“3D printing in atomic level” -- Atomic Layer Deposition (ALD):

On the physical and chemical details of alumina ALD

Dongqing Pan, Chris Yuan

Department of Mechanical Engineering

University of Wisconsin-Milwaukee 4/2015

You probably know 3D printing… Think about a car in microns…

World’s first 3D-printed car: Strati.

http://www.dailymail.co.uk/sciencetech/article-2784792

Micro-model race car: Vienna University of Technology 3D-printing using two-photon lithography

Think about “3D printing in atomic level” …

http://www.bbc.com/news/technology-17357374

Well…Atomic Layer deposition (ALD)!

1. Highly uniform deposition on wafer surface;2. Accurately-controlled film thickness;3. Wide range of film materials;4. Widely utilized in microelectronics industries.

ALD is perfect in …

1. Low throughput;2. Low material/energy efficiency;3. Complex chemical mechanisms;4. Nano-wastes and emissions.

Well, ALD is actually not perfect …

How to make the ALD process perfect ? …

Numerical simulations?…

Numerical modeling is decoupling, and then coupling the real world!

Physical and chemical processes in ALD

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N NN N N Nk

i r i i r i i r i i r i i r i i r ii i i i i i

g G b B s S g G b B s S

expr rr r

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RT

The Arrhenius equation ,,

1 1

g sj ri r

N Nsg

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Experiments… time-consuming and money-consuming…

Actually we are presenting a combined experimental and numerical approach to study the ALD process!

1. Laminar flow (Momentum transport);

2. Heating (Convective heat transfer);

3. Species transport (Mass transfer);

4. Chemical reactions (Surface reactions).

Good idea!

Experiments: Temperature effects on alumina film growth rate.

Correlations of precursor concentration, surface species coverage, methane generation and bulk material deposition rate in the transient pulsing ALD processes.

TMA pulsing animation

Water pulsing animation

Results:

Comparisons of experimental and numerical investigations.

On the transient fluid dynamics: precursor distributions during the full cycle of flow simulations.