Semiconductor device

Patent metadata

Field	Value
Publication number	US-2016334573-A1
Application number	US-201615152117-A
Country	US
Kind code	A1
Filing date	May 11, 2016
Priority date	May 15, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

A low reflectance film with a second reflectance (50% or lower) lower than a first reflectance is formed between an optical directional coupler and a first-layer wiring with the first reflectance. Thus, even when the first-layer wiring is formed above the optical directional coupler, the influence of the light reflected by the first-layer wiring on the optical signal propagating through the first optical waveguide and the second optical waveguide of the optical directional coupler can be reduced. Accordingly, the first-layer wiring can be arranged above the optical directional coupler, and the restriction on the layout of the first-layer wiring is relaxed.

First claim

What is claimed is:

1 . A semiconductor device comprising:
a semiconductor substrate; a first insulating film formed on the semiconductor substrate; an optical waveguide made of a semiconductor layer formed on the first insulating film; a second insulating film formed on the first insulating film so as to cover the optical waveguide; and a wiring with a first reflectance formed on the second insulating film, wherein a low reflectance film with a second reflectance lower than the first reflectance is formed between the optical waveguide and the wiring.

2 . The semiconductor device according to claim 1 ,
wherein the second reflectance of the low reflectance film is 50% or lower.

3 . The semiconductor device according to claim 1 ,
wherein an end of the low reflectance film is located on an outer side relative to an end of the wiring when seen in a plan view.

4 . The semiconductor device according to claim 1 ,
wherein an end of the low reflectance film is located on an outer side relative to an end of the wiring by 1 μm or more when seen in a plan view.

5 . The semiconductor device according to claim 1 ,
wherein an optical signal travels in a first direction in the optical waveguide, in a cross section including a second direction and a third direction orthogonal to the first direction, on the same side as one end of the low reflectance film, the one end of the low reflectance film is located on an outer side relative to a first line connecting one end of a lower surface of the wiring and one end of an upper surface of the optical waveguide, and on the same side as the other end of the low reflectance film, the other end of the low reflectance film is located on an outer side relative to a second line connecting the other end of the lower surface of the wiring and the other end of the upper surface of the optical waveguide.

6 . The semiconductor device according to claim 1 ,
wherein the second insulating film is constituted of a lower-layer insulating film and an upper-layer insulating film, and the low reflectance film is located between the lower-layer insulating film and the upper-layer insulating film.

7 . The semiconductor device according to claim 1 ,
wherein the low reflectance film is located between the second insulating film and the wiring and is in contact with a lower surface of the wiring.

8 . The semiconductor device according to claim 7 ,
wherein the low reflectance film is formed on a side surface of the wiring.

9 . The semiconductor device according to claim 1 ,
wherein the low reflectance film is fixed to a reference potential.

10 . The semiconductor device according to claim 1 ,
wherein the low reflectance film is made of tungsten, tantalum, titanium or titanium nitride.

11 . The semiconductor device according to claim 1 ,
wherein the wiring is made of aluminum or copper.

Assignees

• Renesas Electronics Corp

Inventors

• Kunishima Hiroyuki
• Nakashiba Yasutaka
• Wakabayashi Masaru
• Watanuki Shinichi

Classifications

• H10W72/90

  Bond pads, in general · CPC title

• H10W20/4421

  the principal metal being copper · CPC title

• H10W20/4405

  the principal metal being aluminium · CPC title

• G02F1/025 Primary

  in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) · CPC title

• G02B2006/12061

  Silicon · CPC title