Simultaneous optimization of spectrum, spatial coherence, gap, feature bias, and absorber thickness in synchrotron-based x-ray lithography

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States)

DOI:https://doi.org/10.1116/1.586572· OSTI ID:5420852

Hector, S D; Smith, H I ^[1]; Schattenburg, M L ^[2]

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1. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
2. Center for Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

Of the many factors affecting the x-ray intensity distribution, the variables that can be controlled are the source spectrum, the proximity gap, the source spatial coherence, the mask linewidth bias, and the absorber thickness. To obtain the highest quality aerial image, all of these parameters must be optimized simultaneously. An optimization of the spectrum of the synchrotron Helios, located at IBM's Advanced Lithography Facility is described. The optimum parameter space for proximity x-ray lithography at 0.1 [mu]m minimum linewidth is then determined using the optimized spectrum by adjusting the free parameters. For maximum accuracy, a rigorous electromagnetic model that accounts for the dielectric properties of the absorber, the source partial coherence, and diffraction in the proximity gap is used to calculate the x-ray aerial image at the wafer. Descriptive figures-of-merit (FOMs) of the aerial image are the image contrast [([ital I][sub max][minus][ital I][sub min])/([ital I][sub max]+[ital I][sub min])] and the exposure latitude. These two FOMs are maximized with respect to source spectrum, gap, source spatial coherence, feature size and bias, and mask absorber thickness. The global maximum of these FOMs is coarsely located in parameter space by determining the dependence of the FOMs on two variables at a time. The feature bias is then determined so that all feature types (gratings, lines, spaces) can be printed at the same dose with maximum average contrast and exposure latitude.

• OSTI ID: 5420852
• 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. 11:6; ISSN 0734-211X; ISSN JVTBD9
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
430200* -- Particle Accelerators-- Beam Dynamics
Field Calculations
& Ion Optics
DIMENSIONS
EQUIPMENT
OPTIMIZATION
RADIATION SOURCES
SPECTRA
STORAGE RINGS
THICKNESS
X-RAY EQUIPMENT
X-RAY SOURCES
X-RAY SPECTRA