# US 12,601,708 B2 · Biosensor devices and methods of forming the same

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- Number: US 12,601,708 B2
- Document ID: US12601708B2
- Status: Granted
- Kind: B2
- Application number: 17/315,870
- Filed: 2021-05-10
- Published: 2021-10-21
- Granted: 2026-04-14
- Earliest claimed: 2016-08-31
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Comany Limited
- Inventors: Tung-Tsun Chen; Chien-Kuo Yang; Jui-Cheng Huang; Mark Chen; Ta-Chuan Liao; Cheng-Hsiang Hsieh
- Web page: https://patentgrep.com/patent/US12601708B2

## CPC

- G01N 27/4145: {specially adapted for biomolecules, e.g. gate electrode with immobilised receptors}
- G01N 33/54373: {involving physiochemical end-point determination, e.g. wave-guides, FETS, gratings}
- H10D 62/115: {Dielectric isolations, e.g. air gaps}
- H10D 62/124: {Shapes, relative sizes or dispositions of the regions of semiconductor bodies or of junctions between the regions}
- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- H10D 62/235: {of IGFETs (IGFETs having buried channels H10D30/637)}
- H10D 64/512: {Disposition of the gate electrodes, e.g. buried gates}
- H10D 64/661: {the conductor comprising a layer of silicon contacting the insulator, e.g. polysilicon having vertical doping variation (having lateral variation in the gate structure H10D64/671)}
- H10P 50/283: {by chemical means}
- H10P 50/642: {Chemical etching}
- G01N 27/4148: {Integrated circuits therefor, e.g. fabricated by CMOS processing}
- 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)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Biosensor devices and methods of forming the same are provided. A cavity is formed in a substrate and is configured to receive one or more charged molecules. A transistor is formed in the substrate and includes a source region, a drain region, and a channel region that are spatially separated from the cavity in a lateral direction. A gate of the transistor is disposed below the cavity and extends between the cavity and the source, drain, and channel regions. A voltage potential of the gate is based on a number of the charged molecules in the cavity.

## Claims

### Claim 1

A method of forming a biosensor device comprising:
forming a cavity that extends entirely through a first layer and a second layer, wherein the cavity is configured to receive one or more charged molecules;
forming a transistor, the transistor including source, drain, and channel regions that are spatially separated from the cavity in a lateral direction by an insulator material; and
forming a gate of the transistor disposed below the cavity and extending between the cavity and the source, drain, and channel regions, wherein a voltage potential of the gate is based on a number of charged molecules in the cavity, a bottom surface of the gate is above a top surface of a substrate, the cavity is above a top surface of the gate, the source, drain and channel regions are within the second layer, and the gate is below a bottom surface of the second layer.

### Claim 2 (depends on 1)

The method of claim 1, wherein the second layer is formed over the first layer and comprises a dielectric material.

### Claim 3 (depends on 1)

The method of claim 1, wherein the cavity is formed using a backside etching process.

### Claim 4 (depends on 3)

The method of claim 3, wherein the cavity comprises an opening formed in an oxide layer and a top silicon layer of a silicon-on-insulator (SOI) wafer.

### Claim 5 (depends on 4)

The method of claim 4, wherein the transistor is formed in a top silicon layer of the SOI wafer.

### Claim 6 (depends on 1)

The method of claim 1, wherein the cavity comprises a dry environment.

### Claim 7 (depends on 6)

The method of claim 6, wherein the cavity is configured to immobilize the one or more charged molecules without a fluidic solution.

### Claim 8 (depends on 1)

The method of claim 1, wherein the source, drain, and channel regions are between the first layer and the gate.

### Claim 9

A method of forming a biosensor device comprising:
forming a cavity, wherein the cavity comprises an opening that extends entirely through a first layer and a second layer, wherein the cavity is configured to receive one or more charged molecules;
forming a transistor in the first layer, where the transistor includes source, drain, and channel regions that are spatially separated from the cavity in a lateral direction by an insulator material; and
forming a gate of the transistor disposed below the cavity and extending between the cavity and the source, drain, and channel regions, wherein a voltage potential of the gate is based on a number of charged molecules in the cavity, the gate is above a top surface of a substrate, a top surface and a bottom surface of the cavity are both above a top surface of the gate, the source, drain and channel regions are within the second layer, and the gate is below a bottom surface of the second layer.

### Claim 10 (depends on 9)

The method of claim 9, wherein a current between the source and drain regions of the transistor is based on the voltage potential of the gate.

### Claim 11 (depends on 10)

The method of claim 10, wherein the first layer comprises an active semiconductor region surrounded by shallow trench isolation (STI) insulator material.

### Claim 12 (depends on 11)

The method of claim 11, wherein the second layer comprises a buried oxide layer of a silicon-on-insulator (SOI) wafer.

### Claim 13 (depends on 12)

The method of claim 12, wherein the active semiconductor region is formed in a top silicon layer of the SOI wafer.

### Claim 14 (depends on 9)

The method of claim 9, wherein the gate comprises polysilicon formed below the first layer.

### Claim 15 (depends on 9)

The method of claim 9, wherein the cavity comprises a dry environment.

### Claim 16 (depends on 9)

The method of claim 9, wherein the cavity is configured to immobilize the one or more charged molecules without a fluidic solution.

### Claim 17

A method of forming a biosensor device comprising:
extending a cavity through a first layer and a second layer, wherein the cavity is configured to receive one or more charged molecules;
forming a transistor including source, drain, and channel regions that are spatially separated from the cavity by an insulator material; and
forming a gate of the transistor, wherein the gate is disposed below the cavity and extends between the cavity and the source, drain, and channel regions, a bottom surface of the gate is above a top surface of a substrate, the cavity is above a top surface of the gate, the source, drain and channel regions are within the second layer, and the gate is below a bottom surface of the second layer.

### Claim 18 (depends on 17)

The method of claim 17, wherein the cavity comprises a dry environment.

### Claim 19 (depends on 17)

The method of claim 17, further comprising:
generating an output by the biosensor device, wherein the generated output is indicative of a number of charged molecules present in the cavity.

### Claim 20 (depends on 19)

The method of claim 19, wherein the cavity is formed using a backside etching process.