Remote Plasma Atomic Layer Deposition of SiNx Using Cyclosilazane and H2/N2 Plasma

Haewon Cho,Suhyeon Park,Youngtae Choi,Yurim Kwon,Jong-Woo Kim,Chanwon Jung,Hyunwoo Yuk,Hyeongsu Choi,Keunsik Kim,Hyunwoo Park,Youngjoon Kim,Namgue Lee,Hyeongtag Jeon,Seokhwi Song

doi:10.3390/app9173531

Abstract

Silicon nitride (SiNx) thin films using 1,3-di-isopropylamino-2,4-dimethylcyclosilazane (CSN-2) and N2 plasma were investigated. The growth rate of SiNx thin films was saturated in the range of 200–500 °C, yielding approximately 0.38 Å/cycle, and featuring a wide process window. The physical and chemical properties of the SiNx films were investigated as a function of deposition temperature. As temperature was increased, transmission electron microscopy (TEM) analysis confirmed that a conformal thin film was obtained. Also, we developed a three-step process in which the H2 plasma step was introduced before the N2 plasma step. In order to investigate the effect of H2 plasma, we evaluated the growth rate, step coverage, and wet etch rate according to H2 plasma exposure time (10–30 s). As a result, the side step coverage increased from 82% to 105% and the bottom step coverages increased from 90% to 110% in the narrow pattern. By increasing the H2 plasma to 30 s, the wet etch rate was 32 Å/min, which is much lower than the case of only N2 plasma (43 Å/min).

Highlights

Dielectric films, such as silicon nitride (SiNx ), are extensively studied as etch stop layers, gate dielectrics, stress liners, charge trap layers, and as spacer applications in front-end-of-line (FEOL)semiconductor wafer processing
It was found that a high quality thin film could be obtained for the gate spacer depending on how the unique characteristics of the plasma reactant are utilized in the atomic layer deposition (ALD) process
The fundamental properties of step coverage and plasma time by applying the low temperature process, which is necessary for the deposition of the wet etch rate were analyzed

Summary

Introduction

Dielectric films, such as silicon nitride (SiNx ), are extensively studied as etch stop layers, gate dielectrics, stress liners, charge trap layers, and as spacer applications in front-end-of-line (FEOL)semiconductor wafer processing. The main applications utilize SiNx films as gate spacers in dynamic random access memory, logic devices, and the charge trap layer of vertical NAND flash devices [1,2]. These spacer films act as an oxygen or dopant out-diffusion barrier and control the source/drain doping profiles. They act as a film to prevent etching damage during later processing. Gate spacer research has considered methods to control the dielectric constant by doping carbon into SiNx thin films to reduce the resistive-capacitive (RC) delay [7]

Methods

Results

Conclusion