# US 10,483,123 B2 · Method for making a well disposed over a sensor

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- Number: US 10,483,123 B2
- Document ID: US10483123B2
- Status: Granted
- Kind: B2
- Application number: 15/945,707
- Filed: 2018-04-04
- Published: 2018-12-20
- Granted: 2019-11-19
- Earliest claimed: 2017-04-04
- Assignees: Life Technologies Corporation
- Applicants: Life Technologies Corporation
- Inventors: Phil Waggoner; Jordan Owens
- Web page: https://patentgrep.com/patent/US10483123B2

## CPC

- H10P 50/73: {using masks for insulating materials}
- G01N 27/4146: {involving nanosized elements, e.g. nanotubes, nanowires}
- G01N 27/4148: {Integrated circuits therefor, e.g. fabricated by CMOS processing}
- H10P 14/43: Chemical deposition, e.g. chemical vapour deposition [CVD]
- H10P 50/264: {by chemical means}
- H10P 50/283: {by chemical means}
- H10P 70/23: {during, before or after processing of insulating materials}
- H10P 76/20: of masks comprising organic 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 for forming a well providing access to a sensor pad includes patterning a first photoresist layer over a dielectric structure disposed over the sensor pad; etching a first access into the dielectric structure and over the sensor pad, the first access having a first characteristic diameter; patterning a second photoresist layer over the dielectric structure; and etching a second access over the dielectric structure and over the sensor pad. The second access has a second characteristic diameter. The first and second accesses overlapping. A diameter ratio of the first characteristic diameter to the second characteristic diameter is not greater than 0.7. The first access exposes the sensor pad. The second access has a bottom depth less than a bottom depth of the first access.

## Claims

### Claim 1

A method for forming a well providing access to a sensor pad, the method comprising:
patterning a first photoresist layer over a dielectric structure disposed over the sensor pad;
etching a first access into the dielectric structure and over the sensor pad, the first access having a first characteristic diameter;
depositing a bottom anti-reflective coating following etching the first access, wherein the bottom anti-reflective coating is at least partially disposed in the first access;
patterning a second photoresist layer over the dielectric structure after depositing a bottom anti-reflective coating; and
etching a second access over the dielectric structure and over the sensor pad, the second access having a second characteristic diameter, the first and second accesses overlapping, a diameter ratio of the first characteristic diameter to the second characteristic diameter being not greater than 0.7, the first access exposing the sensor pad, the second access having a bottom depth less than a bottom depth of the first access.

### Claim 2 (depends on 1)

The method of claim 1, wherein the diameter ratio is in a range of 0.01 to 0.7.

### Claim 3 (depends on 2)

The method of claim 2, wherein the diameter ratio is in a range of 0.05 to 0.6.

### Claim 4 (depends on 3)

The method of claim 3, wherein the diameter ratio is in a range of 0.1 to 0.6.

### Claim 5 (depends on 4)

The method of claim 4, wherein the diameter ratio is in a range of 0.3 to 0.6.

### Claim 6 (depends on 1)

The method of claim 1, wherein etching the first access includes etching the first access to a bottom depth to expose the sensor pad.

### Claim 7 (depends on 1)

The method of claim 1, wherein etching the first access includes etching the first access to a bottom depth that does not expose the sensor pad.

### Claim 8 (depends on 1)

The method of claim 1, wherein the dielectric structure includes an oxide layer and a nitride layer.

### Claim 9 (depends on 8)

The method of claim 8, wherein the oxide layer is a high density plasma chemical vapor deposited silicon dioxide layer.

### Claim 10 (depends on 8)

The method of claim 8, wherein the dielectric structure further includes a tetraethyl orthosilicate deposited oxide layer.

### Claim 11 (depends on 10)

The method of claim 10, wherein etching the first access includes etching the first access through the low temperature oxide layer, the nitride layer and the oxide layer.

### Claim 12 (depends on 10)

The method of claim 10, wherein etching the first access includes etching the first access through the low temperature oxide layer and not the oxide layer.

### Claim 13 (depends on 10)

The method of claim 10, wherein etching the second access includes etching the second access through the low temperature oxide layer and the nitride layer.

### Claim 14 (depends on 13)

The method of claim 13, wherein etching the second access includes etching the second access partially into the oxide layer.

### Claim 15 (depends on 1)

The method of claim 1, further comprising cleaning with an oxygen ash step following etching the second access.

### Claim 16 (depends on 15)

The method of claim 15, further comprising performing a vapor hydrogen fluoride treatment following the oxygen ash step.

### Claim 17 (depends on 1)

The method of claim 1, further comprising depositing a conformal metal coating over the first and second accesses following etching the second access.

### Claim 18 (depends on 17)

The method of claim 17, further comprising removing the conformal metal coating from interstitial areas over the dielectric structure.