Improved Etch Characteristics of SiO2 by the Enganced Inductively Coupled Plasma

초록

It has been known that generation of active species and passivation layers is very important for etching contact holes of high aspect ration in sub-half micron technology. Some of the solutions are to use high C/F ratio chemistry and/or to apply pulsed plasma technique. In this work, we suggest better and simpler method, which was time-varying axial magnetic field applied to a normal ICP source. Enhanced ICP has a pair of external coils attached to the conventional ICP, and periodic weak axial magnetic field can be obtained by changing the magnitude and direction of the current through the coils periodically. Etch rate, uniformity and micro-loading effect can be greatly improved by changing the frequency. The etched characteristics by CF4 and C4F8 plasma in E-ICP is very interesting in that the bonding energy of C-C and C-F are different and the electron distribution can be controlled in E-ICP. The SEM pictures show effective removal of micro-loading effect and micro-trench problem, for and optimized E-ICP. More details on E-ICP operation for SiO2 etch and the mixture effects of additional gas (oxygen and hydrogen) are discussed further.