Improve Development Capability Of IP Resist On Photomask With Plasma Surface Pre-Treatment

Optical microlithography plays very important role in the microelectronics industry. Acted as the process base of wafer fab for the past several years while the use of CAR resist is rapidly increasing, the DNQ resist still works well in photomask fabrication due to the 4X or 5X image reduction transferred from photomask to wafer.THMR-IP is a kind of DNQ-type photoresist which is very commonly used on wafer manufacturing with i-line stepper/scanner and the photomask fabrication with i-line pattern generator. i-line pattern generator is recognized as a main litho tool for up to 0.25 DR photomask and even for second layer exposure of 0.13um DR Phase Shift mask. Hence, improving the process properties of DNQ resist is worth researching. Commonly, the worse surface wettability of IP resist is easily causing under-development, as a result the mask products yield is lost due to finally opaque defects generated, especially on the masks with dense pattern or contact feature. Referring to the common application of plasma cleaning in wafer fab, a method was provided in this dissertation, in which moderate plasma surface pre-treatment is added before development, to improve the contamination condition on resist surface, and also to introduce surface micro-roughness and then improve the development capability.In this dissertation, several experiments were designed to evaluate this process change benefits. Contact angle of DIW and develop chemical with resist surface were measured to verify the wetting increment after plasma surface treatment. And after that, upon the process flow change, to analyze...