1 January 2004 Preliminary analysis of laser-pulse-induced pressure variation for immersion lithography
Gregory F. Nellis, Alexander C. Wei
Author Affiliations +
Abstract
We describe an assessment of the pressure rise that may be induced by the short-duration but high-power pulses associated with the immersion lithography exposure process. A conservative model provides an upper bound on the pressure rise related to the expansion of the fluid near the wafer due to rapid heating. This rapid heating process is simulated as a constant heat flux from the substrate. The resulting temperature rise causes a change in pressure that propagates into the fluid at the speed of sound. The net change in the mass of the fluid contained within the pressure wavefront must be zero. This continuity requirement allows an estimate of the pressure rise and its penetration depth into the gap. For the nominal conditions associated with 193-nm immersion lithography, the model predicts that the pressure near the wafer surface may rise by as much as 7.3 kPa during the laser pulse. At the end of the laser pulse, this pressure rise will extend nominally 75 µm into the gap. Following the laser pulse, this pressure rise will rapidly decay as the pressure wavefront continues to propagate across the gap and eventually out of the under-lens region.
©(2004) Society of Photo-Optical Instrumentation Engineers (SPIE)
Gregory F. Nellis and Alexander C. Wei "Preliminary analysis of laser-pulse-induced pressure variation for immersion lithography," Journal of Micro/Nanolithography, MEMS, and MOEMS 3(1), (1 January 2004). https://doi.org/10.1117/1.1636490
Published: 1 January 2004
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Cited by 1 scholarly publication.
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KEYWORDS
Pulsed laser operation

Immersion lithography

Semiconducting wafers

Refraction

Wave propagation

Wavefronts

Heat flux

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