ETCHING OF INP SURFACE OXIDE WITH ATOMIC-HYDROGEN PRODUCED BY ELECTRON-CYCLOTRON-RESONANCE

The plasma output of an electron cyclotron resonance source operating with hydrogen has been characterized using optical emission spectrosco py to observe neutral excited atomic hydrogen H- and a Langmuir probe to observe H+ as a function of currents to the two electromagnets pro ducing the magnetic field. The rate at which the hydrogen plasma etche s the surface oxide on InP substrates has been measured as a function of substrate temperature over the range 250-485 degrees C for two oper ating conditions, one that maximizes H- and the other for which a com bination of high H+ and minimal H- occurs. The results indicate that the plasma stream with maximum H- etches approximately five times fas ter than the plasma stream with high H+ and low H- content. However, the activation energy of the etching reaction, E(a) similar to 0.45 eV , is the same for the two plasma conditions. Considering the oxide as InPO4, produced by exposing the substrates to ozone generated by ultra violet light, the proposed reaction for the etching is nPO4+7.3H-->2H( 2)O+0.5PH(2)+0.5PH(3)+0.8InH+0.2In. (C) 1995 American Vacuum Society.