US4661375A
Expired / Lapsed
US
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Method for increasing the height of solder bumps
Assignee: AT&T Inc
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Filing: 1986-03-07
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Granted: 1987-04-28
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Expires: 2006-03-07
Abstract
Abstract The height of solder bumps (10) on a bonding pad (24) of a semiconductor chip (12) is increased by successively immersing the chip in molten solder alloys having progressively lower melting points.
Inventors
- 👤 Donald A. Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:30
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/20; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/341; H05K3/3431; H05K3/3436; H05K3/346; H05K3/3465; H05K3/3468; H10W72/01; H10W72/012; H10W72/01231; H10W72/01233; H10W72/251; H10W72/50; H10W72/551; H10W72/552; H10W72/5524; H10W72/90; H10W72/921; H10W72/923; H10W72/951; H10W72/952
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
47 words
A method of increasing the height of a bump of solder alloy deposited on a substrate, comprising the steps of: sequentially applying a plurality of different molten solder alloys to the solder alloy bump wherein each alloy has a lower melting temperature than the alloy previously applied.
Claim 2
Independent Claim
47 words
A method of increasing the height of a bump of solder alloy deposited on a substrate, comprising the steps of: sequentially applying a plurality of different molten solder alloys to the solder alloy bump wherein each alloy has a lower melting temperature than the alloy previously applied.
Claim 3
Dependent Claim
33 words
The method as set forth in claim 1 which comprises the further step of heating the solder bump with the sequentially applied alloys thereon to an elevated temperature to homogenize the deposited alloys.
Claim 4
Independent Claim
128 words
A method of forming a solder bump on a bonding pad of an integrated circuit by sequentially applying at least two alloys thereon, comprising the steps of: (1) applying a passivation layer over the integrated circuit; (2) forming an aperture in the passivation layer to expose the bonding pad therethrough; (3) applying a metallic contact layer to the exposed bonding pad; (4) depositing a diffusion barrier layer over the contact layer; (5) applying a solderable metal layer to the barrier layer; (6) forming a bump of solder alloy on the solderable metal layer; and (7) sequentially applying at least one molten solder alloy, which is different than the previously applied alloys, to the solder bump wherein each alloy has a lower melting temperature than the alloy previously applied.
Claim 5
Independent Claim
128 words
A method of forming a solder bump on a bonding pad of an integrated circuit by sequentially applying at least two alloys thereon, comprising the steps of: (1) applying a passivation layer over the integrated circuit; (2) forming an aperture in the passivation layer to expose the bonding pad therethrough; (3) applying a metallic contact layer to the exposed bonding pad; (4) depositing a diffusion barrier layer over the contact layer; (5) applying a solderable metal layer to the barrier layer; (6) forming a bump of solder alloy on the solderable metal layer; and (7) sequentially applying at least one molten solder alloy, which is different than the previously applied alloys, to the solder bump wherein each alloy has a lower melting temperature than the alloy previously applied.
Claim 6
Dependent Claim
25 words
The method as set forth in claim 3, wherein: depositing a gold layer on the solderable metal layer prior to forming a solder bump thereon.
Claim 7
Dependent Claim
17 words
The method as set forth in claim 3 wherein the solder bump is formed by vacuum evaporation.
Claim 8
Dependent Claim
16 words
The method as set forth in claim 3 wherein the solder bump is formed by electroplating.
Claim 9
Dependent Claim
17 words
The method as set forth in claim 3 wherein the solder bump is formed by solder immersion.
Claim 10
Dependent Claim
33 words
The method as set forth in claim 3 which comprises the further step of heating the solder bump with the sequentially applied alloys thereon to an elevated temperature to homogenize the deposited alloys.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-04-27 | 1990-10-27 | 1991-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-27 | 1994-10-27 | 1995-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-27 | 1998-10-27 | 1999-04-28 | $7700.00 | Window Closed / Lapsed |