The study of STI etching micro-loading in reactive ion etch (RIE)

As the semiconductor industry moves to the advanced technology nodes, the process micro-loading in reactive ion etch (RIE) becomes more and more severe. It is critical to control micro-loading to ensure precise profiles among different patterns. In this paper, the mechanism of profile micro-loading in STI etch is investigated from the view of a comprehensive effect of free reactive radicals concentration and direction, passivation polymer deposition of radical etching. The micro-loading can be optimized by adjusting various process parameters properly such as source power, bias power, pressure and different etching gas ratio etc. Based on these investigations, we demonstrate an improvement on the control of STI etching micro-loading in RIE.