# US 2014/0151834 A1 · MEMS Infrared Sensor Including a Plasmonic Lens

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- Number: US 2014/0151834 A1
- Document ID: US20140151834A1
- Status: Published application
- Kind: A1
- Application number: 14/091,550
- Filed: 2013-11-27
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Robert Bosch GmbH
- Applicants: Robert Bosch GmbH
- Inventors: Ashwin K. Samarao; Gary O'Brien; Ando Feyh; Fabian Purkl; Gary Yama
- Web page: https://patentgrep.com/patent/US20140151834A1

## CPC

- G01J 5/0815: {Light concentrators, collectors or condensers}
- G01J 5/024: {Special manufacturing steps or sacrificial layers or layer structures}
- G01J 5/045: {Sealings; Vacuum enclosures; Encapsulated packages; Wafer bonding structures; Getter arrangements (getter arrangements per se H10W76/48, H10P36/03)}
- G01J 5/0837: {Microantennas, e.g. bow-tie}
- G01J 5/0856: {Slit arrangements}
- G01J 5/10: using electric radiation detectors
- G01J 5/20: using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

A method of fabricating a semiconductor device includes forming an absorber on a substrate, and supporting a cap layer over the substrate to define a cavity between the substrate and the cap layer in which the absorber is located. The method further includes forming a lens layer on the cap layer. The lens layer is spaced apart from the cavity and defines a plurality of grooves and an opening located over the absorber.

## Claims

### Claim 1

A semiconductor device comprising:
a substrate having an upper surface;
a cap wafer supported by the substrate and including a cap layer spaced apart from the substrate;
an absorber extending from the upper surface and located between the substrate and the cap layer; and
a lens layer supported by the cap layer, the lens layer defining a plurality of grooves and an opening located over the absorber.

### Claim 2 (depends on 1)

The semiconductor device of claim 1, wherein:
the cap layer defines a lower surface and an opposite upper surface,
a cavity is defined between the upper surface of the substrate and the lower surface of the cap layer,
the lens layer is located generally above the upper surface of the cap layer, and
the absorber is located in the cavity.

### Claim 3 (depends on 2)

The semiconductor device of claim 2, wherein a lower surface of the lens layer defines the plurality of grooves.

### Claim 4 (depends on 3)

The semiconductor device of claim 3, wherein:
the cap wafer is formed from a material, and
the plurality of grooves is at least partially filled with the material of the cap wafer.

### Claim 5 (depends on 3)

The semiconductor device of claim 3, wherein:
the lens layer defines a thickness,
the plurality of grooves define a depth that is less than the thickness, and
the opening extends through the thickness of the lens layer.

### Claim 6 (depends on 1)

The semiconductor device of claim 1, wherein:
the cap layer defines a lower surface and an opposite upper surface,
a cavity is defined between the upper surface of the substrate and the lower surface of the cap layer,
the lens layer is located in the cavity, and
the absorber is located in the cavity.

### Claim 7 (depends on 1)

The semiconductor device of claim 1, wherein:
the opening is a circular opening, and
the plurality of grooves includes a plurality of concentric circular grooves centered about the circular opening.

### Claim 8 (depends on 1)

The semiconductor device of claim 1, wherein:
the opening is a slit extending in a slit direction, and
the grooves of the plurality of grooves are substantially linear and extend in the slit direction.

### Claim 9 (depends on 1)

The semiconductor device of claim 1, wherein:
the lens layer is formed from a first material configured to block a passage of infrared radiation therethrough, and
the cap wafer is formed from a second material configured to transmit infrared radiation therethrough.

### Claim 10 (depends on 9)

The semiconductor device of claim 9, wherein:
the first material is metal, and
the second material is silicon.

### Claim 11

A method of fabricating a semiconductor device, comprising:
forming an absorber on a substrate;
supporting a cap layer over the substrate to define a cavity between the substrate and the cap layer in which the absorber is located; and
forming a lens layer on the cap layer, the lens layer being spaced apart from the cavity and defining a plurality of grooves and an opening located over the absorber.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
forming a post on an upper surface of the cap layer;
forming a plurality of ridges on the upper surface of the cap layer; and
forming the lens layer over the plurality of ridges and the post,
wherein the plurality of ridges define the plurality of grooves.

### Claim 13 (depends on 12)

The method of claim 12, further comprising:
forming the opening by chemically and mechanically polishing the lens layer.

### Claim 14 (depends on 12)

The method of claim 12, further comprising:
removing the plurality of ridges after forming the lens layer.

### Claim 15 (depends on 14)

The method of claim 14, wherein the removing the plurality of ridges includes evaporating the plurality of ridges.

### Claim 16 (depends on 14)

The method of claim 14, wherein the plurality of ridges is formed from a thermally decomposable sacrificial polymer.

### Claim 17 (depends on 14)

The method of claim 14, wherein the plurality of ridges and the post are formed from a first material and the cap layer is formed from a second material that is different from the first material.

### Claim 18 (depends on 11)

The method of claim 11, wherein:
the opening is a circular opening, and
the plurality of grooves includes a plurality of concentric circular grooves centered about the circular opening.

### Claim 19 (depends on 11)

The method of claim 11, wherein:
the opening is a rectangular slit extending in a slit direction, and
the grooves of the plurality of grooves are substantially linear and extend in the slit direction.

### Claim 20 (depends on 11)

The semiconductor device of claim 11, further comprising:
blocking a passage of infrared radiation with a material of the lens layer; and
transmitting infrared radiation through a material of the cap layer.