요즘 ALD 트렌드가 어떤지 공부도 할겸 논문 한 편 구해서 읽는다. 읽으면서 체크했던 내용들 요약하듯 짜깁기해서 정리해본다. 대충 절반으로 쪼개서 앞부분과 뒷부분으로 나눠 올릴 예정이다.

첫 번째 포스팅의 TOC는 다음과 같다.

• New development of Atomic Layer Deposition: Processes, Methods and Applications
  • Abstract
  • 1. Introduction
    • 1.1 Definition of ALD
    • 1.2 Backgroud
      • Figure.01
      • Figure.02
    • 1.3 Thin Film Applications
    • 1.4 Comparison of ALD with other coating techniques
      • Table.01
      • Table.02
    • 1.5 Advantages and Disadvantages of ALD
      • Table.03
    • 1.6 Complex 3D nanostructures
      • Table.04
  • 2. ALD Processes - Table.05 - Figure.05
  • References

New development of Atomic Layer Deposition: Processes, Methods and Applications

- Science and Technology of Advanced Materials, 2019, Vol. 20, NO. 1, 465-496 (Sci. Technol. Adv. Mater., 20, (2019), 66)
- DOI: https://doi.org/10.1080/14686996.2019.1599694

Abstract

1. Introduction

1.1 Definition of ALD

• Chemical precursors are sequentially introduced to the surface of a substrate where they chemically react directly with the surface to form sub-monolayers of film

1.2 Backgroud

• Two of more precursors are pulsed/purged sequentially (self-limiting behaviour)

1. Exposure of the first precursor in the reactor chamber to form a layer on the substrate
2. Purge the excess first precursor and the by-products
3. Exposure of the second precursor
4. Purge or evacuation of the excess second precursor and by-products
5. The process is repeated until the required film thickness is achieved

Figure.01

Figure.01 Illustration of ALD for ZnO thin film deposition 'Numerical modelling in the atomic layerdeposition process: A short review', unpublished.

Figure.02

Figure.02 A model ALD process for depositing TiO2 on hydroxyl groups functionalized substrate using TiCl4 and H2O as precursors¹

1.3 Thin Film Applications

• Semiconductors
• Batteries
• The solar industry
• Membrane technololgy
• Catalyst
• Medicine/Medical devices
• etc.

1.4 Comparison of ALD with other coating techniques

Table.01

Table.01 Different types of film deposition methods (adapted from ²), the sputtering was adapted from ³ while the breath figure method was adapted from ⁴

Table.02

Table.02 Comparison of thinfilmdeposition techniques which are similar to ALD ⁵

1.5 Advantages and Disadvantages of ALD

Table.03

Table.03 Advantages and disadvantages of ALD

1.6 Complex 3D nanostructures

• A variety of materials such as semiconductors, magnetic materials, noble metals, and insulators are being fabricated using ALD to form 3D complex nanostructures
• “The precursor flow will be hindered, and hence the reactions can be different from those reactions on a planar surface, in terms of both mechanism of nucleation and growth of the film. … The specific challenges for the characterization of 3D nanoarchitectures were summarized in the ⁶.”

Table.04

Table.04 Materials, reactants and templates used in ALD coating of nano-porous structures. Republished with permission from ⁷

• ITO: Indum tin oxide
• AAO: anodic aluminum oxide
• Ru(EtCp)2: bis(ethycyclopentadienyl)ruthenium
• Sb(NMe2)3: Tris(dimethylamido)antimony(III)

2. ALD Processes

Table.05

Table.05 Advantages and disadvantages of PEALD

Figure.05

Figure.05 Schematic representation of the three different types of plasma-assisted atomic layer deposition that can be distinguished: (a) direct plasma (b) remote plasma, and (c) radical enhanced

'Recently a branch of ALD, called the photo-assisted ALD or UV-enhanced ALD, has been developed. There the illumination by UV light is adapted as a part of the ALD cycle. UV exposure has been shown to enhance the surface reactions and lead to improved film properties.' ⁸

References