U.S. patent number RE34,489 [Application Number 07/895,984] was granted by the patent office on 1993-12-28 for atomic force microscope with optional replaceable fluid cell.
This patent grant is currently assigned to The Regents of the University of California. Invention is credited to Barney Drake, Paul K. Hansma.
United States Patent |
RE34,489 |
Hansma , et al. |
December 28, 1993 |
**Please see images for:
( Certificate of Correction ) ( Reexamination Certificate
) ** |
Atomic force microscope with optional replaceable fluid cell
Abstract
An atomic force microscope which is readily useable for
researchers for its intended use without extensive lost time for
setup and repair. The probe used therein is a cantilevered optical
lever which imparts surface information in a gentle and reliable
manner by reflecting an incident laser beam. The probe is carried
by a replaceable probe-carrying module which is factory set up and
merely inserted and fine tuned by the user. The probe-carrying
module also includes the provision for forming a fluid cell around
the probe. Fluid can be inserted into and/or be circulated through
the fluid cell through incorporated tubes in the porbe-carrying
module. Electrodes are also provided in the fluid cell for various
uses including real-time studies of electro-chemical operations
taking place in the fluid cell. The piezoelectric scan tube
employed includes a voltage shield to prevent scanning voltages to
the tube from affecting data readings. Samples are easily mounted,
replaced, and horizontally adjusted using a sample stage which is
magnetically attached to the top of the scan tube. Calibration
tools are provided to make initial set up and fine tuning of the
microscope a simple and straightforward operation requiring little
or no technical talent.
Inventors: |
Hansma; Paul K. (Santa Barbara,
CA), Drake; Barney (Santa Barbara, CA) |
Assignee: |
The Regents of the University of
California (Berkeley, CA)
|
Family
ID: |
23252966 |
Appl.
No.: |
07/895,984 |
Filed: |
June 4, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
322001 |
Mar 13, 1989 |
04935634 |
Jun 19, 1990 |
|
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Current U.S.
Class: |
250/559.23;
250/306 |
Current CPC
Class: |
G01Q
60/38 (20130101); B82Y 35/00 (20130101); G01Q
70/04 (20130101); G01Q 30/025 (20130101); G01Q
30/14 (20130101); G01Q 70/02 (20130101); Y10S
977/87 (20130101); Y10S 977/863 (20130101) |
Current International
Class: |
G12B
21/22 (20060101); G12B 21/22 (20060101); G12B
21/08 (20060101); G12B 21/08 (20060101); G12B
21/00 (20060101); G12B 21/00 (20060101); G01N
021/86 () |
Field of
Search: |
;250/560,561,216,306,307,423F |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Applied Physics Letters, vol. 55, No. 24, Dec. 11, 1989, New York,
pp. 2491-2493; S. A. Chalmers et al.; "Determination of Tilted
Superlattice Structure by Atomic Force Microscopy". .
Applied Physics Letters, vol. 50, No. 24, Jun. 15, 1987, New York,
pp. 1742-1744; R. Sonnenfeld et al.; "Semiconductor Topography in
Aqueous Environments: Tunneling Microscopy of Chemomechanically
Polished (001) GaAs. .
Review of Scientific Instruments, vol. 59, No. 6, Jun. 1, 1988, New
York, pp. 833-835; M. D. Kirk et al.; "Low-Temperature Force
Microscopy". .
Applied Physics Letters, vol. 51, No. 7, Aug. 17, 1987, New York,
pp. 484-486; O. Marti et al.; "Atomic Force Microscopy of
Liquid-Covered Surfaces: Atomic Resolution Image". .
Journal of Vacuum Science and Technology: Part A, vol. 6, No. 2,
Mar. 1, 1988, New York, pp. 380-382; P. Davidsson et al.; "A New
Symmetric Scanning Tunneling Microscope Design". .
"Atomic-Resolution Microscopy in Water"; Richard Sonnenfeld et al.,
Apr. 11, 1986, vol. 232, pp. 211-213..
|
Primary Examiner: Nelms; David C.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt
Government Interests
This invention was made with Government support under Contract No.
N00014-87-K-2058 awarded by the Office of Naval Research. The
Government has certain rights in this invention.
Claims
Wherefore, having thus described our invention, what is claimed
is:
1. An atomic force microscope which is quickly and easily set up
and in which the probe thereof is easily replaceable and resists
breakage during setup comprising:
(a) a horizontal base member;
(b) a scan tube vertically supported at a bottom end by said base
member and having a top surface for holding a sample to be scanned
and moveable in x-, y-, and z-directions as a result of scanning
voltages applied thereto;
(c) first support means extending upward from said base member;
(d) a sample holding block having a chamber therein, said sample
holding block having a first bore communicating with said chamber
through a bottom surface, a second bore communicating with said
chamber through a top surface, and a third bore communicating with
said chamber at an acute angle to said second bore, said sample
holding block being positioned with said scan tube passing through
said first bore and supported by said first support means;
(e) second support means extending upward from said bottom surface
into said chamber;
(f) a probe-carrying module having top and bottom surfaces
removably disposed in said chamber and supported by said second
support means, said bottom surface having a probe attached thereto
and extending downward therefrom at an acute angle with respect to
said bottom surface of said probe-carrying module and with a tip of
said probe positioned to contact a sample mounted on said top
surface of said scan tube;
(g) a source of a laser beam mounted for directing said laser beam
down said second bore from said top surface of said sample holding
block to pass through said probe-carrying module, strike said
probe, and be reflected back through said probe-carrying module and
down said third bore to an outer end thereof; and,
(h) photoelectric sensor means having an active surface positioned
over said outer end of said third bore for developing an electrical
signal at an output thereof reflecting the position on said active
surface at which said laser beam strikes said active surface.
2. The atomic force microscope of claim 1 wherein:
said probe-carrying module is of an optically transparent material
whereby said laser beam can pass through said probe-carrying
module, strike said probe, and be reflected back through said
probe-carrying module.
3. The atomic force microscope of claim 1 wherein:
said probe-carrying module is of an optically non-transparent
material and has a laser-passing bore therethrough between said top
and bottom surfaces aligned so that said laser beam can pas through
said laser-passing bore, strike said probe, and be reflected back
through said laser-passing bore.
4. The atomic force microscope of claim 1 wherein said
probe-carrying module includes an angled pad on said bottom surface
thereof and said probe carried by said probe-carrying module
comprises;
(a) a substrate attached to said pad; and,
(b) and arm of a smooth-surfaced, minimally self-biased material
cantilevered outward from a bottom front edge of said substrate to
form an optical lever, said arm having a probe point at an outer
end thereof.
5. The atomic force microscope of claim 1 wherein:
said first support means comprises three first adjusting screws
threaded through said base member with said sample holding block
resting on top ends thereof with one of said top ends disposed in a
slot in a flat bottom surface of said sample holding block, another
of said top ends disposed in a hole in said bottom surface, and a
third of said top ends disposed on said bottom surface whereby said
sample holding block is removable from said base member and
repeatably replaceable to a pre-established position thereon.
6. The atomic microscope of claim 1 wherein:
said second support means comprises three second adjusting screws
threaded through said bottom surface of said sample holding block
with said probe-carrying module resting on top ends thereof with
one of said top ends disposed in a slot in a flat bottom surface of
said probe-carrying module, another of said top ends disposed in a
hole in a member affixed to said bottom surface, and a third of
said top ends disposed on said bottom surface whereby said
probe-carrying module is removable from said chamber of said sample
holding block and repeatedly replaceable to a pre-established
position therein.
7. The atomic force microscope of claim 1 wherein said
probe-carrying module is of an optically transparent material and
additionally comprising:
sealing means surrounding said probe and attached to said bottom
surface of said probe-carrying module for sealing to a top surface
of a sample to form a fluid cell around said probe.
8. The atomic force microscope of claim 7 and additionally
comprising:
an inlet bore and an outlet bore in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module whereby fluid can be inserted into said fluid
cell.
9. The atomic force microscope of claim 7 and additionally
comprising:
(a) an electrode bore in said probe-carrying module communicating
between said fluid cell and the exterior of said probe-carrying
module; and,
(b) an electrode disposed in said electrode bore having a first end
within said fluid cell and a second end at the exterior of said
probe-carrying module to which electrical connection can be
made.
10. The atomic force microscope of claim 7 and additionally
comprising:
(a) three electrode bores in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module; and,
(b) a working electrode, a reference electrode, and an auxiliary
electrode disposed in said electrode bores, each of said electrodes
having a first end within said fluid cell and a second end at the
exterior of said probe-carrying module to which electrical
connection can be made.
11. The atomic force microscope of claim 1 and additionally
comprising:
a voltage shield of an electrically conductive material disposed
over said top surface of said scan tube in non-electrical contact
therewith, said voltage shield being electrically connected to a
fixed voltage source whereby to shield said probe from the effects
of said scanning voltages applied to said scan tube.
12. The atomic force microscope of claim 11 wherein:
said fixed voltage source is ground.
13. The atomic force microscope of claim 1 and additionally
comprising:
a slidably moveable and removeable stage releasably attached to
said top surface of said scan tube for releasably and adjustably
holding a sample to be scanned attached thereto.
14. The atomci force microscope of claim 13 wherein:
(a) said stage contains a magnet therein; and additionally
comprising,
(b) a voltage shield of a ferro-magnetic and electrically
conductive material disposed over said top surface of said scan
tube in non-electrical contact therewith, said voltage shield being
electrically connected to a fixed voltage source to shield said
probe from the effects of said scanning voltages applied to said
scan tube and providing an attachment surface to which said stage
can magnetically attach and upon which it can slide.
15. The atomic force microscope of claim 13 wherein:
(a) said stage is of a ferro-magnetic material; and additionally
comprising,
(b) a voltage shield of an electrically conductive material
disposed over said top surface of said scan tube in non-electrical
contact therewith, said voltage shield containing a magnet therein,
being electrically connected to a fixed voltage source to shield
said probe from the effects of said scanning voltages applied to
said scan tube, and providing an attachment surface to which said
stage can magnetically attach and upon which it can slide.
16. The atomic force microscope of claim 6 and additionally
comprising:
first calibration means for positioning said member affixed to said
bottom surface of said probe-carrying module as a function of the
position of a tip portion of said probe.
17. The atomic force microscope of claim 1 and additionally
comprising:
second calibration means for setting the position of said sample
holding block on said first support means.
18. The atomic force microscope of claim 1 and additionally
comprising:
third calibration means for setting the position of said
probe-carrying module on said second support means.
19. An atomic force microscope having extended use capabilities
comprising:
(a) a horizontal base member;
(b) a scan tube vertically supported at a bottom end by said base
member and having a top surface for holding a sample to be scanned
and moveable in x-, y-, and z-directions as a result of scanning
voltages applied thereto;
(c) first support means extending upward from said base member;
(d) a sample holding block having a chamber therein, said sample
holding block having a first bore communicating with said chamber
through a bottom surface, a second bore communicating with said
chamber through a top surface, and a third bore communicating with
said chamber at an acute angle to said second bore, said sample
holding block being positioned with said scan tube passing through
said first bore and supported by said first support means;
(e) second support means extending upward from said bottom surface
into said chamber;
(f) a probe-carrying module having a probe attached thereto and
extending downward therefrom at an acute angle with a tip of said
probe positioned to contact a sample mounted on said top surface of
said scan tube, said probe carried by said probe-carrying module
comprising a substrate attached to said probe-carrying module and
an arm of a smooth-surfaced, minimally self-biased material
cantilevered outward from a bottom front edge of said substrate to
form an optical lever, said arm having a probe point at an outer
end thereof;
(g) a source of a laser beam mounted for directing said laser beam
down said second bore from said top surface of said sample holding
block to strike said probe and be reflected down said third bore to
an outer end thereof; and,
(h) photoelectric sensor means having an active surface positioned
over said outer end of said third bore for developing an electrical
signal at an output thereof reflecting the position on said active
surface at which said laser beam strikes said active surface.
20. The atomic force microscope of claim 19 wherein:
said probe-carrying module has top and bottom surfaces and is
removably disposed in said chambeer and supported by said second
support means, said bottom surface having said probe attached
thereto and extending downward therefrom at an acute angle with
respect to said bottom surface of said probe-carrying module and
with said tip of said probe positioned to contact a sample mounted
on said top surface of said scan tube whereby said laser beam
passes through said probe-carrying module, strikes said probe, and
is reflected back through said probe-carrying module and down said
third bore to said outer end thereof.
21. The atomic force microscope of claim 20 wherein:
said probe-carrying module is an optically transparent material
whereby said laser beam can pass through said probe-carrying
module, strike said probe, and be reflected back through said
probe-carrying module.
22. The atomic force microscope of claim 20 wherein:
said probe-carrying module is of an optically non-transparent
material and has a laser-passing bore therethrough between said top
and bottom surfaces aligned so that said laser beam can pass
through said laser-passing bore, strike said probe, and be
reflected back through said laser-passing bore.
23. The atomic force microscope of claim 19 wherein:
said first support means comprises three first adjusting screws
threaded through said base member with said sample holding block
resting on top ends thereof with one of said top ends disposed in a
slot in a flat bottom surface of said sample holding block, another
of said top ends disposed in a hole in said bottom surface, and a
third of said top ends disposed on said bottom surface whereby said
sample holding block is removable from said base member and
repeatedly replaceable to a pre-established position thereon.
24. The atomic force microscope of claim 19 wherein:
said second support means comprises three second adjusting screws
threaded through said bottom surface of said sample holding block
with said probe-carrying module resting on top ends thereof with
one of said top ends disposed in a slot in a flat bottom surface of
said probe-carrying module, another of said top ends disposed in a
hole in a member affixed to said bottom surface, and a third of
said top ends disposed on said bottom surface whereby said
probe-carrying module is removable from said chamber of said sample
holding block and repeatedly replaceable to a pre-established
position therein.
25. The atomic force microscope of claim 19 and additionally
comprising:
means for forming a fluid cell around said probe.
26. The atomic force microscope of claim 25 wherein said means for
forming a fluid cell around said probe comprises:
a cover plate of an optically transparent material disposed over
said probe whereby a drop of fluid can be held between said cover
plate and a top surface of a sample by capillary action whereby
said laser beam can pass through said cover plate, strike said
probe, and be reflected back through said cover plate.
27. The atomic force microscope of claim 25 wherein said
probe-carrying module is of an optically transparent material and
said means for forming a fluid cell around said probe
comprises:
sealing means surrounding said probe and attached to said bottom
surface of said probe-carrying module for sealing to a top surface
of a sample to form a fluid cell around said probe.
28. The atomic force microscope of claim 27 and additionally
comprising:
an inlet bore and an outlet bore in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module whereby fluid can be inserted into said fluid
cell.
29. The atomic force microscope of claim 27 and additionally
comprising:
(a) an electrode bore in said probe-carrying module communicating
between said fluid cell and the exterior of said probe-carrying
module; and,
(b) an electrode disposed in said electrode bore having a first end
within said fluid cell and a second end at the exterior of said
probe-carrying module to which electrical connection can be
made.
30. The atomic force microscope of claim 27 and additionally
comprising:
(a) three electrode bores in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module; and,
(b) a working electrode, a reference electrode, and an auxiliary
electrode disposed in said electrode bores, each of said electrodes
having a first end within said fluid cell and a second end at the
exterior of said probe-carrying module to which electrical
connection can be made.
31. The atomic force microscope of claim 19 and additionally
comprising:
a voltage shield of an electrically conductive material disposed
over said top surface of said scan tube in non-electrical contact
therewith, said voltage shield being electrically connected to a
fixed voltage source whereby to shield said probe from the effects
of said scanning voltages applied to said scan tube.
32. The atomic force microscope of claim 31 wherein:
said fixed voltage source is ground.
33. The atomic force microscope of claim 19 and additionally
comprising:
a slidably moveable and removable stage releasably attached to said
top surface of said scan tube for releasably and adjustably holding
a sample to be scanned attached thereto.
34. The atomic force microcscope of claim 33 wherein:
(a) said stage contains a magnet therein; and additionally
comprising,
(b) a voltage shield of a ferro-magnetic and electrically
conductive material disposed over said top surface of said scan
tube in non-electrical contact therewith, said voltage shield being
electrically connected to a fixed voltage source to shield said
probe from the effects of said scanning voltages applied to said
scan tube and providing an attachment surface to which said stage
can magnetically attach and upon which it can slide.
35. The atomic force microscope of claim 33 wherein:
(a) said stage is of a ferro-magnetic material; and additionally
comprising,
(b) a voltage shield of an electrically conductive material
disposed over said top surface of said scan tube in non-electrical
contact therewith, said voltage shield containing a magnet therein,
being electrically connected to a fixed voltage source to shield
said probe from the effects of said scanning voltages applied to
said scan tube, and providing an attachment surface to which said
stage can magnetically attach and upon which it can slide.
36. The atomic force microscope of claim 24 and additionally
comprising:
first calibration means for positioning said member affixed to said
bottom surface of said probe-carrying module as a function of the
position of a tip position of said probe.
37. The atomic force microscope of claim 19 and additionally
comprising:
second calibration means for setting the position of said sample
holding block on said first support means.
38. The atomic force microscope of claim 19 and additionally
comprising:
third calibration means for setting the position of said
probe-carrying module on said second support means.
39. An atomic force microscope containing an easily replaceable
probe-carrying member including an optional fluid cell
comprising:
(a) a horizontal base member;
(b) a scan tube vertically supported at a bottom end by said base
member and having a top surface for holding a sample to be scanned
and moveable in x-, y-, and z-directions as a result of scanning
voltages applied thereto;
(c) first support means extending upward from said base member;
(d) a sample holding block having a chamber therein, said sample
holding block having a first bore communicating with said chamber
through a bottom surface, a second bore communicating with said
chamber through a top surface, and a third bore communicating with
said chamber at an acute angle to said second bore, said sample
holding block being positioned with said scan tube passing through
said first bore and supported by said first support means;
(e) second support means extending upward from said bottom surface
into said chamber;
(f) a probe-carrying module of an optically transparent material
having top and bottom surfaces removably disposed in said chamber
and supported by said second support means, said bottom surface
having a probe attached thereto and extending downward therefrom at
an acute angle with respect to said bottom surface of said
probe-carrying module and with a tip of said probe positioned to
contact a sample mounted on said top surface of said scan tube,
said probe-carrying module including an angled pad on said bottom
surface thereof and said probe carried by said probe-carrying
module comprising,
(f1) a substrate attached to said pad, and
(f2) an arm of a smooth-surfaced, minimally self-biased material
cantilevered outward from a bottom front edge of said substrate to
form an optical lever, said arm having a probe point at an outer
end thereof;
(g) sealing means surrounding said probe and attached to said
bottom surface of said probe-carrying module for sealing to a top
surface of a sample to form a fluid cell around said probe;
(h) a source of a laser beam mounted for directing said laser beam
down said second bore from said top surface of said sample holding
block to pass through said probe-carrying module, strike said
probe, and be reflected back through said probe-carrying module and
down said third bore to an outer end thereof; and,
(i) photoelectric sensor means having an active surface positioned
over said outer end of said third bore for developing an electrical
signal at an output thereof reflecting the position of said active
surface at which said laser beam strikes said active surface.
40. The atomic force microscope of claim 39 wherein:
said first support means comprises three first adjusting screws
threaded through said base member with said sample holding block
resting on top ends thereof with one of said top ends disposed in a
slot in a flat bottom surface of said sample holding block, another
of said top ends disposed in a hole in said bottom surface, and a
third of said top ends disposed on said bottom surface whereby said
sample holding block is removable from said base member and
repeatedly replaceable to a pre-established position thereon.
41. The atomic force microscope of claim 39 wherein:
said second support means comprises three second adjusting screws
threaded through said bottom surface of said sample holding block
with said probe-carrying module resting on top ends thereof with
one of said top ends disposed in a slot in a flat bottom surface of
said probe-carrying module, another of said top ends disposed in a
hole in a member affixed to said bottom surface, and a third of
said top ends disposed on said bottom surface whereby said
probe-carrying module is removable from said chamber of said sample
holding block and repeatably replaceable to a pre-established
position therein.
42. The atomic force microscope of claim 39 and additionally
comprising:
an inlet bore and an outlet bore in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module whereby fluid can be inserted into said fluid
cell.
43. The atomic force microscope of claim 39 and additionally
comprising:
(a) an electrode bore in said probe-carrying module communicating
between said fluid cell and the exterior of said probe-carrying
module; and,
(b) an electrode disposed in said electrode bore having a first end
within said fluid cell and a second end at the exterior of said
probe-carrying module to which electrical connection can be
made.
44. The atomic force microscope of claim 39 and additionally
comprising:
(a) three electrode bores in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module; and,
(b) a working electrode, a reference electrode, and an auxiliary
electrode disposed in said electrode bores, each of said electrodes
having a first end within said fluid cell and a second end at the
exterior of said probe-carrying module to which electrical
connection can be made.
45. The atomic force microscope of claim 39 and additionally
comprising:
a voltage shield of an electrically conductive material disposed
over said top surface of said scan tube in non-electrical contact
therewith, said voltage shield being electrically connected to a
fixed voltage source whereby to shield said probe from the effects
of said scanning voltages applied to said scan tube.
46. The atomic force microscope of claim 39 and additionally
comprising:
a slidably moveable and removable stage releasably attached to said
top surface of said scan tube for releasably and adjustably holding
a sample to be scanned attached thereto.
47. The atomic force microscope of claim 46 wherein:
(a) said stage contains a magnet therein; and additionally
comprising,
(b) a voltage shield of a ferro-magnetic and electrically
conductive material disposed over said top surface of said scan
tube in non-electrical contact therewith, said voltage shield being
electrically connected to a fixed voltage source to shield said
probe from the effects of said scanning voltages applied to said
scan tube and providing an attachment surface to which said stage
can magnetically attach and upon which it can slide.
48. The atomic force microscope of claim 46 wherein:
(a) said stage is of a ferro-magnetic material; and additionally
comprising,
(b) a voltage shield of an electrically conductive material
disposed over said top surface of said scan tube in non-electrical
contact therewith, said voltage shield containing a magnet therein,
being electrically connected to a fixed voltage source to shield
said probe from the effects of said scanning voltages applied to
said scan tube, and providing an attachment surface to which said
stage can magnetically attach and upon which it can slide.
49. An atomic force microscope including an fluid cell surrounding
a scanning probe for preventing damage to a scanned sample and the
scanning probe comprising:
(a) a horizontal base member;
(b) a scan tube vertically supported at a bottom end by said base
member and having a top surface for holding a sample to be scanned
and moveable in x-, y-, and z-directions as a result of scanning
voltages applied thereto;
(c) a probe-carrying module disposed above said top surface of said
scan tube and having a probe attached thereto and extending
downward therefrom with a tip of said probe positioned to contact a
sample mounted on said top surface of said scan tube;
(d) means for sensing movement of said probe and for providing an
electrical signal at an output thereof reflecting said movement of
said probe; and,
(e) fluid cell forming means carried by said probe-carrying module
for forming a fluid cell around said probe on a top surface of a
sample mounted on said top surface of said scan tube when filled
with a fluid.
50. The atomic force microscope of claim 49 wherein:
said fluid cell forming means comprises a cover glass disposed over
said probe and close enough to said top surface of said sample to
maintain a drop of fluid between said top cover glass and said
surface of said sample around said probe by capillary action.
51. The atomic force microscope of claim 49 wherein:
said fluid cell forming means comprises annular sealing means
surrounding said probe and attached to a bottom surface of said
probe-carrying module for sealing to said top surface of said
sample to form a fluid cell around said probe.
52. The atomic force microscope of claim 51 and additionally
comprising:
an inlet bore and an outlet bore in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module whereby fluid can be inserted into said fluid
cell.
53. The atomic force microscope of claim 51 and additionally
comprising:
(a) an electrode bore in said probe-carrying module communicating
between said fluid cell and the exterior of said probe-carrying
module; and,
(b) an electrode disposed in said electrode bore having a first end
within said fluid cell and a second end at the exterior of said
probe-carrying module to which electrical connection can be
made.
54. The atomic force microscope of claim 51 and additionally
comprising:
(a) three electrode bores in said probe-carrying module
communicating between said fluid cell and the exterior of said
probe-carrying module; and,
(b) a working electrode, a reference electrode, and an auxiliary
electrode disposed in said electrode bores, each of said electrodes
having a first end within said fluid cell and a second end at the
exterior of said probe-carrying module to which electrical
connection can be made.
55. The atomic force microscope of claim 51 and additionally
comprising:
a voltage shield of an electrically conductive material disposed
over said top surface of said scan tube in non-electrical contact
therewith, said voltage shield being electrically connected to a
fixed voltage source whereby to shield said probe from the effects
of said scanning voltages applied to said scan tube.
56. The atomic force microscope of claim 51 and additionally
comprising:
a slidably moveable and removable stage releasably attached to said
top surface of said scan tube for releasably and adjustably holding
a sample to be scanned attached thereto.
57. The atomic force microscope of claim 56 wherein:
(a) said stage contains a magnet therein; and additionally
comprising:
(b) a voltage shield of a ferro-magnetic and electrically
conductive material disposed over said top surface of said scan
tube in non-electrical contact therewith, said voltage shield being
electrically connected to a fixed voltage source to shield said
probe from the effects of said scanning voltages applied to said
scan tube and providing an attachment surface to which said stage
can magnetically attach and upon which it can slide.
58. The atomic force microscope of claim 56 wherein:
(a) said stage is of a ferro-magnetic material; and additionally
comprising,
(b) a voltage shield of an electrically conductive material
disposed over said top surface of said scan tube in non-electrical
contact therewith, said voltage shield containing a magnet therein,
being electrically connected to a fixed voltage source to shield
said probe from the effects of said scanning voltages applied to
said scan tube, and providing an attachment surface to which said
stage can magnetically attach and upon which it can slide.
.Iadd.59. An atomic force microscope for determining a
characteristic of a sample, comprising:
a probe adapted to scan said sample;
scanning means for causing relative scanning movement between said
probe and said sample;
sensing means for sensing a position of said probe; and
a non-cryogenic fluid body in communication with said sample and in
which said probe is immersed in contact with said sample so that
during said relative scanning movement capillary attraction between
said probe and said sample, caused by a surface film formed on said
sample due to exposure to ambient atmosphere, is reduced. .Iaddend.
.Iadd.60. The atomic force microscope according to claim 59,
further comprising:
a rigid cover plate disposed on a top surface of said fluid body to
define a fluid cell between said cover plate and said sample.
.Iaddend..Iadd.61. The atomic force microscope according to claim
60, wherein:
said rigid cover plate comprises an optically transparent material;
and
said sensing means comprises optical means for sensing a vertical
movement of said probe by means of light applied to said probe
through said rigid cover plate. .Iaddend. .Iadd.62. The atomic
force microscope according to claim 59, comprising:
means for exchanging fluid within said fluid body. .Iaddend.
.Iadd.63. The atomic force microscope according to claim 59,
further comprising;
two or more electrodes in contact with said fluid body for
performing an electrochemical reaction. .Iaddend. .Iadd.64. The
atomic force microscope according to claim 60, further
comprising;
two or more electrodes in contact with said fluid body for
performing an electrochemical reaction. .Iaddend. .Iadd.65. The
atomic force microscope according to claim 61, further
comprising;
two or more electrodes in contact with said fluid body for
performing an electrochemical reaction. .Iaddend. .Iadd.66. The
atomic force microscope according to claim 62, further
comprising;
two or more electrodes in contact with said fluid body for
performing an electrochemical reaction. .Iaddend. .Iadd.67. The
atomic force microscope according to claim 59, wherein said
scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.68. The atomic force microscope
according to claim 60, wherein said scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.69. The atomic force microscope
according to claim 61, wherein said scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.70. The atomic force microscope
according to claim 62, wherein said scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.71. The atomic force microscope
according to claim 63, wherein said scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.72. The atomic force microscope
according to claim 64, wherein said scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.73. The atomic force microscope
according to claim 65, wherein said scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.74. The atomic force microscope
according to claim 66, wherein said scanning means comprises:
a scanner; and
a conductive shield element at a fixed potential disposed between
said probe and said scanner for electrically shielding said probe
from said scanner. .Iaddend. .Iadd.75. The atomic force microscope
according to claim 59, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.76. The atomic force
microscope according to claim 75, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.77. The atomic force microscope according to
claim 61, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.78. The atomic force
microscope according to claim 77, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.79. The atomic force microscope according to
claim 62, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.80. The atomic force
microscope according to claim 79, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.81. The atomic force microscope according to
claim 63, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.82. The atomic force
microscope according to claim 81, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.83. The atomic force microscope according to
claim 65, further comprising:
a removable problem module on which said probe is fixedly mounted
at a selected location. .Iaddend. .Iadd.84. The atomic force
microscope according to claim 83, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.85. The atomic force microscope according to
claim 66, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.86. The atomic force
microscope according to claim 85, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.87. The atomic force microscope according to
claim 67, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.88. The atomic force
microscope according to claim 87, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.89. The atomic force microscope according to
claim 69, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.90. The atomic force
microscope according to claim 89, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.91. The atomic force microscope according to
claim 70, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.92. The atomic force
microscope according to claim 91, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.93. The atomic force microscope according to
claim 71, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.94. The atomic force
microscope according to claim 93, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.95. The atomic force microscope according to
claim 72, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.96. The atomic force
microscope according to claim 95, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.97. The atomic force microscope according to
claim 73, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.98. The atomic force
microscope according to claim 97, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.99. The atomic force microscope according to
claim 74, further comprising:
a removable probe module on which said probe is fixedly mounted at
a selected location. .Iaddend. .Iadd.100. The atomic force
microscope according to claim 99, further comprising:
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said sensing means so that
when said probe module is mechanically coupled to said probe module
support, said probe is in substantial alignment with said sensing
means. .Iaddend. .Iadd.101. The atomic force microscope according
to claim 59, further comprising:
a slidably moveable and removable sample support releasably coupled
to said scanning means and on which said sample is mounted.
.Iaddend. .Iadd.102. The atomic force microscope according to claim
101, further comprising:
magnetic means for magnetically mechanically coupling said sample
support to said scanning means. .Iaddend. .Iadd.103. The atomic
force microscope according to claim 60, further comprising:
a slidably moveable and removable sample support releasably coupled
to said scanning means and on which said sample is mounted.
.Iaddend. .Iadd.104. The atomic force microscope according to claim
103, further comprising:
magnetic means for magnetically mechanically coupling said sample
support to said scanning means. .Iaddend. .Iadd.105. The atomic
force microscope according to claim 63, further comprising:
a slidably moveable and removable sample support releasably coupled
to said scanning means and on which said sample is mounted.
.Iaddend. .Iadd.106. The atomic force microscope according to claim
105, further comprising:
magnetic means for magnetically mechanically coupling said sample
support to said scanning means. .Iaddend. .Iadd.107. The atomic
force microscope according to claim 67, further comprising:
a slidably moveable and removable sample support releasably coupled
to said scanning means and on which said sample is mounted.
.Iaddend. .Iadd.108. The atomic force microscope according to claim
107, further comprising:
magnetic means for magnetically mechanically coupling said sample
support to said scanning means. .Iaddend. .Iadd.109. The atomic
force microscope according to claim 76, further comprising:
a slidably moveable and removable sample support releasably coupled
to said scanning means and on which said sample is mounted.
.Iaddend. .Iadd.110. The atomic force microscope according to claim
109, further comprising:
magnetic means for magnetically mechanically coupling said sample
support to said scanning means. .Iaddend. .Iadd.111. The atomic
force microscope according to claim 87, further comprising:
a slidably moveable and removable sample support releasably coupled
to said scanning means and on which said sample is mounted.
.Iaddend. .Iadd.112. The atomic force microscope according to claim
111, further comprising:
magnetic means for magnetically mechanically coupling said sample
support to said scanning means. .Iaddend. .Iadd.113. The atomic
force microscope according to claim 59, comprising:
a support on which said sensing means is mounted; and
means mounted on said support for adjusting positioning of said
sensing means. .Iaddend. .Iadd.114. The atomic force microscope
according to claim 113, comprising:
said sensing means comprising a light beam source and a light beam
detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected of said
probe is incident on said detector. .Iaddend. .Iadd.115. The atomic
force microscope according to claim 60, comprising:
a support on which said sensing means is mounted; and
means mounted on said support for adjusting positioning of said
sensing means. .Iaddend. .Iadd.116. The atomic force microscope
according to claim 115, comprising:
said sensing means comprising a light beam source and a light beam
detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected of said
probe is incident on said detector. .Iaddend. .Iadd.117. The atomic
force microscope according to claim 63, comprising:
a support on which said sensing means is mounted; and
means mounted on said support for adjusting positioning of said
sensing means. .Iaddend. .Iadd.118. The atomic force microscope
according to claim 117, comprising:
said sensing means comprising a light beam source and a light beam
detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected of said
probe is incident on said detector. .Iaddend. .Iadd.119. The atomic
force microscope according to claim 67, comprising:
a support on which said sensing means is mounted; and
means mounted on said support for adjusting positioning of said
sensing means. .Iaddend. .Iadd.120. The atomic force microscope
according to claim 119, comprising:
said sensing means comprising a light beam source and a light beam
detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected of said
probe is incident on said detector. .Iaddend. .Iadd.121. The atomic
force microscope according to claim 76, comprising:
a support on which said sensing means is mounted; and
means mounted on said support for adjusting positioning of said
sensing means. .Iaddend. .Iadd.122. The atomic force microscope
according to claim 121, comprising:
said sensing means comprising a light beam source and a light beam
detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected of said
probe is incident on said detector. .Iaddend. .Iadd.123. The atomic
force microscope according to claim 87, comprising:
a support on which said sensing means is mounted; and
means mounted on said support for adjusting positioning of said
sensing means. .Iaddend. .Iadd.124. The atomic force microscope
according to claim 123, comprising:
said sensing means comprising a light beam source and a light beam
detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected of said
probe is incident on said detector. .Iaddend. .Iadd.125. The atomic
force microscope according to claim 106, comprising:
a support on which said sensing means is mounted; and
means mounted on said support for adjusting positioning of said
sensing means. .Iaddend. .Iadd.126. The atomic force microscope
according to claim 125, comprising:
said sensing means comprising a light beam source and a light beam
detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected of said
probe is incident on said detector. .Iaddend. .Iadd.127. In an
atomic force microscope having a deflection detection system for
detecting a deflection of a lever mounted probe as said probe is
scanned across a surface of a sample by a means for scanning the
sample, the improvement comprising:
a non-cryogenic fluid body in communication with said surface of
the sample and in which said probe is immersed in contact with said
sample while said probe is scanned across the surface of the
sample. .Iaddend. .Iadd.128. The atomic force microscope according
to claim 127, further comprising:
a rigid cover plate disposed on a top surface of said fluid body to
define a fluid cell between said cover plate and said sample.
.Iaddend. .Iadd.129. The atomic force microscope according to claim
128, wherein:
said rigid cover plate comprises an optically transparent material;
and
said deflection detection system comprises optical means for
sensing a vertical movement of said probe by means of light applied
to said probe through said rigid cover plate. .Iaddend. .Iadd.130.
The atomic force microscope according to claim 127, further
comprising:
two or more electrodes in contact with said fluid body for
performing an electrochemical reaction. .Iaddend. .Iadd.131. In an
atomic force microscope having a deflection detection system for
detecting a deflection of a lever mounted probe as said probe is
scanned across a surface of a sample, the improvement
comprising:
a scanner for scanning said probe; and
a conductive shield at a fixed potential disposed between said
probe and said scanner. .Iaddend. .Iadd.132. The atomic force
microscope according to claim 131, wherein said scanner comprises a
piezoelectric tube and said conductive shield is mounted on a
distal end of said tube between said tube and said probe. .Iaddend.
.Iadd.133. In a method of operating an atomic force microscope in
which a lever mounted probe is scanned across the surface of a
sample by a scanner and a deflection of said lever mounted probe is
detected by a deflection detection system, the improvement
comprising:
providing a fluid body in communication with the surface of the
sample and not in communication with said scanner;
immersing said lever mounted probe in said fluid body; and
scanning said lever mounted probe across the suface of the sample
while said lever mounted probe is immersed in said fluid body.
.Iaddend. .Iadd.134. The method according to claim 133,
comprising:
placing two or more electrodes in contact with said fluid body;
and
applying a voltage across said electrodes during said scanning step
to produce an electrochemical reaction in said fluid. .Iaddend.
.Iadd.135. In an atomic force microscope having a deflection
detection system for detecting a deflection of a lever mounted
probe as said probe is scanned across a surface of a sample, the
improvement comprising:
a removable probe module on which said probe fixedly mounted at a
selected location; and
a probe module support mechanically coupled to said probe module
during operation of said atomic force microscope and having a
predetermined spatial arrangement with said deflection detection
system so that when said probe module is mechanically coupled to
said probe module support, said probe is in substantial alignment
with said deflection detection system. .Iaddend. .Iadd.136. In an
atomic force microscope having a deflection detection system for
detecting a deflection of a lever mounted probe as said probe is
scanned across a surface of a sample by a means for scanning the
sample, the improvement comprising:
a slidably moveable and removable sample support releasably coupled
to said scanning means and on which said sample is mounted.
.Iaddend. .Iadd.137. The atomic force microscope according to claim
136, further comprising:
magnetic means for magnetically mechanically coupling said sample
support to said scanning means. .Iaddend. .Iadd.138. In an atomic
force microscope having a deflection detection ssystem for
detecting deflection of a lever mounted probe as said probe is
scanned by a scanner across a surface of a sample, the improvement
comprising:
a support on which said deflection detection system and said probe
are mounted; and
means mounted on said support for adjusting positioning of said
deflection detection system. .Iaddend. .Iadd.139. The atomic force
microscope according to claim 138, further comprising:
said deflection detection system comprising a light beam source and
a light beam detector; and
said adjusting means comprising means for adjusting positioning of
at least one of said light beam source and said light beam detector
so that a light beam output by said source and reflected off said
probe is incident on said detector. .Iaddend.
Description
BACKGROUND OF THE INVENTION:
This invention relates to scanning microscopes used for imaging the
topography of surfaces and, more particularly, to an atomic force
microscope having extended use capabilities comprising, a
horizontal base member; a scan tube vertically supported at a
bottom end by the base member and having a top surface for holding
a sample to be scanned and moveable in x-, y-, and z-directions as
a result of scanning voltages applied thereto; first support means
extending upward from the base member; a sample holding block
having a chamber therein, the sample holding block having a first
bore communicating with the chamber through a bottom surface, a
second bore communicating with the chamber through a top surface,
and a third bore communicating with the chamber at an acute angle
to the second bore, the sample holding block being positioned with
the scan tube passing through the first bore and supported by the
first support means; second support means extending upward from the
bottom surface into the chamber, a probe-carrying module having a
probe attached thereto and extending downward therefrom at an acute
angle with a tip of the probe positioned to contact a sample
mounted on the top surface of the scan tube, the probe carried by
the probe-carrying module comprising a substrate attached to the
probe-carrying module and a pair of arms of a smooth-surfaced,
minimally self-biased material cantilevered outward from a bottom
front edge of the substrate in a V-shape to form an optical lever,
the pair of arms having a probe point at the apex of the V-shape
thereof; a source of a laser beam mounted for directing the laser
beam down the second bore from the top surface of the sample
holding block to strike the probe and be reflected down the third
bore to an outer end thereof; and, photoelectric sensor means
having an active surface positioned over the outer end of the third
bore for developing an electrical signal at an output thereof
reflecting the position on the active surface at which the laser
beam strikes the active surface.
The family of scanning probe microscopes that have been introduced
to the scientific community of recent years is broadening the
frontiers of microscopy. As typified by the greatly simplified
general example of FIGS. 1 and 2, these microscopes scan a sharp
probe 10 over the surface 12 of a sample 14 to obtain surface
contours, in some cases actually down to the atomic scale. The
probe 10 may be affixed to a scanning mechanism and moved in a scan
pattern over the surface 12 or alternately (and equally effectively
because of the small sizes involved) the probe 10 may be stationary
with the sample 14 mounted on a scanning mechanism that moves the
surface 12 across the probe 10 in a scanning pattern. The tip 16 of
the probe 10 rides over the surface 12 as the probe 10 is moved
across it. As the tip 16 follows the topography of the surface 12,
the probe 10 moves up and down as indicated by the bi-directional
arrow 18. This up and down movement of the probe 10 is sensed to
develop a signal which is indicative of the z directional component
of the 3-dimensional surface 12.
Early atomic force microscopes (AFMs) mounted the probe 10 to a
wire and electrically sensed the movement of the wire as the probe
tip 16 moved over the surface 12. Recent prior art AFMs employ
technology developed in the microelectronics art as depicted in
FIG. 1. It should be noted that the drawings figures herein are not
to scale as the probe 10 and its tip 16 (typically of a diamond
material) are extremely small so as to be useful at the near-atomic
level. If the drawings were drawn to scale, these components would
not be visible. In fact, when working with AFMs, these components
are not visible to the naked eye and must be viewed with an optical
microscope. As will be seen shortly, this is a source of some of
the problems which are solved by this invention.
As depicted in FIG. 1, recent prior art AFMs have the probe 10
extending outward from the forward edge of a substrate 20 with the
probe 10 being formed thereat by manufacturing techniques which are
not critical to the present invention. It is sufficient to point
out that the probe 10 is typically in the form of an arm extending
outward from the substrate 20 with the diamond tip 16 attached at
the end of the arm. Also, the probe 10 is extremely small and
extremely fragile. The substrate 20 is typically adhesively
attached to the bottom and extending outward from the forward edge
of a large steel block 22 mounted to the surrounding structure.
Where the probe 10 and sample 14 are conductive, the position of
the probe 10 as a result of the deflection caused by the surface 12
during the scanning process can be sensed electrically. Where
non-conductive samples are to be scanned, the prior art literature
suggests bouncing a laser beam 24 off the probe 10 to be sensed by
a photoelectric sensor 26. As depicted in FIG. 2, as the probe 10
deflects up and down, the reflection angle of the laser beam 24 is
changed. It is this change in reflection angle that is sensed by
the photoelectric sensor 26, which then outputs an electrical
signal related to the angle (by way of the beam of light striking a
detecting surface), and thereby the z directional component of the
probe 10.
Regardless of the probe positional sensing method employing
(electrical or laser light), there are a number of problems
associated with the prior art AFMs as typified by the simplified
drawings of FIGS. 1 and 2. As depicted in FIG. 2, the surface 12 of
a sample 14 has a thin (i.e. molecular level) coating of water 28
thereon. Often, the small, lightweight tip 16 of the probe 10 is
"sucked" into the surface 12 against the miniscule resilient
biasing force of the probe 10 by the capillary action of this
coating of water 28. This, of course, can seriously damage the tip
16 to the point of making it non-useful for its intended purpose.
Further on the negative side, the coating of water 28 is not
sufficient to provide any lubricating with respect to the tip 16
sliding over the surface 12. As a result, frictional wear of the
tip 16 is a serious problem causing the tip 16 to wear off quickly
to the point of making it non-useful of its intended purpose. Also,
with some sample materials the tip 16 may dig into and damage the
sample surface 12 rather than sliding over it to provide useful
information. Additionally, the scanning action is accomplished by
the application of fairly high voltages to a scanning member. With
the steel mounting block 22 in close proximity as depicted in FIG.
1, these voltages can be attracted to the steel block 22 and, in
the process, affect the probe 10 thereby introducing false data
into the output stream.
The type of environment and class of persons who are and will be
using AFMs in the future also adds to the problems of this
extremely useful and potentially powerful device. Typically, the
user is a researcher working on various projects in a laboratory
environment. He/she is not interested in having to "play" with the
AFM to get it to produce workable results. In its present
configuration as depicted by the drawings of FIGS. 1 and 2, it is
difficult of set up for scanning. It is easy to break the tip 16
from the probe 10 and/or the probe 10 from the substrate 20.
Replacing the probe/tip assembly is a major undertaking; and,
because of the problems described above, the life expectancy of the
probe/tip is extremely short. Moreover, the sample 14 is glued to
the top of a piezoelectric scanning tube (not shown in FIGS. 1 or
2) which provides the scanning action by moving the sample with
respect to the stationary probe 10 (which must remain fixed in
position to have the laser beam 24 reflect from it for detection
purposes). Thus, once placed, the sample 14 is impossible to move
(so as to change the scanning point) and difficult to change.
Positioning the tip 16 of the probe 10 on the surface 12 of the
sample 14 is difficult at best and virtually impossible in some
cases. In short, while AFMs are moving into a commercial stage of
development, the products which are available in the prior art are
not the efficient, easy to use laboratory aids that the users
thereof desire and need.
Wherefore, it is an object of the present invention to provide an
AFM system which is easy to set up, calibrate, and use in the
typical laboratory environment by the typical laboratory
worker.
It is another object of the present invention to provide an AFM
system in which the probe/tip resist frictional wear.
It is still another object of the present invention to provide an
AFM system in which the probe/tip are not subjected to the
capillary forces of water coating the surface of the sample.
It is yet another object of the present .[.inventio.].
.Iadd.invention .Iaddend.to provide an AFM system in which the
probe/tip slide easily over the sample surface and resist digging
into softer samples and damaging them thereby providing a gentler
and more reliable operation.
It is a further object of the present invention to provide an AFM
system in which the probe/tip are contained in an easily
replaceable module which is recyclable by the AFM supplier.
It is a still further object of the present invention to provide an
AFM system having calibration/setup tools included therewith which
make the setting up of the AFM a simple and straightforward
task.
It is another object of the present invention to provide an AFM
system in which the sample is held by a removeable and adjustable
member which allows the position of the sample to be changed in
situ and allows a new sample to be installed easily and quickly
without destruction of previous samples.
It is also an object of the present invention to provide an AFM
system in which the steel mounting block of the prior art is
removed without affecting the stability of the probe and tip.
Other objects and benefits of this invention will become apparent
from the description which follows hereinafter when taken in
conjunction with the drawing figures which accompany it.
SUMMARY
The foregoing objects have been achieved in the atomic force
microscope of the present invention which is quickly and easily set
up and in which the probe thereof is easily replaceable and resists
breakage during setup comprising, a horizontal base member; a scan
tube vertically supported at a bottom end by the base member and
having a top surface for holding a sample to be scanned and
moveable in x-, y-, and z-directions as a result of scanning
voltages applied thereto; first support means extending upward from
the base member; a sample holding block having a chamber therein;
the sample holding block having a first bore communicating with the
chamber through a bottom surface, a second bore communicating with
the chamber through a top surface, and a third bore communicating
with the chamber at an acute angle to the second bore, the sample
holding block being positioned with the scan tube passing through
the first bore and supported by the first support means; second
support means extending upward from the bottom surface into the
chamber; a probe-carrying module having parallel top and bottom
surfaces removably disposed in the chamber and supported by the
second support means, the bottom surface having a probe attached
thereto and extending downward therefrom at an acute angle with
respect to the bottom surface of the probe-carrying module and with
a tip of the probe positioned to contact a sample mounted on the
top surface of the scan tube; a source of a laser beam mounted for
directing the laser beam down the second bore from the top surface
of the sample holding block to pass through the probe-carrying
module, strike the probe, and be reflected back through the
probe-carrying module and down the third bore to an outer end
thereof; and, photoelectric sensor means having an active surface
positioned over the outer end of the third bore for developing an
electrical signal at an output thereof reflecting the position on
the active surface at which the laser beam strikes the active
surface.
In one embodiment, the probe-carrying module is of an optically
transparent material whereby the laser beam can pass through the
probe-carrying module, strike the probe, and be reflected back
through the probe-carrying module. In another embodiment, the
probe-carrying module is of an optically non-transparent material
and has a laser-passing bore therethrough between the top and
bottom surfaces aligned so that the laser beam can pass through the
laser-passing bore, strike the probe, and be reflected back through
the laser-passing bore.
In the preferred embodiment, the probe-carrying module includes an
angled pad on the bottom surface thereof and the probe carried by
the probe-carrying module comprises a substrate attached to the pad
and a pair of arms of a smooth-surfaced, minimally self-biased
material cantilevered outward from a bottom front edge of the
substrate in a V-shape to form an optical lever, the pair of arms
having a probe point at the apex of the V-shape thereof.
In the preferred embodiment, the first support means comprises
three first adjusting screws threaded through the base member with
the sample holding block resting on top ends thereof with one of
the top ends disposed in a slot in a flat bottom surface of the
sample holding back, another of the top ends disposed in a hole in
the bottom surface, and a third of the top ends disposed on the
bottom surface whereby the sample holding block is removable from
the base member and repeatedly replaceable to a pre-established
position thereon. Additionally, the second support means comprises
three second adjusting screws threaded through the bottom surface
of the sample holding block with the probe-carrying module resting
on top ends thereof with one of the top ends disposed in a slot in
a flat bottom surface of the probe-carrying module, another of the
top ends disposed in a hole in a member affixed to the bottom
surface, and a third of the top ends disposed on the bottom surface
whereby the probe-carrying module is removable from the chamber of
the sample holding block and repeatedly replaceable to a
pre-established position therein.
The preferred fluid cell is .[.prvivded.]. .Iadd.provided
.Iaddend.by the probe-carrying module being of an optically
transparent material and additional sealing means surrounding the
probe and attached to the bottom surface of the probe-carrying
module or sealing to a top surface of a sample to form a fluid cell
around the probe. The preferred fluid cell includes an inlet bore
and an outlet bore in the probe-carrying module communicating
between the fluid cell and the exterior of the probe-carrying
module whereby fluid can be inserted into the fluid cell.
Preferably, there is an electrode bore in the probe-carrying module
communicating between the fluid cell and the exterior of the
probe-carrying module and an electrode disposed in the electrode
bore having a first end within the fluid cell and a second end at
the exterior of the probe-carrying module to which electrical
connection can be made. For electro-chemical use, there are three
electrode bores in the probe-carrying module communicating between
the fluid cell and the exterior of the probe-carrying module as
well as a working electrode, a reference electrode, and an
auxiliary electrode disposed in the electrode bores, each of the
electrodes having a first end within the fluid cell and a second
end at the exterior of the probe-carrying module to which
electrical connection can be made.
Preferred operation is achieved by including a voltage shield of an
electrically conductive material disposed over the top surface of
the scan tube in non-electrical contact therewith, the voltage
shield being electrically connected to a fixed voltage source
whereby to shield the probe from the effects of the scanning
voltages applied to the scan tube.
To provide ease of sample placement, replacement, and lateral
adjustment, there is a slidably moveable and removeable stage
releasably attached to the top surface of the scan tube for
releasably and adjustably holding a sample to be scanned attached
thereto. In one embodiment, the stage contains a magnet therein and
the voltage shield is of a ferro-magnetic material to which the
stage can magnetically attach and upon which it can slide. In
another embodiment, the stage is of a ferro-magnetic material and
the voltage shield contains the magnet therein.
The preferred system includes various calibration means to make a
user's job one of microscope use and not one of detailed setup and
maintenance. In particular, there are first calibration means for
positioning the member affixed to the bottom surface of the
probe-carrying module as a function of the position of a tip
portion of the probe; second calibration means for setting the
position of the sample holding block on the first support means;
and, third calibration means for setting the position of the
probe-carrying module on the second support means.
DESCRIPTION OF THE DRAWINGS:
FIG. 1 is a simplified drawing of a prior art atomic force
microscope showing the probe as mounted to a substrate carried by a
large steel block being detected by a laser beam being reflected
therefrom.
FIG. 2 is an enlarged drawing of the tip of the probe of FIG. 1
showing the movement of the tip over the surface of a sample and
how the reflection angle of the laser beam is changed as a result
of deflection of the probe.
FIG. 3 is a partially cutaway side view of an atomic force
microscope according to the present invention.
FIG. 4 is an enlarged cutaway side view of the sample-holding block
of the atomic force microscope of FIG. 3 showing how the supporting
screws thereof are calibrated to a proper height.
FIG. 5 is an enlarged cutaway side view of the sample-holding block
of FIG. 4 mounted on the base portion of the atomic force
microscope of FIG. 3 showing how the supporting screws thereof are
calibrated to place the probe tip at a proper height.
FIG. 6 is an enlarged cutaway side view of the probe and tip of a
non-preferred embodiment of the present invention in which the
scanning takes place within a fluid drop.
FIG. 7 is a bottom view of the probe-carrying module of the present
invention in its preferred embodiment.
FIG. 8 is a cutaway view of the probe-carrying module of FIG. 7 in
the plane VIII--VIII.
FIG. 9 is a simplified drawing depicting a prior art three point
support/adjustment technique as employed in the present
invention.
FIG. 10 is a side view of a calibration tool employed in the AFM
system of the present invention to make the probe-carrying module
position the probe tip exactly in its proper position when the
probe-carrying module is inserted into the sample-holding block of
FIG. 4.
FIG. 11 is a bottom view of the calibration tool of FIG. 10.
FIG. 12 is a drawing depicting the use of the calibration tool of
FIGS. 10 and 11.
FIG. 13 is a partially cutaway side view of the top of a
piezoelectric scanning tube employing the voltage shield and the
removable/slideable stage of the present invention in a first
embodiment.
FIG. 14 is a detailed drawing of the preferred holding and
adjusting mechanism for the photoelectric sensor employed in the
present invention.
FIG. 15 is a partially cutaway side view of the top of a
piezoelectric scanning tube employing the voltage shield and the
removable/slideable stage of the present invention in an alternate
embodiment.
FIG. 16 is a top view of the preferred probe configuration of the
present invention.
FIG. 17 is a front view of the probe of FIG. 16.
FIG. 18 is a drawing of an optional removeable but non-transparent
probe-carrying module without fluid cell potential that may be
employed in the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT:
The essential elements of an AFM 28 according to the present
invention in its preferred embodiment are depicted in the cutaway
side view of FIG. 3. There is a base 30 which, as in the typical
prior art AFM, is shock mounted in some manner. A piezoelectric
scan tube 32 is mounted extending perpendicularly upward from the
base 30. The scan tube 32 is of a conventional design well known in
the art whereby by the application of .[.z-.]. .Iadd.x-.Iaddend.,
y-, and z-directional scan voltages to the wires 34, the top end 36
of the tube 32 can be moved horizontally in two orthogonal
directions and vertically to provide x and y scanning as well as
fine probe positioning in the z direction to the atomic level.
A sample-holding block 38 is supported on the tips of three
adjusting screws 40 threaded through the base 30 employing a
hole/slot/surface contact and alignment technique which is well
known in the art, to be addressed in greater detail later herein.
As can be seen, the scan tube 32 extends through a bore 42 in the
bottom 44 of the sample-holding block 38 so that the top end 36
thereof is within a chamber 46 within the sample-holding block 38.
A probe-carrying module 48 is disposed within the chamber 46 and
supported on the tips of three adjusting screws 50 threaded through
the bottom 44 employing a special application of the
above-mentioned hole/slot/surface contact and alignment technique,
which will also be addressed in greater detail later herein. The
probe-carrying .[.moduel.]. .Iadd.module .Iaddend.48, as will be
seen shortly, provides the solution to several major problems of
prior art AFMs as described above. The probe-carrying module 48 is
of a transparent material having parallel, planar top and bottom
surfaces, 52, 54, respectively. In order of preference, the
probe-carrying module 48 can be made of quartz, glass, or a plastic
such as polycarbonate. The substrate 20 having the probe 10 mounted
thereto is glued to the bottom surface 54 within an O-ring 56 also
glued to the bottom surface 54. As will be described in further
detail shortly, this arrangement can be employed to place the probe
10 within a fluid cell which can exist between the bottom surface
54 and the sample 14 within the O-ring 56. That, of course,
eliminates the capillary attraction problem described above and
provides a low friction/lubricating environment wherein even soft
tissue samples, and the like, can be scanned without damage
thereto. As will be noted, the steel block 22 of the prior art has
been eliminated, as desired. The probe tip 16 is automatically
aligned with respect to the laser beam 24 in a manner to be
described shortly. Perhaps most important, the probe-carrying
module 48 can be removed and replaced quickly, accurately, and
easily if and when the probe/tip become broken and/or worn. The
used module 48 can then be returned to the factory for the
installation of a new probe 10 under the proper conditions. The
sample 14 is attached to the top of a removable sample stage 58.
Thus, a particular sample 14 can be attached easily to the stage 58
at a bench location away from the AFM 28. If desired, a particular
sample can be removed temporarily and then be reinserted at a later
time. Additionally, the sample stage 58 is magnetically attached to
a ferromagnetic electrical interference shield 60 carried by the
top end 36 of the scan tube 32. The shield 60 prevents electrical
interference from the scan voltages applied to the tube 32 and,
additionally, the magnetic attachment of the sample stage 58
thereto permits the stage 58 (and attached sample 14) to be slid
horizontally in the x and y directions to place the desired area
for scanning under the probe tip 16.
The top of the sample holding block 38 has a flat stage area 62
thereon which is parallel to the bottom 44. A bore 64 extends
perpendicularly from the stage area 62 into the chamber 46
generally concentrically about a point on the probe-carrying module
48 where the tip 16 of the probe 10 is to be located. A laser beam
source 66 is carried by a rectangular holding member 68
magnetically attached to the stage area 62 for horizontal sliding
movement thereon. The laser beam 24 from the source 66, therefore,
shines down the bore 64 to strike the probe 10 from whence it is
angularly reflected up bore 70 to strike the detecting surface 72
of a photoelectric sensor 26 (of a type well known in the art which
individually forms no part of the novelty of this invention). The
sensor 26 is adjustably held in a micro detector adjustor 74. In
presently tested embodiments of this invention, the source 66 of
the laser beam 24 is a holder gripping one end of an optic fiber
which has the laser beam 24 from a commercial laser device input
thereto at the opposite end to prevent heat buildup from the laser
device in the area of the probe 10 and associated apparatus. A
preferred source 66 would include a laser-emitting diode located
within the source 66 itself. The horizontal position of the holding
member 68 is fine-adjusted in the x and y directions (to place the
laser beam 24 exactly on the probe 10 for optimum reflection) by
means of a pair of orthogonally oriented micro laser adjustors 76.
Having thus described the present invention and its various
components and aspects in a general manner, the various point of
novelty will now be addressed in greater detail.
The sample holding block 38 and the method of setting the adjusting
screws 50 is depicted in the enlarged drawing of FIG. 4. As can be
seen from this figure, there are micro laser adjustors 76 oriented
at 90.degree. to one another. Each adjustor 76 comprises a vertical
member 78 extending upward from the sample holding block 38
adjacent the stage area 62. A leaf spring member 80 extends upward
along the inner surface of the vertical member 78 from a point of
attachment thereto at 82. A magnetic probe 84 extends outward
towards the stage area 62 from a point just above the point of
attachment 82. An adjusting screw 86 is threaded through the
vertical member 78 into contact with the leaf spring member 80 near
the top of the vertical member 78. Note that the adjusting screws
86 have a large diameter turning wheel 88 on the outer end thereof
whereby the adjusting screws 86 .[.cna.]. .Iadd.can .Iaddend.be
turned easily a fraction of a rotation when horizontally adjusting
the position of the holding member 68 on the stage area 62. Note
also that there is a large mechanical advantage from the
positioning of the adjusting screw 86 on the leaf spring member 80
with respect to the magnetic probe 84 and the point of attachment
82. As a result, turning the wheel 88 (which can be accomplished
easily and smoothly because of the mechanical advantages provided)
will result in a very small horizontal movement of the holding
member 68, which is desirable in order to be able to accurately
accomplish the final positioning of the laser beam 24 on the probe
10.
As depicted in detail in FIG. 14, the preferred micro detector
adjustor 74 comprises a U-shaped slider member 90 magnetically
adhering to the sliding surface 92 of the sample holding block 38,
which is perpendicular to the bore 70. The sensor 26 is held within
the sideward-facing U of the slider member 90 by a holder 148
having an area 150 therein sized to the contours of the sensor 26.
Both the holder 148 and the slider member 90 are held to the
sliding surface 92 by magnets 116. The slider member 90 is moved up
and down by the adjusting screw 94 which is threaded through the
slider member 90 between the webs 96 in the sample holding block 38
provided for the purpose. The holder 148 is moved sideways by the
adjusting screw 152 threaded through the bottom of the U of the
slider member 90.
The position of the adjusting screws 50 (and thereby the position
of the probe-carrying module 48 when inserted into the chamber 46)
can be set using a calibration blank 98 and height gauge 100 as
shown. The height gauge 100 is inserted into the bore 42 and the
calibration blank 98 is positioned on the adjusting screws 50. The
screws 50 are then raised and/or lowered, as appropriate, until the
calibration blank 98 is just resting evenly on the flat top surface
of the height gauge 100. At that point, the screws 50 are set to a
height such that when the probe-carrying module 48 is positioned on
the screws, the probe tip 16 will be at the desired (and
anticipated) probe height as shown.
The adjusting screws 40 must also be set to a proper height to
support the probe-carrying module 48 at a point where the sample
surface of a mounted sample to be scanned will be at the probe
level anticipated by the calibration procedure just described with
respect to FIG. 4. This is accomplished using the calibration tool
102 in the manner depicted in FIG. 5. Calibration tool 102
comprises a yoke 104 having a bottom 106 configured exactly like
the bottom 44 of the sample holding block 38, including a bore 42'
for the scan tube 32 to pass through. It should be noted that, as
will be seen from a description contained hereinafter, while the
adjusting screws 50 of the sample holding block 38 need be adjusted
only rarely, the adjusting screws 40 will need to be adjusted
whenever the sample 14 is changed. This is because the sample 14 is
glued to the sample stage 58 and the height of the sample surface
may change significantly from one sample to the next, at least in
the sizes being considered in the operation of the AFM 28. The
calibration tool 102 also has a short focal length calibration
microscope 108 positioned perpendicularly to be above the sample
surface 12 when the calibration tool 102 is mounted on the
adjusting screws 40. The focal length of the calibration microscope
108 is chosen such as to focus exactly at the plane the probe tip
16 will be in. To properly adjust the adjusting screws 40, the
sample 14 is mounted on the scan tube 20 and the calibration tool
102 positioned as shown in FIG. 5. While viewing through the
calibration microscope 102, the adjusting screws 40 are used to
move the calibration tool 102 up and down until the entire surface
12 of the sample 14 is in focus. At that point, the adjusting
screws 40 are properly set. Because of the short focal length
employed, the surface 12, when completely in focus, is also
parallel to the scanning action of the probe 10.
Before continuing with the setup and calibration aspects of the
present invention, attention is directed to FIGS. 13 and 15 which
are directly related to the last described aspects of this
invention. As mentioned earlier, the scanning movement of the
piezoelectric scan tube 32 is affected by the application of
voltages (which can be in the 100 volt range) to electrodes 110 on
the exterior and interior surfaces of the tube 32, which is made of
a piezoelectric material. Independently of the attracting potential
of the steel block 22 (which has been removed in the preferred
embodiment of this invention), the inventors herein have observed
(and proved) that the scanning voltages employed to move the scan
tube 32 can still adversely affect the probe 10. To solve this
problem, a disk shaped voltage shield 112 is attached to the top
end 36 of the tube 32. Since the shield 112 must be electrically
conductive, it is attached to the top end 36 of the tube 32 with an
insulating adhesive 114. The voltage shield 112 is then physically
connected to a ground potential. Optionally, it can be connected to
a fixed voltage potential which is available.
The adjustability and removability aspects of the sample stage 58
can be accomplished in two ways as depicted in FIGS. 13 and 15,
respectively. In the embodiment of FIG. 13, the voltage shield 112
is of a ferro-magnetic material and the sample stage 58 has a
magnet 116 mounted therein. In the embodiment of FIG. 15, the
voltage shield 112 has a magnet 116 mounted concentrically therein
and the sample stage 58 is of a ferro-magnetic material.
Accordingly, in either embodiment the voltage shield 112 not only
shields against the effects of stray voltages reaching the probe
10; but, additionally, provides a surface on the top end 36 of the
scan tube 32 onto which the removeable sample stage 58 having a
sample 14 glued thereto can be magnetically attached. Accordingly,
while the sample 14 is positioned on the tube 32 and as part of the
adjustment of the adjusting screws 40 as described with respect to
FIG. 5, the sample stage 58 can be slid horizontally in both the x
and y directions to place an area of interest under the probe to be
scanned thereby.
The problems of capillary action and friction in soft samples as
well as the providing of the gentler and more reliable operation
will now be addressed. An important aspect of the AFM 28 of this
invention is the inclusion of a unique probe design which is, in
fact, a microfabricated cantilever with an optical lever as shown
in FIGS. 16 and 17. The probe 10 comprises a pair of V-shaped arms
154 formed on the bottom forward edge of the supporting substrate
20 by microfabrication techniques well known in the
microelectronics art which, per se, form no part of this invention.
The arms 154 are, therefore, cantilevered out from the bottom
forward edge of the substrate 20. Because of the nature of the
materials employed in such microfabrication, the cantilevered arms
154 deflect easily (i.e. their self biasing force is practically
non-existent). Because such microfabricated materials have a very
smooth surface, the inherently reflect the laser beam 24, thus
forming the desired optical lever. The actual contacting tip 16 is
made of diamond and separately attached where the two arms 154 join
to form the "V".
The problems of capillary action and friction in soft samples can
be solved in the AFM 28 of this invention by optionally having the
probe 10 and area of the sample being scanned immersed in a fluid
bath. In a non-preferred embodiment, this novel aspect of the
present invention can be accomplished in the manner shown in FIG.
6. This approach was employed in early tested embodiments of the
present invention; but, has been superceded by the apparatus to be
described shortly. As will be noted, this embodiment employs the
prior art technique of having the probe 10 mounted on a substrate
20 which, in turn, is mounted to a steel block 22, or the like,
carried by the base portion of the AFM. To provide the fluid bath,
a clear cover glass 118 is attached to the top of the substrate 20
extending outward over the probe 10. A drop of fluid 120 (such as
de-ionized water) is then injected with a syringe into the area
surrounding the probe 10 defined by the cover glass 118, the sample
surface 12, and the edge of the substrate 20, where it adheres by
capillary action and surface tension. The laser beam 24 passes
through the cover glass 118 and fluid 120 to the probe 10 from
which it is reflected to pass back through the fluid 120 and cover
glass 118. Any minor refraction will remain constant and can be
accounted for by adjusting the position of the photoelectric sensor
26. Other than being associated with the non-replaceable, steel
block mounted probe 10, the only other problem with this embodiment
is that the life of the drop of fluid 120 is limited due to
evaporation.
The probe-carrying module 48 .[.shwon.]. .Iadd.shown .Iaddend.in
detail in FIGS. 7 and 8 solves many of the problems associated with
the prior art while, when desired or needed, optionally providing
the novel fluid cell environment of this invention and is,
therefore, the preferred approach. Each probe-carrying module 48 is
assembled and calibrated (in the manner to be described shortly) at
the factory. As mentioned earlier, if the probe 10 wears out or
breaks off, the researcher merely installs a new probe-carrying
module 48 and sends the broken one back to the factory for
recycling. The probe-carrying module 48 has an angled area 122
(approximately 10.degree.) cut into the bottom surface 54 into
which the probe carrying substrate 20 is glued. The probe 10 and
substrate 20 are surrounded by an O-ring 56 which is also
adhesively attached to the bottom surface 54. When the O-ring 56 is
positioned on the surface 12 of the sample 10 as shown in FIG. 8, a
fluid cell 124 is formed between the bottom surface 54 and the
sample surface 12 within the O-ring 56. Inlet and outlet tubes 126,
128 are formed into the material of the probe-carrying module 48
communicating with the fluid cell 124 and the exterior of the
module 48. Fluid 120 can be injected (or even circulated if
applicable) through the tubes 126, 128. The evaporation problem is,
therefore, eliminated. It should be noted that where the fluid cell
is not needed, the optional probe-carrying module 48 of FIG. 18 can
be employed. In this case, the probe-carrying module 48' is of
metal or plastic and, as with the above-described version, has an
angled area 122 (approximately 10.degree.) cut into the bottom
surface 54 into which the probe carrying substrate 20 is glued. A
bore 156 through the probe-carrying module 48' from the top surface
52 to the bottom surface 54 aligned with the probe 10 is provided
to allow the laser beam 24 to pass through the probe-carrying
module 48', strike the probe 10, and be reflected therefrom to the
photoelectric sensor 26.
Returning to the above-described preferred probe-carrying module 48
containing the fluid cell, in addition to providing the benefits
described with respect to eliminating the capillary attraction
affect on the probe 10 and the reduction of friction in soft
samples, the fluid cell can also be employed for electro-chemical
purposes, and the like. To this end, in the preferred embodiment of
this invention three additional tubes 158, 160, and 162 are formed
into the material of the probe-carrying module 48 communicating
with the fluid cell 124 and the exterior of the module 48. Each of
the tubes contains an electrode 164 extending between the fluid
cell 124 on one end and the exterior of the module 48 on the other,
at which point electrical connection can be made thereto. As will
readily be appreciated by those skilled in the art, such an
arrangement has many uses. For example, samples could be "pinned
down" to substrates electrically by applying a voltage between one
or more of the electrodes 164 in the fluid cell (containing the
sample) and the voltage shield 112. The presence of the three
electrodes 164 (i.e. a working electrode, a reference electrode,
and an auxiliary electrode) make possible a wide range of
electro-chemical studies such as plating, corrosion, and
electrostripping within the real-time environment of the AFM
28.
The prior art hole/slot/support system employed in the invention
and mentioned earlier is depicted in simplified form in FIG. 9.
Three points, of course, define a plane as is a well known
mathematical fact just as the fact that two points define a
straight line. A simpler example is the three legged stool, which
will never wobble like its four legged cousin. Thus, in complex
apparatus such as the AFM 28 wherein stability of the components
therein with respect to one another, the use of a three point
support system is a logical approach. To provide accuracy of
placement with adjustability, the hole/slot/support technique of
FIG. 9 is commonly employed. The surface to be supported has a
straight slot 130 formed therein at a first general point of
support. A hole 132 is formed into the surface in longitudinal
alignment with the slot 130 at a second, but specific, point of
support. The surface to be supported is placed on three supports by
first placing one support into the slot 130. The one support is
then slid within the slot as required and the article rotated as
needed to allow a second of the three supports to be inserted into
the hole 132. Two points of support have thus been established. As
two points define a line, the two support points only allow
rotation of the surface to be supported about the support points in
the hole 132 and slot 130. The surface to be supported is then
lower (i.e. rotated about the line defined by the first two support
points) until the surface to be supported is resting on the third
of the three supports. This supporting technique will repeatedly
result in the same positioning of the surface to be supported on
the three supports.
While the above-described prior art three point support system is
used throughout the AFM 28, a novel approach thereto is used to
pre-calibrate the probe-carrying modules 48 at the factory so that
when one is inserted into the chamber 46 to be supported by the
adjusting screws 50, the probe tip 16 will be placed in approximate
accurate alignment with the nominal position of the laser beam 24.
As can be seen from the drawing of FIG. 7 the bottom surface 54 of
the probe-carrying module 48 has only a slot 130 formed therein.
The "hole" 132 is provided according to the calibration technique
shown in FIGS. 10-12. At the factory, after the substrate 20 with
the probe 10 attached is affixed to the angled area 122, the
calibration tool 134 of FIGS. 10 and 11 is employed to position a
washer 136 so that the hole in the center of the washer 136 is the
hole 132' which receives the second of the adjusting screws 50. The
calibration tool 134 has a horizontal base 138 with three pins 140
extending downward therefrom perpendicular to the base 138 and
spaced in the same triangular shape as the three adjusting screws
50. A microscope 142 is vertically fit into a bore 144 through the
base 138 which has the same relationship to the pins 140 that the
bore 64 has to the adjusting screws 50. Crosshairs 146 within the
microscope 142 cross in the approximate position of the laser beam
24 within the bore 64. With the probe-carrying module 48 lying on
its top surface 52, one pin 140 is inserted in the slot 130. A
washer 136 is placed on the bottom surface 54 and another of the
pins 140 is inserted into the hole 132' thereof and then placed on
the bottom surface 54 along with the third pin 140. The calibration
tool 134 is then slid over the bottom surface 54 to place the probe
tip 16 in the center of the crosshairs 146. The washer 136 is then
glued to the bottom surface 54 by the application of a fast-drying
glue thereof such as that sold under the trademark Krazy-Glue. That
completes the calibration procedure as the hole 132' is now fixed
so as to place the probe tip 16 in the proper position when the
probe-carrying module 48 is used in an AFM 28. After insertion of
the probe-carrying module 48 into the chamber 46, the micro laser
adjustors 76 are then used to precisely place the laser beam 24 on
the probe 10 for optimum reflection. Simultaneously, the micro
detector adjustor 76 is used to optimally position the
photoelectric sensor 26. Thus, the AFM 28 of this invention can be
placed into service for useful work quickly and easily without
undue expense of time and without the need for a high degree of
technical training. If the procedures as set forth above are
followed, the probe 10 is virtually unbreakable as a result of the
setup procedure; and, when the probe 10 does wear out or break, it
is quickly and easily replaced.
* * * * *