STUDY OF REACTIVE ION ETCHING PROCESSES FOR SCHOTTKY-BARRIER DIODE FORMATIONS

CHF3 and C2F6 based reactive ion etch processes are compared for the realization of Ti W/n-Si Schottky barrier diodes. As the etch with CHF3 is known to leave large fluorocarbon residue redeposition, the etch with this gas is followed by a quick Ar+ sputter-etch. The diode characteristics are determined using current-voltage and capacitance voltage measurements while deep level transient spectroscopy is used to detect and characterize the process induced deep traps. The electrical characteristics of the diodes are compared to those of diodes that were only Ar+ sputter-etched as a cleaning procedure. It is found that a quick Ar+ etch improves the electrical characteristics of the diodes etched with CHF3 but only partially removes the residue layer while a C2F6 based etch process allows diodes of better characteristic to be directly obtained. However, the electrical properties of the diodes reactive ion-etched are not as good as those obtained when using a long and optimized Ar+ sputter-etch. The concentration of defects measured in the samples reactive ion-etched is low compared to that detected in samples only Ar+ sputter-etched. Nevertheless. deep traps are easily detected in these samples.