Proceedings Article | 24 March 2009
Wei-Jui Tseng, Shean-Hwan Chiou, Ming-Chien Chiu, Po-Shin Lee
KEYWORDS: Reticles, Air contamination, Semiconducting wafers, Pellicles, Sensors, Contamination, Manufacturing, Photomasks, Scanners, Oscilloscopes
The control of haze contamination on reticles has been gaining an ever-increasing focus because of its contribution to the
huge yield loss in semiconductor manufacturing. Yield improvement through the reduction of haze on reticles has been a
significant challenge as the use of 193nm light source and the shrinkage of line width on reticles. For a mass production IC
manufacturing fab, an easy and practical solution is needed to prevent haze generation. In our previous study (Tseng et al.,
2008), we demonstrated a practical and effective solution to reticle haze formation at a mass production DRAM factory.
After implementing this solution, the number of wafers printed without haze development on reticles can be up to 150,000
wafers, and the maximum exposure dosage can be up to 9×108 mJ/cm2 without the detection of any printable haze. Using
the average data from more than 20 reticles, the average wafer printed before cleaning of reticle was more than 100,000
wafers. This solution has been proven to be effective in reducing the generation of haze on reticles.
In current study, our focus is on further improvement of this haze solution and the ultimate goal is to reduce the haze
generation effectively, but also economically. First, we use ultra low outgas material, antistatic PEEK, as the material of
reticle carrier to perform the study and investigate its effect on haze generation. The total outgas data, leaching, electrical
field shielding, and surface resistance data of different polymer materials are also compared. Secondly, we optimize the
purging flow rate to reduce the running cost, but also maintain the performance. Our approach is to design purge nozzles,
which can create a smooth flow field inside reticle SMIF pod (RSP) and make the maintenance of an ultra clean RSP
environment with the smallest flow rate be possible. The results show the PEEK RSP with newly designed purge nozzles
can provide great haze prevention result with a lower flow rate. Detailed data is provided and compared with previous
design. By using this new solution, the number of wafers printed without haze development on reticles can be up to
300,000 wafers, and the maximum exposure dosage can be up to 1.2×109 mJ/cm2 without the detection of any printable haze.
The average wafer printed before cleaning of reticle was more than 170,000 wafers. This is a significant improvement to
delay the generation of haze on reticles. The comparison of N2 / XCDA performance based on wafer exposure shows that
no significant difference can be observed.
