US4345969A
Expired / Lapsed
US
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Metal etch solution and method
Assignee: Motorola Solutions Inc
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Filing: 1981-03-23
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Granted: 1982-08-24
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Expires: 2001-03-23
Abstract
Abstract A solution is disclosed for the one-step etching of a three layer titanium-nickel-copper metallization. The etch solution comprises about 1.8 to 2.0 moles/liter hydrofluoric acid, about 2.5 to 4.0 moles/liter acetic acid, about 8.7 to 9.0 moles/liter nitric acid, and balance water. Use of the solution permits the patterned etching of sequential layers of titanium, nickel, and copper without excessive attack of underlying silicon dioxide layers.
Inventors
- 👤 Kristi L. James
- 👤 A. L. Shields
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 00:30
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; H; H10; H10P; H10P50/00; H10P50/60; H10P50/66; H10P50/663; H10P50/667
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
45 words
An etchant for the patterned etching of sequential layers of titanium, nickel and copper overlying a substrate including silicon dioxide which comprises, in moles/liter: about 1.8 to 2.0 hydrofluoric acid, about 2.5 to 4.0 acetic acid, about 8.7 to 9.0 nitric acid, and balance water.
Claim 2
Dependent Claim
45 words
An etchant for the patterned etching of sequential layers of titanium, nickel and copper overlying a substrate including silicon dioxide which comprises, in moles/liter: about 1.8 to 2.0 hydrofluoric acid, about 2.5 to 4.0 acetic acid, about 8.7 to 9.0 nitric acid, and balance water.
Claim 3
Dependent Claim
11 words
The etchant of claim 1 comprising about 1.9 moles/liter hydrofluoric acid.
Claim 4
Dependent Claim
21 words
The etchant of claim 1 comprising in moles/liter about 1.9 hydrofluoric acid, 2.5 acetic acid, 8.7 nitric acid and balance water.
Claim 5
Dependent Claim
9 words
The etchant of claim 1 further comprising a surfactant.
Claim 6
Independent Claim
81 words
A method for the patterned etching of sequential layers of titanium nickel and copper on a substrate which comprises the steps of: providing an etch mask overlying said sequential layers; immersing said substrate in an etchant solution comprising about 1.8 to 2.0 moles/liter hydrofluoric acid, about 2.5 to 4.0 moles/liter acetic acid, about 8.7 to 9.0 moles/liter nitric acid and balance water; and etching portions of said layers exposed through said mask in said solution until said exposed portions are removed.
Claim 7
Independent Claim
81 words
A method for the patterned etching of sequential layers of titanium nickel and copper on a substrate which comprises the steps of: providing an etch mask overlying said sequential layers; immersing said substrate in an etchant solution comprising about 1.8 to 2.0 moles/liter hydrofluoric acid, about 2.5 to 4.0 moles/liter acetic acid, about 8.7 to 9.0 moles/liter nitric acid and balance water; and etching portions of said layers exposed through said mask in said solution until said exposed portions are removed.
Claim 8
Dependent Claim
19 words
The method of claim 4 wherein said solution is maintained at a temperature of about 43° to 50° C.
Claim 9
Dependent Claim
17 words
The method of claim 5 wherein said solution is maintained at a temperature of about 48° C.
Claim 10
Dependent Claim
11 words
The method of claim 4 wherein said etch mask comprises photoresist.
Claim 11
Independent Claim
94 words
A method for metallizing a semiconductor device which comprises the steps of: applying to said device a first layer of titanium, a second layer of nickel and a third layer of copper; forming a patterned etch mask overlying said layer of copper; immersing said device in an etchant solution comprising about 1.8 to 2.0 moles/liter hydrofluoric acid, about 2.5 to 4.0 moles/liter acetic acid, about 8.7 to 9.0 moles/liter nitric acid and balance water; and removing said device from said solution after removing portions of said metal layers not covered by said etch mask.
Claim 12
Independent Claim
94 words
A method for metallizing a semiconductor device which comprises the steps of: applying to said device a first layer of titanium, a second layer of nickel and a third layer of copper; forming a patterned etch mask overlying said layer of copper; immersing said device in an etchant solution comprising about 1.8 to 2.0 moles/liter hydrofluoric acid, about 2.5 to 4.0 moles/liter acetic acid, about 8.7 to 9.0 moles/liter nitric acid and balance water; and removing said device from said solution after removing portions of said metal layers not covered by said etch mask.
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) | 1985-08-23 | 1986-02-22 | 1986-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-23 | 1990-02-22 | 1990-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-23 | 1994-02-22 | 1994-08-24 | $7700.00 | Window Closed / Lapsed |