Abstract
A novel approach to improve photoresist thickness uniformity after the conventional spin-coating and softbake process is proposed in this paper. Using an array of thickness sensors, a multizone programmable bakeplate, and model-based control techniques, the temperature distribution of the bakeplate is manipulated in real-time to reduce photoresist thickness non-uniformity. To prevent the decomposition of photoactive compound in the photoresist, the bakeplate temperature is constrained. We have experimentally obtained a repeatable improvement in resist thickness uniformity from wafer-to-wafer and across each wafer. Thickness non-uniformity of less than 10 A ̊ has been obtained. On average, there is a 10× improvement in the thickness uniformity as compared to conventional softbake process.
Published Version
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