US5937320A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Barrier layers for electroplated SnPb eutectic solder joints
Assignee: International Business Machines Corp
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Filing: 1998-04-08
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Granted: 1999-08-10
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Expires: 2018-04-08
Abstract
Abstract The present invention provides a means of fabricating a reliable C4 flip-chip structure for low-temperature joining. The electrochemically fabricated C4 interconnection has a barrier layer between the electroplated tin-rich solder bump and the ball-limiting metallurgy that protects the terminal metal in the ball-limiting metallurgy from attack by the Sn in the solder. The barrier layer is electroplated through the same photoresist mask as the solder and thus does not require a separate patterning step. A thin layer of electroplated nickel serves as a reliable barrier layer between a copper-based ball-limiting metallurgy and a tin-lead (Sn--Pb) eutectic C4 ball.
Inventors
- 👤 Panayotis Constantinou Andricacos
- 👤 Madhav Datta
- 👤 Wilma Jean Horkans
- 👤 Sung Kwon Kang
- 👤 Keith Thomas Kwietniak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:06
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/90; H10W72/01; H10W72/012; H10W72/019; H10W72/01251; H10W72/01255; H10W72/01931; H10W72/01933; H10W72/01935; H10W72/01938; H10W72/01951; H10W72/01953; H10W72/01955; H10W72/0198; H10W72/20; H10W72/221; H10W72/251; H10W72/252; H10W72/29; H10W72/921; H10W72/923; H10W72/941; H10W72/9415; H10W72/951; H10W95/00
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
138 words
A method of forming C4 bumps on metallic pads embedded in a semiconductor wafer comprising the steps of: (a) depositing a plurality of blanket metal layers on a passivated surface of a semiconductor wafer, wherein said passivated surface of said semiconductor wafer comprises at least one metallic pad embedded therein and a passivating layer having an opening therein on top of said wafer; (b) applying a photoresist material to said plurality of blanket metal layers; (c) patterning said photoresist material to provide a region for C4 solder bump formation; (d) electroplating a metal barrier layer on said region provided in step (c); (e) fabricating a C4 solder bump material on said electroplating metal barrier layer; (f) removing said photoresist material, and (g) etching said plurality of blanket metal layers using said C4 solder bump material as a mask.
Claim 2
Independent Claim
138 words
A method of forming C4 bumps on metallic pads embedded in a semiconductor wafer comprising the steps of: (a) depositing a plurality of blanket metal layers on a passivated surface of a semiconductor wafer, wherein said passivated surface of said semiconductor wafer comprises at least one metallic pad embedded therein and a passivating layer having an opening therein on top of said wafer; (b) applying a photoresist material to said plurality of blanket metal layers; (c) patterning said photoresist material to provide a region for C4 solder bump formation; (d) electroplating a metal barrier layer on said region provided in step (c); (e) fabricating a C4 solder bump material on said electroplating metal barrier layer; (f) removing said photoresist material, and (g) etching said plurality of blanket metal layers using said C4 solder bump material as a mask.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein said plurality of blanket metal layers includes at least a first adhesion layer and at least a wettable terminal metal layer.
Claim 4
Dependent Claim
29 words
The method of claim 2 wherein said plurality of blanket metal layers further comprises a second adhesion layer between said first adhesion layer and said wettable terminal metal layer.
Claim 5
Dependent Claim
14 words
The method of claim 3 wherein said second adhesion layer is composed of CrCu.
Claim 6
Dependent Claim
33 words
The method of claim 3 wherein the step of etching said plurality of blanket metals includes the step of electrochemical etching of both said wettable terminal metal layer and said second adhesion layer.
Claim 7
Dependent Claim
28 words
The method of claim 5 wherein said electrochemical etching of said wettable terminal metal layer and said second adhesion layer provides an undercut relative to said barrier layer.
Claim 8
Dependent Claim
27 words
The method of claim 2 wherein said first adhesion layer is composed of a metal selected from the group consisting of Ti, W, Cr and alloys thereof.
Claim 9
Dependent Claim
14 words
The method of claim 7 wherein said first adhesion layer is composed of TiW.
Claim 10
Dependent Claim
29 words
The method of claim 2 wherein said wettable terminal metal layer is composed of a metal selected from the group consisting of Cu, Ni, Fe, Au and alloys thereof.
Claim 11
Dependent Claim
15 words
The method of claim 9 wherein said wettable terminal metal layer is composed of Cu.
Claim 12
Dependent Claim
28 words
The method of claim 2 wherein the step of etching said plurality of blanket metal layers includes the step of electrochemical etching of said wettable terminal metal layer.
Claim 13
Dependent Claim
25 words
The method of claim 2 wherein said etching of said plurality of blanket metals includes the step of chemical etching of said first adhesion layer.
Claim 14
Dependent Claim
28 words
The method of claim 1 wherein said electroplated metal barrier layer is composed of a metal selected from the group consisting of Ni, Co, Fe and alloys thereof.
Claim 15
Dependent Claim
15 words
The method of claim 13 wherein said electroplated metal barrier layer is composed of Ni.
Claim 16
Dependent Claim
15 words
The method of claim 13 wherein said electroplated metal barrier layer is composed of NiFe.
Claim 17
Dependent Claim
25 words
The method of claim 1 wherein said C4 solder bump material is a solder selected from the group consisting of Sn, Pb, and alloys thereof.
Claim 18
Dependent Claim
22 words
The method of claim 16 wherein said C4 solder bump material is an alloy of Sn and Pb having a eutectic composition.
Claim 19
Dependent Claim
18 words
The method of claim 1 further comprising reflowing said C4 solder bump material to form a solder ball.
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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) | 2002-08-09 | 2003-02-08 | 2003-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-08-09 | 2007-02-08 | 2007-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-08-09 | 2011-02-08 | 2011-08-10 | $7700.00 | Window Closed / Lapsed |