Patent US4968585A successfully refreshed from Google Patents.
US4968585A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microfabricated cantilever stylus with integrated conical tip
Assignee: Leland Stanford Junior University
•
Filing: 1989-06-20
•
Granted: 1990-11-06
•
Expires: 2009-06-20
Abstract
Abstract A cantilever stylus with an integrally formed conical tip is provided for atomic force microscopy AFM. The method for forming a stylus includes forming a circular masking pattern on the surface of a silicon substrate and anisotropically etching the silicon to form a post under the masking pattern. The post is then isotropically etched to produce a conical silicon tip mold. In one embodiment of the invention the silicon substrate and the conical silicon tip mold are thermally oxidized to form a cantilever stylus having including a cantilever arm with a conical tip fixed to its free end. In another embodiment of the invention the silicon substrate and the conical silicon tip mold are coated with a thin film of a dielectric material to form a cantilever stylus with a conical tip. In this embodiment the backside of the stylus is coated with a conductive material and a strong electric field is applied to the tip to cause electromigration of the conductive material to the point of the tip.
Inventors
- 👤 Thomas R. Albrecht
- 👤 Shinya Akamine
- 👤 Mark J. Zdeblick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:15
CPC Classifications
G; G01; G01Q; G01Q60/00; G01Q60/24; G01Q60/38; B; B82; B82Y; B82Y35/00; G03; G03F; G03F7/00
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
60 words
A method of forming a silicon tip, comprising the steps of: forming a masking layer having a predetermined masking pattern on a portion of the surface of a silicon substrate; anisotropically etching said silicon substrate to form a silicon post on said silicon substrate beneath said masking pattern; and isotropically etching said silicon post to form a pointed silicon tip.
Claim 2
Independent Claim
60 words
A method of forming a silicon tip, comprising the steps of: forming a masking layer having a predetermined masking pattern on a portion of the surface of a silicon substrate; anisotropically etching said silicon substrate to form a silicon post on said silicon substrate beneath said masking pattern; and isotropically etching said silicon post to form a pointed silicon tip.
Claim 3
Independent Claim
101 words
A method of forming a cantilever stylus with an integral pointed tip, comprising the steps of: forming a masking layer having a predetermined masking pattern on a portion of the surface of a silicon substrate; anisotropically etching said silicon substrate to form a silicon post on said silicon substrate beneath said masking pattern; isotropically etching said silicon post to form a pointed silicon tip on said silicon substrate; forming a cantilever stylus which includes a cantilever arm and said pointed silicon tip fixed thereto; selectively removing selected portions of the silicon substrate to release said cantilever stylus from said silicon substrate.
Claim 4
Independent Claim
101 words
A method of forming a cantilever stylus with an integral pointed tip, comprising the steps of: forming a masking layer having a predetermined masking pattern on a portion of the surface of a silicon substrate; anisotropically etching said silicon substrate to form a silicon post on said silicon substrate beneath said masking pattern; isotropically etching said silicon post to form a pointed silicon tip on said silicon substrate; forming a cantilever stylus which includes a cantilever arm and said pointed silicon tip fixed thereto; selectively removing selected portions of the silicon substrate to release said cantilever stylus from said silicon substrate.
Claim 5
Dependent Claim
38 words
The method of claim 1 wherein the step of forming the cantilever stylus includes the steps of: thermally oxidizing said pointed silicon tip and a patterned portion of said silicon substrate to form a silicon dioxide cantilever stylus.
Claim 6
Dependent Claim
44 words
The method of claim 1 wherein the step of forming the cantilever stylus includes the step of depositing a thin film material over said pointed silicon tip and patterned portions of said silicon substrate to form a cantilever stylus of said thin film material.
Claim 7
Dependent Claim
52 words
The method of claim 4 wherein the step of depositing a thin film over said pointed silicon tip and portions of said silicon substrate to form a cantilever stylus includes using a thin film material selected from the group consisting of silicon nitride, deposited silicon dioxide, aluminum, aluminum oxide, gold, and polysilicon.
Claim 8
Dependent Claim
83 words
The method of claim 1 wherein the step of forming the cantilever stylus includes the step of: forming a thin film of a first material over said pointed silicon tip and adjacent areas of said silicon substrate to thereby provide a stylus tip; forming a thin film of a second material over portions of said silicon substrate and areas of said silicon substrate adjacent to said stylus tip to form a cantilever arm of said second material with said stylus tip fixed thereto.
Claim 9
Dependent Claim
24 words
The method of claim 6 wherein said first material is thermally grown SiO 2 and said second material is Si 3 N 4 .
Claim 10
Dependent Claim
54 words
The method of claim 1 wherein the step of forming a masking pattern on the silicon substrate includes the steps of: depositing a masking layer on the silicon substrate; forming a pattern of photoresist material on said masking layer; removing portions of said masking layer to leave said masking pattern on said silicon substrate.
Claim 11
Independent Claim
16 words
The method of claim wherein said masking pattern is circular and approximately 1 micrometer in diameter.
Claim 12
Dependent Claim
19 words
The method of claim 1 wherein the step of anisotropically etching the silicon substrate is done by dry etching.
Claim 13
Dependent Claim
20 words
The method of claim 1 wherein the step of anisotropically etching includes etching the silicon substrate to a predetermined depth.
Claim 14
Dependent Claim
24 words
The method of claim 1 including the step of etching away said silicon post until the masking layer is detached from the silicon substrate.
Claim 15
Dependent Claim
67 words
The method of claim 1 wherein the step of isotropically etching the silicon post includes the step of controlling the slope of the sidewall of the conical tip by varying the ratio between the depth of anisotropic etching for the silicon post and the amount of isotropic etching used to etch the silicon post into a pointed silicon tip, and by controlling the anisotrophy of the etching.
Claim 16
Dependent Claim
23 words
The method of claim 1 wherein the step of isotropically etching the silicon post includes etching said post with a reactive ion plasma.
Claim 17
Dependent Claim
21 words
The method of claim 1 wherein the step of isotropically etching the silicon post includes etching said post by ion milling.
Claim 18
Dependent Claim
29 words
The method of claim 1 wherein said masking layer is selected from the group consisting of thermally grown silicon dioxide, silicon nitride, deposited silicon dioxide, aluminum, or photoresist material.
Claim 19
Dependent Claim
37 words
The method of claim 1 wherein the step of anisotropically etching the silicon substrate to form a silicon post includes using an etchant selected from the group consisting of SF6/C2ClF5, CF 4 , and SF 6 plasma.
Claim 20
Dependent Claim
84 words
The method of claim 1 including the steps of: forming the stylus tip to have a thickness which is less than its height and diameter; coating the backside of the stylus tip with a conductive material to form a conductive layer; applying a voltage between the conductive layer and an electrode spaced apart from the point of said stylus tip to cause electromigration of said conductive material through said dielectric material to the point of said stylus tip to provide a conductive stylus tip.
Claim 21
Dependent Claim
25 words
The method of claim 1 including forming a plurality of cantilever styluses with integral tips on various portions of the surface of said silicon substrate.
Claim 22
Dependent Claim
31 words
The method of claim 1 wherein the masking pattern is shaped in a substantially circular pattern to form a substantially cylindrical silicon post which results in a substantially conical pointed tip.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-11-05 | 1994-05-07 | 1994-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-11-05 | 1998-05-07 | 1998-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-11-05 | 2002-05-07 | 2002-11-06 | $7700.00 | Window Closed / Lapsed |