US3890177A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Technique for the fabrication of air-isolated crossovers
Assignee: AT&T Inc
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Filing: 1973-03-08
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Granted: 1975-06-17
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Expires: 1993-03-08
Abstract
Abstract An economical process for the fabrication of air-isolated crossovers eliminates several evaporation and cleansing steps utilized in prior art processes. The described procedure involves evaporating an adhesion promoter, a noble metal and copper upon a substrate, selectively removing copper from the crossover contact and conductor interconnecting areas, plating gold thereon and replating copper upon the resultant assembly. Following, the crossover preparation process parallels normal procedures.
Inventors
- 👤 Arnold Pfahnl
- 👤 Walter Worobey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:28
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/46; H05K3/4685; H10; H10D; H10D84/00; H10D84/01; H10D86/00; H10D86/01; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49124
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
146 words
THE METHOD OF FABRICATING, UPON AN INSULATING SUBSTRATE, A PATTERN OF DRPOSITED GOLD CIRCUITRY INCLUDING AN AIR-ISOLATED GOLD CROSSOVER CONNECTING A FIRST AND A THIRD CONDUCTIVE AREA OF GOLD AND BRIDGING A SECOND CONDUCTIVE AREA OF GOLD, WITHOUT THE NECESSITY OF MULTIPLE STEPS OF METAL EVAPORATION, WHICH METHOD COMPRISES PLANTING (1) A GOLD CROSSOVER COLUMN UPON EACH OF SAID FIRST AND THIRD CONDUCTIVE AREAS AND (2) A GOLD BEAM OVER A COPPER SPACER LAYER SPANNING SAID THIRD CONDUCTIVE AREA AND CONNECTING SAID COLUMNS, AND ETCHING OUT SAID COPPER SPACER LAYER LEAVING AN AIR-ISOLATED GOLD CROSOVEER CHARACTERIZED IN, AS A FIRST FABRICATION STEP, EVAPORATING ON SAID SUBSTRATE SUCCESSIVE LAYERSOF (1), ADHESION PROMOTER, (2) A NOBLE METAL SELECTED FROM THE GROUP CONSISTING OF PLATINUM, PALLADIUM, AND RHODIUM WHICH RETARDS INTERDIFFUSION BETWEEN GOLD AND ADHESION PROMOTER, AND (3) COPPER, AND THEREAFTER ETCHING AWAY THOSE PORTIONS OF THE COPPER LAYER
Claim 2
Independent Claim
146 words
THE METHOD OF FABRICATING, UPON AN INSULATING SUBSTRATE, A PATTERN OF DRPOSITED GOLD CIRCUITRY INCLUDING AN AIR-ISOLATED GOLD CROSSOVER CONNECTING A FIRST AND A THIRD CONDUCTIVE AREA OF GOLD AND BRIDGING A SECOND CONDUCTIVE AREA OF GOLD, WITHOUT THE NECESSITY OF MULTIPLE STEPS OF METAL EVAPORATION, WHICH METHOD COMPRISES PLANTING (1) A GOLD CROSSOVER COLUMN UPON EACH OF SAID FIRST AND THIRD CONDUCTIVE AREAS AND (2) A GOLD BEAM OVER A COPPER SPACER LAYER SPANNING SAID THIRD CONDUCTIVE AREA AND CONNECTING SAID COLUMNS, AND ETCHING OUT SAID COPPER SPACER LAYER LEAVING AN AIR-ISOLATED GOLD CROSOVEER CHARACTERIZED IN, AS A FIRST FABRICATION STEP, EVAPORATING ON SAID SUBSTRATE SUCCESSIVE LAYERSOF (1), ADHESION PROMOTER, (2) A NOBLE METAL SELECTED FROM THE GROUP CONSISTING OF PLATINUM, PALLADIUM, AND RHODIUM WHICH RETARDS INTERDIFFUSION BETWEEN GOLD AND ADHESION PROMOTER, AND (3) COPPER, AND THEREAFTER ETCHING AWAY THOSE PORTIONS OF THE COPPER LAYER
Claim 3
Dependent Claim
236 words
Technique for the fabrication of an air-isolated crossover between a pair of conductors separated by an intermediate conductor comprising the steps of (a) depositing upon a ceramic substrate member an adhesion promoter, a noble metal selected from the group consisting of platinum, palladium, and rhodium, and a first layer of copper, (b) delineating a conductor pattern upon the resultant structure by selectively removing copper therefrom and exposing noble metal (c) depositing a first layer of gold by plating techniques upon the exposed noble metal, thereby defining first, second, and third conductor regions, (d) depositing a second layer of copper upon the resultant assembly and selectively removing copper from said first and third conductors by etching with an ammonium compound copper etchant thereby exposing said first gold layer, (e) depositing a second layer of gold by plating techniques upon said first and third conductors and upon said second copper layer in the region therebetween, so resulting in the formation of a conductive bridge between said first and third conductors, and (f) selectively removing said first and second layers of copper, adhesion promoter, and noble metal from non-conductor regions and in the area beneath said conductive bridge, by etching with an ammonium compound copper etchant, hydrofluoric acid, and a ferric compound noble metal etchant, respectively, so resulting in the formation of a structure having an insulating air gap between a conductive crossover connecting said first and third conductors.
Claim 4
Dependent Claim
236 words
Technique for the fabrication of an air-isolated crossover between a pair of conductors separated by an intermediate conductor comprising the steps of (a) depositing upon a ceramic substrate member an adhesion promoter, a noble metal selected from the group consisting of platinum, palladium, and rhodium, and a first layer of copper, (b) delineating a conductor pattern upon the resultant structure by selectively removing copper therefrom and exposing noble metal (c) depositing a first layer of gold by plating techniques upon the exposed noble metal, thereby defining first, second, and third conductor regions, (d) depositing a second layer of copper upon the resultant assembly and selectively removing copper from said first and third conductors by etching with an ammonium compound copper etchant thereby exposing said first gold layer, (e) depositing a second layer of gold by plating techniques upon said first and third conductors and upon said second copper layer in the region therebetween, so resulting in the formation of a conductive bridge between said first and third conductors, and (f) selectively removing said first and second layers of copper, adhesion promoter, and noble metal from non-conductor regions and in the area beneath said conductive bridge, by etching with an ammonium compound copper etchant, hydrofluoric acid, and a ferric compound noble metal etchant, respectively, so resulting in the formation of a structure having an insulating air gap between a conductive crossover connecting said first and third conductors.
Claim 5
Independent Claim
208 words
The method of fabricating, upon an insulating substrate, a pattern of deposited gold circuitry including an air-isolated gold crossover connecting a first and a third conductive area of gold and bridging a second conductive area of gold, without the necessity of multiple steps of metal evaporation, which method coMprises plating (1) a gold crossover column upon each of said first and third conductive areas and (2) a gold beam over a copper spacer layer spanning said second conductive area and connecting said columns, and etching out said copper spacer layer leaving an air-isolated gold crossover CHARACTERIZED IN, as a first fabrication step, evaporating on said substrate successive layers of (1) adhesion promoter, (2) a noble metal selected from the group consisting of platinum, palladium, and rhodium which retards interdiffusion between gold and adhesion promoter, and (3) copper, and thereafter etching away those portions of the copper layer corresponding to the desired pattern of conductive circuitry with an ammonium compound copper etchant, plating a layer of gold upon the barrier metal in the areas from which the copper has been etched, and plating a layer of copper constituting the spacer layer over the gold and copper layers in at least the area to be bridged by the crossover beam.
Claim 6
Independent Claim
208 words
The method of fabricating, upon an insulating substrate, a pattern of deposited gold circuitry including an air-isolated gold crossover connecting a first and a third conductive area of gold and bridging a second conductive area of gold, without the necessity of multiple steps of metal evaporation, which method coMprises plating (1) a gold crossover column upon each of said first and third conductive areas and (2) a gold beam over a copper spacer layer spanning said second conductive area and connecting said columns, and etching out said copper spacer layer leaving an air-isolated gold crossover CHARACTERIZED IN, as a first fabrication step, evaporating on said substrate successive layers of (1) adhesion promoter, (2) a noble metal selected from the group consisting of platinum, palladium, and rhodium which retards interdiffusion between gold and adhesion promoter, and (3) copper, and thereafter etching away those portions of the copper layer corresponding to the desired pattern of conductive circuitry with an ammonium compound copper etchant, plating a layer of gold upon the barrier metal in the areas from which the copper has been etched, and plating a layer of copper constituting the spacer layer over the gold and copper layers in at least the area to be bridged by the crossover beam.
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) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |