JP2013250436A - Optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical semiconductor device capable of easily performing accurate positioning in connecting with an optical fiber, and facilitating fabrication.SOLUTION: An optical semiconductor device includes: a first substrate in which an optical waveguide and a modulator for modulating light propagated through the optical waveguide are provided on a semiconductor substrate; and a second substrate on which an electronic circuit is provided. One surface of the first substrate is electrically connected to one surface of the second substrate, and an optical fiber is installed on the first substrate and light is transmitted between the optical waveguide and the optical fiber.

Description

  The present invention relates to an optical semiconductor device.

  An optical waveguide using silicon has a low loss with respect to light having a wavelength of 1.3 to 1.5 μm in optical communication, and can be manufactured using a semiconductor process technology. It can be used for an element. As an optical semiconductor device using such an optical waveguide, for example, as shown in FIGS. 1 and 2, there is an optical semiconductor device in which an optical waveguide, a modulator, a photodetector, an electronic circuit, and the like are integrated.

First, the optical semiconductor device shown in FIG. 1 will be described. This optical semiconductor device is formed by bonding one surface of the first substrate 910 and one surface of the second substrate 930 together. The first substrate 910 includes an optical waveguide 911, a modulator 912 that modulates the phase of light propagating through the optical waveguide, an electronic circuit 913 that serves as a driver for driving the modulator 912, and a photodetector 914 that detects light. , TIA (Transimpedance Amplifier) 915 and the like. Note that the TIA 915 has a function of converting a current output from the photodetector 914 into a voltage and amplifying it, and is formed by an electronic circuit such as a transistor. The first substrate 910 is entirely formed of a silicon oxide (SiO ₂ ) layer 916, and the optical waveguide 911, the modulator 912, the electronic circuit 913, the photodetector 914, the TIA 915, and the like are inside the silicon oxide layer 916. Is formed. A metal wiring 917 is formed inside the silicon oxide layer 916, and a metal wiring 918 is formed on the other surface of the first substrate 910. A part of the metal wiring 917 formed inside the silicon oxide layer 916 and the metal wiring 918 formed on the other surface of the first substrate 910 are electrically connected by a conductive via 919. In addition, the metal wiring 917 formed inside the silicon oxide layer 916 and the modulator 912, the electronic circuit 913, the photodetector 914, the TIA 915, and the like are electrically connected by the conductive via 920 formed inside the silicon oxide layer 916. Connected.

  In the second substrate 930, a silicon oxide layer 932 and a silicon layer 933 are formed over a silicon substrate 931, and an electronic circuit 934 such as a transistor is formed on the surface of the silicon layer 933. A silicon oxide layer 935 is formed on the electronic circuit 934 formed on the surface of the silicon layer 933, and a metal wiring 936 is formed inside the silicon oxide layer 935. In addition, the metal wiring 936 and the electronic circuit 934 are electrically connected by a conductive via 937, and a part of the metal wiring 936 provided on the second substrate 930 is provided on the other surface of the first substrate 910. The metal wiring 918 and the conductive via 938 are connected to each other. The semiconductor device shown in FIG. 1 includes a silicon oxide layer 916 formed on one surface of the first substrate 910 formed in this manner and a silicon oxide layer 935 formed on one surface of the second substrate 930. Are bonded and bonded together.

  Next, the semiconductor device shown in FIG. 2 will be described. Similar to the semiconductor device shown in FIG. 1, this semiconductor device is formed by bonding one surface of the first substrate 950 and one surface of the second substrate 970 together. In the first substrate 950, a silicon layer 952 is formed over the silicon oxide layer 951, and an electronic circuit 953 such as a transistor is formed on the surface of the silicon layer 952. A silicon oxide layer 954 is formed on the electronic circuit 953 formed on the surface of the silicon layer 952, and a metal wiring 955 is formed inside the silicon oxide layer 954. Further, the metal wiring 955 and the electronic circuit 953 are electrically connected by a conductive via 956, and are formed on a part of the metal wiring 955 and the silicon oxide layer 951 on the other surface of the first substrate 950. The metal wiring 957 is electrically connected by a conductive via 958.

  In the second substrate 970, a silicon oxide layer 972 is formed on the surface of the silicon substrate 971. Inside the silicon oxide layer 972, there are an optical waveguide 973, a modulator 974 for modulating the phase of light, an electronic circuit 975 serving as a driver for driving the modulator 974, a photodetector 976 for detecting light, a TIA 977, and the like. Is formed. The TIA 977 has a function of converting the current output from the photodetector 976 into a voltage and amplifying it, and is formed by an electronic circuit such as a transistor. A metal wiring 978 is formed inside the silicon oxide layer 972. Thus, the metal wiring 978 and the modulator 974, the electronic circuit 975, the photodetector 976, the TIA 977, and the like formed in the silicon oxide layer 972 are connected by the conductive via 997 formed in the silicon oxide layer 972. Electrically connected. Further, part of the metal wiring 978 provided inside the second substrate 970 is connected to the metal wiring 957 provided on the other surface of the first substrate 950 by the conductive via 980. The semiconductor device shown in FIG. 2 includes a silicon oxide layer 954 formed on one surface of the first substrate 950 and a silicon oxide layer 972 formed on one surface of the second substrate 970. Are bonded and bonded together.

US Patent Application Publication No. 2009/0294814 US Patent Application Publication No. 2009/0297091

  The optical semiconductor device shown in FIGS. 1 and 2 is used by connecting to an optical fiber or the like, but it is difficult to install the optical fiber in a state where the optical fiber is accurately aligned. In the optical semiconductor device shown in FIG. 1, it is necessary to form the conductive via 938 after the first substrate 910 and the second substrate 930 are bonded to each other. Forming the conductive via 938 is extremely difficult in manufacturing. This also applies to the optical semiconductor device shown in FIG. 2, and it is necessary to form the conductive via 980 after the first substrate 950 and the second substrate 970 are bonded together. Therefore, it is extremely difficult to manufacture such a deep conductive via 980 in manufacturing.

  Accordingly, there is a need for an optical semiconductor device that can be easily accurately aligned when connected to an optical fiber, and that is easy to manufacture.

  According to one aspect of this embodiment, an electronic circuit is provided on a semiconductor substrate, the first substrate provided with an optical waveguide and a modulator that modulates light propagating through the optical waveguide, and an electronic circuit. A second substrate, wherein one surface of the first substrate and one surface of the second substrate are electrically connected, and an optical fiber is connected to the first substrate. It is installed and light is transmitted between the optical waveguide and the optical fiber.

  According to the disclosed optical semiconductor device, accurate alignment can be easily performed when the optical semiconductor device is connected to the optical fiber, and the optical semiconductor device can be easily manufactured.

Structural diagram of optical semiconductor device (1) Structure of optical semiconductor device (2) Structure diagram of optical semiconductor device in first embodiment Explanatory drawing (1) of the optical semiconductor device in 1st Embodiment Sectional drawing in dashed-dotted line 4A-4B of FIG. Explanatory drawing of the connection between the optical semiconductor device and the optical fiber in the first embodiment Explanatory drawing (1) of thickness of the silicon substrate of the optical semiconductor device in 1st Embodiment Explanatory drawing (2) of the thickness of the silicon substrate of the optical semiconductor device in 1st Embodiment Explanatory drawing (2) of the optical semiconductor device in 1st Embodiment Explanatory drawing of the optical semiconductor device in 2nd Embodiment

  Modes for carrying out the invention will be described below. In addition, about the same member etc., the same code | symbol is attached | subjected and description is abbreviate | omitted.

[First Embodiment]
The optical semiconductor device in this embodiment will be described with reference to FIG. The optical semiconductor device in the present embodiment is formed by connecting one surface of the first substrate 110 and the other surface of the second substrate 130 facing each other. In the first substrate 110, a silicon oxide layer 112 is formed on a silicon substrate 111 which is a semiconductor substrate. Inside the silicon oxide layer 112, an optical waveguide 124 and an optical waveguide 124 illustrated in FIG. A modulator 113 that modulates the light propagating through the light is formed. Therefore, the periphery of the optical waveguide 124 and the modulator 113 that modulates the light propagating through the optical waveguide 124 is covered with the silicon oxide layer 112 serving as a cladding. The optical modulator 113 is connected to a metal wiring 114 formed inside the silicon oxide layer 112 by an electrode 127, and a part of the metal wiring 114 is an electrode 115 provided on one surface of the first substrate 110. Are electrically connected by conductive vias 116. In addition, another part of the metal wiring 114 is a TSV (through-silicon) which is a through electrode penetrating the electrode 118 and the silicon substrate 111 formed on the silicon oxide layer 117 on the other surface of the first substrate 110. via: silicon through electrode) 119. The electrode 120 formed on one surface of the first substrate 110 and the electrode 121 formed on the other surface are electrically connected by a TSV 122 that is a through electrode penetrating the silicon substrate 111. The electrodes 118 and 121 are formed with bumps 123 for connection to an interposer described later.

  The second substrate 130 is formed by sequentially laminating a silicon oxide layer 132 and a silicon layer 133 on a silicon substrate 131, and electronic circuits such as transistors 134 and 135 are formed on the surface of the silicon layer 133. ing. In FIG. 3, the electronic circuits such as the transistors 134 and 135 are shown for driving the modulator 113, but the transistors 134, 135, etc. are other than the electronic circuit that drives the modulator 113, for example, logic It may be a circuit or the like.

  A silicon oxide layer 136 is formed on electronic circuits such as the transistors 134 and 135 in the silicon layer 133, and metal wirings 137 and 138 are formed inside the silicon oxide layer 136. Between the electronic circuit such as the transistors 134 and 135 and the metal wirings 137 and 138, the terminals in the electronic circuit such as the transistors 134 and 135 and the metal wirings 137 and 138 corresponding to the terminals are connected by the conductive vias 139 and 140. Electrically connected. A part of the metal wiring 137 and the like are electrically connected to the electrode 141 provided on one surface of the second substrate 130 by the conductive via 142. Similarly, part of the metal wiring 138 and the like is electrically connected to the electrode 143 provided on one surface of the second substrate 130 and the conductive via 144. A silicon oxide layer 145 is formed on the other surface of the second substrate 130.

  In the present embodiment, the first substrate 110 and the second substrate 130 are connected to each other with one surface thereof facing each other. At this time, the electrode 115 on the first substrate 110 and the electrode 141 on the second substrate 130 are connected by the micro bump 146, and the electrode 120 on the first substrate 110 and the electrode 143 on the second substrate 130 are connected. They are connected by micro bumps 147. In the present embodiment, the TSV 122 penetrating from one surface to the other surface is formed only on the first substrate 110, and before the TSV 122 is bonded to the first substrate 110 and the second substrate 130. Can be formed. Further, since the TSV 122 can be formed by forming a through hole only in the first substrate 110, it is easier to form than the conductive via 938 shown in FIG. 1 and the conductive via 980 shown in FIG. Can do.

(Connection with optical fiber etc.)
Next, in the optical semiconductor device according to the present embodiment, installation of light emitting elements and connection of optical fibers will be described with reference to FIGS. FIG. 5 is a cross-sectional view taken along the alternate long and short dash line 4A-4B in FIG. In this embodiment, the silicon substrate 111 in the first substrate 110 is formed to have a thickness of 64 μm or more and 370 μm or less. By forming the silicon substrate 111 with such a thickness, the optical fiber 150 can be installed at a desired position, and an electric signal can be transmitted with desired characteristics. Specifically, an optical waveguide 124 and a grating coupler 125 connected to the modulator 113 are formed on the first substrate 110, and a fiber coupler 151 is provided between the optical waveguide 124 and the optical fiber 150. It has been. In the present embodiment, since the optical fiber 150 can be installed on the silicon substrate 111 in the first substrate 110 by a method described later, the optical fiber 150 is installed at a desired position with respect to the optical waveguide 124. Can do. Therefore, the transmission of the optical signal between the optical waveguide 124 and the optical fiber 150 via the fiber coupler 151 can be ensured. A silicon substrate 152 is provided on the optical fiber 150 on the side opposite to the side on which the silicon substrate 111 is provided in order to fix the position of the optical fiber 150. A light emitting element 153 is provided on the silicon substrate 111 of the first substrate 110. The light emitting element 153 has a heat spreader 155 via a TIM (Thermal Interface Material) 154 formed of a metal paste or the like. It is connected. The heat spreader 155 is provided to release heat generated in the light emitting element 153 because the light emitting element 153 is a diode laser or the like, and is provided on the other surface side of the second substrate 130 via the TIM 154. Installed. In this embodiment, when light having a wavelength of 1.3 to 1.5 μm is used, the light diffracted by the grating coupler 125 is diffracted by the grating coupler 125 because it passes through the silicon substrate 111. It is not necessary to provide an opening through which light passes.

(Silicon substrate in the first substrate)
Next, the thickness of the silicon substrate 111 in the first substrate 110 on which the optical fiber 150 is installed in the present embodiment will be described with reference to FIGS. 6 schematically shows the positional relationship between the silicon substrate 111 and the optical fiber 150. FIG. 6A is a cross-sectional view in the direction along the optical fiber 150, and FIG. ) Is a cross-sectional view taken along the alternate long and short dash line 6A-6B in FIG.

  The diameter D1 of the optical fiber 150 to be used is generally about 80 μm, and a core 150a having a diameter D2 in which light propagates is less than 10 μm is formed in the central portion. A V-groove 158 is formed in the silicon substrate 111 of the first substrate 110 at a portion where the optical fiber 150 is to be installed. Since the V-groove 158 is formed so that the surface 158a of the V-groove 158 becomes the (111) plane, the silicon substrate 111 is a substrate whose surface is (110) or the like. Accordingly, when the optical fiber 150 is installed so that the center of the fiber coupler 151 having a height T of about 10 μm and the center of the core 150a in the optical fiber 150 are substantially coincident with each other, the depth F of the deepest portion of the V groove 158 is obtained. Is about 64 μm. Therefore, the thickness of the silicon substrate in the first substrate 110 is preferably 64 μm or more.

Next, as shown in FIG. 7, the relationship between the thickness h of the silicon substrate 111 and S ₂₁ 3 dB Bandwidth for the silicon substrate 111 a corresponding to the silicon substrate 111 on which the TSV 122 a corresponding to the TSV 122 is formed. The measurement results are shown. The values shown in FIG. 8 are actually measured values. Further, the resistivity of the silicon substrate 111a is 17Ωm, TSV122a is from about 60μm in diameter _{V 1,} is formed of copper (Cu), the thickness _{V 2} around the TSV122a formed by copper A 1 μm silicon oxide layer 122b is formed.

The result is shown in FIG. As shown in FIG. 8, when the thickness h of the silicon substrate 111a is 350 μm, S ₂₁ 3 dB Bandwidth is about 17.5 GHz, and when the thickness h of the silicon substrate 111a is 370 μm, S ₂₁ 3 dB Bandwidth. Was about 2.5 GHz. The value of S ₂₁ 3 dB Bandwidth is preferably 70% or more of the bit rate of the digital binary signal. When a 25 Gb / s signal is handled, it is preferably 17.5 GHz or more corresponding to 70% of 25 GHz. Therefore, the thickness h of the silicon substrate 111a is preferably 370 nm or less, and more preferably 350 nm or less.

(Printed board)
Next, connection between the optical semiconductor device in this embodiment and a printed circuit board on which electronic components and the like are mounted will be described. As shown in FIG. 9, the optical semiconductor device according to the present embodiment in which the light emitting element 153 is mounted and the optical fiber 150 is connected is used by being connected to a printed circuit board 160 or the like, for example. An electronic component (not shown) or the like is mounted on the printed circuit board 160, and the optical semiconductor device and the printed circuit board 160 in this embodiment are connected to each other through a PGA (Pin grid array) socket 161 and an interposer 162. Specifically, the electrode 160a in the printed circuit board 160 is electrically connected to the pin 161a in the PGA socket 161, and the pin 161a is electrically connected to the bump (not shown) of the optical semiconductor device in the present embodiment through the interposer 162. Connected.

  Further, a polymer film optical waveguide 170 capable of forming a sheet-like optical waveguide is provided between the interposer 162, the printed circuit board 160, and the PGA socket 161, and an end portion 170a of the polymer film optical waveguide 170 is provided. Is cut diagonally. Optical elements 171 and 172 are provided in the vicinity of the end 170 a of the polymer film optical waveguide 170. Thereby, an optical signal can be transmitted via the optical elements 171 and 172 between the grating coupler 125 and the end portion 170a of the polymer film optical waveguide 170 in the optical semiconductor device according to the present embodiment.

  In the present embodiment, an IC (Integrated Circuit) 180 for driving the optical semiconductor device in the present embodiment is provided between the interposer 162 and the heat spreader 155. The electrical signal output from the IC 180 can be input to the optical semiconductor device in the present embodiment through the interposer, and the optical semiconductor device in the present embodiment can be controlled. A TIM 181 is provided between the IC 180 and the heat spreader 155, and the heat spreader 155 is connected to the heat pipe 182.

[Second Embodiment]
Next, a second embodiment will be described. The present embodiment is an optical semiconductor device connected to a printed circuit board by a method different from that of the first embodiment. This embodiment will be described with reference to FIG. The optical semiconductor device in the present embodiment is the same as that in the first embodiment, but light emitted through the grating coupler 125a is emitted to the side on which the second substrate 130 is provided. It is a thing of the structure.

  In the optical semiconductor device in this embodiment, an interposer 162 is provided on the other surface of the first substrate 110, and the interposer 162 is connected to the heat spreader 255 via the TIM 254. Further, the interposer 162 is connected to the IC 180, and an electrical signal from the IC 180 is transmitted to the optical semiconductor device in this embodiment through the interposer 162. The IC 180 is connected to the heat spreader 255 via the TIM 181, and the heat spreader 255 is connected to the heat pipe 182.

  The optical semiconductor device in this embodiment is connected to the printed circuit board 160 on the side where the second substrate 130 is provided. Specifically, the optical semiconductor device in the present embodiment is connected to the interposer 162 via the PGA socket 161. A polymer film optical waveguide 170 and a polymer mold 290 are provided between the interposer 162 and the PGA socket 161 and the printed circuit board 160. In the present embodiment, the second substrate 130 is provided with an opening 148 through which light transmitted through the grating coupler 125a passes. The contents other than the above are the same as in the first embodiment.

  Although the embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes can be made within the scope described in the claims.

In addition to the above description, the following additional notes are disclosed.
(Appendix 1)
A first substrate provided on a semiconductor substrate with an optical waveguide and a modulator for modulating light propagating through the optical waveguide;
A second substrate provided with an electronic circuit;
Have
One surface of the first substrate and one surface of the second substrate are electrically connected;
An optical semiconductor device, wherein an optical fiber is installed on the first substrate, and light is transmitted between the optical waveguide and the optical fiber.
(Appendix 2)
2. The optical semiconductor device according to appendix 1, wherein the modulator on the first substrate is driven by the electronic circuit provided on the second substrate.
(Appendix 3)
A V-groove is formed in the first substrate,
The optical semiconductor device according to appendix 1 or 2, wherein the optical fiber is installed in a V-groove.
(Appendix 4)
4. The optical semiconductor device according to any one of appendices 1 to 3, wherein a thickness of the semiconductor substrate in the first substrate is not less than 64 μm and not more than 370 μm.
(Appendix 5)
The one surface of the first substrate and the one surface of the second substrate are formed by bumps provided between the one surface of the first substrate and the one surface of the second substrate. The optical semiconductor device according to any one of appendices 1 to 4, wherein the optical semiconductor device is electrically connected.
(Appendix 6)
6. The optical semiconductor device according to any one of appendices 1 to 5, wherein a through electrode penetrating the semiconductor substrate is provided from one surface to the other surface of the first substrate.
(Appendix 7)
The through electrode is electrically connected to the second substrate through a bump provided between one surface of the first substrate and one surface of the second substrate. The optical semiconductor device according to appendix 6, which is characterized.
(Appendix 8)
8. The optical semiconductor device according to any one of appendices 1 to 7, wherein a light emitting element is provided on the first substrate.
(Appendix 9)
9. The optical semiconductor device according to any one of appendices 1 to 8, wherein the light emitting element is connected to a heat spreader provided on the other surface side of the second substrate.
(Appendix 10)
The first substrate is connected to a printed circuit board via an interposer on the other surface of the first substrate;
10. The optical semiconductor device according to any one of appendices 1 to 9, wherein a sheet-like optical waveguide is provided between the interposer and the printed board.
(Appendix 11)
An interposer is connected to the other surface of the first substrate,
The interposer is connected to a printed circuit board provided on the other surface side of the second substrate,
10. The optical semiconductor device according to any one of appendices 1 to 9, wherein a sheet-like optical waveguide is provided between the printed circuit board and the interposer.
(Appendix 12)
12. The optical semiconductor device according to appendix 10 or 11, wherein the light propagating through the sheet-like optical waveguide is transmitted through a grating coupler connected to the optical waveguide in the first substrate. .
(Appendix 13)
13. The optical semiconductor device according to any one of appendices 1 to 12, wherein the semiconductor substrate is a silicon substrate.
(Appendix 14)
14. The optical semiconductor device according to any one of appendices 1 to 13, wherein the optical waveguide is made of a material containing silicon.
(Appendix 15)
15. The optical semiconductor device according to any one of appendices 1 to 14, wherein the periphery of the optical waveguide is covered with silicon oxide.

110 First substrate 111 Silicon substrate 112 Silicon oxide layer 113 Modulator 114 Metal wiring 115 Electrode 116 Conductive via 117 Silicon oxide layer 118 Electrode 119 TSV
120 electrode 121 electrode 122 TSV
123 Bump 124 Optical waveguide 125 Grating coupler 130 Second substrate 131 Silicon substrate 132 Silicon oxide layer 133 Silicon layer 134 Transistor 135 Transistor 136 Silicon oxide layer 137 Metal wire 138 Metal wire 139 Conductive via 140 Conductive via 141 electrode 142 Conductive via 143 Electrode 144 Conductive via 145 Silicon oxide layer 146 Micro bump 147 Micro bump 150 Optical fiber 150a Core 151 Fiber coupler 152 Silicon substrate 153 Light emitting element 154 TIM
155 heat spreader

Claims (8)

A first substrate provided on a semiconductor substrate with an optical waveguide and a modulator for modulating light propagating through the optical waveguide;
A second substrate provided with an electronic circuit;
Have
One surface of the first substrate and one surface of the second substrate are electrically connected;
An optical semiconductor device, wherein an optical fiber is installed on the first substrate, and light is transmitted between the optical waveguide and the optical fiber.   2. The optical semiconductor device according to claim 1, wherein the modulator in the first substrate is driven by the electronic circuit provided in the second substrate.   3. The optical semiconductor device according to claim 1, wherein a thickness of the semiconductor substrate in the first substrate is not less than 64 μm and not more than 370 μm.   The one surface of the first substrate and the one surface of the second substrate are formed by bumps provided between the one surface of the first substrate and the one surface of the second substrate. The optical semiconductor device according to claim 1, wherein the optical semiconductor device is electrically connected.   5. The optical semiconductor device according to claim 1, wherein a through electrode penetrating the semiconductor substrate is provided from one surface to the other surface of the first substrate. 6.   The through electrode is electrically connected to the second substrate through a bump provided between one surface of the first substrate and one surface of the second substrate. The optical semiconductor device according to claim 5. The first substrate is connected to a printed circuit board via an interposer on the other surface of the first substrate;
The optical semiconductor device according to claim 1, wherein a sheet-like optical waveguide is provided between the interposer and the printed circuit board. An interposer is connected to the other surface of the first substrate,
The interposer is connected to a printed circuit board provided on the other surface side of the second substrate,
The optical semiconductor device according to claim 1, wherein a sheet-like optical waveguide is provided between the printed board and the interposer.

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