Positive resist coated wafers were Immersed in a dilute alkaline base developer, such as 5:1 AZ351, for a short period of time prior to exposure. The purpose of this sequence was to improve development rate discrimination of conventional positive photoresist, which will enhance step coverage. A SEM comparison of a 5 mIcron line/space pair pattern of AZ13SO resist on a 1.2 micron step, showed this pre-treatment yields improved step coverage compared to a conventional process.
"A Method to Improve Step Coverage of Conventional Positive Working Photoresist,"
Journal of the Microelectronic Engineering Conference: Vol. 2
, Article 5.
Available at: http://scholarworks.rit.edu/ritamec/vol2/iss1/5