Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/13786
Title: Microlithography: Control of temperature and resist thickness
Authors: LEE LAY LAY
Keywords: lithography, model-based, real-time, feedforward, temperature, thickness
Issue Date: 6-Mar-2004
Source: LEE LAY LAY (2004-03-06). Microlithography: Control of temperature and resist thickness. ScholarBank@NUS Repository.
Abstract: Lithography is one of the key technology drivers for semiconductor manufacturing. In this thesis, in-situ process monitoring and model-based control techniques are used to control the bakeplate temperature and resist thickness. These are two important process variables in lithography that can affect the final critical dimension.A predictive controller is designed to perform a pre-determined heating sequence prior to the arrival of the photomask to eliminate the load disturbance induced by the placement of the cold photomask onto the bakeplate. An order of magnitude improvement in the temperature error is achieved. Using an array of in-situ thickness sensors and advanced control algorithms, a real-time thickness control strategy is implemented to control the resist thickness during softbake. By manipulating the temperature distribution of the bakeplate in real-time, the resist thickness non-uniformity caused by prior coating process is reduced. An average of 10 times improvement in the resist thickness uniformity is achieved.
URI: http://scholarbank.nus.edu.sg/handle/10635/13786
Appears in Collections:Ph.D Theses (Open)

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