Silicon nitride etching in high- and low-density plasmas using SF6/O2/N2 mixtures

Abstract

Results of a comparative study of SiN x , SiO 2 and Si etching in high-and low-density O 2-N 2 based plasmas with small additions of SF 6 are presented. Higher selectivities of SiN x etching over both SiO 2 ͑up to 50-70͒ and Si ͑up to 20͒ are obtained in a high-density reactor as compared with low-density reactive ion etching. Plasma and surface processes responsible for etching are analyzed. Kinetics of NO molecules responsible for enhanced nitride etching is shown to be distinctly different for low-and high-density plasma conditions. Possible ways of further optimization of the process are discussed.

Plasma etching: Yesterday, today, and tomorrow

“…SiN can be etched with selectivities of 3:1 or higher by SF 6 or SF 6 /O 2 /N 2 mixtures under low-bias conditions. 255 Best results are obtained in the so-called "plasma" configuration, where the wafer is placed on the grounded electrode. Higher selectivities, however, can be obtained with SF 6 /CH 4 , NF 3 /CH 4 or CF 4 /CH 4 mixtures 256 or hydrofluorocarbons with F:C ratio less than 3, 257 such as CH 3 F and CH 2 F 2 .…”

Inductively coupled plasma etching of ultra-shallow Si3N4 nanostructures using SF6/C4F8 chemistry

“…For Si 3 N 4 plasma etching, fluorine gases such as CH 3 F [8], CF 4 [9], SF 6 [10] and NF 3 [11] are mixed with O 2 , N 2 , H 2 or NO in order to get a high anisotropy and a high selectivity over SiO 2 and Si. Fluorine species can react with Si 3 N 4 to form volatile SiF 4 compounds whereas fluorocarbon polymer deposition on surface inhibits the etching of silicon nitride [12].…”

69‐1: Etch Properties of Silicon Nitride Films Using a New In‐Line Equipment with Atmospheric Glow Plasma for the OLED Flexible Display

“…Electrode grooves on single crystalline silicon solar cells were formed by etching SiN films. Etch rate1800 nm/min was obtained using gases such as Ar(800sccm), CF 4 and O 2 (200sccm) in applied power of 30kHz and 4.0 kV [3]. High etch rate and good etch profile of Si 3 N 4 thin films in flexible display are necessary for manufacturing flexible display, first of all.…”