Low-k SiOCH film is indispensable for reduction of RC delay time in high-speed and high-density logic devices. We have developed SiOCH film with k=2.66 by dual frequency plasma-enhanced chemical vapor deposition (PE-CVD) using hexamethyldisiloxane (HMDSO), nitrous oxide (N2O) and helium (He) gases. The low frequency bias power effects on the deposition rate, k value, leakage current and pore diameter were investigated. The deposition rate shows an interesting behavior: it initially decreases, and then increases with increasing bias power. The pore density and pore volume ratio were calculated. It is found that the pore density increases but the pore volume ratio decreases with increasing bias power. The values are on the order of 10~(21) pores/cm~3 and 20 to 30 % in the bias power range, respectively. The k value increases from 2.66 to the order of 4.0 with increasing bias power. The leakage current also increases. The density, stress, dynamic hardness and Young's modulus increase with increasing bias power. The pore diameter decreases, and the distribution changes from separate to continuous type with increasing bias power The property of SiOCH film deposited with the combination of high frequency (13.56 MHz) and low frequency (380 KHz) bias powers can be easily controlled and the film is useful candidate for high-end device process.
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