Semiconductor device and method of manufacturing the same

A semiconductor device includes a first insulating film, a first optical waveguide and a second optical waveguide. The first insulating film has a first surface and a second surface opposite to the first surface. The first optical waveguide is formed on the first surface of the first insulating film. The second optical waveguide is formed on the second surface of the first insulating film. The second optical waveguide, in plan view, overlaps with an end portion of the first optical waveguide without overlapping with another end portion of the first optical waveguide.

BACKGROUND

The present invention relates to a semiconductor device and method of manufacturing the semiconductor device, for example, the present invention relates to a semiconductor device and method of manufacturing the semiconductor device including a first optical waveguide formed on a first surface of an insulating film and a second optical waveguide formed on a second surface of the insulating film.

There is a disclosed technique listed below.

As an optical communication technique, a silicon photonics technique is known. A semiconductor device employing the silicon photonics technique includes, for example, a first insulating film having a first surface and a second surface, a first optical waveguide formed on the first surface of the first insulating film, a second optical waveguide formed on the first surface of the first insulating film, and a second insulating film formed on the first insulating film such that the second insulating film covers the first optical waveguide and the second optical waveguide (see Patent Document 1, for example). An end portion of the second optical waveguide, in a plan view, covers the end portion of the first optical waveguide. Thus, light propagating in the first optical waveguide can travel to the second optical waveguide.

However, when both the first optical waveguide and the second optical waveguide are formed on the first surface of the first insulating film, the semiconductor device may not be properly manufactured. For example, if a material of the second optical waveguide is a material with large stresses, cracks may be formed in the first optical waveguide covered with the second optical waveguide. When a thickness of the first optical waveguide and a thickness of the second optical waveguide are different from each other, the first optical waveguide and the second optical waveguide may not be formed under the same processing condition. If the first optical waveguide and the second optical waveguide are formed under the same processing condition, desired characteristics may not be obtained. In this way, conventional semiconductor device sometimes has poor characteristics of the semiconductor device.

A problem of the present embodiments is improving of the characteristics of a semiconductor device. Other problems and novel features will become apparent from the description of the specification and drawings.

SUMMARY

A semiconductor device according to the embodiments includes a first insulating film having a first surface and a second surface opposite to the first surface, a first optical waveguide formed on the first surface, and a second optical waveguide formed on a second surface. The second optical waveguide overlaps with an end portion of the first optical waveguide without overlapping with another end portion of the first optical waveguide in plan view.

A method of manufacturing a semiconductor device according to embodiments includes (a) providing a semiconductor wafer including a first semiconductor layer, a first insulating film formed on the first semiconductor layer, and a second semiconductor layer formed on the first insulating film, (b) patterning the first semiconductor layer to form a first optical waveguide, and (c) patterning the second semiconductor layer to form a second optical waveguide. The second optical waveguide overlaps with an end portion of the first optical waveguide without overlapping with another end portion of the first optical waveguide in plan view.

According to embodiments, the characteristics of the semiconductor device can be improved.

DETAILED DESCRIPTION

Hereinafter, a semiconductor device and method of manufacturing the semiconductor device according to embodiments will be described in detail by referring to the drawings. In the specification and the drawings, the same or corresponding elements are denoted by the same reference numerals or the same hatching, and a repetitive description thereof is omitted. In the drawings, for convenience of description, the configuration may be omitted or simplified. A cross-sectional view may also be shown as an end view.

(Circuit Configuration of Optoelectronic Hybrid Device)

FIG. 1is a block diagram showing an exemplary circuit configuration of an optoelectronic hybrid device LE1according to a first embodiment.

As shown inFIG. 1, the optoelectronic hybrid device LE1includes a first electronic circuit, a light source LS, an IC chip CP, and a semiconductor device SD1. The IC chip CP includes a second electronic circuit EC2and a third electronic circuit EC3. The semiconductor device SD1includes an optical waveguide OW, an optical modulator OM, a light output part LO, a light input part LI and an optical receiver OR. The configuration of the semiconductor device SD1will be described in detail later.

The first electronic circuit EC1outputs an electrical signal (control signal) for control the second electronic circuit EC2. The first electronic circuit EC1receives an electrical signal outputted from the third electronic circuit EC3. The first electronic circuit EC1is electrically coupled with the second electronic circuit EC2and the third electronic circuit EC3. The first electronic circuit EC1is formed of, for example, a CPU (Central Processing Unit) or an FPGA (Field-Programmable gate array) including a control circuit and a storage circuit.

The light source LS emits light. An Example of type of light sources LS includes laser diode. A wavelength of the light emitted from the light source LS may be set as appropriate in accordance with a material constituting the optical waveguide OW as long as the emitted light can pass through an inside of the optical waveguide OW. For example, a peak wavelength of the emitted light from the light source LS is 1.0 μm or more and 1.6 μm or less. The light source LS is optically connected with the optical modulator OM through the optical waveguide OW.

The second electronic circuit EC2outputs an electric signal (control signal) for controlling the operation of the optical modulator OM. More specifically, the second electronic circuit EC2controls the optical modulator OM based on the control signal received from the first electronic circuit EC1. The second electronic circuit EC2is electrically coupled with the optical modulator OM. The second electronic circuit EC2is constituted by, for example, a known transceiver IC including a control circuit. The second electronic circuit EC2may be formed in the semiconductor device SD1.

The optical modulator OM modulates the phase of the light emitted from the light source LS based on the electrical signal received from the second electronic circuit EC2. The optical modulator OM generates an optical signal including information included in the electrical signal. A type of the optical modulator OM is a Mach-Zehnder type optical modulator. The optical modulator OM may be an electrically controlled optical modulator, or a combined optical modulator using a combination of electrical control and thermal control. The optical modulator OM is optically connected with the light output part LO through the optical waveguide OW.

The light output part LO outputs the optical signal modulated by the optical modulator OM toward an outside of the semiconductor device SD1. For example, the light output part LO emits an optical signal toward an external optical fiber. An Example of type of the light output part LO include a grating coupler (GC) and a spot size converter (SSC).

The light input part LI inputs external light into the semiconductor device SD1. For example, an optical signal emitted from an external optical fiber is inputted into the semiconductor device SD1. An Example of type of light input part LI include a grating coupler (GC) and a spot size converter (SSC). The light input part LI is optically connected with the optical receiver OR through the optical waveguide OW.

The optical receiver OR generates electron-hole pairs based on the optical signal received from the light input part LI. The optical receiver OR converts an optical signal into an electric signal. The optical receiver OR may have photoelectric conversion characteristics. An Example of a type of the optical receiver OR include an avalanche photodiode type optical receiver. The optical receiver OR is electrically coupled with the third electronic circuit EC3.

The third electronic circuit EC3processes the electrical signal received from the optical receiver OR and outputs the processed electrical signal toward the first electronic circuit EC1. More specifically, the third electronic circuit EC3amplifies the electric signal received from the optical receiver OR and outputs the amplified electrical signal to the first electronic circuit EC1. The third electronic circuit EC3is constituted by, for example, a known receiver IC including an amplifier circuit. The third electronic circuit EC3may be formed in the semiconductor device SD1.

Next, an operation example of the optoelectronic hybrid device LE1according to the present embodiment will be described.

First, a transmission part of the optoelectronic hybrid device LE1will be described. The light emitted from the light source LS reaches the optical modulator OM through the optical waveguide OW. The second electronic circuit EC2outputs an electric signal for controlling the operation of the optical modulator OM to the optical modulator OM based on a control signal received from the first electronic circuit EC1. The optical modulator OM modulates light passing through the optical modulator OM. As a result, an electric signal is converted into an optical signal. The optical signal reaches the light output part LO through the optical waveguide OW, and the optical signal is output to an outside of the semiconductor device SD1in the light output part LO. The optical signal emitted from the semiconductor device SD1is guided toward another optoelectronic hybrid device through an optical fiber or the like.

Next, a receiving part of the optoelectronic hybrid device LE1will be described. An optical signal guided from another optoelectronic hybrid device through an optical fiber or the like reach the light input part LI. The optical signal is guided to an inside of the optical waveguide OW in the light input part LI. The optical signal reaches the optical receiver OR through the optical waveguide OW, and is converted into an electric signal. The electric signal is processed by the third electronic circuit EC3and then transmitted to the first electronic circuit EC1.

FIG. 2is a plan view showing an exemplary configuration of a main portion of the semiconductor device SD1according to the first embodiment.FIG. 3is a cross-sectional view showing an exemplary configuration of the main portion of the semiconductor device SD1according to the first embodiment.FIG. 3is a cross-sectional view taken along a line A-A ofFIG. 2. InFIG. 3, hatching of the first optical waveguide OW1and the second optical waveguide OW2is omitted.

The semiconductor device SD1includes a semiconductor substrate SUB, a first insulating film IF1, a first optical waveguide OW1, a second optical waveguide OW2, a second insulating film IF2, and a multilayer wiring layer MWL. Further, the optical fiber OF is disposed at a position corresponding to the optical input and output portion of the semiconductor device SD1. InFIG. 2, from the viewpoint of legibility, a portion of multilayer wiring layer MWL is omitted.

The semiconductor substrate SUB supports the multilayer wiring layer MWL through the first insulating film IF1. The semiconductor substrate SUB has front and back surfaces that are in front and back relationships with each other. The front face is located on the other side of the back face in the semiconductor substrate SUB. The semiconductor substrate SUB is, for example, a silicone substrate. The silicon substrate is, for example, a single crystal substrate containing impurities such as boron (B) and phosphorus (P), or a polycrystalline substrate. For example, a face orientation of the front surface of the silicon substrate is (100), the resistivity of the silicon substrate is 5 Ω·cm or more and 50 Ω·cm or less.

The semiconductor substrate SUB is formed without overlapping with the first optical waveguide OW1and the second optical waveguide OW2in a plan view. Thus, the light seeping from each of the first optical waveguide OW1and the second optical waveguide OW2can be suppressed from being scattered reaching the semiconductor substrate SUB. As a result, the optical propagation loss in the semiconductor device SD1can be reduced.

A thickness of the semiconductor substrate SUB may be different from or the same as a thickness of the second optical waveguide OW2. The thickness of the semiconductor substrate SUB is, for example, 2 μm or more and 400 μm or less.

The first insulating film IF1supports the first optical waveguide OW1and the second optical waveguide OW2. The first insulating film IF1has a first surface SF1and a second surface SF2. The first insulating film IF1is a cladding layer for substantially confining the light propagating inside the first optical waveguide OW1and the second optical waveguide OW2to the inside of the first optical waveguide OW1and the second optical waveguide OW2, respectively. A material of the first insulating film IF1has a refractive index smaller than a refractive index of a material of the first optical waveguide OW1and the second optical waveguide OW2. The first insulating film IF1is comprised of, for example, silicon oxide (SiO2) or silicon nitride (SiN). When the material of the first insulating layer film IF1is silicon oxide, the refractive index of the material of the first insulating film IF1is, for example, 1.46. In the specification, the refractive index is a numerical value for light having a wavelength of 1.5 μm.

In the first embodiment, a thickness of the first insulating film IF1is smaller than a seeping distance of the light from the first optical waveguide OW1and the second optical waveguide OW2. Although described in detail later, thereby, the light is possible to transmit between the first optical waveguide OW1and the second optical waveguide OW2through the first insulating film IF1. It is preferable that the thickness of the first insulating film IF1is small from the viewpoint of reducing stresses generated in the semiconductor device SD1and suppressing sticking of a semiconductor wafer by an electrostatic chuck when manufacturing the semiconductor device SD1. For example, the thickness of the first insulating film IF1is the same as or less than the thickness of one or both of the first optical waveguide OW1and the second optical waveguide OW2. In the first embodiment, the thickness of the first insulating film IF1is the same as or less than the thickness of the second optical waveguide OW2. The thickness of the first insulating film IF1is, for example, 100 nm or more and 200 nm or less.

The configuration of the first insulating film IF1is not particularly limited as long as the transmission of light between the first optical waveguide OW1and the second optical waveguide OW2is not hindered. For example, the first insulating film IF1may be a single film or a stacked film. In the first embodiment, the first insulating film IF1is a single film.

The first optical waveguide OW1is formed on the first surface SF1of the first insulating film IF1. The first optical waveguide OW1include a first end portion (one end portion) EP1, a second end portion (another end portion) EP2and a first extending portion ExP1. The first end portion EP1, the second end portion EP2, and the first extending portion ExP1may be formed integrally with each other as a single member, or may be formed separately from each other. In the first embodiment, the first end portion EP1, the second end portion EP2and the first extending portion ExP1are integrally formed with each other as a single member.

A width of the first end portion EP1may be the same as or different from a width of second end portion EP2and a width of the first extending portion ExP1. In the first embodiment, the width of the first end portion EP1is the same as one or both of the width of second end portion EP2and the width of the first extending portion ExP1. A thickness of the first end portion EP1may be the same as or different from one or both of the thickness of second end portion EP2and the thickness of the first extending portion ExP1. In the first embodiment, the thickness of the first end portion EP1is the same as the thickness of second end portion EP2and the thickness of the first extending portion ExP1.

The first extending portion ExP1is formed between the first end portion EP1and the second end portion EP2. A position and a shape of the first extending portion ExP1are not particularly limited. The shape of the first extending portion ExP1may be a linear shape or a curved shape in plan view. The first extending portion ExP1may include a bent portion.

The second end portion EP2is located on an outer edge of the first insulating film IF1. The second end portion EP2faces a light receiving surface of an optical fiber OF. Thus, the second optical waveguide OW2can guide light from the second end portion EP2to the optical fiber OF. Here, the outer edge of the first insulating film IF1, of the first insulating film IF1, in a direction along the first surface SF1of the first insulating film IF1, a position capable of input-output and outputting light between the second optical waveguide OW2and the optical fiber OF.

The first optical waveguide OW1is a path through which light can propagate (travel). The first optical waveguide OW1is configured to allow light transmit between the first optical waveguide OW1and the second optical waveguide OW2. In the first embodiment, the first optical waveguide OW1is configured to allow light propagate from the second optical waveguide OW2. The first optical waveguide OW1, in plan view, overlaps with an end portion (third end portion EP3described later) of the second optical waveguide OW2, and does not overlap with another end portion of the second optical waveguide OW2(not shown). More specifically, the first end portion EP1of the first optical waveguide OW1overlaps the end portion (the third end portion EP3) of the second optical waveguide OW2. The second end portion EP2and the first extending portion ExP1of the first optical waveguide OW1does not overlap the other end portion of the second optical waveguide OW2(not shown). In the first embodiment, the first optical waveguide OW1, in plan view, of the second optical waveguide OW2, does not overlap with a portion other than the end portion (the third end EP3).

The first end portion EP1of the first optical waveguide OW1, in plan view, may overlap with an entire of the end portion of the second optical waveguide OW2(the third end portion EP3), or may overlap with a portion of the end portion (the third end portion EP3) of the second optical waveguide OW2. From the viewpoint of reducing the propagation loss of light between the first optical waveguide OW1and the second optical waveguide OW2, the first end portion EP1of the first optical waveguide OW1, in plan view, the second optical waveguide OW2it is preferable to overlap with entire of the end portion (the third end portion EP3).

A thickness T1of the first optical waveguide OW1is preferably greater than a thickness T2of the second optical waveguide OW2. The thickness T1of the first optical waveguide OW1is preferably same as a diameter of the optical fiber OF.

Thus, it is possible to reduce the propagation loss of light between the first optical waveguide OW1and the optical fiber OF. The thickness T1of the first optical waveguide OW1, for example, 3 μm or more and 5 μm or less. Here, the thickness T1of the first optical waveguide OW1, in the facing direction of an upper surface and a lower surface of the first optical waveguide OW1, a distance of the upper surface and the lower surface of the first optical waveguide OW1.

A width W1of the first optical waveguide OW1is preferably greater than a width W2of the second optical waveguide OW2. The width W1of the first optical waveguide OW1is preferably a same as the diameter of the optical fiber OF. Thus, it is possible to reduce the propagation loss of light between the first optical waveguide OW1and the optical fiber OF. The first optical waveguide OW1has the width W1of 1 μm or more and 3 μm or less. Here, the width W1of the first optical waveguide OW1is a distance between the first side surface and the second side surface of the first optical waveguide OW1in the facing direction of a first side surface and a second side surface of the first optical waveguide OW1.

A cross-sectional shape of the first optical waveguide OW1is rectangular or trapezoidal. As described above, an example of a material of the first optical waveguide OW1include silicon (Si) and germanium (Ge). An example of crystalline structure of a material of the first optical waveguide OW1include single crystals and polycrystals. From the viewpoint of reducing the propagation loss of light in an optical element, the crystal structure of the material of the first optical waveguide OW1is preferably a single crystal. From the viewpoint of improving the coupling efficiency between the waveguides, the refractive index of the material of the first optical waveguide OW1is preferably smaller than the refractive index of the material of the second optical waveguide OW2. Thus, when a size of the first optical waveguide OW1(thickness and width) is smaller than a size of the second optical waveguide OW2, while maintaining a mode of light, between the first optical waveguide OW1and the second optical waveguide OW2light is easily propagated.

The first edge E1of the first optical waveguide OW1, in plan view, overlaps with the second optical waveguide OW2. The first edge E1of the first optical waveguide OW1is formed along the third edge E3of the second optical waveguide OW2. In the specification, the “edge” of the optical waveguide is a surface (front surface, back surface) or a line (ridge line) intersecting with an optical axis of the light propagating in the optical waveguide, among a plurality of surfaces and lines constituting the optical waveguide.

The second edge E2of the first optical waveguide OW1, in the first optical waveguide OW1, is located on the opposite side of the first edge E1. The second edge E2of the first optical waveguide OW1is an exit surface or the entrance surface of the light. The second edge E2is located on the outer edge of the first insulating film IF1. The second edge E2faces the optical fiber OF.

The second optical waveguide OW2is formed on the second surface SF2of the first insulating film IF1. The second optical waveguide OW2includes a third end portion EP3, a fourth end portion (not shown) and a second extending portion ExP2. The third end portion EP3, the fourth end portion (not shown) and the second extending portion ExP2may be formed integrally with each other as a single member, or separately from each other. In the first embodiment, the third end portion EP3, the fourth end portion (not shown), and second extension portion ExP2are integrally formed with each other as a single member.

The width of third end portion EP3may be the same as or different from the width of the second extending portion ExP2. The width of the third end portion EP3may vary toward the end portion of the second optical waveguide OW2or may be constant. A planar shape of an upper surface of the third end portion EP3may be triangular or trapezoidal. From the viewpoint of efficiently transmitting from the second optical waveguide OW2to the first optical waveguide OW1, the width of the third end portion EP3is preferably reduced toward the end of the second optical waveguide OW2. That is, it is preferable that the upper surface of the third end portion EP3has a triangular shape in plan view. The thickness of the third end portion EP3may be the same as or different from the thickness of the second extending portion ExP2. In the first embodiment, the thickness of the third end portion EP3is the same as the thickness of the second extending portion ExP2.

The second extending portion ExP2is formed between the third end portion EP3and the fourth end portion (not shown). A position and a shape of the second extending portion ExP2are not particularly limited. The shape of the second extending portion ExP2may be a straight shape or a curved shape in plan view. The first extending portion ExP1may include a bent portion.

The second optical waveguide OW2is a path through which light can propagate (travel). The second optical waveguide OW2is configured to allow light to travel between the first optical waveguide OW1and the second optical waveguide OW2. The second optical waveguide OW2, in plan view, overlaps with the first end portion EP1of the first optical waveguide OW1, and does not overlap with the second end portion EP2of the first optical waveguide OW1. Thus, the light propagating in the second optical waveguide OW2can propagate to the first end portion EP1of the first optical waveguide OW1at third end portion EP3.

The thickness T2of the second optical waveguide OW2is not particularly limited as long as the above-mentioned function can be realized. The thickness T2of the second optical waveguide OW2, for example, is 200 nm or more and 400 nm or less. Here, the thickness T2of the second optical waveguide OW2, in the facing direction of an upper surface and a lower surface of the second optical waveguide OW2, is a distance between the upper surface and the lower surface of the second optical waveguide OW2.

The width W2of the second optical waveguide OW2is greater than or equal to 300 nm and less than or equal to 500 nm. The width W2of the second optical waveguides OW2is distance between a first side surfaces SS1and a second side surface SS2of the second optical waveguides OW2in a facing direction of the first side surfaces SS1and the second side surface SS2of the second optical waveguide OW2.

The cross-sectional shape of the second optical waveguide OW2is rectangular or trapezoidal. An Example of a material of the second optical waveguide OW2include silicon (Si) and germanium (Ge). An Example of crystalline structure of the material of the second optical waveguide OW2include single crystals and polycrystals. From the viewpoint of reducing the propagation loss of light in the optical element, the crystal structure of the material of the second optical waveguide OW2is preferably a single crystal. The material of the second optical waveguide OW2may be the same as or different from the material of the first optical waveguide OW1.

In the first embodiment, a first angle θ1formed by the third edge E3of the third end portion EP3in the second optical waveguide OW2, and the second surface SF2of the first insulating film IF1is about the same as a second angle θ2formed by the first side surface SS1or the second side surface SS2of the second optical waveguide OW2, and the second surface SF2of the first insulating film IF1. In the first embodiment, the first angle θ1and the second angle θ2are approximately 90°.

The second insulating film IF2is formed on the first surface SF1of the first insulating film IF1such that the second insulating film IF2covers the first optical waveguide OW1, The second insulating film IF2may or may not cover the semiconductor substrate SUB. In the first embodiment, the second insulating film IF2is formed such that the semiconductor substrate SUB is exposed from the second insulating film IF2.

The thickness of the second insulating film IF2, from the viewpoint of reducing the propagation loss of light, it is preferable to be greater than a seeping distance of the light from the first optical waveguide OW1. Of the second insulating film IF2, the thickness of a portion located on the first optical waveguide OW1, for example, is 2 μm or more and 5 μm or less.

The material of the second insulating film IF2has a refractive index smaller than a refractive index of the material of the first optical waveguide OW1. The material of the second insulating film IF2is, for example, resins, silicon oxides, or silicon nitrides. The refractive index of the second insulating film IF2is, for example, about 1.5. The second insulating film IF2may be a single film or a stacked film.

The multilayer wiring layer MWL is formed on the first insulating film IF1such that the multilayer wiring layer MWL covers the second optical waveguide OW2. The multilayer wiring layer MWL is formed of two or more wiring layers. The wiring layer is a layer including an interlayer insulating layer and one or both of a wiring and a via that are formed in the interlayer insulating layer. The via is a conductive member electrically connecting two wirings formed in layers that differ from each other.

The multilayer wiring layer MWL includes a first interlayer insulating layer IIL1, a second interlayer insulating layer IIL2, a third interlayer insulating layer IIL3, a fourth interlayer insulating layer IIL4, a wiring WR, a via V, an electrode pad PD, and a protective film PF.

The first interlayer insulating layer IIL1is formed on the first insulating film IF1such that the first interlayer insulating layer IIL1covers the second optical waveguide OW2. The first interlayer insulating layer IIL1is a cladding layer for substantially confining the light propagating an inside of the second optical waveguide OW2to the inside of the second optical waveguide OW2. Light in the second extending portion ExP2of the second optical waveguide OW2travels in a state of being seeped by about one-fifth of the wavelength of the light from the second optical waveguide OW2. The light in the third end portion EP3of the second optical waveguide OW2travels through about twice the wavelength thereof. A thickness of the first interlayer insulating layer IIL1is preferably 1 μm or more and 5 μm or less, and more preferably 2 μm or more and not 3 μm or less, from the viewpoint of suppressing scattering of light seeped from the second optical waveguide OW2by a wiring (not shown) formed on the first interlayer insulating layer IIL1. A material of the first interlayer insulating layer IIL1are the same as the material of the first insulating film IF1.

The second interlayer insulating layer IIL2is formed on the first interlayer insulating layer IIL1. The third interlayer insulating layer IIL3is formed on the second interlayer insulating layer IIL2. The fourth interlayer insulating layer IIL4is formed on the third interlayer insulating layer IIL3. Features such as a thickness and a material of the second interlayer insulating layer IIL2, the third interlayer insulating layer IIL3, and the fourth interlayer insulating layer IIL4may be the same or different from each other.

The wiring WR is formed on the third interlayer insulating layer IIL3. For the wiring WR, known configurations employed as wiring in the semiconductor art may be employed. The wiring WR is, for example, a stacked film in which a barrier metal, a conductive film and a barrier metal are stacked in this order. An example of a material constituting the barrier metal include titanium (Ti), titanium nitride (TiN), tantalum (Ta) and tantalum nitride (TaN). An example of a material of the conductive film include aluminum and copper. Incidentally, the wiring WR may be formed on the other interlayer insulating layer.

The via V is formed in the fourth interlayer insulating layer IIL4such that the via V reaches the wiring WR. The first via V includes, for example, a barrier film and a conductive film formed on the barrier film. An example of a material of the barrier film include titanium (Ti), titanium nitride (TiN), tantalum (Ta), and tantalum nitride (TaN). An example of a material of the conductive film include tungsten (W) and aluminum (Al). The barrier film is not an essential element. The via V may be formed on another interlayer insulating layer.

For the electrode pad PD formed on the fourth interlayer insulating layer IIL4, a known structure employed as an electrode pad in the semiconductor technology can be employed as the electrode pad PD. The electrode pad PD is, for example, a stacked film in which a barrier metal, a conductive film and a barrier metal are stacked in this order. An example of a material of the barrier metal include titanium (Ti), titanium nitride (TiN), tantalum (Ta) and tantalum nitride (TaN). An example of a material of the conductive film include aluminum and copper.

The protective film PF is a film for protecting the semiconductor device SD1from water and the like. The protective film PF is formed on the fourth interlayer insulating layer IIL4. In the protective film PF, a pad opening POP exposing a portion of an upper surface of the electrode pad PD is formed. The portion of the electrode pad PD exposed from the pad opening POP is connected with an external wiring such as a bonding wire. From the viewpoint of suppressing damage is applied to the first optical waveguide OW1and the second optical waveguide OW2due to the impact when the external wiring is connected to the electrode pad PD, it is preferable that the pad opening POP is formed in the protective film PF such that the pad opening POP, in plan view, overlaps with the first optical waveguide OW1and the second optical waveguide OW2.

An example of a material of the protective film PF includes silicon oxide, silicon oxynitride, silicon nitride, and PSG (Phospho Silicate Glass). A thickness of the protective film PF is, for example, 0.3 μm or more and 0.7 μm or less. The protective film PF may be a single film or a stacked film of a film comprised of the above materials.

The optical fiber OF is a light guide member that guides light from an external device into the semiconductor device SD1, and guides light from the semiconductor device SD1toward the external device. The optical fiber OF is disposed such that the optical fiber OF faces a portion that functions as the light exiting surface or the light receiving surface of the first optical waveguide OW1. In the first embodiment, the optical fiber OF, in a direction along the first surface SF1of the first insulating film IF1, and faces the second edge E2of the first optical waveguide OW1.

(Optical Path in Semiconductor Device)

Here, an optical path in the semiconductor device SD1according to the first embodiment will be described. For example, in the semiconductor device SD1, the optical path until the light emitted from the light source LS reaches the optical fiber OF through the second optical waveguide OW2and the first optical waveguide OW1will be described.

FIG. 4is a cross-sectional view showing a main portion of an optical path in the semiconductor device SD1according to the first embodiment. InFIG. 4, an arrow indicates a traveling direction of the light, a thickness of the arrow indicates the amount of light. In the first embodiment, the first optical waveguide OW1has a function as a spot-size converter. InFIG. 4, from the viewpoint of viewability of the optical path, hatching of the first optical waveguide OW1and the second optical waveguide OW2is omitted.

As shown inFIG. 4, in the semiconductor device SD1according to the first embodiment, the light traveling in the second extending portion ExP2of the second optical waveguide OW2reaches the third end portion EP3of the second optical waveguide OW2. Light traveling in the third end portion EP3is transmitted to the first optical waveguide OW1as the light approaches the third edge E3. This is because, while seeping out of the second optical waveguide OW2, the light traveling through the second optical waveguide OW2is transferred to the first optical waveguide OW1by evanescent coupling. The width of the third end portion EP3decrease as it approaches the third edge E3. As the width of the third end portion EP3decreases, the amount of light present in the second optical waveguide OW2also decreases. Light moved from the second optical waveguide OW2to the first optical waveguide OW1is emitted at the second end portion EP2(the second edge E2) of the first optical waveguide OW1, and reaches the optical fiber OF.

(Method of Manufacturing Semiconductor Device)

Next, an exemplary method of manufacturing the semiconductor device SD1according to the first embodiment will be described.FIGS. 5 to 10are cross-sectional views showing exemplary steps included in the method of manufacturing the semiconductor device SD1.

The method of manufacturing the semiconductor device SD1includes (1) providing a semiconductor wafer SW (seeFIG. 5), (2) forming the second optical waveguide OW2(seeFIG. 6), (3) forming the multilayer wiring layer MWL (seeFIG. 7), (4) disposing a support member SM (seeFIG. 8), (5) forming the first optical waveguide OW1(seeFIG. 9), and (6) forming the second insulating film IF2(seeFIG. 10).

(1) Providing of a semiconductor wafer SW

As shown inFIG. 5, a semiconductor wafer SW is provided. The semiconductor wafer SW may be formed or purchased as a commercial product. The semiconductor wafer SW is, for example, an SOI (Silicon On Insulator) substrate. A method of forming the SOI substrate can be appropriately selected from a known method. An example of forming the SOI substrate includes SIMOX (Separation by Implantation of Oxygen) method and smart-cut method.

The semiconductor wafer SW includes a first semiconductor layer SL1, a first insulating film IF1formed on the first semiconductor layer SL1, and a second semiconductor layer SL2formed on the first insulating film IF1.

The first semiconductor layer SL1is comprised of, for example, silicon or germanium. A thickness of the first semiconductor layer SL1is 2 μm or more and 900 μm or less. A material of the second semiconductor layer SL2is, for example, silicone or germanium. The thickness of the second semiconductor layer SL2is 200 nm or more and 400 nm or less. The first semiconductor layer SL1may be polished to a desired thickness.

(2) Forming the second optical waveguide OW2

As shown inFIG. 6, the second semiconductor layer SL2is patterned to form the second optical waveguide OW2on the insulating layer IL. A method of patterning the second semiconducting layer SL2is performed by photolithographic and etching techniques.

(3) Forming the multilayer wiring layer MWL

As shown inFIG. 7, the multilayer wiring layer MWL is formed on the first insulating film IF1so as to cover the second optical waveguide OW2. The forming the multilayer wiring layer MWL includes forming the first interlayer insulating layer IIL1, forming the second interlayer insulating layer IIL2, forming the third interlayer insulating layer IIL3, forming the fourth interlayer insulating layer IIL4, forming the wiring WR, forming the via V, forming the electrode pad PD, and forming the protective film PF.

The first interlayer insulating layer IIL1, the second interlayer insulating layer IIL2, the third interlayer insulating layer IIL3, the fourth interlayer insulating layer IIL4, and the protective film PF are formed by, for example, CVD method. The via V is formed by forming a through hole in the fourth interlayer insulating layer IIL4and then embedding the through hole with a conductive material. The wiring WR is formed by forming a conductive layer on the third interlayer insulating layer IIL3by sputtering method and then patterning the conductive layer into a desired shape. The electrode pad PD is formed by forming a conductive layer on the fourth interlayer insulating layer IIL4by sputtering method, and then patterning the conductive layer into a desired shape.

(4) Disposing a support member SM

As shown inFIG. 8, a support member SM is disposed on the multilayer wiring layer MWL. The support member SM may support a structure obtained in the above steps. For example, the support member SM is a stacked structure of an adhesive layer and a glass substrate. The support member SM may be a semiconductor chip CP having the second electronic circuit EC2and the third electronic circuit EC3(seeFIG. 1).

(5) Forming the first optical waveguide OW1

As shown inFIG. 9, the first semiconductor layer SL1is patterned to form the first optical waveguide OW1on the first surface SF1of the first insulating film IF1. In this step, the support member SM is used as a base. Patterning of the first semiconductor layer SL1is performed by photolithography and etching techniques.

(6) Forming the second insulating film IF2

As shown inFIG. 10, the second insulating film IF2is formed on the first surface SF1of the first insulating film IF1so as to cover the first optical waveguide OW1. A material of the second insulating film IF2is resin, silicon oxide, or silicon nitride. An example of a method of forming the second insulating film IF2include lithography, mosquito, and nanoimprinting when the material of the second insulating film IF2is resin. For example, after a curable resin composition is provided on the first surface SF1of the first insulating film IF1, the second insulating film IF2may be formed by curing the curable resin composition. The curable resin composition may be a thermosetting resin composition or a photocurable resin composition. If the material of the second insulating film IF2is silicon oxide or silicon nitride, a method of forming the second insulating film IF2is, for example, CVD method.

Finally, by dicing the structure obtained by the above steps, a plurality of semiconductor device SD1singulated are obtained. The optical fiber OF is disposed such that the optical fiber OF faces the second end portion EP2of the first optical waveguide OW1of the semiconductor device SD1. The support member SM may or may not be removed.

The semiconductor device SD1according to the first embodiment includes the first optical waveguide OW1formed on the first surface SF1of the first insulating film IF1, and the second optical waveguide OW2formed on the second surface SF2of the first insulating film IF1. The second optical waveguide OW2, in plan view, overlaps with one end portion (the first end portion EP1) of the first optical waveguide OW1. Thus, between the second optical waveguide OW2and the first optical waveguide OW1, the light can travel through the first insulating film IF1. Further, the second optical waveguide OW2, in plan view, does not overlap with the other end (the second end portion EP2) of the first optical waveguide OW1. Thus, the light transmitted from the second optical waveguide OW2to the first optical waveguide OW1is guided by the first optical waveguide OW1without returning to the second optical waveguide OW2.

In the first embodiment, the thickness T1of the first optical waveguide OW1is greater than the thickness T2of the second optical waveguide OW2, and the width W1of the first optical waveguide OW1is greater than the width W2of the second optical waveguide OW2. If the first optical waveguide OW1and the second optical waveguide OW2are formed on one surface of the first insulating film IF1, the first optical waveguide OW1and the second optical waveguide OW2that are different in size from each other need to be formed on the one surface of the first insulating film IF1. If the sizes of the first optical waveguide OW1and the second optical waveguide OW2are significantly different, it is difficult to manufacture the semiconductor device. In contrast, in the first embodiment, the first optical waveguide OW1and the second optical waveguide OW2are respectively formed on the first surface SF1and the second surface SF2of the first insulating film IF1. As a consequence, the semiconductor device SD1according to the first embodiment can be easily manufactured even if the size of the first optical waveguide OW1and the size of the second optical waveguide OW2are different from each other.

Further, consider a case where the material of second optical waveguide OW2is a stress film for example, silicon nitride), and the material of the first optical waveguide OW1is a semiconductor layer (for example, silicon). If the first optical waveguide OW1and the second optical waveguide OW2are formed on the one surface of the first insulating film IF1, from the viewpoint of configuring to be able to transmit light between the first optical waveguide OW1and the second optical waveguide OW2, the first optical waveguide OW1and the second optical waveguide OW2are preferable formed to be in contact with each other. However, in this case, due to the second optical waveguide OW2formed of the stress film, there is a possibility that cracks occur in the first optical waveguide OW1. On the other hand, in the semiconductor device SD1according to the first embodiment, since the first optical waveguide OW1and the second optical waveguide OW2are separated from each other, there is no possibility that cracks occur due to the difference in materials, as described above. Consequently, in the first embodiment, the characteristics of semiconductor device SD1can be improved.

FIG. 11is a plan view showing an exemplary configuration of a main portion of a semiconductor device mSD11according to a first modification of the first embodiment.FIG. 12is a cross-sectional view showing an exemplary configuration of a main portion of the semiconductor device mSD11according to the first modification of the first embodiment. InFIG. 12, an arrow indicates a traveling direction of the light, a thickness of the arrow indicates the amount of light.

The semiconductor device mSD11includes a first optical waveguide mOW11and a second optical waveguide mOW21. In the first modification, a first angle θ1formed by the third end portion (end surface) mE3of the second optical waveguide mOW21and the second surface SF2of the first insulating film IF1is smaller than a second angle θ2formed by the first side surface SS1or the second side surface SS2of the second optical waveguide mOW21and the second surface SF2of the first insulating film IF1. Further, the first edge mE1of the first optical waveguide mOW11is inclined along the third edge mE3of the second optical waveguide mOW21. That is, the third angle θ3formed by the first edge (end face) mE1of the first optical waveguide mOW11, the first surface SF1of the first insulating film IF1is about the same as the first angle θ1.

The first angle θ1and the third angle θ3are preferably, for example, 35° or more and 55° or less. At this instance, the first edge mE1of the first optical waveguide mOW11and the third edge mE3of the second optical waveguide mOW21can be easily formed by a wet etching method. A first edge mEP1of the first optical waveguide mOW11, when processed by a wet etching method and the third edge mEP3of the second optical waveguide mOW21, since the etching rate is different by the crystal orientation, the first angle θ1and third angle θ3, tends to be 35° or more and 55° or less. Thus, it is possible to easily realize a desired inclination angle. At this instance, after processing, a crystal plane of the first edge mE1and a crystal plane of the third edge mE3tend to be the (111) plane.

The second angle θ2is not particularly limited. The second angle θ2is, for example, more than 55°, and 90° or less.

A method of manufacturing the semiconductor device SD1according to first modification further includes processing the first end portion mEP1of the first optical waveguide mOW11, and processing the third end portion mEP3of the second optical waveguide mOW21. A method of processing the first end portion mEP1and a method of processing the third end portion mEP3, for example, are a wet etching method or a dry etching method. As described above, the method of processing the first end portion mEP1and the method of processing the third end portion mEP3are preferable wet etching method.

The first end portion mEP1of the first optical waveguide mOW11may be masked to cover portions other than the first end portion mEP1, and the first end portion mEP1may be treated with an etchant. The material of the mask is, for example, silicone dioxide (SiO2). An example of the etching solution includes potassium hydroxide (KOH) aqueous solution, tetramethylammonium hydroxide (TMAH) aqueous solution, ethylenediamine-pyrocatechol (EDP) aqueous solution, hydrazine (N2H) aqueous solution, sodium hydroxide aqueous solution and cesium hydroxide (CsOH) aqueous solution. Incidentally, the method of processing the third end portion mEP3of the second optical waveguide mOW21is the same.

In the first modification, as indicated by an arrow inFIG. 12, light propagating in the second optical waveguide mOW21is reflected at the third end mE3and is reflected at the first edge mE1, thereby transmitting light between second optical waveguide mOW21and the first optical waveguide mOW11. Compared with the transmission of light by evanescent coupling, the propagation loss of light can be further reduced. As a result, the characteristics of the semiconductor device mSD11can be further enhanced.

Further, in the semiconductor device mSD11according to first modification, the transmission of light between the first optical waveguide mOW11and the second optical waveguide mOW21is performed by reflecting light as described above. Therefore, the thickness of the first insulating film IF1is not particularly limited. For example, the thickness of the first insulating film IF1is, for example, 100 nm or more and 3 μm or less.

FIG. 13is a plan view showing an exemplary configuration of a main portion of a semiconductor device mSD12according to a second modification of the first embodiment.FIG. 14is a cross-sectional view showing an exemplary configuration of a main portion of the semiconductor device mSD12according to the second modification of the first embodiment.

The semiconductor device mSDs12includes a first optical waveguide mOW12and a second optical waveguide mOW21. The semiconductor device mSD12according to the second modification differs from the semiconductor device mSD11according to the first modification in the configuration of the first optical waveguide mOW12. The first optical waveguide mOW12includes a first end portion mEP1, a first extending portion mExP1, and a second end portion mEP2.

The first end portion mEP1has a first width W1and a first thickness T1. On the other hand, the second end portion mEP2has a third width W3and a third thickness T3. A portion, of the first extending portion mExP1, adjoining the first end portion mEP1has a first width W1and a first thickness T1. The remainder of the first extension mExP1has a third width W3and a third thickness T3. The third width W3is greater than the first width W1and the third thickness T3is greater than the first thickness T1. The third width W3and the third thicknesses T3are appropriately adjusted in accordance with the size of the optical fiber OF.

In the second modification, the size of the second end portion mEP2is the input and output portion of the light in the first optical waveguide mOW12, can be appropriately adjusted in accordance with the size of the optical fiber OF. Thus, it is possible to increase the coupling efficiency between the first optical waveguide mOW12and the optical fiber OF. Consequently, the characteristics of the semiconductor device mSD12can be further enhanced.

An optoelectronic hybrid device LE2and a semiconductor device SD2according to a second embodiment differ from the optoelectronic hybrid device LE1and the semiconductor device SD1according to the first embodiment mainly in that the semiconductor device SD2includes a third optical waveguide OW3. Therefore, the same constituent elements as those of the semiconductor device SD1according to the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

(Circuit Configuration of Optoelectronic Hybrid Device)

The optoelectronic hybrid device LE2according to the second embodiment includes a first electronic circuit EC1, a light source LS, an IC chip CP, and a semiconductor device SD2(seeFIG. 1).

FIG. 15is a plan view showing an exemplary configuration of a main portion in the semiconductor device SD2according to the second embodiment.FIG. 16is a cross-sectional view showing an exemplary configuration of the main portion in the semiconductor device SD2according to the second embodiment.FIG. 16is a cross-sectional view taken along line A-A ofFIG. 15. InFIG. 16, an arrow indicates a traveling direction of the light, a thickness of the arrow indicates the amount of light.

The semiconductor device SD2includes a semiconductor substrate SUB, a first insulating film IF1, a first optical waveguide OW1, a second optical waveguide OW2, a third optical waveguide OW3, a second insulating film IF2, and a multilayer wiring layer MWL. InFIG. 15, from the viewpoint of legibility, a portion of multilayer wiring layer MWL is omitted.

The first insulating film IF1supports the first optical waveguide OW1, the second optical waveguide OW2and the third optical waveguide OW3. The first insulating film IF1is a cladding layer for substantially confining the light propagating inside the first optical waveguide OW1, the second optical waveguide OW2and the third optical waveguide OW3to the inside of the first optical waveguide OW1, the second optical waveguide OW2and the third optical waveguide OOG, respectively.

The first optical waveguide OW1, at the first end portion EP1, is configured to allow light to travel between the first optical waveguide OW1and the second optical waveguide OW2. The first optical waveguide OW1is configured to allow light to travel between the first optical waveguide OW1and the third optical waveguide OW3at the second end portion EP2. In the second embodiment, through the first optical waveguide OW1, the light from the second optical waveguide OW2may transmit to the third optical waveguide OW3. The first optical waveguide OW1, in plan view, the first end portion EP1overlaps with an end portion (third end portion EP3) of the second optical waveguide OW2, and the second end EP2overlaps with an end portion (described later fourth end portion EP4) of the third optical waveguide OW3. Therefore, in the second embodiment, the positions of the first end portion EP1and the second end portion EP2of the first optical waveguide OW1in the semiconductor device SD2are not particularly limited.

The second end portion EP2of the first optical waveguide OW1, in plan view, may overlap with an entire of the end portion (fourth end portion EP4) of the third optical waveguide OW3, or the end portion (fourth end EP4) of the third optical waveguide OW3. From the viewpoint of reducing the propagation loss of light during the first optical waveguide OW1and the third optical waveguide OW3, the first end portion EP1of the first optical waveguide OW1, in plan view, preferably overlaps the entire of the end portion (fourth end portion EP4) of the third optical waveguide OW3.

The third optical waveguide OW3is formed on the second surface SF2of the first insulating film IF1. The third optical waveguide OW3includes a fifth end portion EP5, a sixth end portion (not shown) and a third extending portion ExP3. The fifth end portion EP5, the sixth end portion (not shown) and the third extending portion ExP3may be formed integrally with each other as a single member, or separately from each other. In the second embodiment, the fifth end portion EP5, the sixth end portion (not shown), and the third extending portion ExP3are integrally formed with each other as a single member.

A width of the fifth end portion EP5may be the same as or different from a width of third extending portion ExP3. The width of the fifth end portion EP5may vary toward an end of the fifth end portion EP5or may be constant. A planar shape of an upper surface of the fifth end portion EP5may be triangular, it may be trapezoidal. A thickness of the fifth end portion EP5may be the same as or different from a thickness of the third extending portion ExP3. In the second embodiment, a thickness of the fifth end portion EP5is the same as the thickness of the third extending portion ExP3.

The third extending portion ExP3is formed between the fifth end portion EP5and the sixth end portion (not shown). A position and a shape of the third extending portion ExP3are not particularly limited. The shape of the third extending portion ExP3may be a straight shape or a curved shape in plan view. The third extending portion ExP3may include a bent portion.

The third optical waveguide OW3is a path through which light can propagate (travel). The third optical waveguide OW3is configured to allow light to travel between the first optical waveguide OW1and the third optical waveguide OW3. In the second embodiment, examples such as a thickness, a material and a shape of the third optical waveguide OW3are similar to the second optical waveguide OW2, except at a position.

The third optical waveguide OW3, in plan view, overlaps with an end portion of the first optical waveguide OW1, and does not overlap another end portion of the first optical waveguide OW1. The fifth end portion EP5of the third optical waveguide OW3, in plan view, overlaps with the second end portion EP2of the first optical waveguide OW1. Thus, the light in the first optical waveguide OW1, at the fifth end portion EP5, is transmitted to the third optical waveguide OW3.

The multilayer wiring layer MWL is formed on the first insulating film IF1such that the multilayer wiring layer MWL covers the second optical waveguide OW2and the third optical waveguide OW3.

(Optical Path in Semiconductor Device)

Here, the optical path in the semiconductor device SD2according to the second embodiment will be described. For example, in the semiconductor device SD2, the optical path when the light emitted from the light source propagates through the second optical waveguide OW2, the first optical waveguide OW1, and the third optical waveguide OW3will be described. In the second embodiment, as indicated by an arrow inFIG. 16, the evanescent coupling causes the light emitted from the light source to move from the second optical waveguide OW2to the first optical waveguide OW1(seeFIG. 4) and then to move from the first optical waveguide OW1to the third optical waveguide OW3by the evanescent coupling as well.

(Method of Manufacturing Semiconductor Device)

Next, an exemplary method of manufacturing the semiconductor device SD2according to the second embodiment will be described.FIGS. 17 to 21are cross-sectional views showing exemplary steps included in the method of manufacturing the semiconductor device SD2.

The method of manufacturing the semiconductor device SD2includes (1) providing a semiconductor wafer SW (seeFIG. 17), (2) forming the second optical waveguide OW2and the third optical waveguide OW3(seeFIG. 18), (3) forming the multilayer wiring layer MWL (seeFIG. 19), (4) disposing the support member SM (seeFIG. 20), and (5) forming the first optical waveguide OW1(seeFIG. 21).

(1) Providing of a semiconductor wafer SW

As shown inFIG. 17, a semiconductor wafer SW is provided.

(2) Forming the second optical waveguide OW2and the third optical waveguide OW3

As shown inFIG. 18, the second semiconductor layer SL2is patterned to form the second optical waveguide OW2and the third optical waveguide OW3on the second surface SF2of the first insulating film IF1.

(3) Forming the multilayer wiring layer MWL

As shown inFIG. 19, the multilayer wiring layer MWL is formed on the first insulating film IF1so as to cover the second optical waveguide OW2and the third optical waveguide OW3.

(4) Disposing the support member SM

As shown inFIG. 20, the support member SM is disposed on the multilayer wiring layer MWL.

(5) Forming the first optical waveguide OW1

Then, as shown inFIG. 21, the first semiconductor layer SL1is patterned to form the first optical waveguide OW1on the first surface SF1of the first insulating film IF1.

Finally, by dicing the structures obtained by the above steps, a plurality of semiconductor device SD2singulated are obtained. The support member SM may or may not be removed.

The second embodiment has the same effects as the first embodiment. In the second embodiment, the semiconductor device SD2includes the first optical waveguide OW1formed on the first surface SF1of the first insulating film IF1, and the second optical waveguide OW2and the third optical waveguide OW3formed on the second surface SF2of the first insulating film IF1. Thus, even when the forming step of the first optical waveguide OW1and the forming step of the second optical waveguide OW2and the third optical waveguide OW3differ from each other, each of the first optical waveguide OW1, the second optical waveguide OW2, and the third optical waveguide OW3can be formed in the desired forming condition. For example, only the optical waveguide for optical transmission may be formed on the second surface SF2of the first insulating film IF1, and an optical element such as a optical modulator and an optical amplifier may be formed on the first surface SF1of the first insulating film IF1. As a result, the semiconductor device SD2can be manufactured by desired condition for each of the constituent elements of the semiconductor device SD2. Further, by forming the optical element in the vicinity of the large first optical waveguide OW1, it is possible to reduce the effect of positional deviation between the optical element and the first optical waveguide OW1. As a result, the characteristics of the semiconductor device SD2can be enhanced.

An optoelectronic hybrid device LE3and a semiconductor device SD3according to a third embodiment differ from the optoelectronic hybrid device LE1and the semiconductor device SD1according to the first embodiment mainly in that the semiconductor device SD2includes a reflective member RM and a fourth optical waveguide OW4. Therefore, the same constituent elements as those of the semiconductor device SD1according to the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

(Circuit Configuration of Optoelectronic Hybrid Device)

The optoelectronic hybrid device LE3according to the third embodiment includes a first electronic circuit, a light source LS, an IC chip CP, and a semiconductor device SD3(seeFIG. 1).

FIG. 22is a plan view showing an exemplary configuration of a main portion of a semiconductor device SD3according to the third embodiment.FIG. 23is a cross-sectional view showing an exemplary configuration of the main portion of the semiconductor device SD3according to the third embodiment.FIG. 23is a cross-sectional view taken along line A-A ofFIG. 22.

The semiconductor device SD3includes a semiconductor substrate SUB, a first insulating film IF1, a first optical waveguide OW13, a reflective member RM, a fourth optical waveguide OW4, a second optical waveguide OW2, a second insulating layer IL2, and a multilayer wiring layer MWL. InFIG. 22, from the viewpoint of legibility, the multilayer wiring layer MWL is omitted.

The first optical waveguide OW13is formed on the first surface SF1of the first insulating film IF1. The first optical waveguide OW13includes a first end portion (one end portion) EP1, a second end portion (another end portion) EP23and the first extending portion ExP1.

The second edge E23of the second end portion EP23is inclined with respect to a normal line of the first surface SF1of the first insulating film IF1. The fourth angle θ4formed by the second edge E23of the second end portion EP23and the first surface SF1is greater than the third angle θ3formed by the first edge E1of the second end portion EP23and the first surface SF1. Thus, the second edge E23of the second end portion EP23can reflect the light propagating in the first optical waveguide OW1away from the first surface SF1of the first insulating film IF1. The fourth angle θ4is preferably, for example, 125° or more and 145° or less. At this instance, the second edge E23of the first optical waveguide OW13, by a wet etching method, can be easily formed.

The reflective member RM is formed on the second edge E23of the first optical waveguide OW13. The material and thickness of the reflective member RM is not particularly limited as long as it can reflect light propagating in the first optical waveguide OW13. The reflective member RM is, for example, a single film comprised of metal. An example of the metal includes Al, Ag, Au, Cr and SiCr. From the viewpoint of preventing deterioration, the reflective member RM may be coated with a protective film comprised of SiO2 or SiN. A thickness of the reflective member RM is, for example, 5 nm or more and 20 nm or less.

The fourth optical waveguide OW4is formed in the second insulating film IF2. The fourth optical waveguide OW4guides the reflected light from the reflective member RM, away from the first surface SF1of the first insulating film IF1. The configuration of the fourth optical waveguide OW4is not particularly limited as long as the above-mentioned function can be obtained. The fourth optical waveguide OW4is formed in a trench formed in the second insulating film IF2. The material of the fourth optical waveguide OW4has a refractive index greater than a refractive index of the material of the second insulating film IF2. The material of the fourth optical waveguide OW4is, for example, silicon nitride. In the third embodiment, the fourth optical waveguide OW4(the trench), in a plan view, is formed such that the fourth optical waveguide OW4surrounds the reflective member RM. A planar shape of the fourth optical waveguide OW4(the trench), for example, a square shape or a circular shape.

(Optical Path in Semiconductor Device)

Here, the optical path in the semiconductor device SD3according to the third embodiment will be described. For example, in the semiconductor device SD3, the light emitted from the light source, through the second optical waveguide OW2and the first optical waveguide OW13, the optical path until reaching the optical fiber OF will be described.

FIG. 24is a cross-sectional view showing an optical path in the semiconductor device SD3according to the third embodiment. InFIG. 24, an arrow indicates a traveling direction of the light, a thickness of the arrow indicates the amount of light. In the third embodiment, the first optical waveguide OW13has a function as a spot-size converter.

As shown inFIG. 24, in the semiconductor device SD3according to the third embodiment, the light transmitted from the second optical waveguide OW2to the first optical waveguide OW1reaches the reflective member RM formed on the second edge E23of the first optical waveguide OW1along the first surface SF1of the first insulating film IF1. Light reaching the reflective member RM is reflected in a direction away from the first surface SF1of the first insulating film IF1. Reflected light from the reflective member RM is emitted from the surface of the first optical waveguide OW1, by the fourth optical waveguide OW4, is guided to the optical fiber OF.

(Method of Manufacturing Semiconductor Device)

Next, an exemplary method of manufacturing the semiconductor device SD3according to the third embodiment will be described.FIGS. 25 to 28are cross-sectional views showing exemplary steps included in the method of manufacturing the semiconductor device SD3.

The method of manufacturing the semiconductor device SD3includes (1) providing a semiconductor wafer SW (seeFIG. 5), (2) forming the second optical waveguide OW2(seeFIG. 6), (3) forming the multilayer wiring layer MWL (seeFIG. 7), (4) disposing a support member SM (seeFIG. 8), (5) forming the first optical waveguide OW13(seeFIG. 25), (6) forming the reflective member RM (seeFIG. 26), (7) forming the second insulating film IF2(seeFIG. 27), and (8) forming the fourth optical waveguide OW4(seeFIG. 28).

As shown inFIGS. 5 to 8, similar to the method of manufacturing the semiconductor device SD1according to the first embodiment, (1) preparing the semiconductor wafer SW, (2) forming the second optical waveguide OW2, (3) forming the multilayer wiring layer MWL, and (4) disposing the support member SM are performed.

(5) Forming the first optical waveguide OW1

As shown inFIG. 25, after patterning the first semiconductor layer SL1, by processing the second end portion EP23, the first optical waveguide OW13is formed on the first surface SF1of the first insulating film IF1. Patterning of the first semiconductor layer SL1is performed by photolithography and etching techniques. The method of processing the second end portion EP23is, for example, a wet etching method.

(6) Formation the reflective member RM

As shown inFIG. 26, to form the reflective member RM on the second edge E23of the first optical waveguide OW13. The reflective member RM is formed by, for example, sputtering method.

(7) Forming the second insulating film IF2

As shown inFIG. 27, the second insulating film IF2is formed on the first surface SF1of the first insulating film IF1so as to cover the first optical waveguide OW13. The second insulating film IF2is also formed on the reflective member RM.

(8) Forming the fourth optical waveguide OW4

As shown inFIG. 28, the fourth optical waveguide OW4is formed in the second insulating film IF2. After forming a trench in the second insulating film IF2, the fourth optical waveguide OW4is formed by embedding the trench with the fourth optical waveguide OW4. The method of forming the trench is, for example, by photolithography method and etching method. The method of embedding the material of the fourth optical waveguide OW4into the trench is, for example, CVD method.

Finally, by dicing the structures obtained by the above process, a plurality of semiconductor devices SD3singulated are obtained. The support member SM may or may not be removed.

An effect according to the third embodiment is the same as the first embodiment. In the third embodiment, to emit light in a direction perpendicular to the first surface SF1of the first insulating film IF1. This allows the semiconductor device to be designed with greater flexibility.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist thereof.

In addition, even when a specific numerical value example is described, it may be a numerical value exceeding the specific numerical value, or may be a numerical value less than the specific numerical value, except when it is theoretically obviously limited to the numerical value. In addition, the component means “B containing A as a main component” or the like, and the mode containing other components is not excluded.

Furthermore, the embodiments and the modifications may be arbitrarily combined with each other. That is, the transmission of light between the second optical waveguide OW2and the third optical waveguide OW3and the optical waveguide OW1may be performed by evanescent coupling or may be performed by reflection.

Furthermore, for example, the first optical waveguide including the end portion (the first end portion EP1) and the other end portion (the second end portion EP2) may include a third end portion.