In Situ Measurement & Control of Photoresist Develpment in Microlithorgraphy

This paper has highlighted develop temperature as a promising factor to reduce CD non-uniformity. Traditional methods of film thickness estimation is not suitable for use in develop process. The use of LTR can effectively compensate the change in optical property of the developer solution as photoresist is dissolved and give an estimation of the film thickness with accuracy of up to 2nm. From the experimental results, it has been shown that by controlling develop temperature, non-uniformity in reaching endpoint on a particular site on the wafer can be reduced significantly. From the experimental results, the standard deviation of the time to reach endpoint has been reduced by 4 times. Thus, the future work for this is the proof that uniformity within wafer can also be achieved. This can simply be done by the expansion of the current work to multi-point monitoring and control strategy approach