High-temperature etching of SiC in SF6/O2 inductively coupled plasma

Artem A Osipov,Irina A Tyurikova,Sergey E Alexandrov,Vladimir I Berezenko,Anastasia B Speshilova,Gleb A Iankevich,Kirill S Tyurikov,Armenak A Osipov,Ekaterina V Endiiarova

doi:10.1038/s41598-020-77083-1

Abstract

In this work, we demonstrate an effective way of deep (30 µm depth), highly oriented (90° sidewall angle) structures formation with sub-nanometer surface roughness (Rms = 0.7 nm) in silicon carbide (SiC). These structures were obtained by dry etching in SF6/O2 inductively coupled plasma (ICP) at increased substrate holder temperatures. It was shown that change in the temperature of the substrate holder in the range from 100 to 300 °C leads to a sharp decrease in the root mean square roughness from 153 to 0.7 nm. Along with this, it has been established that the etching rate of SiC also depends on the temperature of the substrate holder and reaches its maximum (1.28 µm/min) at temperatures close to 150 °C. Further temperature increase to 300 °C does not lead to the etching rate rising. The comparison of the results of the thermally stimulated process and the etching with a water-cooled substrate holder (15 °C) is carried out. Plasma optical emission spectroscopy was carried out at different temperatures of the substrate holder.

Highlights

Silicon carbide (SiC) is a wide-bandgap semiconductor material which has found wide application in electronic industry
Emission depends on the temperature of the substrate holder, namely, there is a general tendency to decrease the intensity of the spectral peaks highlighted in Fig. 3c, with a temperature increase at which the etching process was conducted
In the region of 430–450 nm (Fig. 3b), on the contrary, the substrate holder temperature rise leads to a systematic increase of emission intensity

Summary

Introduction

Silicon carbide (SiC) is a wide-bandgap semiconductor material (the bandgap width is lying in between 2.36 to 3.3 eV depending on crystal structure) which has found wide application in electronic industry. Radiation and chemical stability is due to the high energy of the bond between Si and C which ensures the stability of SiC-based devices under extreme operating c onditions[1,2,3,4,5] Due to these properties, silicon carbide is a promising material for power electronics devices[6] design as well as various microelectromechanical systems (MEMS) widely used in the automotive industry (hybrid and electric cars), energy industry, oil and gas industry, etc[7,8,9,10,11,12,13,14]. This work was aimed at studying the potential use of substrate temperature as one of the variable PCE process parameters to develop a high rate anisotropic etching process of SiC with minimal defect generation. To form the bias potential, a 13.56 MHz HF voltage from a separate HF generator was applied to the substrate holder (electrode)

Objectives

Results

Conclusion