# US 6,297,160 B1 · Application of pure aluminum to prevent pad corrosion

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- Number: US 6,297,160 B1
- Document ID: US6297160B1
- Status: Granted
- Kind: B1
- Application number: 09/266,881
- Filed: 1999-03-12
- Granted: 2001-10-02
- Earliest claimed: 1999-03-12
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Wen-Cheng Chien
- Web page: https://patentgrep.com/patent/US6297160B1

## CPC

- H10W 20/425: {Barrier, adhesion or liner layers}
- H10W 20/031: {of conductive parts of the interconnections}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method of forming a layer of top level metal within a semiconductor bonding pad that eliminates the formation of surface pitting and surface corrosion that using Prior Art occur due to the presence of minor traces of copper or silicon in that surface. A layer of pure aluminum is deposited on top of the first level metal surface, this level of pure aluminum prevents the occurrence of surface pitting and surface corrosion.

## Claims

### Claim 1

A method of fabricating bonding pads on a semiconductor device formed on a semiconductor wafer, said semiconductor device including a substrate, said method comprising the steps of:
providing top level metal within said bonding pads, said top level metal comprising an aluminum-copper alloy;
depositing a layer of pure aluminum on top of said top level metal; and
establishing a path for electrical contact between said top level metal and said semiconductor device.

### Claim 2 (depends on 1)

The method of claim 1, the step of depositing a layer of pure aluminum comprising depositing pure aluminum using reactive sputtering.

### Claim 3 (depends on 1)

The method of claim 1 wherein said establishing a path for electrical contact between said top level metal and said semiconductor device is:
forming an anti-reflective coating on the top surface of said pure aluminum;
depositing a passivation layer over said anti-reflective coating; and
etching an opening into said passivation layer through said anti-reflective coating down to the top surface of said layer of pure aluminum.

### Claim 4 (depends on 1)

The method of claim 1 wherein said layer of pure aluminum over said metal layer provides an oxide film of Al2O3.

### Claim 5 (depends on 1)

The method of claim 1 wherein providing top level metal within said bonding pads comprises the steps of:
depositing a first metallization layer over said substrate;
depositing a dielectric layer over said metallization layer;
etching a via hole into said dielectric; and
depositing a second metal layer over said dielectric and within said via hole, said second level metal layer comprising an aluminum-copper alloy.

### Claim 6 (depends on 5)

The method of claim 5, the step of depositing a first metallization layer comprising depositing aluminum by reactive sputtering.

### Claim 7 (depends on 5)

The method of claim 5, the step of depositing a second metallization layer comprising depositing Al—Cu using reactive sputtering.

### Claim 8 (depends on 2)

The method of claim 2 wherein said etching step is performed by a dry etching method.

### Claim 9 (depends on 5)

The method of claim 5, said metallization layer over said substrate forming an electrical interface between said bonding pad and electrical components and devices that provide stimuli to and extract electrical responses from said semiconductor device.

### Claim 10

A method of fabricating bonding pads on a semiconductor device formed on a semiconductor wafer, said semiconductor device including a substrate, said method comprising the steps of:
depositing a first metallization layer over said substrate, forming an electrical interface between said bonding pad and electronic components and devices that supply stimuli to or extract electrical responses from said semiconductor device;
depositing a dielectric layer over said metallization layer,
forming a basis for creating a via opening;
etching a via hole through said dielectric, establishing a first phase of an electrical path between said metallization layer over said substrate and top level metal of said bonding pad;
depositing a second metal layer over the surface of said layer of dielectric and in said via hole, creating top level metal layer of said bonding pad, completing an electrical path between said metallization layer over said substrate and top level metal of said bonding pad, said second level metal layer comprising an aluminum-copper alloy;
depositing a layer of pure aluminum over the surface of said top level metal layer, preventing surface pitting and surface corrosion of the surface of said top level metal;
forming an anti-reflective coating over the surface of said layer of pure aluminum;
depositing a passivation layer over the surface of said anti reflective coating, protecting and electrically isolating said layer of top level metal; and
etching an opening through said passivation layer, further through said anti-reflective coating down to the surface of said layer of pure aluminum, creating an electrical point of contact for said semiconductor device.

### Claim 11 (depends on 10)

The method of claim 10, said first metallization layer over said substrate forming an electrical interface between said bonding pad and electrical components and devices providing stimuli to and extracting electrical responses from said semiconductor device.

### Claim 12 (depends on 10)

The method of claim 10 wherein said layer of pure aluminum over said metal layer provides an oxide film of Al2O3.

### Claim 13 (depends on 10)

The method of claim 10, the step of depositing a first metallization layer comprising depositing aluminum by reactive sputtering.

### Claim 14 (depends on 10)

The method of claim 10, the step of depositing a second metallization layer comprising depositing Al—Cu using reactive sputtering.

### Claim 15 (depends on 10)

The method of claim 10 wherein said etching steps are performed by a dry etching method.

### Claim 16 (depends on 10)

The method of claim 10, the step of depositing a layer of pure aluminum comprising depositing pure aluminum using reactive sputtering.

### Claim 17

A method of fabricating bonding pads on a semiconductor device formed on a semiconductor wafer, said semiconductor device including a substrate, said method comprising the steps of:
depositing a first metallization layer over said substrate;
depositing a dielectric layer over said metallization layer;
masking a portion of said dielectric layer in preparation for a first etching step;
etching the dielectric layer utilizing the dielectric mask as a mask for the dielectric layer;
depositing a second metallization layer overlaying said dielectric layer with the inclusion of the openings etched into said dielectric layer, said second level metallization layer comprising an aluminum-copper alloy;
depositing a layer of pure aluminum overlaying said second metallization layer;
forming a anti-reflective coating over the surface of said layer of pure aluminum;
depositing a passivation layer over the surface of said anti-reflective coating;
masking a portion of said passivation layer in preparation for a second etching step; and
etching said passivation layer, further etching through the anti-reflective coating to the surface of said layer of pure aluminum, forming an exposed region of pure aluminum, forming a bond region of pure aluminum.

### Claim 18 (depends on 17)

The method of claim 17, said first metallization layer over said substrate forming an electrical interface between said bonding pad and electrical components and devices that provide stimuli to and extract electrical responses from said semiconductor device.

### Claim 19 (depends on 17)

The method of claim 17, said layer of pure aluminum over said metal layer providing an oxide film of Al2O3.

### Claim 20 (depends on 17)

The method of claim 17, the step of depositing a first metallization layer comprising depositing aluminum by reactive sputtering.

### Claim 21 (depends on 17)

The method of claim 17, the step of depositing a second metallization layer comprising depositing Al—Cu using reactive sputtering.

### Claim 22 (depends on 17)

The method of claim 17 wherein said etching steps are performed by a dry etching method.

### Claim 23 (depends on 17)

The method of claim 17, the step of depositing a layer of pure aluminum comprising depositing pure aluminum using reactive sputtering.