Patent US4810335A successfully refreshed from Google Patents.
US4810335A
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US
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Method for monitoring etching processes
Assignee: Siemens AG
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Filing: 1988-01-11
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Granted: 1989-03-07
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Expires: 2008-01-11
Abstract
Abstract The method for monitoring an end point of an etching process of electrically insulating layers effected by ions, radicals and/or neutral particles in a plasma is accomplished with the assistance of a reference substrate having a defined specimen geometry which is situated on a mobile substrate holder with the layers to be etched. The electrical resistance is measured and a voltage drop of a known constant current is impressed at known time intervals onto an electrically conductive layer lying under the layer to be etched. Measurement of the voltage drop is continued until an injection current is additionally injected into the conductive layer by the plasma to change the voltage drop. Test data is transmitted in non-contacting fashion by pulse code modulated electromagnetic radiation using a telemetry system so that the movable substrate is an independent unit. A process control computer controls the etching process via the etching rate by local monitoring of the end point of the etching carried out in the plasma.
Inventors
- 👤 Konrad Hieber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:42
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32917; H01J37/32935; G; G01; G01R; G01R27/00; G01R27/02
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
128 words
A method for monitoring etching processes effected by ions, radicals and/or neutral particles activated in a plasma, comprising the steps of: identifying an end point of material erosion of a layer to be etched by using a reference substrate including an electrically insulating layer applied to a metallically conductive layer, said reference substrate including a photoresist mask and a low impedance contact on said electrically insulating layer, said step of identifying including: (a) measuring sheet resistivity of said reference substrate to define a specimen geometry, (b) applying a constant known test current to said metallically conductive layer at defined points in time, (c) measuring a voltage drop until an additional current injected into said metallically conductive layer by ions and electrons in the plasma changes the voltage drop.
Claim 2
Independent Claim
128 words
A method for monitoring etching processes effected by ions, radicals and/or neutral particles activated in a plasma, comprising the steps of: identifying an end point of material erosion of a layer to be etched by using a reference substrate including an electrically insulating layer applied to a metallically conductive layer, said reference substrate including a photoresist mask and a low impedance contact on said electrically insulating layer, said step of identifying including: (a) measuring sheet resistivity of said reference substrate to define a specimen geometry, (b) applying a constant known test current to said metallically conductive layer at defined points in time, (c) measuring a voltage drop until an additional current injected into said metallically conductive layer by ions and electrons in the plasma changes the voltage drop.
Claim 3
Dependent Claim
23 words
A method as claimed in claim 1, wherein step (c) is carried out at a time interval of every 0.01 through 1 second.
Claim 4
Dependent Claim
15 words
A method as claimed in claim 2, wherein said time interval is approximately 0.2 seconds.
Claim 5
Dependent Claim
27 words
A method as claimed in claim 1, further comprising the step of: transmitting data obtained during step (c) in non-contacting fashion by pulse code modulated electromagnetic radiation.
Claim 6
Dependent Claim
26 words
A method as claimed in claim 1, further comprising the step of: calculating a local etching rate dependent on time from data obtained during step (c).
Claim 7
Dependent Claim
23 words
A method as claimed in claim 1, further comprising the step of: acquiring data obtained during step (c) using a process control computer.
Claim 8
Dependent Claim
42 words
A method as claimed in claim 1, further comprising the steps of: using an evacuatable lock chamber as an etching reactor; and moving a substrate holder carrying said reference substrate and said layer of be etched during material erosion in the plasma.
Claim 9
Independent Claim
100 words
A method for identifying an end point of etching by electrically charged particles activated in a plasma, comprising the steps of: etching a layer of electrically insulating material that lies over a layer of electrically conductive material; applying a known test current through said layer of electrically conductive material; and detecting a change in current flow in said layer of electrically conductive layer as the result of an additional injection current of said electrically charged particles, said change being indicative of an end point of said etching of said layer of electrically insulating material from said layer of conductive material.
Claim 10
Independent Claim
100 words
A method for identifying an end point of etching by electrically charged particles activated in a plasma, comprising the steps of: etching a layer of electrically insulating material that lies over a layer of electrically conductive material; applying a known test current through said layer of electrically conductive material; and detecting a change in current flow in said layer of electrically conductive layer as the result of an additional injection current of said electrically charged particles, said change being indicative of an end point of said etching of said layer of electrically insulating material from said layer of conductive material.
Claim 11
Dependent Claim
27 words
A method as claimed in claim 8, wherein said change in current is detected by identifying a drop in voltage across said layer of electrically conductive material.
Claim 12
Dependent Claim
18 words
A method as claimed in claim 8, wherein said test current is applied periodically at distinct time intervals.
Claim 13
Independent Claim
97 words
A method for identifying complete removal of at least regions of a non-conductive layer lying over a conductive layer, comprising the steps of: etching said non-conductive layer in a plasma of electrically charged particles; conducting a current of a predetermined amplitude through said conductive layer; establishing a voltage across said conductive layer as the result of said current of predetermined amplitude, and detecting a change in said established voltage caused by injection of said electrically charged particles into said conductive layer, said change in voltage being indicative of removal of said non-conducting layer from said conductive layer.
Claim 14
Independent Claim
97 words
A method for identifying complete removal of at least regions of a non-conductive layer lying over a conductive layer, comprising the steps of: etching said non-conductive layer in a plasma of electrically charged particles; conducting a current of a predetermined amplitude through said conductive layer; establishing a voltage across said conductive layer as the result of said current of predetermined amplitude, and detecting a change in said established voltage caused by injection of said electrically charged particles into said conductive layer, said change in voltage being indicative of removal of said non-conducting layer from said conductive layer.
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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) | 1992-03-06 | 1992-09-05 | 1993-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-06 | 1996-09-05 | 1997-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-06 | 2000-09-05 | 2001-03-07 | $7700.00 | Window Closed / Lapsed |