Evolution of the physical gate length in micro processors (MPU)
The values represent the real/printed gate length of MOS field effect transistors on the wafer; these correlate approximately to the effective channel length. In the past the smallest structure (half pitch) was used as indication of size.
Source:
- http://www.itrs.net/Links/2011ITRS/Home2011.htm
Note: this data make no claim to be complete but should give a brief overview of semiconductor industries development.