A STUDY OF QUANTUM INTERFERENCE FLUCTUATIONS IN DEEP SUB-MU-M MOSFETSUNDER CRYOGENIC CONDITIONS

We investigated the phase coherence length, l(phi), in large Si-MOSFET 's fabricated using current process technology, with a particular emph asis on highly doped silicon substrates, and then studied the effects of quantum conductance fluctuations in deep sub-mum MOSFET's, with cha nnel length comparable to l(phi). We identified, in a 0.2 mum MOSFET, universal conductance fluctuations in the strong inversion regime and conductance fluctuations due to variable range hopping in the weak inv ersion regime. The drain bias dependence of these fluctuations indicat es clearly that they become a serious concern only at drain voltages l ower than 10 mV. Therefore, even if the wave nature of electrons resul ts in quantum conductance fluctuations, it will not lead to a limitati on on device miniaturization in future Si-ULSI's.