Foundations of atomic-level plasma processing in nanoelectronics

Abstract

This article discusses key elementary surface-reaction processes in state-of-the-art plasma etching and deposition relevant to the nanoelectronic device fabrication and presents a concise guide to the forefront of research on plasma-enhanced atomic layer etching (PE-ALE) and plasma-enhanced atomic layer deposition (PE-ALD). As the critical dimensions of semiconductor devices approach the atomic scale, atomic-level precision is required in plasma processing. The development of advanced plasma processes with such accuracy necessitates an in-depth understanding of the surface reaction mechanisms. With this in mind, we first review the basics of reactive ion etching (RIE) and high-aspect aspect-ratio (HAR) etching and we elaborate on the methods of PE-ALE and PE-ALD as surface-controlled processing, as opposed to the conventional flux-controlled processing such as RIE and chemical vapor deposition (CVD). Second, we discuss the surface reaction mechanisms of PE-ALE and PE-ALD and the roles played by incident ions and radicals for in their reactions. More specifically, we discuss the role of transport of ions and radicals, including their surface reaction probabilities and ion-energy-dependent threshold effects in processing over HAR features such as deep holes and trenches.

A transient site balance model for atomic layer etching

“…We assume most of the species desorbing from the walls to the surface is atomic Cl. The value of the flux we use in the model is 1.4×10 15 Cl atoms cm −2 s −1 . This value was chosen to match experimental OES data.…”

“…[4,5] The present model is based on similar ideas and directed towards modeling plasma-assisted atomic layer etching (ALE). ALE provides several advantages over more conventional etching processes [7][8][9][10][11][12][13][14][15][16]. For example, it has the potential to achieve an unprecedented level of fidelity approaching the atomic scale.…”

First-principles simulation of optical emission spectra for low-pressure argon plasmas and its experimental validation

“…The Einstein coefficient A j→i and the escape factor η i→j correspond to the coefficients used for the spontaneous emission from state j to state i, and radiation trapping from state i to state j processes. The reactions associated with these coefficients are listed in table 4.…”

Numerical optimization of dielectric properties to achieve process uniformity in capacitively coupled plasma reactors

“…Capacitively coupled plasmas (CCPs) are increasingly being used for a variety of critical thin-film processes with satisfactory uniformity and efficiency [1,2]. Owing to its functional usefulness, CCP is often adopted in the plasma enhanced chemical vapor deposition (PECVD) process for the production of state-of-the-art microchips despite various technical difficulties in the design of CCP reactors [3][4][5].…”