US4207137A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of controlling a plasma etching process by monitoring the impedance changes of the RF power
Assignee: AT&T Inc
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Filing: 1979-04-13
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Granted: 1980-06-10
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Expires: 1999-04-13
Abstract
Abstract A plasma etching process wherein the end point of the reaction can be accurately determined for fine line definition. This is accomplished by monitoring the impedance of the plasma during the reaction. The reaction is stopped at, or a predetermined time after, the change in impedance reaches a zero value, which is either a maximum or minimum depending upon the gases utilized.
Inventors
- 👤 Angelo R. Tretola
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:30
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32917; H01J37/32935; C; C23; C23F; C23F4/00; H01J37/32009; H01J37/32082; H01J37/32174; H01J37/32183; H01J37/32963
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
107 words
A method of etching a selected area of a layer (33 of FIG. 2) formed over a body (31) comprising the steps of placing the body in a chamber (10 of FIG. 1) between electrode means (14 and 19), introducing a reactant gas into said chamber, and supplying power to said electrodes so as to create a plasma in said chamber capable of etching said layer, characterized in that the impedance change of the plasma is monitored during the etching reaction and the power to the elecrodes means is turned off at a predetermined time with respect to the point where the impedance change essentially reaches zero.
Claim 2
Independent Claim
107 words
A method of etching a selected area of a layer (33 of FIG. 2) formed over a body (31) comprising the steps of placing the body in a chamber (10 of FIG. 1) between electrode means (14 and 19), introducing a reactant gas into said chamber, and supplying power to said electrodes so as to create a plasma in said chamber capable of etching said layer, characterized in that the impedance change of the plasma is monitored during the etching reaction and the power to the elecrodes means is turned off at a predetermined time with respect to the point where the impedance change essentially reaches zero.
Claim 3
Dependent Claim
22 words
The method according to claim 1 wherein the power is turned off at the point where the impedance change essentially reaches zero.
Claim 4
Dependent Claim
23 words
The method according to claim 1 wherein the power is turned off at a predetermined time after the impedance change essentially reaches zero.
Claim 5
Dependent Claim
30 words
The method according to claim 1 wherein the power is turned off at a predetermined time with respect to the point where the impedance essentially reaches an absolute maximum value.
Claim 6
Dependent Claim
38 words
The method according to claim 1 wherein the power is turned off at a predetermined time with respect to the point where the impedance essentially reaches an absolute minimum value after having risen to an absolute maximum value.
Claim 7
Dependent Claim
20 words
The method according to claim 4 wherein the reactant gas comprises a mixture of CF 4 and O 2 .
Claim 8
Dependent Claim
14 words
The method according to claim 5 wherein the reactant gas comprises CClF 3 .
Claim 9
Dependent Claim
12 words
The method according to claim 1 wherein the layer comprises polycrystalline silicon.
Claim 10
Dependent Claim
22 words
The method according to claim 3 wherein the power is turned off approximately 30 seconds after the impedance change essentially reaches zero.
Claim 11
Dependent Claim
29 words
The method according to claim 1 wherein the impedance change is monitored by tracing a curve of the impedance by means of a stripline recorder (18 of FIG. 1).
Claim 12
Dependent Claim
22 words
The method according to claim 1 wherein the impedance change is monitored by a differentiator and comparator circuit (41 of FIG. 6).
Claim 13
Dependent Claim
28 words
The method according to claim 1 wherein the impedance change is monitored by detecting the impedance mismatch between the power supply and the plasma during the etching reaction.
Claim 14
Independent Claim
121 words
A method of etching a selected area of a polycrystalline silicon layer (33 of FIG. 2) formed over a semiconductor body (31) comprising the steps of placing the body in a chamber (10 of FIG. 1) between electrode means (14 and 19), introducing a reactant gas comprising CF 4 and O 2 into said chamber, and supplying power to said electrode means so as to create a plasma in said chamber capable of etching said layer, characterized in that the impedance change of the plasma is monitored during the etching reaction and the power to the electrode means is turned off at a predetermined time with respect to the point where the impedance change essentially reaches zero at an absolute maximum.
Claim 15
Independent Claim
121 words
A method of etching a selected area of a polycrystalline silicon layer (33 of FIG. 2) formed over a semiconductor body (31) comprising the steps of placing the body in a chamber (10 of FIG. 1) between electrode means (14 and 19), introducing a reactant gas comprising CF 4 and O 2 into said chamber, and supplying power to said electrode means so as to create a plasma in said chamber capable of etching said layer, characterized in that the impedance change of the plasma is monitored during the etching reaction and the power to the electrode means is turned off at a predetermined time with respect to the point where the impedance change essentially reaches zero at an absolute maximum.
Claim 16
Independent Claim
129 words
A method of etching a selected area of a polycrystalline silicon layer (33 of FIG. 2) formed over a semiconductor body (31) comprising the steps of placing the body in a chamber (10 of FIG. 1) between electrode means (14 and 19), introducing a reactant gas comprising CClF 3 into said chamber, and supplying power to said electrode means so as to create a plasma in said chamber capable of etching said layer, characterized in that the impedance change of the plasma is monitored during the etching reaction and the power to the electrode means is turned off at a predetermined time with respect to the point where the impedance change essentially reaches zero at an absolute minimum after the impedance has initially risen to an absolute maximum value.
Claim 17
Independent Claim
129 words
A method of etching a selected area of a polycrystalline silicon layer (33 of FIG. 2) formed over a semiconductor body (31) comprising the steps of placing the body in a chamber (10 of FIG. 1) between electrode means (14 and 19), introducing a reactant gas comprising CClF 3 into said chamber, and supplying power to said electrode means so as to create a plasma in said chamber capable of etching said layer, characterized in that the impedance change of the plasma is monitored during the etching reaction and the power to the electrode means is turned off at a predetermined time with respect to the point where the impedance change essentially reaches zero at an absolute minimum after the impedance has initially risen to an absolute maximum value.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-06-10 | 1983-12-10 | 1984-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-06-10 | 1987-12-10 | 1988-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-06-10 | 1991-12-10 | 1992-06-10 | $7700.00 | Window Closed / Lapsed |