< BK21 플러스 BEST 정보기술 사업단 세미나 개최 안내 >

개최일시 : 2016년 01월 21일 목요일 17:00 ~ 19:00

개최장소 : 제 3공학관 C716호

세미나 제목 : Topographically-Selective Atomic Layer Deposition and Atomic Layer Etching for Novel Nanopatterning Processes

발표초록 :

Recently, as the Si-based technology node nears ~10 nm and approaches its physical limit, alternative methodologies are required for further extension of Moore’s law, with current strategies focusing on the implementation of integration-feasible structures such as 3D FinFETs and nanowires (NWs) in place of the conventional planar MOSFET. In accordance with these structural challenges, extremely small feature patterning is required to satisfy the increasing process complexity of modern electronic devices beyond the sub-10 nm technology regime. In conventional device fabrication, patterning has been achieved by a top-down process based largely on photolithography and subsequent etching, but these critical processing steps are facing fundamental limits for device downscaling.

Of several paths being explored for novel nanopatterning, area-selective atomic layer deposition (AS-ALD) is attracting increasing interest because of its ability to enable both continued dimensional scaling and accurate pattern placement for next-generation nanoelectronics. Here we report a strategy for depositing material onto three-dimensional (3D) nanostructures with topographic selectivity using an ALD process with the aid of an ultrathin hydrophobic surface layer. Using ion implantation of fluorocarbons (CFx), a hydrophobic interfacial layer is formed, which in turn causes significant retardation of nucleation during ALD. We demonstrate the process for Pt ALD on both blanket and 2D patterned substrates. We extend the process to 3D structures, demonstrating that this method can achieve selective anisotropic deposition, selectively inhibiting Pt deposition on deactivated horizontal regions while ensuring that only vertical surfaces are decorated during ALD. The present work advances practical applications that require area-selective coating of surfaces in a variety of 3D nanostructures according to their topographical orientation.

In addition, atomic layer etching (ALE) is being considered as an alternative method for another nanopatterning in which atomic layers of material are removed by sequential self-limiting surface reactions. Here, we report a new cyclic process for atomic layer etching of Si3N4 films achieved by alternating exposure steps of CH3F gas adsorption and Ar+ bombardment. We demonstrate self-limiting etching characteristics of the ALE process as a function of both CH3F etchant flow rate and CH3F exposure time. From comparative studies on the amount of Si3N4 etched using the ALE mode versus pure Ar+ ion sputtering, it is found that the ALE process is more effective in removing the Si3N4 layer and does so with better uniformity due to cooperative interactions between the self-limited CH3F chemisorption and the Ar+ ion sputtering. Based on both the chemical bonding changes following the CH3F etchant exposure and reaction product analyses during the Ar+ plasma step, we propose possible etch reaction steps for the ALE Si3N4 process. The current ALE scheme we present here is envisaged to extend opportunities for highly controllable and uniform etching technologies applicable to upcoming 3D nanoelectronic devices.

강연자 : 김우희 박사 / Stanford University

초청자 : 전기전자공학과 교수 김형준