Damage of Micropatterned Surfaces Due to Bubble Cavitation-Erosion

The capability to reliably reproduce submicrometer-scale patterns is of fundamental importance in semiconductor industry. Higher transistor speeds have been achieved through advances in device miniaturization, resulting in reduced power consumption and manufacturing cost. However, miniaturization below a critical dimension (on the order of ∼100 nm) has been linked with micropattern damage during megasonic cleaning, which decreases the device yield and increases the production cost. Micropattern surface damage due to cavitation-erosion encountered during megasonic cleaning is examined in the context of single- and multi-bubble cavitation models. The critical pressure for micropattern damage predicted by these models is interpreted in terms of important process parameters. Analytical predictions are supported by experimental results of cavitation-erosion damage of gold micropatterns induced by collapsing hydrogen bubbles generated by electrolysis. The results of this study provide insight into surface damage due to bubble cavitation-erosion, which is of great significance in megasonic cleaning of semiconductor devices, such as alternating phase-shift optical masks.