US5112448A
Expired / Lapsed
US
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Self-aligned process for fabrication of interconnect structures in semiconductor applications
Assignee: PARPROC TECHNOLOGIES Ltd LLC
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Filing: 1989-11-28
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Granted: 1992-05-12
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Expires: 2009-11-28
Abstract
Abstract A method for fabricating conductors in dielectric trenches in a self-aligned manner. Interconnect modules with a high conductor density are achieved by using a copper-polyimide system as a versatile packaging approach. A photosensitive polyimide is applied to a substrate and lithographically patterned to form polyimide steps having a characteristic positive slope, between which are defined trenches in which the substrate is exposed. A thin electroplating seed layer is deposited over the polyimide steps and the substrate. Copper is electroplated into trenches, but does not plate onto the tops of the polyimide steps, since the electroplating seed layer at that location is not electrically connected to the electroplating seed layer in the bottom of the trenches. The electroplating seed layer on top of the polyimide steps is then removed by chemical etching, plasma machining, or ion-milling. A planar structure is eventually obtained without the use of multiple coatings of polyimide layers or any additional masking layers or lift-off layers.
Inventors
- 👤 Kishore K. Chakravorty
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:48
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/063; H10P; H10P14/00; H10P14/40; H10P14/46; H10P14/47; H10W20/056; H10W70/00; H10W70/01; H10W70/05; H05; H05K; H05K3/00; H05K3/10; H05K3/107; H05K3/22; H05K3/24; H05K3/243; H05K3/46; H05K3/4644; Y; Y10; Y10S; Y10S205/00; Y10S205/917
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
95 words
A method for forming an interconnect structure in a self-aligned manner, comprising the steps of: applying a dielectric film on a substrate; patterning the dielectric film to form a plurality of trenches that define the interconnect structure; depositing a thin electroplating seed layer on the dielectric film and in the trenches on the substrate, the electroplating seed layer on the substrate being electrically isolated from the electroplating seed layer on the dielectric film; electroplating a conductive layer on the electroplating seed layer in the trenches; and removing the electroplating seed layer on the dielectric film.
Claim 2
Independent Claim
95 words
A method for forming an interconnect structure in a self-aligned manner, comprising the steps of: applying a dielectric film on a substrate; patterning the dielectric film to form a plurality of trenches that define the interconnect structure; depositing a thin electroplating seed layer on the dielectric film and in the trenches on the substrate, the electroplating seed layer on the substrate being electrically isolated from the electroplating seed layer on the dielectric film; electroplating a conductive layer on the electroplating seed layer in the trenches; and removing the electroplating seed layer on the dielectric film.
Claim 3
Dependent Claim
14 words
The method in accordance with claim 1, wherein the dielectric film comprises a polyimide.
Claim 4
Dependent Claim
17 words
The method in accordance with claim 2, wherein the polyimide is applied to the substrate by spin-coating.
Claim 5
Dependent Claim
16 words
The method in accordance with claim 1, wherein the patterning step is performed by lithographic techniques.
Claim 6
Dependent Claim
22 words
The method in accordance with claim 1, wherein the electroplating seed layer comprises a first metal film and a second metal film.
Claim 7
Dependent Claim
21 words
The method in accordance with claim 5, wherein the first metal film comprises copper and the second metal film comprises titanium.
Claim 8
Dependent Claim
24 words
The method in accordance with claim 6, wherein the first metal film has a thickness substantially greater than that of the second metal film.
Claim 9
Dependent Claim
18 words
The method in accordance with claim 1, wherein the electroplating seed layer comprises a plurality of metal films.
Claim 10
Dependent Claim
22 words
The method in accordance with claim 1, wherein during the depositing step, the electroplating seed layer is applied using an E-beam system.
Claim 11
Dependent Claim
43 words
The method in accordance with claim 1, wherein the depositing step applies the electroplating seed layer as a film that coates the bottom of the treches and surfaces of the dielectric film, said surfaces that are coated being generally parallel with the substrate.
Claim 12
Dependent Claim
40 words
The method in accordance with claim 1, further comprising the step of curing the dielectric film at a temperature sufficient to cause anisotropic shrinkage of the dielectric film, the step of curing the dielectric film occurring before the electroplating step.
Claim 13
Dependent Claim
25 words
The method in accordance with claim 1, wherein the electroplating step provides a copper layer having a thickness less than that of the dielectric film.
Claim 14
Dependent Claim
41 words
The method in accordance with claim 12, further comprising the step of heating the structure to a temperature sufficient to cause shrinkage of the dielectric film to about the same thickness of the copper layer, thereby producing a generally planar surface.
Claim 15
Dependent Claim
21 words
The method in accordance with claim 1, wherein the step of removing the electroplating seed layer is performed by chemical etching.
Claim 16
Dependent Claim
27 words
The method in accordance with claim 1, wherein the step of removing the electroplating seed layer is performed at least partially, by selective etching with an acid.
Claim 17
Dependent Claim
13 words
The method in accordance with claim 15, wherein the acid comprises hydrofluoric acid.
Claim 18
Dependent Claim
24 words
The method in accordance with claim 1, wherein the step of removing the electroplating seed layer is performed at least in part, by ion-milling.
Claim 19
Dependent Claim
31 words
The method in accordance with claim 1, wherein the step of removing the electroplating seed layer is performed at least in part, by reactive ion-machining in a fluorine-oxygen combination containing plasma.
Claim 20
Dependent Claim
17 words
The method in accordance with claim 18, wherein the fluorine-oxygen combination comprises CF 4 :O 2 .
Claim 21
Dependent Claim
17 words
The method in accordance with claim 18, wherein the fluorine-oxygen combination comprises SF 6 :O 2 .
Claim 22
Dependent Claim
15 words
The method in accordance with claim 1, wherein the interconnect structure is a multi-layer structure.
Claim 23
Independent Claim
149 words
A method for forming an interconnect structure fabricated in a dielectric in a self-aligned manner, the method comprising the steps of: applying a dielectric film on a substrate; patterning the dielectric film to form a trench in the dielectric film; depositing a thin electroplating seed layer on the dielectric film and on the substrate in the trench, wherein the electroplating seed layer on the substrate is electrically isolated from the electroplating seed layer on the dielectric film; curing the dielectric film, thereby anisotropically shrinking the dielectric film; applying a photoresist layer over the dielectric film and the substrate; heating the photoresist layer sufficiently to cause it to shrink; etching the photoresist layer and thereby exposing the electroplating seed layer on the dielectric film; removing the electroplating seed layer from the dielectric film; stripping the photoresist layer; and electroplating a conductive layer on the electroplating seed layer, within the trench.
Claim 24
Independent Claim
149 words
A method for forming an interconnect structure fabricated in a dielectric in a self-aligned manner, the method comprising the steps of: applying a dielectric film on a substrate; patterning the dielectric film to form a trench in the dielectric film; depositing a thin electroplating seed layer on the dielectric film and on the substrate in the trench, wherein the electroplating seed layer on the substrate is electrically isolated from the electroplating seed layer on the dielectric film; curing the dielectric film, thereby anisotropically shrinking the dielectric film; applying a photoresist layer over the dielectric film and the substrate; heating the photoresist layer sufficiently to cause it to shrink; etching the photoresist layer and thereby exposing the electroplating seed layer on the dielectric film; removing the electroplating seed layer from the dielectric film; stripping the photoresist layer; and electroplating a conductive layer on the electroplating seed layer, within the trench.
Claim 25
Dependent Claim
14 words
The method in accordance with claim 22, wherein the dielectric film comprises a polymide.
Claim 26
Dependent Claim
12 words
The method in accordance with claim 22, wherein the substrate comprises silicon.
Claim 27
Dependent Claim
13 words
The method in accordance with claim 22, wherein the substrate comprises gallium arsenide.
Claim 28
Dependent Claim
22 words
The method in accordance with claim 22, wherein the dielectric film comprises a polymide that is applied to the substrate by spin-coating.
Claim 29
Dependent Claim
17 words
The method in accordance with claim 22, wherein the patterning step is performed by a lithographic technique.
Claim 30
Dependent Claim
20 words
The method in accordance with claim 22, wherein the electroplating seed layer comprises a titanium film and a copper film.
Claim 31
Dependent Claim
24 words
The method in accordance with claim 28, wherein the titanium film has a thickness that is substantially less than that of the copper film.
Claim 32
Dependent Claim
55 words
The method in accordance with claim 28, wherein the step of removing the electroplating seed layer comprises the steps of: exposing the electroplating seed layer to a dilute nitric acid etching solution, thereby removing the copper film; and exposing the electroplating seed layer to a dilute hydrofluoric acid etching solution, thereby removing the titanium film.
Claim 33
Dependent Claim
38 words
The method in accordance with claim 28, wherein the step of removing the electroplating seed layer from the dielectric film is performed by exposure of the electroplating seed layer to an etching solution comprising nitric and hydrochloric acids.
Claim 34
Dependent Claim
40 words
The method in accordance with claim 28, wherein the step of removing the electroplating seed layer from the dielectric film includes the step of machining the titanium layer to remove it using a plasma comprising CF 4 :O 2 .
Claim 35
Dependent Claim
37 words
The method in accordance with claim 28, wherein the step of removing the electroplating seed layer from the dielectric film includes the step of removing the titanium film with a plasma comprising SF 6 :O 2 .
Claim 36
Dependent Claim
14 words
The method in accordance with claim 22, wherein the electroplating seed layer comprises gold.
Claim 37
Dependent Claim
14 words
The method in accordance with claim 22, wherein the electroplating seed layer comprises palladium.
Claim 38
Dependent Claim
43 words
The method in accordance with claim 22, wherein the step of depositing applies the electroplating seed layer as a film substantially coating exposed surfaces of the trench and of the dielectric film, said surfaces that are coated being generally parallel with the substrate.
Claim 39
Dependent Claim
21 words
The method in accordance with claim 22, wherein the step of depositing applies the electroplating seed layer using an E-beam system.
Claim 40
Dependent Claim
25 words
The method in accordance with claim 22, wherein the curing step is performed by heating the dielectric film to a temperature of approximately 250° C.
Claim 41
Dependent Claim
15 words
The method in accordance with claim 22, wherein the curing step occurs at 90°-120° C.
Claim 42
Dependent Claim
22 words
The method in accordance with claim 22, wherein the etching step is performed by exposing the photoresist layer to an oxygen-containing plasma.
Claim 43
Dependent Claim
33 words
The method in accordance with claim 22, wherein the step of removing the electroplating seed layer from the dielectric film is performed by exposure of the electroplating seed layer to an etching solution.
Claim 44
Dependent Claim
32 words
The method in accordance with claim 22, wherein the step of removing the electroplating seed layer from the dielectric film is performed by exposure of the electroplating seed layer to a plasma.
Claim 45
Dependent Claim
19 words
The method in accordance with claim 22, wherein the step of stripping the photoresist layer is performed with acetone.
Claim 46
Dependent Claim
32 words
The method in accordance with claim 22, further comprising the step of baking the interconnect structure after the electroplating step, to provide a planar surface on which additional layers can be applied.
Claim 47
Dependent Claim
17 words
The method in accordance with claim 44, wherein the baking step occurs at a substantially elevated temperature.
Claim 48
Dependent Claim
15 words
The method in accordance with claim 22, wherein the interconnect structure is a multi-layer structure.
References Cited (Backward Citations)
US4339305A
Cited
US4526810A
Cited
US4440804A
Cited
US4451971A
Cited
US4508815A
Cited
US4532002A
Cited
US4519872A
Cited
US4575402A
Cited
US4661204A
Cited
US4661214A
Cited
US4810332A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1995-05-12 | 1995-11-11 | 1996-05-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-05-12 | 1999-11-11 | 2000-05-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-05-12 | 2003-11-11 | 2004-05-12 | $7700.00 | Window Closed / Lapsed |