No abstract

In this paper, optimization method for gas cluster generation was studied both theoretically and experimentally for a new dry cleaning process using gas cluster beam. Since the typical size of gas cluster is less than 50 nm, it is expected to cause no damage on the surface. CO2 gas cluster cleaning system was built to evaluate the feasibility of the cleaning by gas cluster beam, which is generated by expansion through the converging-diverging nozzle and chilling. Cleaning test was performed for 25 nm silica particle cleaning on a bare Si wafer, and on a wafer with 80 nm poly-silicon structure. Preliminary result has been obtained, which showed that we could achieve cleaning of contaminants without damage. To optimize the gas cluster cleaning process, we propose the use of particle beam mass spectrometer (PBMS) for the measurement of size distribution and numerical simulation of gas cluster generation process.

CO 2 gas cluster cleaning process for nano particles removal without pattern damage was investigated. Gas cluster cleaning process was performed for generating the nano-sized gas cluster in the vacuum chamber. When pressurized CO 2 gas was passed through the convergence-divergence (C-D) nozzle, the high speed and high energy gas clusters were generated. The cleaning force of CO 2 gas cluster is related to flow rate of the gas and gap distance between the nozzle and substrate. In our studies, the optimum gas flow rate and gap distance for nano-sized particles removal was found, respectively. Pattern damage tests of the poly-Si and a-Si pattern were also evaluated by SEM images. No pattern damages were observed at these optimum conditions.