New Barrel Type MOVPE Reactor for 6" Epitaxial Wafers
T. Osada, N. Fukuhara, T. Takada, and M. Hata
Sumitomo Chemical Co., Ltd. Tsukuba Research Laboratory
Kitahara 6, Tsukuba, 300-3266 JAPAN
A unique designed barrel type MOVPE reactor with 8 graphite susceptors capable of holding wafers from 4" up to 6" in diameter has been developed. The uniformity of carrier concentration, layer thickness and composition of 6" epitaxial wafers were investigated. Optimizing the susceptor design and the d=crystal growth condition, uniformity of +1.8% for carrier concentration +1.2% for layer thickness of n-GaAs layer. +0.6% for Al composition of AlGaAs and +1.2% for In composition of InGaAs over 6" wafer have been achieved.
InGaP layer with lattice matched on GaAs substrate also showed an excellent layer thickness uniformity of +2.5%, and energy gap at room temperature, Eg, 1.844eV over 6" diameter wafer with standard deviation of 6meV.
MESFETs were fabricated on 6" wafers and threshold voltage (Vth)
uniformity as low as +40 MV on average Vth= -2.9V was obtained, which was
comparable value to that of 4" MESFET. InGaP-HBTs were also fabricated on
wafers and its performance including DC current gain and its uniformity, I-V characteristics were studied. Current gain of 145+6 at base sheet resistance of 310+12ohm/sq. was obtained. Also, uniformity of +1.9% and +2.2% for current gain and base sheet resistance has been achieved. These performances are comparable to those of conventional AlGaAs-GaAs HBTs.
These results show the promising capability of our manufacturing equipment and show that the growth process on 5" and 6" epitaxial wafers was successfully optimized. Also, it is shown that this growth technology can be applied to the large volume production of MESFETs, pHEMTs and HBTs made of AlGaAs, GaAs, InGaAs, and InGaP.