Effects of RCA claning upon breakdown voltages of thin gate oxides

The authors investigated the effects of pre and post-oxidation RCA cleaning on thin oxides using breakdown voltages at current densities of 100 μA/cm² and 100 mA/cm². The RCA clean consisted of SC1 (NH₄OH in water and H₂O₂ ), a dilute HF dip and SC2 (HCl in water and H₂O₂ ). Three experiments were performed to test the effect of each step of the pre- and post-oxidation cleans, the effect of the order in which the steps of the clean were performed, and the effect of the age of the solutions. HF was found to decrease oxide thickness without increasing the number of fails. In the post-oxidation clean, SC2 increased the number of failing oxides, but this effect was alleviated if SC1 was performed beforehand. This and other data led to the conclusion that SC2 was selectively etching the oxide. In addition, an experiment dealing with holding time of the solutions (0-12 h) was performed, but the results were not conclusive