Angular Dependence of Si₃N₄ Etching in C₄F₆/CH₂F₂/O₂/Ar Plasmas

Abstract

The dependence of Si3N4 etching on ion‐incident angles is investigated at various CH2F2 flow rates in C4F6/CH2F2/O2/Ar plasmas. The normalized etch yield (NEY) curves for Si3N4 imply that physical sputtering is a major contributor to Si3N4 etching. An increase in the amount of CH2F2 in the plasma produces thicker and more etch‐resistant fluorocarbon films. Systematic analyses on deposition and etching of the passively deposited fluorocarbon films on Si3N4 in a C4F6/CH2F2/O2/Ar plasma show that the normalized deposition rate of the fluorocarbon film is nearly the same and unaffected by the CH2F2 flow rate while etching of fluorocarbon films is similar to etching of Si3N4, thus, etching of the fluorocarbon film, rather than its deposition, limits Si3N4 etching in C4F6/CH2F2/O2/Ar plasmas.

Controlling Bowing and Narrowing in SiO2 Contact-Hole Etch Profiles Using Heptafluoropropyl Methyl Ether as an Etchant with Low Global Warming Potential

“…The process conditions for fluorocarbon film deposition were the same as those for SiO 2 contact hole etching, except that no DC bias voltage was applied to the SiO 2 substrate during fluorocarbon film deposition (source power = 250 W, DC bias voltage = 0 V, chamber pressure = 1.33 Pa, electrode temperature = 15 • C). The deposition rates of fluorocarbon films determined in this study decreased monotonically with increasing the ion-incident angle under all conditions and agreed well with the previous reports on the etching of Si-based substrates using fluorocarbon plasma [21]. Although the deposition rates of the fluorocarbon film decreased with increasing the ion-incident angle, the degree to which the deposition rate was reduced depended on the HFE-347mcc3/Ar ratio.…”