A Study of the Optical Emission from an rf Plasma during Semiconductor Etching

Abstract

Spectroscopic analysis of optical emission during rf plasma etching of semiconductor materials has been used to gain a better understanding of the plasma chemistry involved in these systems. The emission was studied principally in CF4-O2 gas mixtures, but other gases were observed as well. It is known that the addition of a relatively small percentage of O2 to CF4 yields a much faster etching rate for silicon and silicon nitride. With the addition of 02 to CF4 discharges we have studied emission from atomic O and molecular CO with a large increase in the emission of atomic F. When the plasma is actively etching silicon or silicon nitride, the emission intensities of both F and O atoms are significantly lower. The etching process can be monitored by observing the intensities of these lines. Analysis of the emission features has also been used to determine abnormal conditions which can adversely affect the etching process.

Use of particle-in-cell simulations to improve the actinometry technique for determination of absolute atomic oxygen density

“…For in-situ measurements of [O] at the process chamber optical emission based techniques offer the best possibility of developing a non-invasive diagnostic. The use of optical emission to monitor [O] in industrial plasma was first performed by Harshbarger et al [12]. In this paper an examination of actinometry as a method for monitoring atomic oxygen ground state number density in an industrial RF capacitive etch plasmas is undertaken.…”

Plasma Etching

“…plasmas of N 2 (a) and a CF 4 /0 2 mixture (b). This study (113) established a strong correlation between atomic fluorine emission and the etch rate of silicon (Figure 23), suggesting that atomic fluorine was the active etchant in CF 4 /0 2 discharges. Figure 22 are indi cated, and a rudimentary understanding can be gained by comparison with the corresponding energy level diagrams shown in Figure 24.…”

Controlling picolitre droplet impact dynamics by tailoring the solid subsurface

“…38 Infrared assignments for non-crosslinked polybutadiene are as follows: 25,39 CH=CH 2 stretch (3010 cm In all cases, the AFM RMS surface roughness was measured to be less than 17 nm, which confirms the low level of plasmachemical roughening/texturing within the selected downstream plasma glow region due to the lack of surface bombardment by energetic electrical discharge species (e.g. ions), 28,29 Picolitre water droplet impact onto all of these surfaces displayed an initial spreading of the contact line to reach a maximum diameter. In the case of CF 4 plasma fluorinated polybutadiene, this was followed by dissipation of excess surface free energy observed as oscillations of the droplet height (stemming from lower energy dissipation during spreading across a more hydrophobic surface), whilst motion of the contact line was inhibited due to pinning, Figure 4(a).…”