US5501893A
Expired / Lapsed
US
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Method of anisotropically etching silicon
Assignee: Robert Bosch GmbH
•
Filing: 1993-11-27
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Granted: 1996-03-26
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Expires: 2013-11-27
Abstract
Abstract A method of anisotropic plasma etching of silicon to provide laterally defined recess structures therein through an etching mask employing a plasma, the method including anisotropic plasma etching in an etching step a surface of the silicon by contact with a reactive etching gas to removed material from the surface of the silicon and provide exposed surfaces; polymerizing in a polymerizing step at least one polymer former contained in the plasma onto the surface of the silicon during which the surfaces that were exposed in a preceding etching step are covered by a polymer layer thereby forming a temporary etching stop; and alternatingly repeating the etching step and the polymerizing step. The method provides a high mask selectivity simultaneous with a very high anisotropy of the etched structures.
Inventors
- 👤 Franz Laermer
- 👤 Andrea Schilp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:18
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/69; H10P50/691; H10P50/693; H10P50/694; B; B81; B81C; B81C1/00; B81C1/00436; B81C1/00555; B81C1/00619; H10P50/20; H10P50/24; H10P50/242; H10P50/244; B81C2201/00; B81C2201/01; B81C2201/0101; B81C2201/0111; B81C2201/0112; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24479; Y10T428/24521
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
114 words
A method of anisotropic plasma etching of silicon to provide laterally defined recess structures therein through an etching mask employing a plasma, the method comprising: a. anisotropic plasma etching in an etching step a surface of the silicon by contact with a reactive etching gas to removed material from the surface of the silicon and provide exposed surfaces; b. polymerizing in a polymerizing step at least one polymer former contained in the plasma onto the surface of the silicon during which the surfaces that were exposed in a preceding etching step are covered by a polymer layer thereby forming a temporary etching stop; and c. alternatingly repeating the etching step and the polymerizing step.
Claim 2
Independent Claim
114 words
A method of anisotropic plasma etching of silicon to provide laterally defined recess structures therein through an etching mask employing a plasma, the method comprising: a. anisotropic plasma etching in an etching step a surface of the silicon by contact with a reactive etching gas to removed material from the surface of the silicon and provide exposed surfaces; b. polymerizing in a polymerizing step at least one polymer former contained in the plasma onto the surface of the silicon during which the surfaces that were exposed in a preceding etching step are covered by a polymer layer thereby forming a temporary etching stop; and c. alternatingly repeating the etching step and the polymerizing step.
Claim 3
Dependent Claim
16 words
The method according to claim 1, wherein the polymerization steps are controlled independently of one another.
Claim 4
Dependent Claim
21 words
The method according to claim 1, wherein the etching steps are performed without the presence of polymer formers in the plasma.
Claim 5
Dependent Claim
30 words
The method according to claim 1, wherein a polymer layer applied during the polymerization step to the laterally defined recess structures is partially restripped during an immediately subsequent etching step.
Claim 6
Dependent Claim
40 words
The method according to claim 1, wherein etching removes material from the surface of the silicon to a preselected etching depth, and wherein the etching steps are performed over a preselected period of time which provides the preselected etching depth.
Claim 7
Dependent Claim
46 words
The method according to claim 1, wherein polymerizing polymer formers contained in the plasma onto the surface of the silicon provides a polymer layer having a preselected thickness, and wherein the polymerization steps are performed over a preselected period of time which provides the preselected thickness.
Claim 8
Dependent Claim
19 words
The method according to claim 1, wherein the silicon is bombarded by an ionic energy during the etching steps.
Claim 9
Dependent Claim
20 words
The method according to claim 1, wherein the silicon is alternatingly bombarded by an ionic energy during the polymerization steps.
Claim 10
Dependent Claim
34 words
The method according to claim 1, wherein the silicon is bombarded by an ionic energy during the etching steps, and wherein the ionic energy ranges between 1 and 50 eV during the etching steps.
Claim 11
Dependent Claim
20 words
The method according to claim 9, wherein the ionic energy ranges between 5 and 30 eV during the etching steps.
Claim 12
Dependent Claim
34 words
The method according to claim 1, wherein the silicon is bombarded by an ionic energy during the polymerization steps, and wherein, during the polymerization steps, the ionic energy ranges between 1 and 10 eV.
Claim 13
Dependent Claim
16 words
The method according to claim 11, wherein the ionic energy ranges between 4 and 6 eV.
Claim 14
Dependent Claim
13 words
The method according to claim 12, wherein the ionic energy is 5 eV.
Claim 15
Dependent Claim
19 words
The method according to claim 1, wherein the reactive etching gas is at least one gas that releases fluorine.
Claim 16
Dependent Claim
23 words
The method according to claim 1, wherein the reactive etching gas is a mixture of sulfur hexafluoride, SF 6 , and argon, Ar.
Claim 17
Dependent Claim
22 words
The method according to claim 1, wherein the at least one polymer former contained in the plasma is at least one hydrofluorocarbon.
Claim 18
Dependent Claim
17 words
The method according to claim 16, wherein the at least one hydrofluorocarbon has a low fluorine-to-carbon ratio.
Claim 19
Dependent Claim
28 words
The method according to claim 1, wherein the at least one polymer former contained in the plasma is a mixture of trifluoromethane, CHF 3 , and argon, Ar.
Claim 20
Dependent Claim
36 words
The method according to claim 1, wherein the etching steps and polymerization steps employ the recited respective media have gas flows ranging from 0 to 100 sccm and processing pressures ranging from 10 to 100 μbar.
Claim 21
Dependent Claim
23 words
The method according to claim 1, wherein the plasma is generated with microwave irradiation at an output ranging between 100 and 1500 W.
Claim 22
Dependent Claim
23 words
The method according to claim 1, wherein the plasma is generated with microwave irradiation at an output ranging between 300 and 1200 W.
Claim 23
Dependent Claim
23 words
The method according to claim 1, wherein the silicon is cooled during at least one of the etching steps and the polymerization steps.
Claim 24
Dependent Claim
29 words
The method according to claim 1, wherein the silicon has a rear side, and wherein the rear side of the silicon is acted upon by a helium gas current.
Claim 25
Dependent Claim
29 words
The method according to claim 1, wherein a cooled substrate electrode is provided with a thermal contact material, and wherein the silicon is positioned on the thermal contact material.
Claim 26
Dependent Claim
25 words
The method according to claim 1, wherein the etching steps and polymerization steps are preformed with a high plasma density of reactive species and ions.
Claim 27
Dependent Claim
20 words
The method according to claim 1, wherein the plasma density and the ionic energy are controlled independently of one another.
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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) | 1999-03-26 | 1999-09-25 | 2000-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-26 | 2003-09-25 | 2004-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-26 | 2007-09-25 | 2008-03-26 | $7700.00 | Window Closed / Lapsed |