduce wiring space. It is possible to reduce the size and density of the device, and to reduce time and cost.

  In addition to the above-described LN optical modulator, flip-chip mounting that eliminates wire bonding by superimposing the element surface on the wiring substrate surface is also used for Si-IC and InP semiconductors. Since Si-IC, InP system, and LN optical modulator do not transmit visible light, an element is mounted by observing with an infrared camera and aligning with a wiring board.

JP 2006-284838 A

  However, even in the conventional PLC-LN optical modulator 200 shown in FIG. 2, the connection portion between the LN optical modulation element 203 and the PLCs 204 and 205 is caused by heat applied at the time of flip-chip mounting or heat at the time of hardening the filler for fixing. There was a problem that the adhesive used in the process deteriorated. For example, heat of about 300 ° C. is applied for gold-tin solder mounting, about 150 ° C. for thermal ultrasonic mounting of gold bumps, and about 150 ° C. for filler curing temperature.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a PLC-nitride-based semiconductor optical modulator in which the adhesive is not deteriorated by heat and a method for producing the same. .

According to a first aspect of the present invention, there is provided a method for manufacturing an optical modulator, in which a light modulation element on a transparent substrate transparent in the visible light region is fixed to a bump provided on a wiring board with the element surface facing downward. A chip mounting step; and a step of bonding the PLC to the light modulation element on the transparent substrate with the element surface facing upward after the flip chip mounting.

  The method for manufacturing an optical modulator according to claim 2 of the present invention is the method for manufacturing the optical modulator according to claim 1, wherein the light modulator on the transparent substrate is made of a GaN-based material. It is characterized by.

The method for producing an optical modulator according to claim 3 of the present invention is the method for producing an optical modulator according to claim 1 or 2, wherein the optical modulator on the transparent substrate is formed on the transparent substrate. The surface of the light modulation element opposite to the element surface is constituted by a mirror surface that can transmit visible light .

According to a fourth aspect of the present invention, there is provided an optical modulator comprising: a transparent wiring board having a bump; and a transparent transparent substrate in a visible light region, wherein the transparent substrate is mounted on the bump of the wiring board with an element surface facing downward and flip-chip mounted. A light modulation element on a substrate and a PLC bonded to the light modulation element on the transparent substrate with the element surface facing upward after flip-chip mounting of the light modulation element on the transparent substrate.

  An optical modulator according to a fifth aspect of the present invention is the optical modulator according to the fourth aspect, wherein the optical modulator on the transparent substrate is made of a GaN-based material.

An optical modulator according to a sixth aspect of the present invention is the optical modulator according to the fourth or fifth aspect, wherein the element surface of the light modulation element on the transparent substrate is a transparent substrate of the light modulation element on the transparent substrate. The surface on the opposite side is constituted by a mirror surface that can transmit visible light .

  According to the light modulator and the manufacturing method thereof according to the present invention, it is possible to connect the PLC to the light modulation element on the transparent substrate after the light modulation element on the transparent substrate is flip-chip mounted. Therefore, it is possible to avoid deterioration of the adhesive used in the connection portion between the light modulation element on the transparent substrate and the PLC due to heat applied during flip chip mounting or heat during underfill curing.

  Furthermore, when the light modulation element on the transparent substrate is made of a GaN-based material, the alignment between the electrode pattern and the wiring substrate can be performed by observing with a microscope without forming an alignment pattern during flip chip mounting. It becomes possible. Therefore, the alignment between the electrode pattern and the wiring board is easy, the alignment time can be shortened, and the process can be simplified.

It is a figure which shows the structure of the conventional PLC-LN optical modulator. It is a figure which shows the conventional PLC-LN optical modulator using flip-chip mounting. It is a figure which shows the PLC-nitride type | system | group semiconductor optical modulator using the flip-chip mounting based on this invention. It is a figure which shows the shape which looked at the PLC-nitride type | system | group semiconductor optical modulator based on this invention from the upper surface of the package 301, before mounting the cover of the package 301. FIG.

  FIG. 3 shows a PLC-nitride semiconductor optical modulator 300 using flip chip mounting according to the present invention. In FIG. 3, a nitride-based semiconductor element 303 on a transparent substrate is flip-chip mounted by being fixed to a bump 308 provided on a wiring substrate 302 in a package 301 with the element surface facing downward (face down). A PLC-nitride semiconductor optical modulator 300 is shown in which 305 is connected to the nitride semiconductor element 303 with the element surface facing upward (face-up).

  The nitride-based semiconductor element 303 on the transparent substrate does not require an opaque conductive film necessary for the LN light modulation element, and uses a transparent substrate such as a sapphire substrate or a GaN substrate, and the back surface of the transparent substrate, that is, The surface opposite to the element surface is constituted by a mirror surface, and a reflection film (metal or the like) applied to the back surface to reflect light from the sensor of the apparatus during the process is removed. Thereby, it will be in the state which visible light can permeate | transmit the back surface of a board | substrate. Therefore, the nitride-based semiconductor elements using these transparent substrates are transparent in the visible light range, and the waveguide position and electrode pattern can be confirmed from the back surface of the element that is flip-chip mounted.

  Since the waveguide position can be confirmed from the rear surface of the flip chip mounted device, it is easy to connect the PLCs 304 and 305 to the nitride semiconductor device 303 on the transparent substrate after the nitride semiconductor device 303 on the transparent substrate is flip chip mounted. become. Therefore, according to the PLC-nitride-based semiconductor optical modulator 300 of the present invention, the adhesive used for the connecting portion between the nitride-based semiconductor element 303 on the transparent substrate and the PLCs 304 and 305 is subjected to heat or under applied at the time of flip chip mounting. It is possible to avoid deterioration due to heat during the curing of the fill.

  Further, in the conventional PLC-LN optical modulators 100 and 200 shown in FIGS. 1 and 2, since the conductive film formed on the element surface is opaque, the electrode pattern cannot be observed during mounting. In the PLC-nitride-based semiconductor optical modulator 300 according to the present invention, flip chip mounting is necessary. Since the electrode pattern can be confirmed from the back surface of the element, it is possible to align the electrode pattern and the wiring board 302 by observing with a microscope without forming an alignment pattern during flip chip mounting. Therefore, according to the PLC-nitride semiconductor optical modulator 300 of the present invention, the alignment between the electrode pattern and the wiring substrate 302 is easy, the alignment time can be shortened, and the process can be simplified.

[Example]
Examples of the PLC-nitride semiconductor optical modulator 300 according to the present invention will be described below. In the PLC-nitride-based semiconductor optical modulator 300 according to the embodiment of the present invention, a GaN substrate-on-GaN modulator whose back surface is a mirror surface is used as the nitride-based semiconductor element 303 on the transparent substrate. A Si substrate was used as the substrate 305.

  When the PLC-nitride semiconductor optical modulator 300 is manufactured, the element surface is faced down (face down), and the nitride-based semiconductor element 303 on the transparent substrate is flip-chip mounted on the bump 308, and then the element surface is directed upward ( Then, the PLCs 304 and 305 are aligned and bonded and fixed to the nitride semiconductor element 303 on the transparent substrate.

  Since the nitride-based semiconductor element 303 on the transparent substrate is transparent in the visible light range, the position of the waveguide can be observed. The PLCs 304 and 305 using Si as a substrate do not transmit light. Since the optical waveguides of the PLCs 304 and 305 can be confirmed from the upper surface, the adhesive connection between the nitride-based semiconductor element 303 on the transparent substrate and the PLCs 304 and 305 is performed by observing the positions of the respective waveguides using a microscope. Is performed by aligning with the wiring board 302.

  FIG. 4 shows a shape of the PLC-nitride semiconductor optical modulator 300 of the present invention viewed from the top surface of the package 301 before the cover of the package 301 is mounted. As shown in FIG. 4, the electrode pattern 401 of the nitride-based semiconductor element 303 on the transparent substrate can be confirmed from the upper surface of the PLC-nitride-based semiconductor optical modulator 300 through the transparent substrate. The optical waveguides 402 of the PLCs 304 and 305 can be confirmed from the upper surface of the PLC-nitride-based semiconductor optical modulator 300 in the same manner because the element surface faces upward.

  In the embodiment of the present invention, GaN is used as a semiconductor material constituting the nitride-based semiconductor element 303 on the transparent substrate, but is not limited thereto, for example, AlN, AlGaN, InN, BN, InGaN, InAlN, etc. In addition, since a known nitride-based semiconductor material can be used, and the LN optical modulation element can confirm the optical waveguide from the back surface, an alignment pattern is formed at a location where the conductive film is removed, and a wiring board is formed. It is also possible to use an LN light modulation element. Moreover, although the GaN substrate was used as the transparent substrate of the nitride semiconductor element 303 on the transparent substrate, for example, a sapphire substrate can also be used. In the present invention, the nitride-based semiconductor element 303 on the transparent substrate is flip-chip mounted on the package 301, but may be flip-chip mounted on the submount.

100, 200 PLC-LN optical modulator 101, 201, 301 Package 102, 202, 302 Wiring substrate 103, 203 LN optical modulator 104, 105, 204, 205, 304, 305 PLC
106, 107, 206, 207, 306, 307 Optical fiber 208, 308 Bump 300 Nitride-based semiconductor optical modulator 303 Nitride-based semiconductor element on transparent substrate 401 Electrode pattern 402 Optical waveguide

Claims (6)

Fixing the light modulation element on the transparent substrate transparent in the visible light region to the bump provided on the wiring board with the element surface facing downward, and flip-chip mounting;
Bonding the PLC to the light modulation element on the transparent substrate with the element surface facing upward after the flip chip mounting.   The method for manufacturing an optical modulator according to claim 1, wherein the light modulation element on the transparent substrate is made of a GaN-based material. The surface of the transparent substrate of the light modulation element on the transparent substrate opposite to the element surface of the light modulation element on the transparent substrate is configured by a mirror surface that can transmit visible light. A manufacturing method of the optical modulator as described. A wiring board having bumps;
A light modulation element on a transparent substrate that is transparent in the visible light range and is flip-chip mounted fixed to the bump of the wiring board with the element surface facing downward;
An optical modulator comprising: a PLC bonded to the light modulation element on the transparent substrate with the element surface facing upward after flip chip mounting of the light modulation element on the transparent substrate.   The light modulator according to claim 4, wherein the light modulation element on the transparent substrate is made of a GaN-based material. 6. The transparent substrate of the light modulating element on the transparent substrate, wherein the surface opposite to the element surface of the light modulating element on the transparent substrate is configured by a mirror surface that can transmit visible light. The light modulator described.

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