# US 2015/0145084 A1 · Diffraction Grating with Multiple Periodic Widths

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- Number: US 2015/0145084 A1
- Document ID: US20150145084A1
- Status: Published application
- Kind: A1
- Application number: 14/092,592
- Filed: 2013-11-27
- Published: 2015-05-28
- Earliest claimed: 2013-11-27
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Hsin-Chieh Chang
- Web page: https://patentgrep.com/patent/US20150145084A1

## CPC

- H10F 39/024: {of coatings or optical elements}
- G02B 5/1819: {Plural gratings positioned on the same surface, e.g. array of gratings (plural diffractive elements positioned sequentially along the optical path G02B27/4272)}
- G02B 5/203: {having holographic or diffractive elements (diffraction gratings per se G02B5/18; holographic elements per se G02B5/32; generating the spectrum using diffraction elements G01J3/18)}
- H10F 39/8053: {Colour filters}
- G02B 2005/1804: {Transmission gratings}
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An integrated circuit includes a substrate, a plurality of photo detectors formed in the substrate, and a diffraction grating having multiple sections disposed over the plurality of photo detectors. Each section of the diffraction grating has a respective periodic width for a respective target wavelength. The diffraction grating has at least two different target wavelengths. The diffraction grating is interlaced with filters. The filters in each section of the diffraction grating are configured to pass a respective electromagnetic wave with the respective target wavelength.

## Claims

### Claim 1

An integrated circuit, comprising:
a substrate;
a plurality of photo detectors formed in the substrate; and
a diffraction grating having multiple sections disposed over the plurality of photo detectors,
wherein each section of the diffraction grating has a respective periodic width for a respective target wavelength, the diffraction grating has at least two different target wavelengths, the diffraction grating is interlaced with filters, and the filters in each section of the diffraction grating are configured to pass a respective electromagnetic wave with the respective target wavelength.

### Claim 2 (depends on 1)

The integrated circuit of claim 1, wherein the plurality of photo detectors are located at a Talbot length away from the diffraction grating.

### Claim 3 (depends on 2)

The integrated circuit of claim 2, wherein the periodic width, the target wavelength, and the Talbot length are related as expressed in the equation
Z
T
=
2

a
2
λ
,
or


Z
T
=
λ
1
-
1
-
λ
2
a
2
,
wherein α is the periodic width, λ is the target wavelength, and ZT is the Talbot length.

### Claim 4 (depends on 1)

The integrated circuit of claim 1, further comprising at least one dielectric layer between the plurality of photo detectors and the diffractive grating.

### Claim 5 (depends on 4)

The integrated circuit of claim 4, wherein the at least one dielectric layer comprises SiO2, SiN, or any combination thereof.

### Claim 6 (depends on 1)

The integrated circuit of claim 1, wherein the plurality of photo detectors and the diffraction grating have the same periodic widths.

### Claim 7 (depends on 6)

The integrated circuit of claim 6, wherein the plurality of photo detectors are aligned with the diffraction grating with a phase difference by 0 degrees, 90 degrees, 180 degrees, 270 degrees, or any combination thereof.

### Claim 8 (depends on 1)

The integrated circuit of claim 1, wherein the diffraction grating comprises Cu, AlCu, SiN, or SiO2.

### Claim 9 (depends on 1)

The integrated circuit of claim 1, wherein the filters comprise photoresist or polymer.

### Claim 10 (depends on 1)

The integrated circuit of claim 1, wherein the photo detectors are PN junction diodes.

### Claim 11

A method, comprising:
forming a plurality of photo detectors in a substrate; and
forming a diffraction grating with multiple sections over the photo detectors, wherein each section of the diffraction grating has a respective periodic width for a respective target wavelength, the diffraction grating has at least two different target wavelengths, the diffraction grating is interlaced with filters, and the filters in each section of the diffraction grating are configured to pass a respective electromagnetic wave with the respective target wavelength.

### Claim 12 (depends on 11)

The method of claim 11, further comprising forming at least one dielectric layer between the plurality of photo detectors and the diffraction grating.

### Claim 13 (depends on 12)

The method of claim 12, wherein the at least one dielectric layer comprises SiO2, SiN, or any combination thereof.

### Claim 14 (depends on 11)

The method of claim 11, further comprising thinning a backside of the substrate after forming the plurality of photo detectors.

### Claim 15 (depends on 11)

The method of claim 11, wherein the diffraction grating is formed at a Talbot length away from the plurality of photo detectors.

### Claim 16 (depends on 11)

The method of claim 11, wherein the plurality of photo detectors are PN junction diodes.

### Claim 17 (depends on 16)

The method of claim 16, wherein the PN junction diodes are formed by ion implantation.

### Claim 18 (depends on 11)

The method of claim 11, wherein the diffraction grating comprises Cu, AlCu, SiN, or SiO2.

### Claim 19 (depends on 11)

The method of claim 11, wherein the filters comprise photoresist or polymer.

### Claim 20

An integrated circuit, comprising:
a substrate;
a plurality of divisions of the substrate, wherein each division includes:
a plurality of photo detectors formed in the substrate; and
a diffraction grating having multiple sections disposed over the plurality of photo detectors,
wherein each section of the diffraction grating has a respective periodic width for a respective target wavelength, the diffraction grating has at least two different target wavelengths, the diffraction grating is interlaced with filters, the filters in each section of the diffraction grating are configured to pass a respective electromagnetic wave with the respective target wavelength, and the respective plurality of photo detectors in each division are aligned with the respective diffraction grating with a different phase from another division.