Residual polymer effect on shallow trench Bosch process stability

This paper offers a solution to address the unstable shallow trench Bosch process problem by altering several major contributing factors involved in chamber polymer deposition. This approach has been implemented to product lines and has proven to be very effective in resolving this long-standing problem. This method can be generalized to all Bosch process related applications in a manufacturing environment. Experimental results indicate that film patterns and pre-conditioning species generate residual polymers, which interact with the etching plasma to cause process drifts. During a sequence run, wafer-less cleaning can be used to reach a steady-state concentration of residual polymers. A qualitative description of the influential factors of the etch rate at various conditions is given in an empirical formula. A prototypical mechanism was set up to reveal possible complications. Typical process charts and statistics were also collected for analysis. Suggestions for further development and fab-line wafer sequence flow will be discussed in this paper.