Electric lamp or space discharge component or device manufacturi – Process – Electrode making
Reexamination Certificate
1998-11-19
2001-01-09
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
Electrode making
C445S035000, C445S046000
Reexamination Certificate
active
06171165
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electron beam microcolumns, and in particular to a methodology for aligning an electron emitter and an extractor hole of a microcolumn.
BACKGROUND OF THE INVENTION
Electron beam microcolumns based on microfabricated electron optical components and field emission sources operating under the scanning tunneling telescope (STM) aided alignment principle were first introduced in the late 1980s. Electron beam microcolumns are used to form a finely focused electron beam and offer the advantages of extremely high resolution with improved beam current, small physical size, and low cost, and can be used in a wide variety of applications, such as electron beam lithography. See “Electron-Beam Microcolumns for Lithography and Related Applications” by Chang, T. et al., Journal of Vacuum Science Technology Bulletin 14(6), pp. 3774-3781, November/December 1996, incorporated herein by reference.
The alignment principles used by microcolumns are similar to STMs in that a precision X-Y-Z positioner is used to control a sharp tip, in the case of a microcolumn a field emission tip, and to utilize the emission from the tip to measure the position of the tip. For additional information relating to three-axis micropositioners, see “Miniature Three-Axis Micropositioner for Scanning Proximal Probe and Other Applications,” by S. Kleindiek et al., Journal of Vacuum Science Technology Bulletin 13(6), pp. 2653-2656, November/December 1995.
FIG. 1
is an exploded diagram of field emitter source
110
and electron optical column
120
. Field emitter source
110
includes a field emitter tip
112
, which may be a Zr/O/W Schottky field emitter tip or a cold-field emitter tip, such as a single crystal tungsten, hafnium carbide or diamond tip. Field emitter tip
112
is mounted on a miniature three-axis micropositioner
114
. Micropositioner
114
has a range of movement in the order of tens of micrometers to more than 1 mm in each of the X-Y-Z directions and has subnanometer positioning capability. Micropositioner
114
is used to align field emitter tip
112
with electron optical column
120
. Typical dimensions of miniature three-axis micropositioner
114
are approximately 2×2×1.1 cm.
The typical components of electron optical column
120
include a microsource lens
122
with an extractor
124
and an anode
128
with apertures of approximately a few micrometers and 100 &mgr;m in diameter, respectively. Extraction electrode
124
is fabricated from 2 &mgr;m thick silicon (Si) membrane with a bore diameter of a few microns. For optimum lens operation, emitter
112
is required to be positioned very closely and precisely aligned to extractor hole
126
.
Due to the proximity of emitter source
110
to extractor
122
, aligning emitter tip
112
to extractor hole
126
is difficult. The problem is exacerbated by the dimension of extractor electrode
124
and the overall column dimensions. For fine alignment, an STM-type X-Y positioner has been used in-situ to scan the tip over the extractor electrode. However, this approach requires time consuming scanning of relatively large areas.
Accordingly, it is clear that there is a need for a method to easily and precisely align an electron emitter and an extractor hole of a microcolumn.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method and an accompanying apparatus for aligning an electron emitter with an extractor hole of a microcolumn are provided. Four V-grooves with their vertices situated on two axes are microfabricated on a chip. The axes intersect at a right angle and define a center point for the extractor hole. The V-grooves are then used as references to align the electron emitter with the extractor hole.
In one embodiment, four V-grooves are defined together with the window for forming the extraction electrode membrane and microfabricated in a chip. The extractor hole is formed with reference to the V-grooves. The emitter is then aligned with the extractor hole by referencing the V-grooves, one axis at a time. The emitter is precisely aligned to the extractor hole because the extractor hole was formed with reference to the V-grooves. In another embodiment, the thickness of the chip is used as the spacing reference between the emitter and the extractor.
REFERENCES:
patent: 4049991 (1977-09-01), Collins
patent: 4309638 (1982-01-01), Van Roosmalen et al.
patent: 6023060 (2000-02-01), Chang et al.
Lee, Kang, and Chun. Micromachined Self Aligned Microlens (SAM) For Microcolumn Electron Beam. Microelectric Engineering 35 (1997) 413-416, 1997.
Choi et al. Fabrication of Microelectron Gun Arrays Using Laser Micromachining. Microelectronic Emgineering 41/42 (1998) 167-170, 1998.
Despont et al. Microfabrication of Lenses for a Miniaturized Electron Column. Microelectronic Engineering 27 (1995) 467-470, 1995.
Despont et al. Electron Beam Microcolumn Fabrication and Testing. Microelectronic Engineering 30 (1996) 69-72, 1996.
Zlatkin, Garcia. Low-energy (300 eV) Versatile Scanning Electron Microscope with 30 nm Resolution. Microelectronic Engineering 45 (1999) 39-46, 1997.
S. Kleindiek, et al., “Miniature three-axis micropositioner for scanning proximal probe and other applications”, Journal of Vacuum Science & Technology Bulletin, vol. 13, No. 6 Nov./Dec. 1995, pp. 2653-2656.
T. Chang, et al., “Electron-Beam Microcolumns for Lithography and Related Applications”, Journal of Vacuum Science Technology Bulletin vol. 14, No. 6, pp. 3774-3781, Nov./Dec.1996.
“The Scanning Tunneling Microscope-What it is and how it works . . . ”, http://www.iap.tuwien.ac.at/www/surface/STM-Gallery/stm-schematic.html.
“Scanning Tunneling Microscope Update 1997”, http://www.umsl.edu/~fraundor/stm97×.html.
E. Kratchmer, et al., “Sub-40 nm resolution 1 keV scanning tunneling microscope field-emission microcolumn”, Journal of Vacuum Science & Technology Bulletin, vol. 12 No. 6 Nov. 1 1994 pp. 3503.
Patent Abstracts of Japan, vol. 009, No. 023 (E-293), Jan. 30 1985 (JP 59 169130 A.
K.Y. Lee, et al., “High aspect ration aligned multilayer microstructure fabrication”, Journal of Vacuum Science & Technology Bulletin, vol. 12, No. 6 Nov. 1 1994, pp. 3425-3430.
Chang T. H. P.
Kim Ho-Seob
Lee Kim Y.
Etec Systems, Inc.
Ramsey Kenneth J.
Skjerven, Morril, MacPherson, Franklin, and Friel
Smith Michael J.
LandOfFree
Precision alignment of microcolumn tip to a micron-size... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Precision alignment of microcolumn tip to a micron-size..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Precision alignment of microcolumn tip to a micron-size... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2507357