# US 2019/0356032 A1 · Monolithic splitter using re-entrant poly silicon waveguides

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- Number: US 2019/0356032 A1
- Document ID: US20190356032A1
- Status: Published application
- Kind: A1
- Application number: 16/461,554
- Filed: 2016-12-30
- Published: 2019-11-21
- Earliest claimed: 2016-12-30
- Assignees: Intel Corporation
- Applicants: Intel Corporation
- Inventors: Rahul RAMASWAMY; Chia-Hong JAN; Walid HAFEZ; Neville DIAS; Hsu-Yu CHANG; Roman OLAC-VAW; Chen-Guan LEE
- Web page: https://patentgrep.com/patent/US20190356032A1

## CPC

- G02B 6/132: by deposition of thin films
- H01P 3/121: {integrated in a substrate}
- G02B 6/00: Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B 6/122: Basic optical elements, e.g. light-guiding paths
- G02B 6/125: Bends, branchings or intersections
- H01P 3/122: {Dielectric loaded (not air)}
- H01P 3/127: with a circular, elliptic, or parabolic cross-section
- H01P 5/12: Coupling devices having more than two ports (H01P5/04 takes precedence)
- H01P 11/002: {Manufacturing hollow waveguides}
- H10D 84/0149: {Manufacturing their interconnections or electrodes, e.g. source or drain electrodes}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10W 20/056: {by filling conductive material into holes, grooves or trenches}
- H10W 44/20: at high-frequency [HF] or radio frequency [RF]
- G02B 2006/1215: {Splitter}
- H01P 3/165: {Non-radiating dielectric waveguides}
- H10W 44/216: {Waveguides, e.g. strip lines}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H01P: WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE (operating at optical frequencies G02B)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

Embodiments of the invention include an electromagnetic waveguide and methods of forming the electromagnetic waveguide. In an embodiment the electromagnetic waveguide includes a first spacer and a second spacer. In an embodiment, the first and second spacer each have a reentrant profile. The electromagnetic waveguide may also include a conductive body formed between in the first and second spacer, and a void formed within the conductive body. In an additional embodiment, the electromagnetic waveguide may include a first spacer and a second spacer. Additionally, the electromagnetic waveguide may include a first portion of a conductive body formed along sidewalls of the first and second spacer and a second portion of the conductive body formed between an upper portion of the first portion of the conductive body. In an embodiment, the first portion of the conductive body and the second portion of the conductive body define a void through the electromagnetic waveguide.

## Claims

### Claim 1

An electromagnetic waveguide, comprising:
a first spacer;
a second spacer, wherein the first and second spacer each have a re-entrant profile;
a conductive body formed between the first and second spacer; and
a void formed within the conductive body.

### Claim 2 (depends on 1)

The electromagnetic waveguide of claim 1, wherein the re-entrant profile of the first and second spacers is formed by each spacer having a non-uniform width.

### Claim 3 (depends on 2)

The electromagnetic waveguide of claim 2, wherein the first and second spacers have a first width proximate to a bottom portion of the spacer that is larger than a second width proximate to a middle portion of the spacer.

### Claim 4 (depends on 3)

The electromagnetic waveguide of claim 3, wherein the first and second spacers have a third width proximate to a top portion of the spacer that is larger than a second width proximate to a middle portion of the spacer.

### Claim 5 (depends on 1)

The electromagnetic waveguide of claim 1, further comprising:
a sacrificial layer formed between the conductive body and a substrate on which the electromagnetic waveguide is formed.

### Claim 6 (depends on 1)

The electromagnetic waveguide of claim 1, wherein the first spacer and the second spacer are spaced apart by a distance that is approximately 50 nm or less.

### Claim 7 (depends on 1)

The electromagnetic waveguide of claim 1, further comprising:
a cladding layer formed over surfaces of the void.

### Claim 8 (depends on 7)

The electromagnetic waveguide of claim 7, wherein the cladding layer is a dielectric layer.

### Claim 9 (depends on 7)

The electromagnetic waveguide of claim 7, further comprising:
a core formed within the void.

### Claim 10 (depends on 1)

The electromagnetic waveguide of claim 1, wherein the electromagnetic waveguide includes a splitter or a combiner.

### Claim 11

A method for forming an electromagnetic waveguide, comprising:
forming a dummy gate electrode over a substrate;
forming spacers along sidewalls of the dummy gate electrode, wherein the spacers include a re-entrant profile;
removing the dummy gate electrode; and
depositing a conductive body between the spacers with a conformal deposition process, wherein a void is formed within the conductive body during the deposition of the conductive body.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
forming a sacrificial layer over the spacers with a non-conformal deposition process, wherein the sacrificial layer reduces the length of an opening between top portions of the spacers.

### Claim 13 (depends on 11)

The method of claim 11, wherein the spacers are separated by a distance that is approximately 50 nm or less.

### Claim 14 (depends on 11)

The method of claim 11, wherein the spacers each have a first width proximate to a bottom portion of the spacer that is greater than a second width that is proximate to a middle portion of the spacer, and wherein the spacers each have a third width proximate to a top portion of the spacer that is larger than the second width of the spacer.

### Claim 15 (depends on 11)

The method of claim 11, further comprising:
forming a cladding layer on the surfaces of the void with a conformal deposition process.

### Claim 16 (depends on 15)

The method of claim 15, further comprising:
forming a core within the void, wherein the core has a lower index of refraction than the cladding layer.

### Claim 17

An electromagnetic waveguide, comprising:
a first spacer;
a second spacer;
a first portion of a conductive body formed along sidewalls of the first and second spacer and over a substrate on which the electromagnetic waveguide is formed; and
a second portion of the conductive body formed between an upper portion of the first portion of the conductive body, wherein the first portion of the conductive body and the second portion of the conductive body define a void through the electromagnetic waveguide.

### Claim 18 (depends on 17)

The electromagnetic waveguide of claim 17, wherein a spacing between the first spacer and the second spacer is greater than approximately 50 nm.

### Claim 19 (depends on 17)

The electromagnetic waveguide of claim 17, further comprising:
a cladding layer formed over surfaces of the void.

### Claim 20 (depends on 19)

The electromagnetic waveguide of claim 19, further comprising:
a core formed within the void.

### Claim 21

A method of forming an electromagnetic waveguide, comprising:
forming a dummy gate electrode;
forming spacers on sidewalls of the dummy gate electrode;
removing the dummy gate electrode;
depositing a first portion of a conductive body along sidewall surfaces of the spacers and over a top surface of a substrate on which the electromagnetic waveguide is formed with a conformal deposition process;
depositing a sacrificial material over the first portion of the conductive body with a non-conformal deposition process;
depositing a second portion of a conductive body over the sacrificial material; and
removing the sacrificial material to form a void defined by the first portion of the conductive body and the second portion of the conductive body.

### Claim 22 (depends on 21)

The method of claim 21, wherein a spacing between the spacers is greater than approximately 50 nm.

### Claim 23 (depends on 21)

The method of claim 21, further comprising:
forming a cladding layer on the surfaces of the void with a conformal deposition process.

### Claim 24 (depends on 23)

The method of claim 23, wherein the cladding layer is doped.

### Claim 25 (depends on 23)

The method of claim 23, further comprising:
forming a core within the void, wherein the core has a lower index of refraction than the cladding layer.