A N_2/CDA Reticle Purging Approach with Enhanced Efficiency

摘要

Haze is a kind of contamination on the surface of mask which observed in the wafer production clean room only onreticles exposed with 193nm or 248nm wavelength process. In the lithography process, the wafer damage has beenoccurred due to the growth of haze in semiconductor manufacturing, haze defect for 193 nm lithography needs to beimproved, and the improvement involves not only the selection and use of appropriate materials but also theminimization of running cost and reticle purging time as well as the prevention of haze generation. During certainconditions crystals formation of haze form on reticle surfaces, the sulfate ion (SO_4~(2-)) left on the mask surface after SPM(scanning probe microscopes) step is known the most important source cause for the formation of haze defects. Andammonium sulfate has been known to be mostly responsible for haze defects formation on the mask surface, recentinvestigation reveals that other chemicals such as hydrocarbons, Na, F, Mg, K, Cl or Al are also cause haze defects. Amajor problem in the integrated circuit (IC) industry is that the manufacturing process may experience malfunction dueto haze contamination on the mask once the reticle has been exposed to ArF radiation. It is therefore crucial to detect andcontrol the haze defects to keep the manufacturing process in smooth operation and to improve throughput.