# US 10,763,232 B1 · Electrical joint structure

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- Number: US 10,763,232 B1
- Document ID: US10763232B1
- Status: Granted
- Kind: B1
- Application number: 16/367,277
- Filed: 2019-03-28
- Granted: 2020-09-01
- Earliest claimed: 2019-03-28
- Assignees: Mikro Mesa Technology Co., Ltd.
- Applicants: Mikro Mesa Technology Co., Ltd.
- Inventors: Li-Yi Chen
- Web page: https://patentgrep.com/patent/US10763232B1

## CPC

- C22C 9/02: with tin as the next major constituent
- H10W 72/30: Die-attach connectors
- B23K 35/0238: {layered}
- B23K 35/262: {Sn as the principal constituent}
- B23K 35/302: {Cu as the principal constituent}
- B32B 15/018: {one layer being formed of a noble metal or a noble metal alloy}
- B23K 2101/36: Electric or electronic devices
- B23K 2101/40: Semiconductor devices
- H10W 72/073: {of die-attach connectors}
- H10W 72/07304: {the auxiliary member being temporary, e.g. a sacrificial coating}
- H10W 72/07321: {Aligning}
- H10W 72/07336: {Soldering or alloying}
- H10W 72/07352: {changes in structures or sizes}
- H10W 72/07354: {changes in dispositions}
- H10W 72/07355: {changes in materials}
- H10W 72/321: {Structures or relative sizes of die-attach connectors}
- H10W 72/322: {Multilayered die-attach connectors, e.g. a coating on a top surface of a core}
- H10W 72/348: {Top-view layouts, e.g. mirror arrays}
- H10W 72/352: {comprising metals or metalloids, e.g. solders}
- H10W 72/3528: {Intermetallic compounds}
- H10W 72/357: {Multiple die-attach connectors having different materials}
- H10W 90/734: {between a chip and a stacked insulating package substrate, interposer or RDL}
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM

## Abstract

An electrical joint structure including a substrate, a multi-layer bonding structure, and a blocking layer is provided. The multi-layer bonding structure is present on the substrate and includes a diffusive metal layer and a tin-rich layer. The diffusive metal layer includes a copper-tin alloy on a surface of the diffusive metal layer. The surface faces the substrate. A thickness of the copper-tin alloy is less than or equal to 2 μm. The tin-rich layer is present on and in contact with the diffusive metal layer. The blocking layer is present between the multi-layer bonding structure and the substrate and at least in contact with a part of said copper-tin alloy, such that the multi-layer bonding structure is spaced apart from the substrate.

## Claims

### Claim 1

An electrical joint structure, comprising:
a substrate;
a multi-layer bonding structure present on the substrate and comprising:
a diffusive metal layer comprising a copper-tin alloy on a surface of the diffusive metal layer facing the substrate, wherein a thickness of the copper-tin alloy is less than or equal to 2 μm; and
a tin-rich layer present on and in contact with the diffusive metal layer; and
a blocking layer present between the multi-layer bonding structure and the substrate and at least in contact with a part of said copper-tin alloy, such that the multi-layer bonding structure is spaced apart from the substrate, wherein a contact area between the blocking layer and the multi-layer bonding structure is less than or equal to 1 square millimeter.

### Claim 2 (depends on 1)

The electrical joint structure of claim 1, further comprising an adhesive layer present between the blocking layer and the substrate.

### Claim 3 (depends on 2)

The electrical joint structure of claim 2, wherein the adhesive layer comprises titanium, molybdenum, chromium, or combinations thereof.

### Claim 4 (depends on 1)

The electrical joint structure of claim 1, wherein more than 60% of Sn present in the tin-rich layer.

### Claim 5 (depends on 1)

The electrical joint structure of claim 1, wherein the copper-tin alloy comprises Cu3Sn.

### Claim 6 (depends on 1)

The electrical joint structure of claim 1, wherein the copper-tin alloy comprises Cu6Sn5.

### Claim 7 (depends on 1)

The electrical joint structure of claim 1, wherein a thickness of the tin-rich layer is greater than or equal to about 0.2 μm.

### Claim 8 (depends on 1)

The electrical joint structure of claim 1, wherein a thickness of the tin-rich layer is greater than or equal to about 0.3 μm.

### Claim 9 (depends on 1)

The electrical joint structure of claim 1, wherein the blocking layer comprises titanium, molybdenum, or a combination thereof.

### Claim 10 (depends on 1)

The electrical joint structure of claim 1, wherein the diffusive metal layer comprising copper.

### Claim 11 (depends on 1)

The electrical joint structure of claim 1, further comprising a micro device present on the multi-layer bonding structure.

### Claim 12 (depends on 11)

The electrical joint structure of claim 11, wherein the micro device comprises:
a first type semiconductor layer in contact with the tin-rich layer;
an active layer present on the first type semiconductor layer; and
a second type semiconductor layer joined with the first type semiconductor layer through the active layer.