# US 10,373,900 B2 · Tin-zinc microbump structures and method of making same

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- Number: US 10,373,900 B2
- Document ID: US10373900B2
- Status: Granted
- Kind: B2
- Application number: 15/806,231
- Filed: 2017-11-07
- Published: 2018-03-15
- Granted: 2019-08-06
- Earliest claimed: 2016-09-15
- Assignees: Intel Corporation
- Applicants: Intel Corporation
- Inventors: Sri Chaitra J. Chavali; Amanda E. Schuckman; Kyu Oh Lee
- Web page: https://patentgrep.com/patent/US10373900B2

## CPC

- H10W 90/701: {characterised by the relative positions of pads or connectors relative to package parts}
- H10W 70/095: {of vias therein}
- H10W 70/635: {Through-vias}
- H10W 72/20: Bump connectors, e.g. solder bumps or copper pillars; Dummy bumps; Thermal bumps
- H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu}
- H10W 90/401: {characterised by multiple insulating or insulated package substrates, interposers or RDLs}
- H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

Techniques and mechanisms for providing effective connectivity with surface level microbumps on an integrated circuit package substrate. In an embodiment, different metals are variously electroplated to form a microbump which extends through a surface-level dielectric of a substrate to a seed layer including copper. The microbump includes a combination of tin and zinc that mitigates precipitation of residual copper by promoting the formation of miconstituents in the microbump. In another embodiment, the microbump has a mass fraction of zinc, or a mass fraction of tin, that is different in various regions along a height of the microbump.

## Claims

### Claim 1

A method for forming microbumps on a substrate, the method comprising:
patterning a dielectric layer, wherein a copper contact is exposed by an opening formed by the dielectric layer;
forming a surface finish directly on the copper contact;
performing a deposition of a seed layer directly on the surface finish, the seed layer including copper;
electroplating tin of a first microbump directly on the seed layer; and
electroplating zinc of the first microbump directly on the tin.

### Claim 2 (depends on 1)

The method of claim 1, wherein the tin of the microbump is electroplated directly on the copper seed layer.

### Claim 3 (depends on 1)

The method of claim 1 wherein a bottom ten percent of a volume of the first microbump has a first zinc mass fraction, wherein a top 10% of a volume of the first microbump has a second zinc mass fraction and wherein the second zinc mass fraction differs from the first zinc mass fraction by at least 5% of the first zinc mass fraction.

### Claim 4 (depends on 3)

The method of claim 3, wherein the second zinc mass fraction differs from the first zinc mass fraction by at least 10% of the first zinc mass fraction.

### Claim 5 (depends on 1)

The method of claim 1, wherein a total volume of zinc of the first microbump is equal to at least 5% of a total volume of tin of the first microbump.

### Claim 6 (depends on 5)

The method of claim 5, wherein the total volume of zinc of the first microbump is equal to at least 10% of the total volume of tin of the first microbump.

### Claim 7 (depends on 1)

The method of claim 1, wherein a total zinc mass fraction of the first microbump is in a range of 5% to 30%.

### Claim 8 (depends on 7)

The method of claim 7, wherein the total zinc mass fraction of the first microbump is in a range of 5% to 20%.