Paper
8 November 2012 CD uniformity improvement through elimination of hardware influences on post-exposure bake
Author Affiliations +
Abstract
The acceptable tolerance level for CD signatures induced by any process step in the mask manufacturing process has been dramatically reduced with each technology node. Chemical amplified resists (CAR) are used extensively for first layer mask imaging. Therefor a post exposure bake (PEB) process is required after resist exposure, adding yet another potential source of CD signatures. Consequentially, the thermal imprint of the bake process must be further reduced to meet the requirements of future technology nodes.

The influence of the measurement devices (wireless and wired sensor arrays) used to optimize the hotplate, on the performance of the Post Exposure Bake (PEB) process is discussed in [1,2]. A concept of utilizing two wired sensor arrays, with wire connections attached in opposite locations on the sensor array surface, called “Mirror Bake” is introduced. Based on the individual hotplate optimization for each of those two sensor arrays, a combined bake recipe for the multi-zone hotplate is calculated. This method eliminates the systematic temperature non-uniformity introduced by the sensor array hardware, when optimizing the recipes with only one sensor array.

In this paper the “mirror bake” concept is validated by comparing the CD uniformity data of masks manufactured with a PEB process, optimized using a single standard sensor array vs. the “mirror bake” concept. The “mirror bake” concept achieved a CD uniformity improvement of up to 30% (CD range). During this work additional hardware influences from the sensor arrays were identified.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jong Hoon Lim, Sung Ha Woo, Eui-Sang Park, Sang Pyo Kim, Dong Gyu Yim, Osamu Katada, Tobias Wähler, Peter Dress, and Uwe Dietze "CD uniformity improvement through elimination of hardware influences on post-exposure bake", Proc. SPIE 8522, Photomask Technology 2012, 85222L (8 November 2012); https://doi.org/10.1117/12.979470
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KEYWORDS
Sensors

Mirrors

Photomasks

Photoresist processing

Temperature metrology

Manufacturing

Optimization (mathematics)

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