US5149615A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing a planar surface on which a conductive layer can be applied
Assignee: Boeing Co
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Filing: 1991-01-08
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Granted: 1992-09-22
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Expires: 2011-01-08
Abstract
Abstract A method for producing a planar surface on which conductive traces can be formed to fabricate a multi-layer integrated circuit. In this method, a substrate (20) serves as a base for the formation of conductive traces including copper conductors (30). These conductors are preferably bonded to an adhesion layer (22) and coated with a corrosion barrier (31). A first polyimide coating (34) is spin coated over the substrate and the copper conductors, leaving an undulating surface. Portions of the first polyimide coating lying above the copper conductors are removed, and the resulting surface is coated with a second polyimide coating (44). The polyimide comprising the first and second coatings is selected for its characteristic ability to partially dissolve a previously applied layer of the material, so that the two layers combine, thereby leveling out an non-planar irregularities existing in the first layer. The resulting planar surface forms a base for application of subsequently applied copper conductors (54), which are connected to the previously applied copper conductors at vias, photolithographically formed in the second polyimide coating. Additional layers of copper conductors can be applied to the planar surface as the process is repeated.
Inventors
- 👤 Kishore K. Chakravorty
- 👤 Minas H. Tanielian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:21
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/40; H10W20/41; H10W20/42; G; G03; G03F; G03F7/00; G03F7/0035; H10W20/01; H10W20/031; H10W20/056; H10W20/063; H10W20/071; H10W20/092; H10W20/425; H05; H05K; H05K3/00; H05K3/46; H05K3/4644
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
172 words
A method of producing a planar surface on which successive conductor layers can be formed in a multi-layer circuit, comprising the steps of: a. forming a conductive trace on a substrate; b. applying a first coat of a dielectric material over the conductive trace and the substrate; c. removing a portion of the dielectric material that overlies the conductive trace; d. applying a second coat of the dielectric material over the conductive trace and over the first coat of the dielectric material, the second coat at least partially dissolving and combining with the first coat, thereby leveling out any non-planar irregularities in the first coat and leaving a substantially planar surface; and e. removing a portion of the second coat of the dielectric material overlying the conductive trace where an electrically conductive via is to be formed between the conductive trace already formed on the substrate and a subsequent conductive trace, the substantially planar surface of the combined first coat and second coat providing a base for forming the subsequent conductive trace.
Claim 2
Independent Claim
172 words
A method of producing a planar surface on which successive conductor layers can be formed in a multi-layer circuit, comprising the steps of: a. forming a conductive trace on a substrate; b. applying a first coat of a dielectric material over the conductive trace and the substrate; c. removing a portion of the dielectric material that overlies the conductive trace; d. applying a second coat of the dielectric material over the conductive trace and over the first coat of the dielectric material, the second coat at least partially dissolving and combining with the first coat, thereby leveling out any non-planar irregularities in the first coat and leaving a substantially planar surface; and e. removing a portion of the second coat of the dielectric material overlying the conductive trace where an electrically conductive via is to be formed between the conductive trace already formed on the substrate and a subsequent conductive trace, the substantially planar surface of the combined first coat and second coat providing a base for forming the subsequent conductive trace.
Claim 3
Dependent Claim
32 words
The method of claim 1, wherein the dielectric material comprises a polyimide that is selected for its characteristic ability to combine with and level a previously applied non-planar coat of the polyimide.
Claim 4
Dependent Claim
31 words
The method of claim 2, wherein the steps of applying the first and second coats of polyimide include the step of curing the polyimide by heating it to an elevated temperature.
Claim 5
Dependent Claim
76 words
The method of claim 1, further comprising the steps of repeating steps (a) through (e) for each successive layer of the multi-layer circuit, wherein successive conductive traces are formed on the substantially planar surface resulting from the combined first and second coat of dielectric material applied, and electrical continuity is provided between the successive conductive traces where the second coat of dielectric material is removed to form the via into which the successive conductive traces extend.
Claim 6
Dependent Claim
26 words
The method of claim 1, wherein the step of forming the conductive trace includes the step of applying an adhesion layer before applying the conductive trace.
Claim 7
Dependent Claim
39 words
The method of claim 1, wherein if the conductive trace is formed by plating, the step of forming the conductive trace includes the step of applying a seed layer prior to plating the conductive trace on the seed layer.
Claim 8
Dependent Claim
34 words
The method of claim 1, wherein the steps of applying the first and second coats of dielectric material each comprise the step of spinning the substrate to spread the dielectric material using centrifugal force.
Claim 9
Dependent Claim
26 words
The method of claim 1, wherein the steps of applying the first and second coats of dielectric material comprise the step of spraying the dielectric material.
Claim 10
Dependent Claim
48 words
The method of claim 1, wherein the steps of removing the first and second coatings of dielectric material overlying the conductive trace each comprise the steps of photolithographically patterning the coatings to define areas that are to be removed and chemically removing the dielectric material in those areas.
Claim 11
Independent Claim
154 words
A method of forming a substantially planar surface on which a conductive trace can be applied to build up successive layers of a multi-layer circuit, comprising the steps of: a. electroplating a conductive trace on an underlying surface; b. applying a first coat of a polyimide over the conductive trace and the underlying surface, leaving a surface that includes undulations and is non-planar; c. patterning the first coat of the polyimide to define portions of the polyimide that overlie the conductive trace; d. removing those portions of the polyimide, thereby exposing the conductive trace; e. applying a second coat of the polyimide over the first coat and over the conductive trace, the second coat at least partially dissolving and combining with the first coat, thereby leveling out the undulations in the first coat and leaving a substantially planar surface; and f. defining any vias that are required to electrically connect to the conductive trace.
Claim 12
Independent Claim
154 words
A method of forming a substantially planar surface on which a conductive trace can be applied to build up successive layers of a multi-layer circuit, comprising the steps of: a. electroplating a conductive trace on an underlying surface; b. applying a first coat of a polyimide over the conductive trace and the underlying surface, leaving a surface that includes undulations and is non-planar; c. patterning the first coat of the polyimide to define portions of the polyimide that overlie the conductive trace; d. removing those portions of the polyimide, thereby exposing the conductive trace; e. applying a second coat of the polyimide over the first coat and over the conductive trace, the second coat at least partially dissolving and combining with the first coat, thereby leveling out the undulations in the first coat and leaving a substantially planar surface; and f. defining any vias that are required to electrically connect to the conductive trace.
Claim 13
Dependent Claim
53 words
The method of claim 10, further comprising steps (a) through (e) for each successive conductive layer that is built up to form the multi-layer circuit, wherein a successive conductive trace is applied to the substantially planar surface produced in step (e) and is electrically connected to the conductive trace exposed at each via.
Claim 14
Dependent Claim
57 words
The method of claim 10, wherein to form the first coating and the second coating, the polyimide is applied to a surface to be coated in a liquid form, and the surface is spun about an axis at a sufficient rotational speed so that centrifugal force spreads the polyimide to form the first and the second coats.
Claim 15
Dependent Claim
29 words
The method of claim 10, wherein to form the first coating and the second coating, the polyimide is sprayed in a liquid form onto a surface to be coated.
Claim 16
Dependent Claim
72 words
The method of claim 10, wherein the step of electroplating the conductive trace comprises the steps of depositing an electroplating seed layer onto the underlying surface, patterning the electroplating seed layer to define an area where the conductive trace is to be electroplated, and applying a photoresist layer on each side of the area to form a trench, the conductive trace thereafter being electroplated into the trench formed in the photoresist layer.
Claim 17
Dependent Claim
25 words
The method of claim 14, further comprising the step of removing a remaining portion of the electroplating seed layer not covered by the conductive trace.
Claim 18
Dependent Claim
20 words
The method of claim 14, further comprising the step of depositing an adhesion layer before depositing the electroplating seed layer.
Claim 19
Dependent Claim
30 words
The method of claim 10, further comprising the steps of curing the polyimide at an elevated temperature after each of the steps of applying the first and the second coats.
Claim 20
Dependent Claim
53 words
The method of claim 10, wherein the step of patterning the combined first and second coats of the polyimide comprises the steps of photolithographically patterning the polyimide to define areas that are to be removed, and steps of removing the polyimide each comprise the step of dissolving the polyimide away from those areas.
Claim 21
Dependent Claim
42 words
The method of claim 10, further comprisng the step of forming a passivating layer over the conductive trace before applying the first coat of the polyimide to prevent a chemical interaction between the conductive trace and the first coat of the polyimide.
Claim 22
Dependent Claim
25 words
The method of claim 10, further comprising the step of forming an adhesion layer over the substrate before applying the first coat of the polyimide.
References Cited (Backward Citations)
US4642162A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-09-22 | 1996-03-23 | 1996-09-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-09-22 | 2000-03-23 | 2000-09-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-09-22 | 2004-03-23 | 2004-09-22 | $7700.00 | Window Closed / Lapsed |