US5345815A
Expired / Lapsed
US
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Atomic force microscope having cantilever with piezoresistive deflection sensor
Assignee: Bruker Nano Inc
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Filing: 1992-09-30
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Granted: 1994-09-13
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Expires: 2012-09-30
Abstract
Abstract A microminiature cantilever structure is provided having a cantilever arm with a piezoresistive resistor embedded in at least the fixed end of the cantilever arm. Deflection of the free end of the cantilever arm produces stress in the base of the cantilever. That stress changes the piezoresistive resistor's resistance at the base of the cantilever in proportion to the cantilever arm's deflection. Resistance measuring apparatus is coupled to the piezoresistive resistor to measure its resistance and to generate a signal corresponding to the cantilever arm's deflection. The microminiature cantilever is formed on a semiconductor substrate. A portion of the free end of the cantilever arm is doped to form an electrically separate U-shaped piezoresistive resistor. The U-shaped resistor has two legs oriented parallel to an axis of the semiconductor substrate having a non-zero piezoresistive coefficient. A metal layer is deposited over the semiconductor's surface and patterned to form an electrical connection between the piezoresistive resistor and a resistance measuring circuit, enabling measurement of the piezoresistive resistor's resistance. Finally, the semiconductor substrate below the cantilever arm is substantially removed so as to form a cantilevered structure, and a tip is connected to the free end of the cantilever arm to facilitate the structure's use in an atomic force microscope.
Inventors
- 👤 Thomas Albrecht
- 👤 Marco Tortonese
- 👤 Robert Barrett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 08:19
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/34; G01Q; G01Q60/00; G01Q60/24; G01Q60/38; G01Q20/00; G01Q20/04; Y; Y10; Y10S; Y10S977/00; Y10S977/84; Y10S977/849; Y10S977/85; Y10S977/851; Y10S977/86; Y10S977/873
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
110 words
An atomic force microscope comprising: a sample holder; a cantilever arm having a fixed end and a free end and a piezoresistive element included within the cantilever arm, deflection of the free end of the cantilever arm changing the resistance of the piezoresistive element; scanning means for moving the cantilever arm and sample holder relative to one another so as to scan a surface of a sample positioned in the sample holder; and deflection detection means for detecting changes in the resistance of the piezoresistive element and for generating signals in response to those changes in resistance, the generated signals being representative of features of the surface of the sample.
Claim 2
Dependent Claim
110 words
An atomic force microscope comprising: a sample holder; a cantilever arm having a fixed end and a free end and a piezoresistive element included within the cantilever arm, deflection of the free end of the cantilever arm changing the resistance of the piezoresistive element; scanning means for moving the cantilever arm and sample holder relative to one another so as to scan a surface of a sample positioned in the sample holder; and deflection detection means for detecting changes in the resistance of the piezoresistive element and for generating signals in response to those changes in resistance, the generated signals being representative of features of the surface of the sample.
Claim 3
Dependent Claim
42 words
The atomic force microscope of claim 1 wherein the cantilever arm is in contact with the surface of the sample while the surface is being scanned, the cantilever arm contacting the surface with a tracking force of less than 10 -5 N.
Claim 4
Dependent Claim
51 words
The atomic force microscope of claim 1 further comprising a controller or computer, the controller or computer being adapted to control the distance between the cantilever arm and the sample in a direction perpendicular to the surface of the sample, in response to the signals generated by the deflection detection means.
Claim 5
Dependent Claim
23 words
The atomic force microscope of claim 1 wherein the cantilever arm comprises a tip located near the free end of the cantilever arm.
Claim 6
Dependent Claim
30 words
The atomic force microscope of claim 4 wherein the tip is held a distance greater than 5 Å from the surface of the sample while the surface is being scanned.
Claim 7
Dependent Claim
31 words
The atomic force microscope of claim 4 wherein the tip is sufficiently sharp to enable the microscope to detect features of the surface of the sample down to an atomic scale.
Claim 8
Dependent Claim
22 words
The atomic force microscope of claim 1 wherein the scanning means moves the cantilever arm to scan the surface of the sample.
Claim 9
Dependent Claim
21 words
The atomic force microscope of claim 1 wherein the scanning means moves the sample to scan the surface of the sample.
Claim 10
Dependent Claim
20 words
The atomic force microscope of claim 1 wherein the cantilever arm has a mechanical resonant frequency greater than 10 KHz.
Claim 11
Dependent Claim
28 words
The atomic force microscope of claim 1 wherein the deflection detection means detects a deflection of the free end of the cantilever arm of less than 100 Å.
Claim 12
Dependent Claim
22 words
The atomic force microscope of claim 1 wherein the piezoresistive element comprises a region of semiconductor material included within the cantilever arm.
Claim 13
Dependent Claim
44 words
The atomic force microscope of claim 11 wherein the piezoresistive element is formed in a silicon crystal having an axis with a non-zero piezoresistive coefficient, the piezoresistive resistor having a longitudinal axis oriented parallel to the silicon crystal axis having a non-zero piezoresistive coefficient.
Claim 14
Dependent Claim
16 words
The atomic force microscope of claim 11 wherein the region of semiconductor material comprises P-type material.
Claim 15
Dependent Claim
33 words
The atomic force microscope of claim 13 wherein the semiconductor material comprises a silicon crystal, the <110> axis of the silicon crystal being oriented parallel to a longitudinal axis of the piezoresistive element.
Claim 16
Dependent Claim
16 words
The atomic force microscope of claim 11 wherein the region of semiconductor material comprises N-type material.
Claim 17
Dependent Claim
33 words
The atomic force microscope of claim 15 wherein the semiconductor material comprises a silicon crystal, the <100> axis of the silicon crystal being oriented parallel to a longitudinal axis of the piezoresistive element.
Claim 18
Dependent Claim
132 words
A surface feature detection system comprising: a sample holder; a cantilever arm having a fixed end and a free end and a piezoresistive element included within the cantilever arm, deflection of the free end of the cantilever arm changing the resistance of the piezoresistive element; scanning means for moving the cantilever arm and sample holder relative to one another so as to scan a surface of a sample positioned in the sample holder; and deflection detection means for detecting changes in the resistive of the piezoresistive element and for generating signals in response to those changes in resistance, the generated signals being representative of features of the surface of the sample; wherein the deflection detection means detects a deflection of the free end of the cantilever arm of less than 100 Å.
Claim 19
Dependent Claim
132 words
A surface feature detection system comprising: a sample holder; a cantilever arm having a fixed end and a free end and a piezoresistive element included within the cantilever arm, deflection of the free end of the cantilever arm changing the resistance of the piezoresistive element; scanning means for moving the cantilever arm and sample holder relative to one another so as to scan a surface of a sample positioned in the sample holder; and deflection detection means for detecting changes in the resistive of the piezoresistive element and for generating signals in response to those changes in resistance, the generated signals being representative of features of the surface of the sample; wherein the deflection detection means detects a deflection of the free end of the cantilever arm of less than 100 Å.
Claim 20
Dependent Claim
147 words
A surface feature detection system comprising: a sample holder; a cantilever arm having a fixed end and a free end and a piezoresistive element included within the cantilever arm, deflection of the free end of the cantilever arm changing the resistance of the piezoresistive element; scanning means for moving the cantilever arm and sample holder relative to one another so as to scan a surface of a sample positioned in the sample holder; and deflection detection means for detecting changes in the resistance of the piezoresistive element and for generating signals in response to those changes in resistance, the generated signals being representative of features of the surface of the sample; said cantilever arm comprising a tip located near the free end thereof; wherein said slip is sufficiently sharp to enable the system to detect features of the surface of the sample down to an atomic scale.
Claim 21
Dependent Claim
147 words
A surface feature detection system comprising: a sample holder; a cantilever arm having a fixed end and a free end and a piezoresistive element included within the cantilever arm, deflection of the free end of the cantilever arm changing the resistance of the piezoresistive element; scanning means for moving the cantilever arm and sample holder relative to one another so as to scan a surface of a sample positioned in the sample holder; and deflection detection means for detecting changes in the resistance of the piezoresistive element and for generating signals in response to those changes in resistance, the generated signals being representative of features of the surface of the sample; said cantilever arm comprising a tip located near the free end thereof; wherein said slip is sufficiently sharp to enable the system to detect features of the surface of the sample down to an atomic scale.
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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) | 1997-09-12 | 1998-03-14 | 1998-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-12 | 2002-03-14 | 2002-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-12 | 2006-03-14 | 2006-09-13 | $7700.00 | Window Closed / Lapsed |