Shallow trench etch with a planar inductively coupled plasma discharge

The shallow silicon trench etching for shallow trench isolation was investigated using a planar inductively coupled plasma discharge chamber with different chemistries and etch mask. Both HBr/Cl-2/O-2 and Cl-2/O-2 chemistries with nitride hard mask demonstrated the process capability in terms of etch non-uniformity, etch rate, depth microloading, profile microloading effect, profile angle control. The study also demonstrated that the O-2 flow is the key factor to achieve sloped trench profile, and the pressure and source power are the parameters to tune the non-uniformity and improve bottom corner rounding. Compared with photoresist mask, the trench etching with Si3N4 as hardmask showed better profile, profile angle variation and etch rate non-uniformity.