# US 11,309,269 B2 · Method for producing a solder bump on a substrate surface

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- Number: US 11,309,269 B2
- Document ID: US11309269B2
- Status: Granted
- Kind: B2
- Application number: 16/977,987
- Filed: 2019-03-01
- Published: 2021-03-11
- Granted: 2022-04-19
- Earliest claimed: 2018-03-09
- Assignees: Commissariat A L'energie Atomique Et Aux Energies Alternatives
- Applicants: Commissariat A L'energie Atomique Et Aux Energies Alternatives
- Inventors: Arnaud Garnier; Laetitia Castagne; Anthony De Luca; Daniel Mermin; Pierre Montmeat
- Web page: https://patentgrep.com/patent/US11309269B2

## CPC

- H10W 72/012: {of bump connectors, dummy bumps or thermal bumps}
- H10P 76/202: {for lift-off processes}
- H10W 72/01204: {using temporary auxiliary members, e.g. using sacrificial coatings or handle substrates}
- H10W 72/01223: {in liquid form, e.g. by dispensing droplets or by screen printing}
- H10W 72/01253: {by etching}
- H10W 72/01255: {by using masks}
- H10W 72/01257: {by reflowing}
- H10W 72/01265: {Thermally treating (reflowing H10W72/01257)}
- H10W 72/242: {relative to the surface, e.g. recessed, protruding}
- H10W 72/252: {comprising solid metals or solid metalloids, e.g. PbSn, Ag or Cu}
- H10W 72/29: Bond pads specially adapted therefor
- H10W 72/9415: {relative to the surface, e.g. recessed, protruding}
- H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- H10W 74/129: {forming a chip-scale package [CSP]}
- H10W 74/15: on active surfaces of flip-chip devices, e.g. underfills
- 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
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A serigraphy method for producing a soulder bump on the front surface of a substrate includes: forming a film on the front surface, forming an opening in the film, filling the opening with a souldering material, and removing the film. Forming a film on the front surface is preceded by the formation of an intermediate layer between the film and the front surface, the intermediate layer being adapted to exhibit a force of adherence at one and/or the other interface formed with the first front surface and the film lower than the force of adherence that can be formed between the film and the first front surface.

## Claims

### Claim 1

A method for producing by screen printing at least one solder bump on a first front face of a first substrate, the method comprising the following steps:
a) a step of forming a film covering the first front face;
b) a step of forming at least one opening in the film, said at least one opening being for delimiting the at least one solder bump;
c) a step of filling, by screen printing, the at least one opening with a solder material so as to form the at least one solder bump;
d) a step of removing the film; and
a step preceding step a) includes forming an intermediate layer sandwiched between the film and the first front face,
wherein the intermediate layer has an adhesion energy, at either interface formed with the first front face and the film, which is lower than the adhesion energy of an interface likely to be formed between the film and the first front face.

### Claim 2 (depends on 1)

The method according to claim 1, wherein step a) comprises laminating the preformed film, on the first front face.

### Claim 3 (depends on 1)

The method according to claim 1, wherein a heat treatment step c1) is carried out between steps c) and d), the heat treatment comprising temperature rise.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the first front face is provided with at least one metal pad on which the at least one solder bump is formed.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the film comprises a photosensitive material.

### Claim 6 (depends on 5)

The method according to claim 5, wherein step b) comprises a photolithography step.

### Claim 7 (depends on 1)

The method according to claim 1, wherein step b) also comprises removing the intermediate layer from the bottom of the at least one opening.

### Claim 8 (depends on 7)

The method according to claim 7, wherein removing the intermediate layer from the bottom of the at least one opening is carried out by plasma etching.

### Claim 9 (depends on 7)

The method according to claim 7, wherein removing the intermediate layer from the bottom of the at least one opening is carried out by ion beam etching so as to re-deposit etching residues from the intermediate layer on the flanks of the at least one opening.

### Claim 10 (depends on 7)

The method according to claim 7, wherein removing the intermediate layer from the bottom of the at least one opening is preceded by forming an additional intermediate layer, having the same nature as the intermediate layer, covering the film, and from the bottom and the flanks of the at least one opening.

### Claim 11 (depends on 10)

The method according to claim 10, wherein forming the additional intermediate layer is followed by an anisotropic etching step adapted to remove the additional intermediate layer and the intermediate layer from the bottom of the at least one opening, and keep at least partly the additional intermediate layer on the flanks of the at least one opening.

### Claim 12 (depends on 1)

The method according to claim 1, wherein step d) is carried out by peeling.

### Claim 13 (depends on 1)

The method according to claim 1, wherein step d) is followed by a second heat treatment step, called a step e) which comprises temperature rise for providing the at least one solder bump with a truncated sphere shape.

### Claim 14 (depends on 13)

The method according to claim 13, wherein step e) is followed by a step f) of assembling the first substrate with a second substrate, the assembling comprising contacting the at least one solder bump with a face, called a second front face, of the second substrate.

### Claim 15 (depends on 14)

The method according to claim 14, wherein step f) is followed by a step of filling the space included between the first and the second front faces with a polymeric material.

### Claim 16 (depends on 1)

The method according to claim 1, wherein the intermediate layer has a thickness lower than 100 nm.

### Claim 17 (depends on 1)

The method according to claim 1, wherein the intermediate layer comprises a fluorinated polymer.

### Claim 18 (depends on 1)

The method according to claim 1, wherein the adhesion energy between the intermediate layer and either of the interfaces with the first front face and the film, is lower than 1 J/m2.