Using a Wireless Temperature Measurement Wafer to Analyze the Cause of Critical Dimension Differences between Tools

We used a wireless temperature measurement wafer to determine actual wafer temperatures under real production process conditions. We compared the temperature profile during baking and cooling stages between two photoresist track tools and discovered significant differences in the cooling phase affecting the structural properties of the deposited film. These film variations were found to impact the downstream etch process giving rise to a larger number of defects related to Critical Dimension (CD) variation in one of the tools.