2. The Photolithography Process

As already stated in the introduction optical lithography continues to be the mainstream technology for the semiconductor industry because of its high wafer throughput. From the late 1960s, when ICs had linewidths of roughly 10 $\mu$m, to 1998, when minimum linewidths have reached 0.2 $\mu$m, optical lithography has been used ubiquitously for manufacturing. This situation will be continued for the next generation with a linewidth of 0.15 $\mu$m. Beyond this point, at 0.1 $\mu$m and below, proximity 1x X-ray is the most likely alternative, but there are also great efforts to extend optical methods like extreme ultraviolet (EUV) towards the 100 nm-regime. Below 100 nm minimum feature size particle beam lithography techniques like electron-beam and ion-beam are considered [3].