PEALDn processes employing Strem Chemicals supplied TDMASn precursor presented by diverse groups of researchers
Atomic layer deposition (ALD) using Tin (Sn) based compounds have been widespread in applications, such as sensors, Li-ion batteries, catalysts, photovoltaics. Recently, researchers have reported state-of-the-art applications like 3D thin-film solid-state batteries (by Pearse et. al.) and efficient perovskite solar cells (by Guan et. al. and Sun et. al.). Many of these applications feature layers that are susceptible to degradation at elevated temperatures. It’s mandatory to deposit SnO2 below 200°C for applications such as perovskite and silicon heterojunction solar cells. Alternatively, plasma-enhanced atomic layer deposition (PEALD) with Strem Chemicals’ highly reactive metalorganic precursor, tetrakis(dimethylamino)tin (TDMASn), with a decomposition temperature range of 250–300°C, also enables low deposition temperatures.
Strem Chemicals offers TDMASn [Sn[N(CH3)2]4] (catalog number 50-1815) precursor, which has been widely accepted in the PEALD community worldwide for the deposition of tin-based compounds. The colourless to pale yellow liquid phase precursor with a density of 1.169 at 20°C and vapor pressure of 15 Torr is sold pre-packed, in an ALD cylinder by Strem Chemicals (98-4050).
Figure 2: Strem Chemicals pre-packed ALD cylinders
The following are some of the examples of PEALD processes employing Strem supplied TDMASn precursor
Hoffmann et. al. report the preparation of transparent conductive gas permeation barriers based on thin films of tin oxide (SnOx) grown by spatial atomic layer deposition (ALD) at atmospheric pressure. They present a comparative study using tetrakis(dimethylamino)tin(IV) and various oxidants (atmospheric pressure oxygen plasma, ozone, and water) at process temperatures in the range of 80–165°C.
Recent reports by researchers from the Eindhoven University of Technology in collaboration with the Netherlands Organisation for Applied Scientific Research (TNO), present an extensive characterization of plasma-assisted atomic-layer-deposited SnO2 layers. They aim at identifying key material properties of SnO2 to serve as an efficient electron transport layer in perovskite solar cells. The SnO2 thin films were deposited at substrate temperatures of 50, 100, 150, and 200°C on Czochralski polished c-Si (100) wafers and indium tin oxide (ITO) glass substrates in an Oxford Instruments OpAL ALD reactor using tetrakis(dimethylamino)tin (TDMASn) (99% purity, Strem Inc.) as the tin precursor and radio-frequency (RF) inductively coupled oxygen plasma as the co-reactant. (Link)
Figure 3: Perovskite solar cells are one of the most promising emerging cell technologies with fast recent improvement in cell efficiency shown above red/yellow circles reaching >22% cell efficiency (From Wikimedia Commons, the free media repository).
An American researcher from University of Maryland, U.S. Naval Research Laboratory and Sandia National Lab, has reported the experimental realization of fully conformal 3D thin-film solid-state batteries (3D TSSBs) incorporating a SnNx anode (deposited at 200°C using TDMASn and an N2 plasma), demonstrating the simultaneous power-and-energy benefits of 3D structuring. All active battery components—electrodes, solid electrolyte, and current collectors—were deposited by atomic layer deposition (ALD) onto standard CMOS processable silicon wafers. The wafers were microfabricated to form arrays of deep pores with aspect ratios up to approximately 10. Their work shows that the exceptional conformality of ALD, combined with conventional semiconductor fabrication methods, provides an avenue for the successful realization of long-sought 3D TSSBs which provide power performance scaling in regimes inaccessible to planar form factor cells. (Link)
For more than fifty years, we’ve been manufacturing inorganic and organometallic chemicals which has led us to expand our product offering of MOCVD, CVD and ALD precursors. We are continually adding new products for this dynamic and exciting field. Our product range includes:
Volatile metal carbonyls
Electronic grade chemicals
Single source precursors for mixed metal oxides
Full Line of High Purity CVD/ALD Precursors
CVD/ALD Precursors contained in Swagelok® Cylinders
Cylinder and Adaptors
Metal Amidinates for CVD/ALD Applications
MOCVD, CVD & ALD Precursors Booklet
Stainless Steel Bubblers: Vertical Electropolished
*This blog had been researched, produced and written by Jonas Sundqvist. It is reposted from BALD Engineering’s blog on November 21, 2019. Original blog: https://www.blog.baldengineering.com/2019/11/peald-processes-employing-strem.html