Etching Gas

Generally, silicon dioxide (SiO2) etching is performed using fluorocarbon gases to deposit a fluoropolymer on the underlying silicon. This chapter reviews a new method for selective radical generation for high-performance sub-0.1μm SiO2 patterning, using CF3I and C2F4 in an Ultra High Frequency (UHF) plasma. As the feature size of ultra large-scale integrated circuits (ULSIs) becomes smaller, the resistance-capacitance (RC) delay time of their interconnects restricts the circuit performance. Low-damage and highly selective low-k etching could be achieved by using an environmentally harmonized gas chemistry (CF3I) plasma. This is because the CF3I plasma could reduce generating UV photons and F radicals. The etching rate for low-k film is drastically increased by the pulsed CF3I plasma. It is concluded from these results that CF3I gas plasma has a higher potential as the gas chemistry for practical low-k etching.