DAMAGE INVESTIGATION IN ALGAAS AND INGAP EXPOSED TO HIGH ION DENSITY AR AND SF6 PLASMAS

Both electrical and optical properties of AlGaAs and InGaP were change d by exposure to high density Ar and SF6 plasmas. Capacitance-voltage measurements, photoluminescence, and sheet resistance measurements wer e used to characterize the degradation of the materials properties as a function of microwave power, rf power, exposure time, and chamber pr essure. The results showed the n-type InGaP suffered more damage than the p-type InGaP in Ar plasmas, while the reverse was true for AlGaAs. Annealing of the damaged semiconductors needed high temperature (for example, similar to 750 degrees C for InGaP), which is not suitable fo r typical III-V semiconductor processing because the high temperature may cause thermal degradation. Electron cyclotron resonance (ECR) SF6 plasmas produce more surface states than reactive ion etching (RIE) (i .e., rf power only). Both C-V measurements and photoluminescence data showed rf power (>50 W) and pressure (<2 mTorr) played important roles in introducing electrical and optical degradation of both AlGaAs and InGaP under ECR conditions, while there was little change as a functio n of rf power in the RIE case. The minimal overetching time of SF, pla smas is necessary to avoid severe damage in the materials during openi ng the windows for the active semiconductors from photoresist, dielect ric, or metal layers. (C) 1997 American Vacuum Society.