Patent US5384283A successfully refreshed from Google Patents.
US5384283A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resist protection of ball limiting metal during etch process
Assignee: International Business Machines Corp
•
Filing: 1993-12-10
•
Granted: 1995-01-24
•
Expires: 2013-12-10
Abstract
Abstract A method of making integrated circuit chip to substrate connections first deposits a blanket layer of CrCu over a completed wafer which has terminal vias etched in the final insulator. Then PbSn solder is electrolytically plated through a photoresist mask. After the plating is done, the resist is removed and the Cu is etched using the solder dot as a mask, and then the solder dots are melted to form spheroid or ball shapes. Next, a positive photoresist is applied in a manner that distributes the photoresist around the base of the solder balls. The solder balls are then used as a self-aligned exposure mask. Since the photoresist under the balls is not exposed, each ball has a concentric layer of resist at the base after exposure and development. This concentric layer of resist protects the Cu/PbSn interface and is used as the mask for etching excess Cr. The resist is then removed.
Inventors
- 👤 Richard E. Gegenwarth
- 👤 Anthony F. Arnold
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:22
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/01; H10W72/012; H10W72/019; H10W72/01951; H10W72/20; H10W72/251; H10W72/252; H10W72/90; H10W72/921; H10W72/923; H10W72/951; H10W72/952
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
187 words
A method of forming a metallic contact on an integrated circuit comprising the steps of: a) depositing a first layer of metal; b) depositing a second layer of metal; c) plating and patterning a layer of solder above said second layer of metal; d) reflowing the patterned solder by melting to form a set of spheroidal solder ball contacts having a bottom diameter abutting said second layer of metal: e) etching the second layer of metal using the solder ball contacts as a mask; f) applying a positive photoresist having a viscosity, and a solvent having a chemical composition, at a temperature such that the solvent wets the solder at said bottom diameter; g) exposing and stripping said photoresist using the solder ball contacts as a self aligned exposure mask, thereby forming a protective ring about said bottom diameter: and h) etching said first layer of metal, so that said solder is resting on a shoulder of said first layer of metal, the etched first layer of metal forming a disk under each solder ball contact larger than a disk formed by the second layer of metal.
Claim 2
Independent Claim
187 words
A method of forming a metallic contact on an integrated circuit comprising the steps of: a) depositing a first layer of metal; b) depositing a second layer of metal; c) plating and patterning a layer of solder above said second layer of metal; d) reflowing the patterned solder by melting to form a set of spheroidal solder ball contacts having a bottom diameter abutting said second layer of metal: e) etching the second layer of metal using the solder ball contacts as a mask; f) applying a positive photoresist having a viscosity, and a solvent having a chemical composition, at a temperature such that the solvent wets the solder at said bottom diameter; g) exposing and stripping said photoresist using the solder ball contacts as a self aligned exposure mask, thereby forming a protective ring about said bottom diameter: and h) etching said first layer of metal, so that said solder is resting on a shoulder of said first layer of metal, the etched first layer of metal forming a disk under each solder ball contact larger than a disk formed by the second layer of metal.
Claim 3
Dependent Claim
31 words
The method recited in claim 1 wherein said first metal is chromium and said second metal is copper, the photoresist covering and protecting an interface between the copper and the solder.
Claim 4
Dependent Claim
20 words
The method recited in claim 1 further comprising the step of removing the photoresist ring after said etching step (h).
Claim 5
Dependent Claim
32 words
The method recited in claim 1 wherein depositing said second layer of metal is performed by sputter depositing chromium in compression, followed by evaporating CrCuAu in tension to reduce the film stress.
Claim 6
Dependent Claim
37 words
The method recited in claim 1 wherein depositing said second layer of metal is performed by sputter depositing chromium to control stress levels and adhesion to certain insulators, followed by evaporating CrCuAu through a Molybdenum lift-off mask.
Claim 7
Dependent Claim
19 words
The method recited in claim 1 wherein said first and second layers of metal are Ti/Ni and Cu/Au, respectively.
Claim 8
Dependent Claim
20 words
The method recited in claim 1 wherein said first and second layers of metal are Cr/phased CrCu and Cu, respectively.
Claim 9
Dependent Claim
19 words
The method recited in claim 1 wherein said first and second layers of metal are TiW and Cu/Ni, respectively.
Claim 10
Dependent Claim
20 words
The method recited in claim 1 further comprising the step of removing the photoresist ring after said etching step (h).
Claim 11
Independent Claim
190 words
A method of forming a metallic contact on an integrated circuit comprising the steps of: a) depositing a first layer of metal; b) depositing a second layer of metal; c) evaporating and patterning a layer of solder above said second layer of metal; d) applying a lift-off mask to mask said layer of solder; e) etching the second layer of metal; f) reflowing the patterned solder by melting to form a set of spheroidal solder ball contacts having a bottom diameter abutting said second layer of metal; g) applying a positive photoresist having a viscosity, and a solvent having a chemical composition, at a temperature such that the solvent wets the solder at said bottom diameter; h) exposing and stripping said photoresist using the solder ball contacts as a self aligned exposure mask, thereby forming a protective ring about said bottom diameter; and i) etching said first layer of metal, so that said solder is resting on a shoulder of said first layer of metal, the etched first layer of metal forming a disk under each solder ball contact larger than a disk formed by the second layer of metal.
Claim 12
Independent Claim
190 words
A method of forming a metallic contact on an integrated circuit comprising the steps of: a) depositing a first layer of metal; b) depositing a second layer of metal; c) evaporating and patterning a layer of solder above said second layer of metal; d) applying a lift-off mask to mask said layer of solder; e) etching the second layer of metal; f) reflowing the patterned solder by melting to form a set of spheroidal solder ball contacts having a bottom diameter abutting said second layer of metal; g) applying a positive photoresist having a viscosity, and a solvent having a chemical composition, at a temperature such that the solvent wets the solder at said bottom diameter; h) exposing and stripping said photoresist using the solder ball contacts as a self aligned exposure mask, thereby forming a protective ring about said bottom diameter; and i) etching said first layer of metal, so that said solder is resting on a shoulder of said first layer of metal, the etched first layer of metal forming a disk under each solder ball contact larger than a disk formed by the second layer of metal.
Claim 13
Dependent Claim
32 words
The method recited in claim 10 wherein said first metal is chromium and said second metal is copper, and the photoresist covers and protects an interface between the copper and the solder.
Claim 14
Dependent Claim
20 words
The method recited in claim 10 further comprising the step of removing the photoresist ring after said etching step (i).
Claim 15
Independent Claim
119 words
A method of forming a metallic contact on an integrated circuit comprising the steps of: a) depositing a first layer of metal; b) depositing a second layer of metal; c) plating and patterning a layer of solder above said second layer of metal; d) etching the second layer of metal using the solder layer as a mask; e) applying a positive photoresist having a viscosity, and a solvent having a chemical composition, at a temperature such that the solvent wets the solder at said bottom diameter: f) exposing and stripping said photoresist using the solder layer as a self aligned exposure mask, thereby forming a protective ring about said bottom diameter: and g) etching said first layer of metal.
Claim 16
Independent Claim
119 words
A method of forming a metallic contact on an integrated circuit comprising the steps of: a) depositing a first layer of metal; b) depositing a second layer of metal; c) plating and patterning a layer of solder above said second layer of metal; d) etching the second layer of metal using the solder layer as a mask; e) applying a positive photoresist having a viscosity, and a solvent having a chemical composition, at a temperature such that the solvent wets the solder at said bottom diameter: f) exposing and stripping said photoresist using the solder layer as a self aligned exposure mask, thereby forming a protective ring about said bottom diameter: and g) etching said first layer of metal.
Claim 17
Dependent Claim
32 words
The method recited in claim 13 wherein said first metal is chromium and said second metal is copper, and the photoresist covers and protects an interface between the copper and the solder.
References Cited (Backward Citations)
US4293637A
Cited
US4427715A
Cited
US4272561A
Cited
US4273859A
Cited
JPS59117135A
Cited
US4742023A
Cited
JPS63305533A
Cited
JPH01194336A
Cited
US4861425A
Cited
US5027188A
Cited
US5298459A
Cited
US5010389A
Cited
US5171711A
Cited
US5268072A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-01-23 | 1998-07-25 | 1999-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-23 | 2002-07-25 | 2003-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-23 | 2006-07-25 | 2007-01-24 | $7700.00 | Window Closed / Lapsed |