Resolution limits and process latitude of x-ray mask fabrication

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/10.1116/1.586568· OSTI ID:5572783

McCord, M A; Wagner, A; Donohue, T ^[1]

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1. IBM Semiconductor Research and Development Center, Yorktown Heights, New York 10598 (United States)

This article reports on the process latitude and resolution limits of x-ray mask fabrication by electron beam lithography for both additive (gold plated) and subtractive (etched tungsten) masks. The experiments were performed using a vector scan thermal field emission electron beam lithography machine with a maximum beam voltage of 100 kV and a minimum beam diameter of 27 nm. Features as small as 0.075 [mu]m have been patterned on x-ray masks. Exposure latitude was studied as a function of beam diameter and acceleration voltage. The results indicate that forward scattering in the resist is a major cause of degradation in process latitude, and that going to a higher beam energy or thinner resist provides substantial benefits. For subtractive processes where a high-[ital Z] material (e.g., tungsten) underlies the resist, backscattered electrons are also a significant factor in limiting exposure latitude and resolution. For both substrate types, increasing the accelerating voltage from 50 to 100 kV can improve the exposure latitude by a factor of 2. At 100 kV the resolution limits are caused by the high aspect ratios found in the sub-tenth micron structures. As the aspect ratio exceeds 5:1 three major problems are encountered. First, the resist tends to fall over due to a lack of mechanical strength. Second, a noticable decrease in linewidth control occurs. Finally, the plating rate becomes dependent on the feature size, causing absorber thickness nonuniformity.

• OSTI ID: 5572783
• 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

440600* -- Optical Instrumentation-- (1990-)
47 OTHER INSTRUMENTATION
BEAMS
ELECTRON BEAMS
EQUIPMENT
FABRICATION
LEPTON BEAMS
PARTICLE BEAMS
RESOLUTION
SPATIAL RESOLUTION
X-RAY EQUIPMENT