US5409567A
Expired / Lapsed
US
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Method of etching copper layers
Assignee: Apple Inc
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Filing: 1994-04-28
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Granted: 1995-04-25
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Expires: 2014-04-28
Abstract
Abstract A method for etching a composite copper layer (40) of plated copper (20) overlying physical vapor deposited copper (30) comprises etching the plated copper (20) at a rate less than the rate of etch of the physical vapor deposited copper (30). The etching may be accomplished with an aqueous solution of ammonium peroxydisulfate with molar concentrations of ammonium ions between 0.0438 and 0.1052, at a temperature between 30° and 35° C. and with the pH buffered to remain at a value between 1 and 1.8.
Inventors
- 👤 William H. Lytle
- 👤 Kevin H. Chang
- 👤 Peter C. East
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:09
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/18; H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/067; H05K3/10; H05K3/108; H05K2201/00; H05K2201/03; H05K2201/0302; H05K2201/0317; H05K3/38; H05K3/388
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
60 words
A method of etching comprising the steps of: providing a composite copper layer; providing an aqueous etch solution comprising a concentration of ammonium ions, a concentration of peroxydisulfate ions and a pH, the pH being within a range of 1.0 to 1.8; heating said etch solution to a first temperature; and disposing said etch solution on said composite copper layer.
Claim 2
Independent Claim
60 words
A method of etching comprising the steps of: providing a composite copper layer; providing an aqueous etch solution comprising a concentration of ammonium ions, a concentration of peroxydisulfate ions and a pH, the pH being within a range of 1.0 to 1.8; heating said etch solution to a first temperature; and disposing said etch solution on said composite copper layer.
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein the copper composite layer comprises a first layer of copper formed by physical vapor deposition and a second layer of copper formed by electroplating.
Claim 4
Dependent Claim
23 words
The method of claim 1, wherein the step of heating comprises heating said etch solution to a range of 30° to 35° C.
Claim 5
Dependent Claim
23 words
The method of claim 1 wherein the step of disposing the etch solution comprises immersing said composite copper layer into said etch solution.
Claim 6
Dependent Claim
19 words
The method of claim 1 wherein the concentration of ammonium ions is between 0.1 and 0.02 moles per liter.
Claim 7
Independent Claim
61 words
A method for etching a composite copper layer comprising plated copper overlying physical vapor deposited copper, the method comprising the steps of: exposing the composite copper layer to an etch solution; and concurrently etching the plated copper at a first rate and the physical vapor deposited copper at a second rate, wherein the first rate is less than the second rate.
Claim 8
Independent Claim
61 words
A method for etching a composite copper layer comprising plated copper overlying physical vapor deposited copper, the method comprising the steps of: exposing the composite copper layer to an etch solution; and concurrently etching the plated copper at a first rate and the physical vapor deposited copper at a second rate, wherein the first rate is less than the second rate.
Claim 9
Dependent Claim
40 words
The method of claim 6 wherein the etch solution comprises an aqueous solution comprising a concentration of ammonium ions and a concentration of peroxydisulfate ions and wherein the concentration of ammonium ions is between 0.1 and 0.02 moles per liter.
Claim 10
Dependent Claim
21 words
The method of claim 6 further comprising heating the etch solution to within a temperature range of 30° to 35° C.
Claim 11
Dependent Claim
28 words
The method of claim 6 wherein the step of exposing the composite copper layer to an etch solution comprises immersing the composite copper layer into the etch solution.
Claim 12
Dependent Claim
22 words
The method of claim 7 wherein the aqueous solution of ammonium peroxydisulfate has a pH within a range of 1.0 to 1.8.
Claim 13
Dependent Claim
21 words
The method of claim 6, wherein the first rate is less than or equal to one half of the second rate.
Claim 14
Dependent Claim
37 words
The method of claim 6, wherein the step of exposing the copper composite layer to an etch solution comprises exposing the copper composite layer to a solution comprising a monodentate ligand in combination with an oxidizing agent.
Claim 15
Dependent Claim
32 words
The method of claim 12, wherein the monodentate ligand has a pKa between 3 and 5 and a formation constant with Cu +2 , log K 1 , between 3 and 6.
Claim 16
Dependent Claim
19 words
The method of claim 12, wherein the monodentate ligand is selected from the group triethylamine, ethanolamine, dimethylsulfoxide and phenol.
Claim 17
Dependent Claim
17 words
The method of claim 12, wherein the oxidizing agent has a redox potential greater than 0.35 V.
Claim 18
Dependent Claim
20 words
The method of claim 12, wherein the oxidizing agent is selected from the group chlorite, bromate, perchlorate, permangate and dichromate.
References Cited (Backward Citations)
US4354895A
Cited
US5242535A
Cited
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