Novel electrostatic column for ion projection lithography

Journal Article · Tue Nov 01 04:00:00 EST 1994 · Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States)

DOI:https://doi.org/10.1116/1.587461· OSTI ID:6804106

Chalupka, A; Stengl, G; Buschbeck, H; Lammer, G; Vonach, H; Fischer, R; Hammel, E; Loeschner, H; Nowak, R; Wolf, P ^[1]; Finkelstein, W; Hill, R W ^[2]; Berry, I L ^[3]; Harriott, L R ^[4]; Melngailis, J ^[5]; Randall, J N ^[6]; Wolfe, J C ^[7]; Stroh, H; Wollnik, H ^[8]; Mondelli, A A ; Petillo, J J ^[9]; Leung, K ^[10]

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1. IMS - Ion Microfabrication Systems GmbH, A-1020 Vienna (Austria)
2. Advanced Lithography Group, Columbia, Maryland 21045 (United States)
3. Department of Defense, Microelectronics Research Laboratory, Columbia, Maryland 21045 (United States)
4. AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)
5. University of Maryland, College Park, Maryland 20742 (United States)
6. Texas Instruments, Dallas, Texas 75243 (United States)
7. University of Houston, Houston, Texas 77204 (United States)
8. University of Giessen, D-35392 Giessen (Germany)
9. Science Applications International Corporation, McLean, Virginia 22102 (United States)
10. Lawrence Berkeley Laboratory, University of Californi

Ion projection lithography (IPL) is being considered for high volume sub-0.25-[mu]m lithography. A novel ion-optical column has been designed for exposing 20[times]20 mm[sup 2] fields at 3[times] reduction from stencil mask to wafer substrates. A diverging lens is realized by using the stencil mask as the first electrode of the ion-optical column. The second and third electrode form an accelerating field lens. The aberrations of the first two lenses (diverging lens and field lens) are compensated by an asymmetric Einzel lens projecting an ion image of the stencil mask openings onto the wafer substrate with better than 2 mrad telecentricity. Less than 30 nm intrafield distortion was calculated within 20[times]20 mm[sup 2] exposure fields. The calculation uncertainty is estimated to be about 10 nm. The calculation holds for helium ions with [approx]10 keV ion energy at the stencil mask and 150 keV ion energy at the wafer plane. A virtual ion source size of 10 [mu]m has been assumed. The calculated chromatic aberrations are less than 60 nm, assuming 6 eV energy spread of the ions extracted from a duoplasmatron source. Recently a multicusp ion source has been developed for which preliminary results indicate an energy spread of less than 2 eV. Thus, with a multicusp source chromatic aberrations of less than 20 nm are to be expected. The ion energy at the crossover between the field lens and the asymmetric Einzel lens is 200 keV. Therefore, stochastic space charge induced degradations in resolution can be kept sufficiently low. The divergence of the ion image projected to the wafer plane is less than 2 mrad. Thus, the usable'' depth of focus for the novel ion optics is in the order of 10 [mu]m.

• OSTI ID: 6804106
• Journal Information: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States), Journal Name: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States) Vol. 12:6; ISSN JVTBD9; ISSN 0734-211X
• Country of Publication: United States
• Language: English

Related Subjects

665000* -- Physics of Condensed Matter-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BEAM OPTICS
CHARGED PARTICLES
CHROMATIC ABERRATIONS
ELECTROSTATIC LENSES
ENERGY RANGE
HELIUM IONS
IMAGES
ION SOURCES
IONS
KEV RANGE
LENSES