Photoluminescent Quantum Dot-Assisted Photolithography By Incorporating Cesium Iodide Molecules In The Photoresists

The surface roughness of photoresist plays a crucial role for photolithography resolution enhancement. The fluorescence of quantum dot is highly possible to be utilized to improve the surface roughness of resist pattern due to its property of photoluminescence. The thesis investigates the UV lithography and X-ray lithography enhancement by cesium iodide quantum dot fluorescence. Cesium iodide fluorescent quantum dot is added into ultraviolet positive photoresist. Thermostability, UV absorption, UV transmittance, UV reflection, density, viscosity and infrared spectrum of the photorsists are compared. The UV absorption increase 2.5 times from the original photoresist after incorporating with cesium iodide quantum dot. The UV transmittance decrease to 30% of the original photoresist. The UV reflection is weak and more stable. The optical properties become more excellent. And the added cesium iodide quantum dot doesn’t destroy internal group and photoresist system. At the same time, the resist pattern edge is smoother with lower surface roughness. These phenomena benefit the enhancement of photolithography resolution. The photoresist incorporated with cesium iodide fluorescent quantum dot obtain more exposure. The quantum dots reduce ultraviolet reflection and interference and increase depth of field. Finally internal light intensity distribution tends to stable and balance. Stable light intensity distribution helps to improve photolithography resolution. The method is simple and practicable. It is significative for the future nano lithography.