Ultra-high tensile stress capping layer using novel excimer laser annealing technology for 32nm nMOSFET and beyond

A novel processing technology for stressed capping-layer by 248nm KrF excimer laser is reported. The treated tensile capping layer is composed of silicon nitride fabricated by normal PECVD. The effects of laser annealing with different conditions on tensile nitride are extensively investigated. The number of excimer laser pulses is from 3 to 15 and energy density from 500mJ/cm2 to 800mJ/cm2. Different from conventional post-processing techniques applied in current mainstream CMOS technology for tensile SiN curing, the excimer laser annealing demonstrated much higher energy efficency and as a result, the laser annealing broke more silicon-hydrogen and nitrogen-hydrogen bonds within a much shorter time during film curing. The maximum stress of this cured layer is about 2.2GPa through typical Raman spectroscopy measuring, which is much higher than that as deposited tensile nitride film. This new process supplies one of promising solution for stress-enhancement in sub-32nm CMOS technology.