Oxide capacitor electro-optical phase shifter

Patent metadata

Field	Value
Publication number	US-2016109732-A1
Application number	US-201514981139-A
Country	US
Kind code	A1
Filing date	Dec 28, 2015
Priority date	Oct 2, 2013
Publication date	Apr 21, 2016
Grant date	—

Abstract

An electro-optical phase shifter to be located in an optical waveguide may include a rib of a semiconductor material extending along a length of the optical waveguide and a control structure configured to modify a concentration of carriers in the rib according to a control voltage present between first and second control terminals of the phase shifter. The control structure may include a conductive layer covering a portion of the rib and electrically connected to a first of the control terminals. An insulating layer may be configured to electrically isolate the conductive layer from the rib.

First claim

1 - 12 . (canceled)

13 . A method of making an electro-optical phase shifter associated with an optical waveguide, the method comprising:
forming a control structure to modify a concentration of carriers in a rib according to a control voltage present between first and second control terminals, the rib comprising a semiconductor material along a length of the optical waveguide, forming the control structure comprising
forming at least one conductive layer to cover at least a portion of the rib and be electrically coupled to the first control terminal, and
forming at least one insulating layer coupled to and between the rib and the at least one conductive layer to electrically isolate the at least one conductive layer from the rib, the at least one conductive layer and at least one insulating layer being coextensive.

14 . The method according to claim 13 , wherein forming the control structure comprises forming at least one first wing comprising a semiconductor material having a homogeneous conductivity type adjacent a first face of the rib.

15 . The method according to claim 14 , wherein the at least one insulating layer isolates the at least one first wing from the rib; the at least one conductive layer being defined by a region of the at least one first wing having a doping level greater than a doping level of the rib; and wherein the first control terminal is in electrical contact with a distal end of the at least one first wing.

16 . The method according to claim 14 , wherein forming the control structure further comprises forming at least one second wing comprising a semiconductor material having a homogeneous conductivity type adjacent a second face of the rib opposite the first face.

17 . The method according to claim 16 , wherein forming the at least one insulating layer comprises forming first and second insulating layers respectively to isolate at least one first and second wings from the rib; and wherein forming the at least one conductive layer comprises forming first and second conductive layers defined by respective first and second areas of the at least one first and second wings having a doping level greater than the doping level of the rib.

18 . The method according to claim 13 , further comprising forming a plurality of wings comprising a semiconductor material of same conductivity type as the rib and extending outwardly from both sides of the rib.

19 . The method according to claim 18 , wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting from a plane of the plurality of wings.

20 . The method according to claim 18 , wherein the at least one conductive layer comprises polysilicon; wherein forming the control structure comprises, on one of the plurality of wings, forming a polysilicon track coupling the at least one conductive layer to the first control terminal; wherein the first control terminal is located on a distal end of the one of the plurality of wings; and wherein the at least one insulating layer is formed to have an extension to isolate the first control terminal and the polysilicon track from the one of the plurality of wings.

21 . The method according to claim 18 , wherein forming the control structure comprises:
forming, on a second one of the plurality of wings, a configuration symmetrical to a first one of the plurality of wings; forming, in a plane offset from that of the first and second one of the plurality of wings, third and fourth ones of the plurality wings comprising a semiconductor material of a same conductivity type as the rib and extending outwardly from both sides of the rib, wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting from the plane of the third and fourth ones of the plurality of wings; and forming at least one electrical contact on a distal end of each of the third and fourth ones of the plurality of wings.

22 . The method according to claim 13 comprising forming the at least one conductive layer and at least one insulating layer to have a same height as the rib.

23 . A method of making an electro-optical phase shifter comprising:
forming a control structure to modify a concentration of carriers in a rib according to a control voltage by at least
forming at least one conductive layer to cover at least a portion of the rib, and
forming at least one insulating layer coupled to and between the rib and the at least one conductive layer to electrically isolate the at least one conductive layer from the rib, the at least one conductive layer and at least one insulating layer being coextensive.

24 . The method according to claim 23 , wherein forming the control structure comprises forming at least one first wing comprising a semiconductor material having a homogeneous conductivity type adjacent a first face of the rib.

25 . The method according to claim 24 , wherein the at least one insulating layer isolates the at least one first wing from the rib; the at least one conductive layer being defined by a region of the at least one first wing having a doping level greater than a doping level of the rib; and wherein a first control terminal is in electrical contact with a distal end of the at least one first wing.

26 . The method according to claim 24 , wherein forming the control structure further comprises forming at least one second wing comprising a semiconductor material having a homogeneous conductivity type adjacent a second face of the rib opposite the first face.

27 . The method according to claim 26 , wherein forming the at least one insulating layer comprises forming first and second insulating layers respectively to isolate at least one first and second wings from the rib; and wherein forming the at least one conductive layer comprises forming first and second conductive layers defined by respective first and second areas of the at least one first and second wings having a doping level greater than the doping level of the rib.

28 . The method according to claim 23 , further comprising forming a plurality of wings comprising a semiconductor material of same conductivity type as the rib and extending outwardly from both sides of the rib.

29 . The method according to claim 28 , wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting from a plane of the plurality of wings.

30 . The method according to claim 28 , wherein the at least one conductive layer comprises polysilicon; wherein forming the control structure comprises, on one of the plurality of wings, forming a polysilicon track coupling the at least one conductive layer to a first control terminal; wherein the first control terminal is located on a distal end of the one of the plurality of wings; and wherein the at least one insulating layer is formed to have an extension to isolate the first control terminal and the polysilicon track from the one of the plurality of wings.

31 . The method according to claim 28 , wherein forming the control structure comprises:
forming, on a second one of the plurality of wings, a configuration symmetrical to a first one of the plurality of wings; forming, in a plane offset from that of the first and second one of the plurality of wings, third and fourth ones of the plurality wings comprising a semiconductor material of a same conductivity type as the rib and extending outwardly from both sides of the rib, wherein the at least one conductive layer is formed to cover at least a portion of the rib projecting fro

Assignees

• St Microelectronics Sa
• St Microelectronics Crolles 2

Inventors

• Manouvrier Jean-Robert
• Boeuf Frederic

Classifications

• G02F1/025 Primary

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

• G02F1/212

  Mach-Zehnder type · CPC title

• G02F1/225

  in an optical waveguide structure · CPC title