US5242541A
Expired / Lapsed
US
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Method of producing ultrafine silicon tips for the afm/stm profilometry
Assignee: GlobalFoundries Inc
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Filing: 1990-08-16
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Granted: 1993-09-07
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Expires: 2010-08-16
Abstract
Abstract A method is described for producing ultrafine silicon tips for the AFM/STM profilometry comprising: 1. providing a silicon substrate and applying a silicon dioxide layer thereto; 2. producing a mask in said silicon dioxide layer by photolithography and wet or dry etching; 3. producing a tip shaft by transferring the mask pattern, produced in step 2, by reactive ion etching into the silicon substrate; 4. thinning the shaft and forming a base by isotropic wet etching; and 5. removing the mask by etching. The resulting tip shaft with a rectangular end may be pointed by argon ion milling. In a second embodiment there is an anisotropic wet etching step, prior to step 5, through the intact silicon dioxide mask, producing a negative profile of the shaft immediately below the mask. After this etching step the mask is removed by etching.
Inventors
- 👤 Thomas Bayer
- 👤 Johann Greschner
- 👤 Yves Martin
- 👤 Helga Weiss
- 👤 Hemantha K. Wickramasinghe
- 👤 Olaf Wolter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:58
CPC Classifications
G; G01; G01Q; G01Q60/00; G01Q60/24; G01Q60/38; G01Q60/02; G01Q60/04; G01Q60/10; G01Q60/16; G01Q70/00; G01Q70/08; G01Q70/10; Y; Y10; Y10S; Y10S977/00; Y10S977/84; Y10S977/849; Y10S977/86; Y10S977/875; Y10S977/878
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
49 words
A method of producing ultrafine silicon tips for the AFM/STM profilometry comprising the steps of: 1. providing a silicon substrate and applying a masking layer thereto; 2. producing a mask pattern in said masking layer by photolithography and etching, said mask pattern having a maximum width across said pattern;
Claim 2
Independent Claim
49 words
A method of producing ultrafine silicon tips for the AFM/STM profilometry comprising the steps of: 1. providing a silicon substrate and applying a masking layer thereto; 2. producing a mask pattern in said masking layer by photolithography and etching, said mask pattern having a maximum width across said pattern;
Claim 3
Dependent Claim
96 words
producing a tip shaft by transferring the mask pattern, produced in step 2, by reactive ion etching into the silicon substrate to a predetermined depth to provide a corresponding length of said tip shaft and a width determined from said masking pattern, said length to maximum width ratio of said tip shaft in excess of 1; 4. thinning said tip shaft and forming a base by etching; 5. anisotropic wet etching through said masking layer, thereby producing a negative profile of the shaft immediately below said masking layer; and 6. removing said masking layer by etching.
Claim 4
Dependent Claim
96 words
producing a tip shaft by transferring the mask pattern, produced in step 2, by reactive ion etching into the silicon substrate to a predetermined depth to provide a corresponding length of said tip shaft and a width determined from said masking pattern, said length to maximum width ratio of said tip shaft in excess of 1; 4. thinning said tip shaft and forming a base by etching; 5. anisotropic wet etching through said masking layer, thereby producing a negative profile of the shaft immediately below said masking layer; and 6. removing said masking layer by etching.
Claim 5
Dependent Claim
24 words
The method of claim 1, wherein the rectangular shaft end, obtained by the removal of said masking layer, is pointed by argon ion milling.
Claim 6
Dependent Claim
23 words
The method of claim 1, wherein a silicon dioxide layer is applied to the silicon substrate in a thickness of about 1 μm.
Claim 7
Dependent Claim
31 words
The method of claim 3, wherein an about 3 μm thick photoresist layer is applied to the silicon dioxide layer, and the desired mask pattern is defined in said photoresist layer.
Claim 8
Dependent Claim
41 words
The method of claim 1, wherein the mask pattern in the photoresist layer is transferred into the masking layer by wet etching or reactive ion etching with CF 4 as etch gas, and with a pressure of about 10 .sup.μ bar.
Claim 9
Dependent Claim
38 words
The method of claim 1, wherein the mask pattern is transferred into the silicon substrate to the desired depth by anisotropic reactive ion etching with chlorine/argon as an etch gas, and with a pressure of about 20 μbar.
Claim 10
Dependent Claim
30 words
The method of claim 6, wherein by isotropic wet etching a side wall redeposition layer is removed from said tip shaft, and the latter is thinned at the same time.
Claim 11
Dependent Claim
34 words
The method of claim 1, wherein a negative profile of said tip shaft immediately below the mask pattern is produced by anisotropic wet etching with aqueous 37.5 wt % KOH at about 60° C.
Claim 12
Dependent Claim
18 words
The method of claim 1, wherein the masking layer is removed by etching with 5:1 buffered hydrofluoric acid.
Claim 13
Dependent Claim
22 words
The method of claim 1 wherein said step of producing a mask pattern includes the step of producing a circular mask pattern.
Claim 14
Dependent Claim
14 words
The method of claim 1 wherein said step of thinning includes isotropic wet etching.
Claim 15
Dependent Claim
26 words
The method of claim 1 wherein said step of forming a base includes isotropic wet etching to form a conically shaped base of said tip shaft.
Claim 16
Independent Claim
15 words
A method of producing ultrafine silicon tips for the AFM/STM profilometry comprising the steps of:
Claim 17
Independent Claim
15 words
A method of producing ultrafine silicon tips for the AFM/STM profilometry comprising the steps of:
Claim 18
Dependent Claim
167 words
providing a silicon substrate and applying a masking layer thereto; 2. producing a mask pattern in said masking layer by photolithography and etching, said mask pattern having a maximum width across said pattern; 3. producing a tip shaft by transferring the mask pattern, produced in step 2, by reactive ion etching into the silicon substrate to a predetermined depth to provide a corresponding length of said tip shaft and a width determined from said masking pattern, said length to maximum width ratio of said tip shaft in excess of 1; 4. thinning said tip shaft and forming a base by etching; 5. removing said masking layer by etching, wherein the mask pattern is transferred into the silicon substrate to the desired depth by anisotropic reactive ion etching with chlorine/argon as an etch gas, and with a pressure of about 20 μbar and wherein by isotropic wet etching a side wall redeposition layer is removed from said tip shaft, and the latter is thinned at the same time.
Claim 19
Dependent Claim
167 words
providing a silicon substrate and applying a masking layer thereto; 2. producing a mask pattern in said masking layer by photolithography and etching, said mask pattern having a maximum width across said pattern; 3. producing a tip shaft by transferring the mask pattern, produced in step 2, by reactive ion etching into the silicon substrate to a predetermined depth to provide a corresponding length of said tip shaft and a width determined from said masking pattern, said length to maximum width ratio of said tip shaft in excess of 1; 4. thinning said tip shaft and forming a base by etching; 5. removing said masking layer by etching, wherein the mask pattern is transferred into the silicon substrate to the desired depth by anisotropic reactive ion etching with chlorine/argon as an etch gas, and with a pressure of about 20 μbar and wherein by isotropic wet etching a side wall redeposition layer is removed from said tip shaft, and the latter is thinned at the same time.
Claim 20
Dependent Claim
22 words
The method of claim 13 wherein said step of producing a mask pattern includes the step of producing a circular mask pattern.
Claim 21
Dependent Claim
26 words
The method of claim 13, wherein said step of forming a base includes isotropic wet etching to form a conically shaped base of said tip shaft.
Claim 22
Dependent Claim
27 words
The method of claim 13 wherein a negative profile of said tip shaft immediately below the mask pattern is produced by anisotropic wet etching with aqueous KOH.
Claim 23
Dependent Claim
22 words
The method of claim 13 wherein said step of producing a mask pattern includes the step of producing a rectangular mask pattern.
Claim 24
Independent Claim
106 words
A method of producing ultrafine silicon tips for the AFM/STM profilometry comprising the steps of: 1. providing a silicon substrate and applying a masking layer thereto; 2. producing a mask pattern in said masking layer by photolithographic and etching, said mask pattern having a maximum width across said pattern; 3. producing a tip shaft by transferring the mask pattern, produced in step 2, by reactive ion etching into the silicon substrate to a predetermined depth to provide a corresponding length of said tip shaft and a width determined from said masking pattern, said length to maximum width ratio of said tip shaft in excess of 1;
Claim 25
Independent Claim
106 words
A method of producing ultrafine silicon tips for the AFM/STM profilometry comprising the steps of: 1. providing a silicon substrate and applying a masking layer thereto; 2. producing a mask pattern in said masking layer by photolithographic and etching, said mask pattern having a maximum width across said pattern; 3. producing a tip shaft by transferring the mask pattern, produced in step 2, by reactive ion etching into the silicon substrate to a predetermined depth to provide a corresponding length of said tip shaft and a width determined from said masking pattern, said length to maximum width ratio of said tip shaft in excess of 1;
Claim 26
Dependent Claim
47 words
thinning said tip shaft and forming a base by etching; and 5. removing said masking layer by etching, wherein a negative profile of said tip shaft immediately below the mask pattern is produced by anisotropic wet etching with aqueous 37.5 wt % KOH at about 60° C.
Claim 27
Dependent Claim
47 words
thinning said tip shaft and forming a base by etching; and 5. removing said masking layer by etching, wherein a negative profile of said tip shaft immediately below the mask pattern is produced by anisotropic wet etching with aqueous 37.5 wt % KOH at about 60° C.
Claim 28
Dependent Claim
22 words
The method of claim 18 wherein said step of producing a mask pattern includes the step of producing a circular mask pattern.
Claim 29
Dependent Claim
14 words
The method of claim 18 wherein said step of thinning includes isotropic wet etching.
Claim 30
Dependent Claim
26 words
The method of claim 18 wherein said step of forming a base includes isotropic wet etching to form a conically shaped base of said tip shaft.
References Cited (Backward Citations)
US4968585A
Cited
US5021364A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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