Improving eco-efficiency via elimination of greenhouse gases from semiconductor dry cleaning processes

For each device sk Hynix produces, an eco-efficiency indicator is calculated which takes into account both the product value (performance, power consumption etc) and its environmental influence (material consumption, global warming emissions and regulation compliance). To reduce the environmental influence, a detailed analysis of the contribution of each gas used during manufacturing was carried out which identified NF3 as contributing almost 50% of the total process gas used (by weight), with the majority of this used for dry cleaning. In this study, sk Hynix has evaluated on-site generated F2 from Linde as an alternative cleaning gas to NF3 for our 300mm process line. F2 has been used for cleaning 300mm batch type LPCVD process tools since 2003 and we now study 2 single wafer PECVD process tools for different processes. When F2 was used for PECVD chamber cleaning, the etch rate was increased by up to a factor of 2. There was also greater process chamber temperature stability which meant that post clean conditioning could be significantly shortened even without clean recipe optimization giving a reduction in total non-productive time of around 40%. RPS plasma power consumption is reduced by up to 50% and there are also significant reductions in the mass of gas required. Thermal cleaning with F2 was also demonstrated.