Method for making a well disposed over a sensor

Patent metadata

Field	Value
Publication number	US-11004690-B2
Application number	US-201916687630-A
Country	US
Kind code	B2
Filing date	Nov 18, 2019
Priority date	Apr 4, 2017
Publication date	May 11, 2021
Grant date	May 11, 2021

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.

First claim

What is claimed is:

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; the dielectric structure comprising a nitride layer disposed over an oxide layer;
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 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.

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

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

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

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

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

7. 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.

8. The method of claim 1 , wherein the oxide layer is a high density plasma chemical vapor deposited silicon dioxide layer.

9. The method of claim 1 , wherein the dielectric structure further includes a tetraethyl orthosilicate deposited oxide layer.

10. The method of claim 9 , wherein the low temperature oxide layer is disposed over the nitride layer.

11. The method of claim 9 , wherein etching the first access includes etching the first access through the low temperature oxide layer, the nitride layer and the oxide layer.

12. The method of claim 9 , wherein etching the first access includes etching the first access through the low temperature oxide layer and not the oxide layer.

13. The method of claim 9 , wherein etching the second access includes etching the second access through the low temperature oxide layer and the nitride layer.

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

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

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

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

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

Assignees

• Life Technologies Corp

Inventors

• Waggoner Phil
• Owens Jordan

Classifications

• H10P76/20

  of masks comprising organic materials · CPC title

• H10P70/23

  during, before or after processing of insulating materials · CPC title

• H10P50/283

  by chemical means · CPC title

• H10P50/264

  by chemical means · CPC title

• H10P14/43

  Chemical deposition, e.g. chemical vapour deposition [CVD] · CPC title