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Proceedings Paper

Fine-tune lens-heating-induced focus drift with different process and illumination settings
Author(s): Yuanting Cui
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Paper Abstract

This study is to establish the relationship of lens heating (LH) performance with related process variables and develop the methodology for reducing LH induced focus drift for different products based on ASML LH algorithms and experiment data. Focus drift data is collected at certain LH machine constants for different process settings, such as different clear window images (CLW) in stepper jobs, different exposure doses, reticle transmission rates, and substrates. The further study is done at different illumination settings to establish the correlation between NA/sigma settings, focus drift and LH scaling factors ((mu) 1 (mu) 2). The characteristic (mu) 1, (mu) 2 -- NA/Ill relationship for this i-line stepper is generated using production batches. LH machine constants are fine-tuned based on the Poly layer for 0.30 micrometer Logic Mix-mode, 0.30 micrometer SRAM and 0.35 micrometer Embedded SRAM products. This work provides an accurate and practical way to fine-tune LH for all the i-line/DUV steppers based on the critical layer of representative products in a foundry fab.

Paper Details

Date Published: 14 September 2001
PDF: 10 pages
Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001); doi: 10.1117/12.435675
Show Author Affiliations
Yuanting Cui, WaferTech LLC (United States)


Published in SPIE Proceedings Vol. 4346:
Optical Microlithography XIV
Christopher J. Progler, Editor(s)

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