DONOR NEUTRALIZATION IN GAAS AFTER PLASMA SILICON-NITRIDE DEPOSITION

Loss of conductance has been observed in Si-doped GaAs after plasma silicon nitride deposition in a 2.45 GHz electron cyclotron resonance reactor and in a 30 kHz parallel-plate reactor, but not in a 13.56 MHz parallel-plate reactor. Based on the temperature at which conductance is restored in test structures subjected to a variety of plasmas, observation of atomic hydrogen in the plasmas by optical emission, and secondary ion mass spectrometry measurement of hydrogen in the test structures, the loss of conductance appears to be from formation of the hydrogen-silicon complex. The extent of neutralization correlates with an abundance of atomic hydrogen in the plasmas and the nitride deposition rate. When the deposition rate is high, the GaAs surface is protected quickly and donor neutralization is minimized.