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Removal of 10-nm contaminant particles from Si wafers using CO2 bullet particles

Inho Kim1, Kwangseok Hwang2 and JinWon Lee1*

Author Affiliations

1 Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Hyoja 31, Pohang, Kyungbuk 790-784, South Korea

2 Pohang Steel Company (POSCO), Dongchon 5, Pohang, Kyungbuk 790-784, South Korea

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Nanoscale Research Letters 2012, 7:211  doi:10.1186/1556-276X-7-211

Published: 11 April 2012


Removal of nanometer-sized contaminant particles (CPs) from substrates is essential in successful fabrication of nanoscale devices. The particle beam technique that uses nanometer-sized bullet particles (BPs) moving at supersonic velocity was improved by operating it at room temperature to achieve higher velocity and size uniformity of BPs and was successfully used to remove CPs as small as 10 nm. CO2 BPs were generated by gas-phase nucleation and growth in a supersonic nozzle; appropriate size and velocity of the BPs were obtained by optimizing the nozzle contours and CO2/He mixture fraction. Cleaning efficiency greater than 95% was attained. BP velocity was the most important parameter affecting removal of CPs in the 10-nm size range. Compared to cryogenic Ar or N2 particles, CO2 BPs were more uniform in size and had higher velocity and, therefore, cleaned CPs more effectively.

Nano-bullet; CO2; Supersonic nozzle; Gas-phase nucleation; Cleaning efficiency