Patent US3874072A successfully refreshed from Google Patents.
US3874072A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor structure with bumps and method for making the same
Assignee: Signetics Corp
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Filing: 1973-08-27
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Granted: 1975-04-01
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Expires: 1993-08-27
Abstract
Abstract Semiconductor structure having a semiconductor body with a planar surface and with metallic contact pads formed over the surface. A layer of insulating material is formed over the contact pads. Bumps or pillars are formed which extend through the layer of insulating material and are bonded to the contact pads. The bumps or pillars are formed of a relatively ductile aluminum layer. A base portion is secured to the ductile layer and has a mushroom-shaped configuration. Gold-tin layers are carried by the base and form a gold-tin system so that the bumps or pillars can be readily bonded to the lead frames. In the method, a semiconductor body is provided having a planar surface and having metallic contact pads formed over the surface. An insulating layer is formed over the contact pads. Openings are formed in the insulating layer. Bumps or pillars are formed which extend through the openings in the insulating material and make contact with and are secured to the pads. The bumps or pillars are formed by first forming a relatively thick aluminum layer making contact with the pads and then forming bases which are secured to the relatively thick aluminum layers. Gold-tin layers are formed on the bases to provide a gold-tin system. During the formation of the base and the gold-tin layers, a layer of photoresist is provided so that the bumps or pillars assume a mushroom-shaped configuration.
Inventors
- 👤 Ralph E Rose
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:53
CPC Classifications
H; H10; H10P; H10P95/00; H10W; H10W72/00; H10W72/01; H10W72/012; H10W72/019; H10W72/20; H10W72/251; H10W72/50; H10W72/551; H10W72/552; H10W72/5522; H10W72/90; H10W72/921; H10W72/923; H10W72/951; H10W72/952
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
180 words
In a method for forming a semiconductor structure, providing a semiconductor body having a planar surface and having metallic contact pads formed over said surface, forming a layer of insulating material overlying said contact pads and adherent to said contact pads, forming windows in said layer of insulating material overlying said contact pads to expose said contact pads, forming a relatively thick ductile layer of solely one metal on said insulating layer and extending through said windows to make contact with said contact pads, forming a metal layer on the thick ductile layer which will not react with the thick ductile layer and which will form a diffusion barrier so that the thick ductile layer will retain the characteristics of said one metal, forming metallic stand-offs on said metal layer and overlying said contact pads to provide surfaces which are spaced a substantial distance above the ductile layer, forming solder on said surface of said stand-offs, and removing the undesired portions of the ductile layer so that discrete spaced bumps are formed overlying and in contact with the contact pads.
Claim 2
Dependent Claim
180 words
In a method for forming a semiconductor structure, providing a semiconductor body having a planar surface and having metallic contact pads formed over said surface, forming a layer of insulating material overlying said contact pads and adherent to said contact pads, forming windows in said layer of insulating material overlying said contact pads to expose said contact pads, forming a relatively thick ductile layer of solely one metal on said insulating layer and extending through said windows to make contact with said contact pads, forming a metal layer on the thick ductile layer which will not react with the thick ductile layer and which will form a diffusion barrier so that the thick ductile layer will retain the characteristics of said one metal, forming metallic stand-offs on said metal layer and overlying said contact pads to provide surfaces which are spaced a substantial distance above the ductile layer, forming solder on said surface of said stand-offs, and removing the undesired portions of the ductile layer so that discrete spaced bumps are formed overlying and in contact with the contact pads.
Claim 3
Dependent Claim
35 words
A method as in claim 1 wherein said ductile layer is aluminum wherein said stand-offs are formed of nickel and wherein said metal layer is chromium to prevent migration of the nickel into the aluminum.
Claim 4
Dependent Claim
21 words
A method as in claim 2 together with the steps of forming a protective layer of nickel on the chromium layer.
Claim 5
Dependent Claim
22 words
A method as in claim 3 wherein the chromium and nickel layers are formed prior to the formation of the nickel stand-offs.
Claim 6
Dependent Claim
54 words
A method as in claim 2 wherein a layer of photoresist is provided which overlies the aluminum layer, forming windows in the photoresist overlying the contact pads, electroforming the nickel stand-offs in said openings so they extend a substantial distance above said openings and overlap said photoresist layer and thereafter removing the photoresist layer.
Claim 7
Dependent Claim
22 words
A method as in claim 5 wherein said solder is formed on said nickel stand-offs while said photoresist layer is in place.
Claim 8
Dependent Claim
21 words
A method as in claim 6 together with the step of removing the exposed portions of the nickel and chromium layers.
Claim 9
Dependent Claim
35 words
A method as in claim 1 together with the step of depositing a layer of photoresist over said structure and over said bumps or pillars and within the undercut regions of the bumps or pillars.
Claim 10
Dependent Claim
48 words
A method as in claim 8 together with the step of removing all portions of the photoresist except those portions underlying the undercut regions of the bumps or pillars, removing the exposed portions of the nickel and chromium layers, and thereafter removing the photoresist below the undercut regions.
Claim 11
Dependent Claim
16 words
A method as in claim 6 together with the step of bonding leads to the solder.
Claim 12
Dependent Claim
56 words
A method as in claim 1 wherein said solder is formed of gold-tin layers and wherein the gold-tin layers are formed by first depositing a gold layer in contact with the stand-offs forming a tin layer on the gold layer and then forming an additional gold layer on the tin layer to protect the tin layer.
Claim 13
Dependent Claim
32 words
A method as in claim 11 wherein the gold-tin layers are formed to a thickness so that upon heatiNg of the same, a gold-tin eutectic is formed ranging from 285*C to 450*C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |