Bond-pad integration scheme for improved moisture barrier and electrical contact

Patent metadata

Field	Value
Publication number	US-9304283-B2
Application number	US-201414533967-A
Country	US
Kind code	B2
Filing date	Nov 5, 2014
Priority date	May 22, 2014
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

An apparatus includes first and second electrodes separated by an insulative material (such as a piezoelectric material). The apparatus also includes a protective layer over the first and second electrodes. The protective layer has a first opening that exposes a portion of the first electrode and a second opening that exposes a portion of the second electrode. The apparatus further includes a first electrical contact at least partially within the first opening and electrically coupled to the first electrode. In addition, the apparatus includes a second electrical contact at least partially within the second opening and electrically coupled to the second electrode. Each of the first and second electrical contacts includes a stack of metal layers. The stack of metal layers includes a titanium nitride layer, a titanium layer over the titanium nitride layer, and an aluminum copper layer over the titanium nitride layer and the titanium layer.

First claim

What is claimed is:

1. An apparatus comprising:
first and second electrodes separated by an insulative material;
a protective layer over the first and second electrodes, the protective layer having a first opening that exposes a portion of the first electrode and a second opening that exposes a portion of the second electrode;
a first electrical contact at least partially within the first opening and electrically coupled to the first electrode; and
a second electrical contact at least partially within the second opening and electrically coupled to the second electrode;
wherein each of the first and second electrical contacts comprises a stack of metal layers, the stack of metal layers comprising a titanium nitride layer, a titanium layer over the titanium nitride layer, and an aluminum copper layer over the titanium nitride layer and the titanium layer.

2. The apparatus of claim 1 , wherein:
the apparatus further comprises a lens material forming a lens; and
the insulative material comprises a piezoelectric material configured to change a shape of the lens material in response to a voltage across the first and second electrodes to thereby change a focus of the lens.

3. The apparatus of claim 1 , further comprising:
a first bond pad electrically coupled to the first electrical contact; and
a second bond pad electrically coupled to the second electrical contact.

4. The apparatus of claim 3 , wherein:
the first bond pad resides within a first window through the first electrode; and
the second bond pad resides within a second window through the first electrode.

5. The apparatus of claim 1 , wherein the first and second electrodes comprise platinum.

6. The apparatus of claim 1 , wherein the insulative material comprises lead zirconium titanate.

7. The apparatus of claim 1 , wherein, in each of the first and second electrical contacts:
the titanium nitride layer is configured to substantially block moisture from reaching the insulative material through the first or second opening of the protective layer;
the aluminum copper layer is configured to provide an electrical surface through which the apparatus is electrically coupled to an external device; and
the titanium layer substantially prevents a reaction involving the titanium nitride layer from occurring during a wet etch of the aluminum copper layer.

8. A system comprising:
an auto-focus lens comprising a lens material forming a lens; and
a driver configured to change a shape of the lens material in order to change a focus of the lens;
wherein the auto-focus lens further comprises:
first and second electrodes separated by an insulative piezoelectric material, the insulative piezoelectric material configured to change the shape of the lens material in response to a voltage across the first and second electrodes;
a protective layer over the lens material and over the first and second electrodes, the protective layer having a first opening that exposes a portion of the first electrode and a second opening that exposes a portion of the second electrode;
a first electrical contact at least partially within the first opening and electrically coupled to the first electrode and to the driver; and
a second electrical contact at least partially within the second opening and electrically coupled to the second electrode and to the driver;

wherein each of the first and second electrical contacts comprises a stack of metal layers, the stack of metal layers comprising a titanium nitride layer, a titanium layer over the titanium nitride layer, and an aluminum copper layer over the titanium nitride layer and the titanium layer.

9. The system of claim 8 , wherein:
the lens further comprises a first bond pad electrically coupled to the first electrical contact and a second bond pad electrically coupled to the second electrical contact; and
the “first bond pad and the second bond pad” electrically couple the auto-focus lens to the driver.

10. The system of claim 9 , wherein:
the first bond pad resides within a first window through the first electrode; and
the second bond pad resides within a second window through the first electrode.

11. The system of claim 8 , wherein the first and second electrodes comprise platinum.

12. The system of claim 8 , wherein the insulative piezoelectric material comprises lead zirconium titanate.

13. The system of claim 8 , wherein in each of the first and second electrical contacts:
the titanium nitride layer is configured to substantially block moisture from reaching the insulative material through the first or second opening of the protective layer;
the aluminum copper layer is configured to provide an electrical surface through which the apparatus is electrically coupled to an external device; and
the titanium layer substantially prevents a reaction involving the titanium nitride layer from occurring during a wet etch of the aluminum copper layer.

14. The system of claim 8 , further comprising:
an image detector configured to capture images using light that passes through the auto-focus lens.

15. The system of claim 14 , further comprising:
at least one processing device configured to process information generated by the image detector to create image files; and
at least one memory configured to store the image files.

16. A method comprising:
forming a stack of metal layers over multiple electrodes and over a protective layer of a device, the protective layer having a first opening that exposes a portion of the first electrode and a second opening that exposes a portion of the second electrode; and
etching the stack of metal layers to form (i) a first electrical contact at least partially within the first opening and electrically coupled to the first electrode and (ii) a second electrical contact at least partially within the second opening and electrically coupled to the second electrode;
wherein the stack of metal layers comprises a titanium nitride layer, a titanium layer over the titanium nitride layer, and an aluminum copper layer over the titanium nitride layer and the titanium layer.

17. The method of claim 16 , wherein etching the stack of metal layers comprises:
performing a wet etch through the aluminum copper layer; and
performing a dry plasma etch through the titanium layer and the titanium nitride layer.

18. The method of claim 16 , further comprising:
depositing a lens material on a substrate;
forming the first electrode over the lens material, a piezoelectric layer over the first electrode, and the second electrode over the piezoelectric layer;
forming the protective layer over the lens material and over the first and second electrodes;
forming the first and second openings through the protective layer; and
removing at least part of the substrate.

19. The method of claim 16 , further comprising:
forming a first bond pad and electrically coupling the first bond pad to the first electrical contact; and
forming a second bond pad and electrically coupling the second bond pad to the second electrical contact.

20. The method of claim 19 , wherein:
the first bond pad resides within a first window through the first electrode; and
the second bond pad resides within a second window through the first electrode.

Assignees

• Texas Instruments Inc

Inventors

• Soman Joel
• Jiang Neng
• Summerfelt Scott
• Lassiter Thomas Warren
• Mohammed Nayeemuddin
• Roby Mary Alyssa Drummond

Classifications

• H10P50/267

  using plasmas · CPC title

• H10P50/71

  using masks for conductive or resistive materials · CPC title

• H04N23/80

  Camera processing pipelines; Components thereof · CPC title

• H04N23/55

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• G02B7/09 Primary

  adapted for automatic focusing or varying magnification · CPC title