# US 2014/0191292 A1 · Methods and systems for point of use removal of sacrificial material

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- Number: US 2014/0191292 A1
- Document ID: US20140191292A1
- Status: Published application
- Kind: A1
- Application number: 13/734,696
- Filed: 2013-01-04
- Published: 2014-07-10
- Earliest claimed: 2013-01-04
- Assignees: Life Technologies Corporation
- Applicants: Life Technologies Corporation
- Inventors: Christina INMAN; Alexander MASTROIANNI; Wolfgang HINZ; Shifeng LI; Scott BENSON
- Web page: https://patentgrep.com/patent/US20140191292A1

## CPC

- H10P 50/282: {of inorganic materials}
- G01N 27/4145: {specially adapted for biomolecules, e.g. gate electrode with immobilised receptors}
- H10P 50/73: {using masks for insulating materials}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- 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)

## Abstract

A method of manufacturing a sensor, the method including forming an array of chemically-sensitive field effect transistors (chemFETs), depositing a dielectric layer over the chemFETs in the array, depositing a protective layer over the dielectric layer, etching the dielectric layer and the protective layer to form cavities corresponding to sensing surfaces of the chemFETs, and removing the protective layer. The method further includes, etching the dielectric layer and the protective layer together to form cavities corresponding to sensing surfaces of the chemFETs. The protective layer is at least one of a polymer, photoresist material, noble metal, copper oxide, and zinc oxide. The protective layer is removed using at least one of sodium hydroxide, organic solvent, aqua regia, ammonium carbonate, hydrochloric acid, acetic acid, and phosphoric acid.

## Claims

### Claim 1

A method of manufacturing a sensor, the method comprising:
forming an array of chemically-sensitive field effect transistors (chemFETs);
depositing a dielectric layer over the chemFETs in the array;
depositing a protective layer over the dielectric layer;
etching the dielectric layer and the protective layer to form cavities corresponding to sensing surfaces of the chemFETs; and
removing the protective layer.

### Claim 2 (depends on 1)

The method of claim 1, further comprising patterning a photosensitive etch mask on the protective layer and wherein the etching of the dielectric layer and the protective layer is a photolithographic process.

### Claim 3 (depends on 1)

The method of claim 1, further comprising etching the dielectric layer and the protective layer together to form cavities corresponding to sensing surfaces of the chemFETs.

### Claim 4 (depends on 1)

The method of claim 1, wherein the protective layer is at least one of a polymer, photoresist material, noble metal, copper oxide, and zinc oxide.

### Claim 5 (depends on 1)

The method of claim 1, wherein the protective layer is removed using at least one of an acid, a base, and an oxidizing solution.

### Claim 6 (depends on 1)

The method of claim 1, wherein the protective layer is removed using at least one of sodium hydroxide, organic solvent, aqua regia, ammonium carbonate, hydrochloric acid, acetic acid, and phosphoric acid.

### Claim 7 (depends on 2)

The method of claim 2, wherein the removing the protective layer includes removal of photoresist residue contamination resulting from the etching step.

### Claim 8 (depends on 1)

The method of claim 1, wherein the dielectric layer includes at least one of silicon oxide, silicon nitride and silicon oxynitride.

### Claim 9

A sensor, comprising:
an array of chemically-sensitive field effect transistors (chemFETs), each chemFET in the array having a floating gate structure including an upper surface;
a dielectric layer over the upper surfaces of the floating gate structures of the chemFETs in the array, the dielectric layer including cavities extending to the upper surfaces of the floating gate structures and corresponding to sensing surfaces of the chemFETs;
a conformal protective layer over the sensing surfaces, sidewalls of the cavities, and top surface of the array.

### Claim 10 (depends on 9)

The sensor of claim 9, wherein the protective layer defines a removable layer.

### Claim 11 (depends on 9)

The sensor of claim 9, wherein the protective layer is at least one of a polymer, photoresist, noble metal, copper oxide, and zinc oxide.

### Claim 12 (depends on 9)

The sensor of claim 9, wherein the protective layer is removed using at least one of sodium hydroxide, organic solvent, aqua regia, ammonium carbonate, hydrochloric acid, acetic acid, and phosphoric.

### Claim 13 (depends on 9)

The sensor of claim 9, wherein the dielectric layer includes at least one of silicon oxide, silicon nitride and silicon oxynitride.

### Claim 14 (depends on 9)

The sensor of claim 9, wherein the sensing surface comprises at least one of tantalum oxide, titanium oxide, and titanium nitride.

### Claim 15 (depends on 9)

The sensor of claim 9, wherein the sensing surface comprises a metal oxide or metal nitride selected from one or more of the group of Al2O3, Ta2O5, HfO3, WO3, ZrO2, TiO2 or mixtures thereof.