US5492235A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for single mask C4 solder bump fabrication
Assignee: Intel Corp
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Filing: 1994-12-01
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Granted: 1996-02-20
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Expires: 2014-12-01
Abstract
Abstract A method for removing Ball Limiting Metallurgy (BLM) layers from the surface of a wafer in the presence of Pb/Sn solder bumps. In one embodiment, the BLM comprises two layers: titanium and copper. After Pb/Sn solder bumps have been formed over the electrical contact pads of the wafer, the BLM copper layer is etched with a H 2 SO 4 +H 2 O 2 +H 2 O solution. While removing the copper layer, the H 2 SO 4 +H 2 O 2 +H 2 O etchant also reacts with the Pb/Sn solder bumps to form a thin PbO protective layer over the surface of the bumps. When the copper layer has been etched away, the titanium layer is etched with a CH 3 COOH+NH 4 F+H 2 O solution. The PbO layer formed over the surface of the Pb/Sn solder bumps remain insoluble when exposed to the CH 3 COOH+NH 4 F+H 2 O etchant, thereby preventing the solder bumps from being etched in the presence of the CH 3 COOH+NH 4 F+H 2 O etchant. When the titanium etch is complete, the PbO layer is removed from the surface of the Pb/Sn solder bumps by exposing the bumps to a HCl+NH 2 CSNH 2 +NH 4 Cl+H 2 O solution.
Inventors
- 👤 Douglas E. Crafts
- 👤 Venkatesan Murali
- 👤 Caroline S. Lee
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:01
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/01; H10W72/019; H10W72/012; H10W72/01204; H10W72/01231; H10W72/01233; H10W72/01235; H10W72/01251; H10W72/01255; H10W72/01257; H10W72/01271; H10W72/01931; H10W72/01938; H10W72/01951; H10W72/01953; H10W72/071; H10W72/072; H10W72/07221; H10W72/20; H10W72/221; H10W72/222; H10W72/223; H10W72/241; H10W72/242; H10W72/251; H10W72/252; H10W72/29; H10W72/90; H10W72/921; H10W72/923; H10W72/931; H10W72/934; H10W72/941; H10W72/9415; H10W72/951; H10W72/952
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
154 words
A method of removing metal layers from a surface of a wafer in the presence of a Pb/Sn solder bump, said method comprising the steps of: a) removing a first metal layer from said surface of said wafer by exposing said wafer to a first etchant wherein said first layer is removed from said surface of said wafer and wherein a protective layer is formed on said Pb/Sn solder bump; b) removing a second metal layer from said surface of said wafer by exposing said wafer to a second etchant wherein said second metal layer is removed from said surface of said wafer and wherein at least a portion of said protective layer remains on said Pb/Sn solder bump after being exposed to said second etchant; c) removing said protective layer from said Pb/Sn solder bump by exposing said wafer to a third etchant wherein said protective layer is removed from said Pb/Sn bump.
Claim 2
Independent Claim
154 words
A method of removing metal layers from a surface of a wafer in the presence of a Pb/Sn solder bump, said method comprising the steps of: a) removing a first metal layer from said surface of said wafer by exposing said wafer to a first etchant wherein said first layer is removed from said surface of said wafer and wherein a protective layer is formed on said Pb/Sn solder bump; b) removing a second metal layer from said surface of said wafer by exposing said wafer to a second etchant wherein said second metal layer is removed from said surface of said wafer and wherein at least a portion of said protective layer remains on said Pb/Sn solder bump after being exposed to said second etchant; c) removing said protective layer from said Pb/Sn solder bump by exposing said wafer to a third etchant wherein said protective layer is removed from said Pb/Sn bump.
Claim 3
Dependent Claim
13 words
The method according to claim 1 wherein said first metal layer comprises copper.
Claim 4
Dependent Claim
13 words
The method according to claim 1 wherein said first metal layer comprises nickel.
Claim 5
Dependent Claim
13 words
The method according to claim 1 wherein said first metal layer comprises palladium.
Claim 6
Dependent Claim
13 words
The method according to claim 1 wherein said first metal layer comprises platinum.
Claim 7
Dependent Claim
13 words
The method according to claim 1 wherein said second metal layer comprises titanium.
Claim 8
Dependent Claim
22 words
The method according to claim 1 wherein said first etchant comprises H 2 SO 4 +H 2 O 2 +H 2 O.
Claim 9
Dependent Claim
18 words
The method according to claim 1 wherein said second etchant comprises CH 3 COOH+NH 4 F+H 2 O.
Claim 10
Dependent Claim
14 words
The method according to claim 1 wherein said second etchant comprises HF+H 2 O.
Claim 11
Dependent Claim
20 words
The method according to claim 1 wherein said third etchant comprises HCl+NH 2 CSNH 2 +NH 4 Cl+H 2 O.
Claim 12
Dependent Claim
18 words
The method according to claim 1 wherein said third etchant comprises 2HCH 3 SO 3 +H 2 O.
Claim 13
Dependent Claim
14 words
The method according to claim 1 wherein said Pb/Sn solder bump comprises 97/3 Pb/Sn.
Claim 14
Dependent Claim
12 words
The method according to claim 1 wherein said protective layer comprises PbO.
Claim 15
Independent Claim
135 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said surface of said substrate and said Pb/Sn bump to a first etchant wherein a first metal layer is removed from said surface of said substrate and wherein a PbO layer is formed over said Pb/Sn bump; b) exposing said surface of said substrate and said Pb/Sn bump to a second etchant wherein a second metal layer is removed from said surface of said substrate and wherein at least a portion of said PbO layer remains on said Pb/Sn bump after being exposed to said second etchant; c) exposing said Pb/Sn bump to a third etchant wherein said PbO layer is removed from said Pb/Sn bump.
Claim 16
Independent Claim
135 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said surface of said substrate and said Pb/Sn bump to a first etchant wherein a first metal layer is removed from said surface of said substrate and wherein a PbO layer is formed over said Pb/Sn bump; b) exposing said surface of said substrate and said Pb/Sn bump to a second etchant wherein a second metal layer is removed from said surface of said substrate and wherein at least a portion of said PbO layer remains on said Pb/Sn bump after being exposed to said second etchant; c) exposing said Pb/Sn bump to a third etchant wherein said PbO layer is removed from said Pb/Sn bump.
Claim 17
Dependent Claim
13 words
The method according to claim 14 wherein said first metal layer comprises copper.
Claim 18
Dependent Claim
13 words
The method according to claim 14 wherein said first metal layer comprises nickel.
Claim 19
Dependent Claim
13 words
The method according to claim 14 wherein said first metal layer comprises palladium.
Claim 20
Dependent Claim
13 words
The method according to claim 14 wherein said first metal layer comprises platinum.
Claim 21
Dependent Claim
13 words
The method according to claim 14 wherein said second metal layer comprises titanium.
Claim 22
Dependent Claim
22 words
The method according to claim 14 wherein said first etchant comprises H 2 SO 4 +H 2 O 2 +H 2 O.
Claim 23
Dependent Claim
18 words
The method according to claim 14 wherein said second etchant comprises CH 3 COOH+NH 4 F+H 2 O.
Claim 24
Dependent Claim
14 words
The method according to claim 14 wherein said second etchant comprises HF+H 2 O.
Claim 25
Dependent Claim
20 words
The method according to claim 14 wherein said third etchant comprises HCl+NH 2 CSNH 2 +NH 4 Cl+H 2 O.
Claim 26
Dependent Claim
18 words
The method according to claim 14 wherein said third etchant comprises 2HCH 3 SO 3 +H 2 O.
Claim 27
Dependent Claim
14 words
The method according to claim 14 wherein said Pb/Sn solder bump comprises 97/3 Pb/Sn.
Claim 28
Independent Claim
158 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said substrate and said Pb/Sn bump to a H 2 SO 4 +H 2 O 2 +H 2 O etchant wherein a copper layer is removed from said surface of said substrate and wherein a PbO layer is formed over said Pb/Sn bump; b) exposing said substrate and said Pb/Sn bump to a CH 3 COOH+NH 4 F+H 2 O etchant wherein a titanium layer is removed from said surface of said substrate and wherein said at least a portion of said PbO layer remains on said Pb/Sn bump after being exposed to said CH 3 COOH+NH 4 F+H 2 O etchant; c) exposing said Pb/Sn bump to a HCl+NH 2 CSNH 2 +NH 4 Cl+H 2 O solution wherein said PbO layer is removed from said Pb/Sn bump.
Claim 29
Independent Claim
158 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said substrate and said Pb/Sn bump to a H 2 SO 4 +H 2 O 2 +H 2 O etchant wherein a copper layer is removed from said surface of said substrate and wherein a PbO layer is formed over said Pb/Sn bump; b) exposing said substrate and said Pb/Sn bump to a CH 3 COOH+NH 4 F+H 2 O etchant wherein a titanium layer is removed from said surface of said substrate and wherein said at least a portion of said PbO layer remains on said Pb/Sn bump after being exposed to said CH 3 COOH+NH 4 F+H 2 O etchant; c) exposing said Pb/Sn bump to a HCl+NH 2 CSNH 2 +NH 4 Cl+H 2 O solution wherein said PbO layer is removed from said Pb/Sn bump.
Claim 30
Independent Claim
148 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said substrate and said Pb/Sn bump to a H 2 SO 4 +H 2 O 2 +H 2 O etchant wherein a nickel layer is removed from said surface of said substrate and wherein a PbO layer is formed over said Pb/Sn bump; b) exposing said substrate and said Pb/Sn bump to a HF+H 2 O etchant wherein a titanium layer is removed from said surface of said substrate and wherein said at least a portion of said PbO layer remains on said Pb/Sn bump after being exposed to said HF+H 2 O etchant; c) exposing said Pb/Sn bump to a 2HCH 3 SO 3 +H 2 O solution wherein said PbO layer is removed from said Pb/Sn bump.
Claim 31
Independent Claim
148 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said substrate and said Pb/Sn bump to a H 2 SO 4 +H 2 O 2 +H 2 O etchant wherein a nickel layer is removed from said surface of said substrate and wherein a PbO layer is formed over said Pb/Sn bump; b) exposing said substrate and said Pb/Sn bump to a HF+H 2 O etchant wherein a titanium layer is removed from said surface of said substrate and wherein said at least a portion of said PbO layer remains on said Pb/Sn bump after being exposed to said HF+H 2 O etchant; c) exposing said Pb/Sn bump to a 2HCH 3 SO 3 +H 2 O solution wherein said PbO layer is removed from said Pb/Sn bump.
Claim 32
Independent Claim
115 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said surface of said substrate and said Pb/Sn bump to a first etchant wherein a first metal layer is removed from said surface of said substrate and wherein a protective layer is formed over said Pb/Sn bump; b) exposing said surface of said substrate and said Pb/Sn bump to a second etchant wherein a second metal layer is removed from said surface of said substrate and wherein said protective layer is removed from said Pb/Sn bumps such that no substantial etching of said Pb/Sn bump occurs.
Claim 33
Independent Claim
115 words
A method of removing Ball Limiting Metallurgy layers from a surface of a substrate in the presence of a Pb/Sn bump, said method comprising the steps of: a) exposing said surface of said substrate and said Pb/Sn bump to a first etchant wherein a first metal layer is removed from said surface of said substrate and wherein a protective layer is formed over said Pb/Sn bump; b) exposing said surface of said substrate and said Pb/Sn bump to a second etchant wherein a second metal layer is removed from said surface of said substrate and wherein said protective layer is removed from said Pb/Sn bumps such that no substantial etching of said Pb/Sn bump occurs.
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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) | 1999-02-19 | 1999-08-21 | 2000-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-02-19 | 2003-08-21 | 2004-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-02-19 | 2007-08-21 | 2008-02-20 | $7700.00 | Window Closed / Lapsed |