In-situ and Real Time Spinner Processing Visualization and Control

In chip fabrication, spinner equipment is used for many steps such as creating a uniform layer of photo-resist or etching solvent over wafer. Spinner equipment works by rotating wafer at high speed (∼ 0.1 - 1 kHz) after depositing liquid solvent over wafer. The rotation causes solvent to distribute uniformly over wafer under ideal conditions. Due to impurities and rough terrain (chip layout), the spread is non-uniform. This results in spatially inconsistent chemical processing even though same pattern is printed throughout wafer. Process defects arise due to this non-uniformity. Currently, wafer inspection is done post the spinner process completion. Even though the spinner step is crucial, efficient real time quality tracking and in-line process control methods do not exist. In this paper, we present a novel hardware setup and corresponding software algorithm which makes the spinner track its process and dynamically adjust processing parameters (e.g. speed of rotation, tilt etc.) in order to improve the spread uniformity. We perform theoretical modelling of proposed novel hardware setup and present simulation result to prove its feasibility.