US4968552A
Expired / Lapsed
US
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Versatile reactive ion etch barriers from polyamic acid salts
Assignee: International Business Machines Corp
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Filing: 1989-10-13
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Granted: 1990-11-06
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Expires: 2009-10-13
Abstract
Abstract The present invention provides a novel approach to forming a RIE etch barrier in processes where thermally stable polymeric materials containing free carboxyl groups, such as polyamic acid polymers, are present as masking layers in the electrical device to be fabricated. The present process takes advantage of the discovery that polyamic acids complex with certain metallic cations under slightly acidic conditions to form polyamic acid salts. These salts can be made to further react with a variety of etching gases to form a non-volatile salt or oxide which imparts etch barrier properties to that portion of the polyamic acid layer exposed to the metallic cations.
Inventors
- 👤 Harold G. Linde
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:44
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/004; G03F7/09; G03F7/094; H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/286; H10P50/287; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/24835
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
126 words
A method of forming an RIE etch barrier comprising the steps of: (a) applying a layer comprising an organic polymer resin to a substrate, said organic polymer resin containing functional groups capable of reacting with metal ions; (b) applying a film of polymeric resist material to said layer; (c) imagewise exposing and developing said film so as to selectively expose portions of said polymer layer; (d) contacting said exposed portions of said polymer layer with a solution containing metal ions to incorporate said ions into said exposed portions; and (e) exposing the system to reactive ion etching using an etch gas reactive with said ions to uncover portions of the substrate and thereby generate a masked relief structure which can be used to image the substrate.
Claim 2
Independent Claim
126 words
A method of forming an RIE etch barrier comprising the steps of: (a) applying a layer comprising an organic polymer resin to a substrate, said organic polymer resin containing functional groups capable of reacting with metal ions; (b) applying a film of polymeric resist material to said layer; (c) imagewise exposing and developing said film so as to selectively expose portions of said polymer layer; (d) contacting said exposed portions of said polymer layer with a solution containing metal ions to incorporate said ions into said exposed portions; and (e) exposing the system to reactive ion etching using an etch gas reactive with said ions to uncover portions of the substrate and thereby generate a masked relief structure which can be used to image the substrate.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said organic polymer is a polyamic acid.
Claim 4
Dependent Claim
12 words
The method of claim 2 wherein said substrate is a silicon wafer.
Claim 5
Dependent Claim
20 words
The method of claim 2 wherein said polyamic acid is the reaction product of aromatic dianhydride and an aromatic diamine.
Claim 6
Dependent Claim
12 words
The method of claim 2 wherein said resist material is positive acting.
Claim 7
Dependent Claim
17 words
The method of claim 2 wherein said reactive ion etching step utilizes a gaseous etchant comprising oxygen.
Claim 8
Dependent Claim
17 words
The method of claim 2 wherein said reactive ion etching step utilizes a gaseous etchant comprising halogen.
Claim 9
Dependent Claim
21 words
The method of claim 2 wherein said solution containing metal cations has a pH ranging from about 3.5 to about 7.0.
Claim 10
Dependent Claim
47 words
The method of claim 7 wherein said gaseous etchant is selected from the group consisting of halogen, CX 4 , C 2 X 6 , CFC1 3 , CF 3 Cl, SX 6 , CCl 2 F 2 , and NX 3 , wherein X is halogen.
Claim 11
Dependent Claim
11 words
The method of claim 9 wherein X is Cl or F.
Claim 12
Dependent Claim
26 words
The method of claim 2 wherein said metal ions are alkaline earth or heavy metal ions selected from Groups IIA or IB of the Periodic Table.
Claim 13
Dependent Claim
30 words
The method of claim 2 wherein said metal ions are selected from the group consisting of calcium, magnesium, barium, strontium, lead, zinc, cobalt, copper, silver, nickel, titanium, chromium, and manganese.
Claim 14
Dependent Claim
78 words
The method of claim 2 further including the step between step (d) and step (e) comprising stripping away the undeveloped areas of said resist film and contacting the thus exposed portions of said polymer layer with a solution containing metal ions of different species from the ions employed in step (d), one of said species of ions being reactive with said etch gas and the other of said species of ions being substantially non-reactive with said etch gas.
Claim 15
Dependent Claim
24 words
The method of claim 2 wherein said developing step (c) is sufficient to develop both the resist film layer and the underlying polymer layer.
Claim 16
Dependent Claim
25 words
The method of claim 14 further including the step between step (c) and step (d) comprising stripping away the undeveloped areas of said resist film.
Claim 17
Dependent Claim
10 words
A relief structure prepared by the method of claim 1.
Claim 18
Dependent Claim
15 words
The relief structure of claim 16 wherein said organic polymer layer is a polyamic acid.
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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) | 1993-11-05 | 1994-05-07 | 1994-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-05 | 1998-05-07 | 1998-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-05 | 2002-05-07 | 2002-11-06 | $7700.00 | Window Closed / Lapsed |