# US 2018/0321184 A1 · Sensor systems and related fabrication techniques

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- Number: US 2018/0321184 A1
- Document ID: US20180321184A1
- Status: Published application
- Kind: A1
- Application number: 15/773,247
- Filed: 2016-11-04
- Published: 2018-11-08
- Earliest claimed: 2015-11-04
- Assignees: Massachusetts Institute of Technology
- Applicants: Massachusetts Institute of Technology
- Inventors: Charles E. Mackin; Tomás Apostol Palacios
- Web page: https://patentgrep.com/patent/US20180321184A1

## CPC

- G01N 27/4146: {involving nanosized elements, e.g. nanotubes, nanowires}
- G03F 7/095: having more than one photosensitive layer (G03F7/075 takes precedence)
- G03F 7/2022: {Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure}
- G03F 7/30: Imagewise removal using liquid means
- H10D 62/80: characterised by the materials
- H10D 62/86: being Group II-VI materials, e.g. ZnO
- H10D 62/882: {Graphene}
- H10P 14/3406: {Carbon, e.g. diamond-like carbon}
- H10P 14/3426: {Oxides}
- H10P 14/3436: {being chalcogenide semiconductor materials not being oxides, e.g. ternary compounds}
- H10P 76/2041: {Photolithographic processes}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A sensor device including a substrate that is transparent and/or flexible, and a transparent sensor array disposed on the substrate. The transparent sensor array includes transparent sensor circuits and transparent interconnects electrically coupled to the transparent sensor circuits. Each of the transparent sensor circuits includes a transparent transistor. A transparent slide may include a transparent sensor circuit disposed on a transparent substrate. The slide may be prepared for observation of a specimen by placing the specimen in fluidic communication with the transparent sensor circuit. A flexible sensor device may include an array of transparent sensor circuits disposed on a flexible substrate. The flexible sensor device may be placed on the surface of an object to determine parameters at locations adjacent to the surface of the object. A method of fabricating an integrated circuit may include using a multilayer etch mask of electron-beam resist and photoresist.

## Claims

### Claim 1

A sensor system comprising:
a sensor device, including:
a substrate selected from the group consisting of a transparent substrate and a flexible polymer substrate; and
a transparent sensor array disposed on the substrate, the transparent sensor array including a plurality of transparent sensor circuits and a plurality of transparent interconnects electrically coupled to the plurality of transparent sensor circuits,
wherein each of the transparent sensor circuits includes a respective transparent transistor having (i) a transparent drain electrically coupled to at least one of the transparent interconnects, (ii) a transparent source electrically coupled to at least one of the transparent interconnects, and (iii) a transparent channel region electrically coupled to the source and the drain, and
wherein at least one of the transparent interconnects is coupled to a plurality of the transparent drains or to a plurality of the transparent sources.

### Claim 2 (depends on 1)

The sensor system of claim 1, wherein the transparent sensor array includes:
M*N of the transparent sensor circuits arranged in M rows and N columns; and
the plurality of transparent interconnects including M row selection interconnects and N column readout interconnects,
wherein (i) each of the row selection interconnects corresponds to a respective row of N transparent sensor circuits and is coupled to the drains of the N transparent sensor circuits in the respective row, and (ii) each of the column readout interconnects corresponds to a respective column of M transparent sensor circuits and is coupled to the sources of the M transparent sensor circuits in the respective column.

### Claim 3 (depends on 2)

The sensor system of claim 2, further comprising:
a readout device including:
a row selection circuit comprising M row selection switches configured to communicatively couple, respectively, to the M row selection interconnects of the sensor device; and
an amplifier circuit comprising N amplifiers configured to communicatively couple, respectively, to the N column readout interconnects of the sensor device,
wherein the readout device is not integrated on the substrate of the sensor device.

### Claim 4 (depends on 3)

The sensory system of claim 3, wherein each of the N amplifiers comprises a voltage amplifier.

### Claim 5 (depends on 3)

The sensory system of claim 3, wherein each of the N amplifiers comprises a transimpedance amplifier.

### Claim 6 (depends on 3)

The sensor system of claim 3, wherein the readout device further comprises a control circuit configured to:
selectively activate a selected one of the row selection switches corresponding to a selected one of the rows of transparent sensor circuits; and
provide a first signal to the drains of the transparent sensor circuits in the selected row via the selected row selection switch and the corresponding row selection interconnect.

### Claim 7 (depends on 6)

The sensor system of claim 6, wherein each of the N transparent sensor circuits in the selected row is configured to provide a respective second signal to the corresponding amplifier, wherein each second signal is based, at least in part, on the first signal and on a state of the channel region of the respective transparent sensor circuit.

### Claim 8 (depends on 6)

The sensor system of claim 6, wherein each of the N transparent sensor circuits in the selected row is configured as a common source amplifier.

### Claim 9 (depends on 1)

The sensor system of claim 1, wherein the substrate is the transparent substrate, and the transparent substrate comprises borosilicate glass.

### Claim 10 (depends on 1)

The sensor system of claim 1, wherein the substrate is the flexible polymer substrate, and the flexible polymer substrate comprises a material selected from the group consisting of polyethylene terephthalate, polystyrene, polyimide, and polyether ether ketone.

### Claim 11 (depends on 1)

The sensor system of claim 1, wherein the transparent interconnects, transparent drains, and transparent sources each comprise indium tin oxide (ITO).

### Claim 12 (depends on 1)

The sensor system of claim 1, wherein each of the transparent channel regions comprises a material selected from the group consisting of graphene, a transition metal dichalcogenide, and a metal oxide.

### Claim 13

A method comprising:
preparing a transparent slide for observation of a specimen by placing the specimen in fluidic communication with a transparent sensor circuit,
wherein the transparent slide comprises the transparent sensor circuit disposed on a transparent substrate.

### Claim 14 (depends on 13)

The method of claim 13, wherein (i) the transparent sensor circuit comprises a transparent transistor having a transparent channel region, and (ii) placing the specimen in fluidic communication with the transparent sensor circuit comprises placing the specimen in fluidic communication with the transparent channel region.

### Claim 15 (depends on 14)

The method of claim 14, wherein the transparent channel region is in physical contact with the specimen.

### Claim 16 (depends on 15)

The method of claim 15, wherein the slide comprises a transparent sensor array disposed on the transparent substrate, the transparent sensor array including a plurality of transparent sensor circuits and a plurality of transparent interconnects electrically coupled to the plurality of transparent sensor circuits, the plurality of transparent sensor circuits including the sensor circuit,
wherein each of the transparent sensor circuits includes a respective transparent transistor having (i) a transparent drain electrically coupled to at least one of the transparent interconnects, (ii) a transparent source electrically coupled to at least one of the transparent interconnects, and (iii) a transparent channel region electrically coupled to the source and the drain.

### Claim 17 (depends on 13)

The method of claim 13, wherein the transparent substrate comprises material selected from the group consisting of borosilicate glass, silica glass, and polystyrene.

### Claim 18 (depends on 13)

The method of claim 13, further comprising:
detecting an electrical signal from the transparent sensor circuit; and
determining at least one attribute of the specimen based at least in part on the electrical signal.

### Claim 19 (depends on 18)

The method of claim 18, wherein the determined attribute of the specimen is selected from a group consisting of chemical attributes of the specimen and electrical attributes of the specimen.

### Claim 20 (depends on 18)

The method of claim 18, wherein the specimen comprises a cell culture medium.

### Claim 21 (depends on 20)

The method of claim 20, wherein the determined attribute of the specimen is selected from a group consisting of a nutrient level of the cell culture medium and a pH of the cell culture medium.

### Claim 22 (depends on 20)

The method of claim 20, wherein the cell culture medium comprises electrogenic cells and a drug candidate.

### Claim 23 (depends on 13)

The method of claim 13, further comprising obtaining an image of the specimen on the transparent slide by using a microscope.

### Claim 24 (depends on 23)

The method of claim 23, wherein the specimen comprises a fluorescent material, and the microscope is a fluorescence microscope.

### Claim 25 (depends on 13)

The method of claim 13, wherein preparing the transparent slide further comprises adding a stain to the specimen.

### Claim 26

A method comprising:
placing a sensor device on a surface of an object, wherein (i) the sensor device includes a sensor array disposed on a flexible polymer substrate, (ii) the sensor array includes a plurality of transparent sensor circuits, (iii) a surface of the flexible polymer substrate is in contact with and conforms to at least a portion of the surface of the object, and (iv) each of the transparent sensor circuits is disposed at a respective location adjacent to the surface of the object;
detecting electrical signals from the transparent sensor circuits; and
determining parameters at the respective locations adjacent to the surface of the object based on the electrical signals.

### Claim 27 (depends on 26)

The method of claim 26, wherein the portion of the surface of the object is non-planar.

### Claim 28 (depends on 26)

The method of claim 26, wherein the object is selected from the group consisting of a space shuttle, an aircraft, and a body portion of a person.

### Claim 29 (depends on 26)

The method of claim 26, wherein the sensor device further comprises a plurality of interconnects electrically coupled to the plurality of transparent sensor circuits, and wherein each of the transparent sensor circuits includes a respective transparent transistor having (i) a transparent drain electrically coupled to at least one of the interconnects, (ii) a transparent source electrically coupled to at least one of the interconnects, and (iii) a transparent channel region electrically coupled to the source and the drain.

### Claim 30 (depends on 29)

The method of claim 29, wherein the interconnects are transparent.

### Claim 31 (depends on 26)

The method of claim 26, wherein the sensor array is transparent.

### Claim 32 (depends on 26)

The method of claim 26, wherein the parameters are selected from the group consisting of temperatures and electrolyte levels.

### Claim 33

A method for fabricating an integrated circuit, the method comprising the steps of:
forming a layer of a first material on a substrate;
depositing an electron-beam resist layer of a multilayer etch mask on the first material layer;
depositing a photoresist layer of the multilayer etch mask on the electron-beam resist layer, wherein the electron-beam resist layer and the photoresist layer of the multilayer etch mask comprise different materials;
defining a pattern in the photoresist layer, thereby uncovering portions of the electron-beam resist layer; and
developing the uncovered portions of the electron-beam resist layer of the multilayer etch mask, thereby defining the pattern in the electron-beam resist layer.

### Claim 34 (depends on 33)

The method of claim 33, further comprising:
exposing the electron-beam resist layer to high energy radiation.

### Claim 35 (depends on 34)

The method of claim 34, wherein exposing the electron-beam resist layer to the high-energy radiation comprises flood exposing the electron-beam resist layer to the high energy radiation before the deposition of the photoresist layer.

### Claim 36 (depends on 34)

The method of claim 34, wherein the electron-beam resist layer is exposed to the high energy radiation after the definition of the pattern in the photoresist layer.

### Claim 37 (depends on 34)

The method of claim 34, wherein the high energy radiation comprises radiation selected from the group consisting of deep ultraviolet light and electron beam radiation.

### Claim 38 (depends on 34)

The method of claim 34, wherein flood exposing the electron-beam resist layer to high energy radiation comprises exposing the electron-beam resist layer to the high energy radiation without first defining a pattern in the electron-beam resist layer.

### Claim 39 (depends on 33)

The method of claim 33, further comprising etching at least a portion of the first material exposed by the patterned multilayer etch mask.

### Claim 40 (depends on 39)

The method of claim 39, wherein portions of the etched first material underlying the patterned multilayer etch mask comprise channel regions of transparent transistors.

### Claim 41 (depends on 40)

The method of claim 40, further comprising:
removing the patterned multilayer etch mask.

### Claim 42 (depends on 41)

The method of claim 41, wherein removing the patterned multilayer etch mask comprises immersing the etch mask in a solvent.

### Claim 43 (depends on 42)

The method of claim 42, wherein the solvent is selected from the group consisting of acetone and N-methyl-2-pyrrolidone (NMP).

### Claim 44 (depends on 41)

The method of claim 41, further comprising, after removing the patterned multilayer etch mask:
forming a layer of a second material on the integrated circuit; and
defining a pattern in the layer of second material, thereby exposing at least portions of the channel regions of the transparent transistors.

### Claim 45 (depends on 44)

The method of claim 44, wherein the second material comprises an electrical insulator.

### Claim 46 (depends on 33)

The method of claim 33, wherein the first material is transparent.

### Claim 47 (depends on 46)

The method of claim 46, wherein the first material comprises a material selected from the group consisting of graphene, a transition metal dichalcogenide, a metal oxide, and combinations thereof.