Since the invention of the transistor, the fundamental element of the integrated circuit (IC) in 1960s, with the revolution in semiconductor industry, the transistor size has been getting smaller every year. Due to this reason, the number of transistors on a single IC chip increases following Moore's Law, electronic devices are able to provide more advanced and complex functionality with higher effectiveness. Therefore, the advancement of semiconductor technology is measured by the size of the smallest transistor possible to be fabricated. When the transistor size goes down to hundreds of nano-meter, it enter the submicrometer scale, rather than nano-meter scale. This is because, the physics in the transistor with sub-micrometer scale is similar to that in micrometer scale. Therefore, the existing IC design concepts and fabrication processes in micrometer scale can be easily transferred to the semiconductor technology in sub-micrometer scale, and this is the reason behind the continuity of development in semiconductor technology. The transistor size was 180 nm in year 1999, and was 32 nm in year 2011.