High Performance GaN HEMT and Ge Fin FET Device Realizing by Atomic-layer Defect-free Etching with Chlorine Neutral Beam

In the fabrication of semiconductor devices, reactive plasmas are widely used in key processes such as microfabrication, surface modification and film deposition, and there are now demands for processing precision at the atomic layer level, and for deposition accuracy that allows the control of structures at the molecular level. However, in ultra-miniature nanoscale devices that will become the mainstream in the future, the use of plasma processes can cause serious problems such as abnormal etching and breakdown of insulation films by the accumulation of ions or electrons emitted from the plasma as shown in Fig. 1, also the formation of surface defects (dangling bond) of over a few tens nm in depth by exposure to ultraviolet (UV) emissions from the plasma. [1] -[4] In particular, since nano-scale devices have a larger surface area compared with the bulk material, plasma processes can have a large influence on the electrical and optical properties of devices due to process-induced defects caused by ultraviolet exposure, which has not caused a problem in the presented devices of 32 nm. Furthermore, since future nanodevices will require size control of three-dimensional structures at the atomic layer level, it will be absolutely essential to control surface chemical reactions with high precision and selectivity at the atomic layer level. Neutral beam process technology has attracted attention as a way of solving these issues [5], [6], as shown in Fig. 2. The neutral beam suppresses the incidence of charged particles and UV photon radiation onto the substrate, and is able to expose the substrate only to energy controlled neutral beam (neutral beam motion energy can be precisely controlled by ion acceleration energy with the applied electric field before neutralization), resulting in ultra-precise nano-processing that can suppress the formation of defects at the atomic layer level and control surface chemical reactions with high precision.