Won Sang Lee is currently Director and General Manager of GaN/Diamond Division at RFHIC US Corp., Morrisville, North Carolina. He earned his Ph.D in 1999 from Kwang Woon University in Korea and his Post-doc from University of California at Los Angeles in USA. Since 1991, he joined LG Central Institute of Technology as principal engineer. In 2004, he joined Korea Advanced Nano FAB Center as principal engineer. He has been experienced for bring various III-V compound semiconductor technologies from R&D to production, including GaAs 0.15 um p-HEMT/MMIC, 1 um GaAs HBT/MMIC etc. Since he invented PEC (Photo-Electro Chemical) etching process of GaN/Sapphire MESFET for gate recess etching process on 1997, is currently focused on GaN/SiC HEMT, GaN/Diamond HEMT and GaN/Diamond BAW filter for RF and high power electronics market.
A matured flip process to make 4” GaN/Diamond epitaxial wafer is driven by a need of commercialization for GaN/Diamond HEMTs. RFHIC announced that the power density of 23.2 W/mm at Vds = 100V is obtained at 2 GHz pulsed power measurement using on-wafer 4” GaN/Diamond HEMT manufactured at automation foundry FAB. The 0.35 um GaN/Diamond HEMT revealed Pout of 21.94 W/mm (at Vds = 100 V), 17.88 W/mm (at Vds = 100 V) in the frequency range of 3.6 GHz and 4.9 GHz, respectively. To make an improving yield and process consistency, RFHIC is developing permanent wafer bonding technology for GaN/Diamond HEMT processing not only for SiN passivation but also high temperature annealing without requiring a de-bonding step. A new type of flip process technology to make GaN/Diamond epitaxial wafer using GaN/SiC epitaxial wafer will be sure to generate a better quality of GaN/Diamond HEMT in the future.