SIMS and AES investigations of contamination effects by RIE of PIQ layers

In a tri-level process PIQ layers on top of silicon have been dry etched with oxygen using different techniques: reactive ion etching (RIE) in a so-called HEX-reactor, reactive ion beam etching (RIBE), and plasma etching in a planar reactor. The contamination and damage of the silicon substrate have been investigated with SIMS and AES. It has been found that micro-villies occur under certain etching conditions. They can be avoided if small amounts of CF sub 4 are added, but then at the expense of selectivity. The influence of the gas pressure is shown. At low pressure (smaller than 2 Pa) no micro-villies occur, whereas at higher pressure (greater than 2 Pa), micro-villies appear at the same input power and dc-bias in the HEX-reactor. SIMS and AES investigations show that Al contamination is high if micro-villies are present and that Al and F are implanted to considerably depth of about 10nm.