US5624582A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optimization of dry etching through the control of helium backside pressure
Assignee: Philips Semiconductors Inc
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Filing: 1994-03-28
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Granted: 1997-04-29
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Expires: 2014-03-28
Abstract
Abstract In a dry non-isotropic etching process, backside cooling by helium controls the rate and uniformity of etching in a thermal silicon layer, the taper of profiles etched into silicon dioxide layers, and the dimension and uniformity of etched structures in a polycide or polysilicon layer, on the surface of a silicon wafer. Helium pressures from greater than 2 torr to more than 10 torr are satisfactorily utilized to produce these effects.
Inventors
- 👤 John L. Cain
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:01
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
153 words
A method of increasing the rate and uniformity of silicon dioxide etching during the dry non-isotropic etching of a oxide layer on the surface of a silicon wafer which comprises: (a) placing a patterned resist layer over the oxide layer found on the surface of said silicon wafer so as to define areas where the oxide layer is exposed and areas where the oxide layer is covered by the resist layer; (b) placing the silicon wafer prepared in step (a) in the wafer holder of an etching reactor; (c) removing the exposed oxide layer from the surface of the silicon wafer by dry non-isotropic etching employing wafer backside cooling by means of helium gas flow to the backside of the wafer holder, wherein the helium gas flow is adjusted to maintain a backside pressure greater than about 2 torr and less than about 10 torr to control the rate and uniformity of etching.
Claim 2
Independent Claim
153 words
A method of increasing the rate and uniformity of silicon dioxide etching during the dry non-isotropic etching of a oxide layer on the surface of a silicon wafer which comprises: (a) placing a patterned resist layer over the oxide layer found on the surface of said silicon wafer so as to define areas where the oxide layer is exposed and areas where the oxide layer is covered by the resist layer; (b) placing the silicon wafer prepared in step (a) in the wafer holder of an etching reactor; (c) removing the exposed oxide layer from the surface of the silicon wafer by dry non-isotropic etching employing wafer backside cooling by means of helium gas flow to the backside of the wafer holder, wherein the helium gas flow is adjusted to maintain a backside pressure greater than about 2 torr and less than about 10 torr to control the rate and uniformity of etching.
Claim 3
Dependent Claim
15 words
A method according to claim 1 wherein said etching reactor is a plasma etching reactor.
Claim 4
Dependent Claim
28 words
A method according to claim 1 wherein employing wafer backside cooling comprises introducing gas to the backside of said wafer holder wherein the gas consists essentially of helium.
Claim 5
Dependent Claim
17 words
A method according to claim 1 wherein wafer backside cooling maintains said wafer at a constant temperature.
Claim 6
Dependent Claim
25 words
A method according to claim 3 wherein said backside pressure is greater than about 2 torr and equal to or less than about 5.8 torr.
Claim 7
Dependent Claim
21 words
A silicon wafer containing patterned layers of silicon dioxide on the surface thereof made according to the method of claim 1.
Claim 8
Independent Claim
148 words
A method for controlling the taper of a profile etched in silicon dioxide during the dry non-isotropic etching of a silicon dioxide layer on the surface of a silicon wafer which comprises: (a) placing a patterned resist layer over the oxide layer found on the surface of said silicon wafer so as to define areas where the oxide layer is exposed and areas where the oxide layer is covered by the resist layer; (b) placing the silicon wafer prepared in step (a) in the wafer holder of an etching reactor; (c) removing the exposed oxide layer from the surface of the silicon wafer by dry non-isotropic etching employing wafer backside cooling by means of helium gas flow to the backside of the wafer holder, wherein the helium gas flow is adjusted to maintain a backside pressure greater than about 3 torr to control the taper of the profile.
Claim 9
Independent Claim
148 words
A method for controlling the taper of a profile etched in silicon dioxide during the dry non-isotropic etching of a silicon dioxide layer on the surface of a silicon wafer which comprises: (a) placing a patterned resist layer over the oxide layer found on the surface of said silicon wafer so as to define areas where the oxide layer is exposed and areas where the oxide layer is covered by the resist layer; (b) placing the silicon wafer prepared in step (a) in the wafer holder of an etching reactor; (c) removing the exposed oxide layer from the surface of the silicon wafer by dry non-isotropic etching employing wafer backside cooling by means of helium gas flow to the backside of the wafer holder, wherein the helium gas flow is adjusted to maintain a backside pressure greater than about 3 torr to control the taper of the profile.
Claim 10
Dependent Claim
17 words
A method according to claim 7 wherein said helium backside pressure is greater than about 10 torr.
Claim 11
Dependent Claim
28 words
A method according to claim 7 wherein employing wafer backside cooling comprises introducing gas to the backside of said wafer holder wherein the gas consists essentially of helium.
Claim 12
Dependent Claim
17 words
A method according to claim 7 wherein wafer backside cooling maintains said wafer at a constant temperature.
Claim 13
Dependent Claim
21 words
A silicon wafer containing a patterned layer of silicon dioxide on its surface made according to the method of claim 8.
Claim 14
Independent Claim
155 words
A method for controlling the dimension and uniformity of etched structures during the dry non-isotropic etching of a polycide or polysilicon layer on the surface of a silicon wafer which comprises: (a) placing a patterned resist layer over the polycide or polysilicon layer found on the surface of said silicon wafer so as to define areas where the polycide or polysilicon layer is exposed and areas where said layer is covered by the resist layer; (b) placing the silicon wafer prepared in step (a) in the wafer holder of an etching reactor; (c) removing the exposed polycide or polysilicon layer from the surface of the silicon wafer by dry non-isotropic etching employing wafer backside cooling by means of a helium gas flow to the backside of the wafer holder, wherein the helium gas flow is adjusted to maintain a backside pressure greater than about 3 torr to control the dimension and uniformity of etched structures.
Claim 15
Independent Claim
155 words
A method for controlling the dimension and uniformity of etched structures during the dry non-isotropic etching of a polycide or polysilicon layer on the surface of a silicon wafer which comprises: (a) placing a patterned resist layer over the polycide or polysilicon layer found on the surface of said silicon wafer so as to define areas where the polycide or polysilicon layer is exposed and areas where said layer is covered by the resist layer; (b) placing the silicon wafer prepared in step (a) in the wafer holder of an etching reactor; (c) removing the exposed polycide or polysilicon layer from the surface of the silicon wafer by dry non-isotropic etching employing wafer backside cooling by means of a helium gas flow to the backside of the wafer holder, wherein the helium gas flow is adjusted to maintain a backside pressure greater than about 3 torr to control the dimension and uniformity of etched structures.
Claim 16
Dependent Claim
17 words
A method according to claim 12 wherein said helium backside pressure is greater than about 10 torr.
Claim 17
Dependent Claim
22 words
A method according to claim 12 wherein said polysilicon or said polycide layer has a thickness from about 0.05 to 1.0 microns.
Claim 18
Dependent Claim
11 words
The method of claim 12 wherein said polycide is tungsten silicide.
Claim 19
Dependent Claim
20 words
The method of claim 12 wherein said patterned resist layer is from about 0.5 to about 2 microns in thickness.
Claim 20
Dependent Claim
19 words
The method of claim 12 wherein the dry non-isotropic etching method utilizing helium backside cooling is reactive ion etching.
Claim 21
Dependent Claim
22 words
A silicon wafer containing a patterned layer of polycide or polysilicon on its surface made according to the method of claim 12.
Claim 22
Dependent Claim
17 words
A method according to claim 12 wherein wafer backside cooling maintains said wafer at a constant temperature.
Claim 23
Dependent Claim
28 words
A method according to claim 12 wherein employing wafer backside cooling comprises introducing gas to the backside of said wafer holder wherein the gas consists essentially of helium.
Claim 24
Dependent Claim
16 words
A method according to claim 20 wherein said backside pressure is greater than about 14 torr.
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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) | 2000-04-28 | 2000-10-28 | 2001-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-04-28 | 2004-10-28 | 2005-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-04-28 | 2008-10-28 | 2009-04-29 | $7700.00 | Window Closed / Lapsed |