Abstract
In order to make the lightly doped drain region structure Ⅲ-Ⅴ MOSFET self-aligned process well-controlled, information about dry etching and wet etching must be investigated. In this thesis, the dry etching of PECVD-SixNy and sputtered TiN was performed with inductively-coupled plasma reactive ion etching system to ascertain the etching rates and selectivity of SixNy to TiN. Wet etching rates of sputtered TiN, in-situ ALD-Al2O3, PECVD-SixNy with SC1 solution were also demonstrated. With the etching chemistry CHF3/O2 whose flow rate was 20/10 SCCM, the highest selectivity of SixNy to TiN as 9.0 was demonstrated with Prf = 200 W, Pbias = 10 W. The etching rates of SixNy and TiN were 170.1 and 18.9 separately in this condition. In addition, the opposite tendencies of etching rate with increasing rf power between SixNy and TiN were explained. For SixNy, high rf power discharged more gaseous etchants, resulting in the reduction of large amount of O2 volumes. Therefore, the fluorocarbon polymer film which was deposited during etching process could be removed with much less O2 and then the etching rate of SixNy would decrease. For TiN, high rf power discharged more gaseous etchants and generated more ions to bombard the TiN surface. This removed TiN dry etching solid byproducts faster, so it enhanced the etching rate. The same mechanism could also explain tendencies of etching rate with increasing bias power of SixNy and TiN. As for wet etching, the etching rate of TiN with SC1 solution was about 9.1 nm/min, while Al2O3 and SixNy etched little with SC1. it meant the damage of Al2O3 gate oxide and SixNy sidewall spacer didn’t need to be worried about. Besides, principles of film deposition instruments, plasma physics, and etching reaction were introduced in this thesis.