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Strem’s High Purity Liquid Ruthenium Precursor for Emerging ALD and CVD Applications

Ruthenium has been under investigation for years among researchers all across the globe for applications such as high-work function electrodes in dynamic random access memory (DRAM) capacitors or gate stack in p-channel metal oxide semiconductor (MOS) in the front end of line (FEOL). It has also been considered for alloyed diffusion barriers, adhesion layers or seed layers in interconnects or through silicon vias (TSVs) for direct electrochemical deposition of copper in the back end of line (BEOL). In these applications, atomic layer deposition based on
ultra-thin Ru films offer unique advantages.

Most of the available Ru ALD or CVD precursors have issues concerning low vapor pressure and high impurity levels, such as carbon and oxygen, which get incorporated in the films. In addition to that, long incubation times impacting throughput and process controllability, poor film adherence, and non-uniformity in high-aspect-ratio structures are some critical limitations of the field. However, Strem offers a well-preferred Bis(ethylcyclopentadienyl)ruthenium(II) [[(CH3CH2)C5H4]2Ru] (catalog number 44-0040) precursor for depositing Ru based ALD/CVD films for niche applications, such as aligned RuO2 nanorods.  The pale yellow liquid precursor with a density of 1.3412 and vapor pressure ~0.2mm (85°C), is sold pre-packed in ALD cylinders.  These fit many of the ALD tools on the market as well as many custom laboratory designed tools. 

Strem at EFDS ALD

Recently, (March 19-20, 2019) Strem exhibited at the annual EFDS ALD for Industry Workshop in Berlin, Germany and we had a chance to discuss Ruthenium precursors with attendees. Here is a short section from the well-known Strem “MOCVD, CVD & ALD Precursors” Catalogue.

Here are just a few examples of thermal as well as plasma driven thin film deposition processes based on bis(ethylcyclopentadienyl)ruthenium(II) precursor presented by the diverse group of researchers at this meeting.

Thomas Waechtler et. al. have reported plating results on layers of ALD Cu with underlying Ru deposited using bis(ethylcyclopentadienyl)ruthenium(II) outperforming ones achieved on PVD Cu seed layers with respect to morphology and resistivity.  Application of these processes suggest that a combination of ALD Cu with PVD or ALD-grown Ru could significantly improve the ECD Cu growth.

Researchers from the National Taiwan University of Science and Technology studied structures and electrochemical capacitive properties of RuO2 vertical nanorods encased in hydrous RuO2. They grew vertically aligned RuO2 nanorods with an aspect ratio in the range of 28-30 on the LiNbO3(100) substrate via metal-organic CVD (MOCVD) using 44-0040 from Strem Chemicals. 

Korean research group has also reported plasma-enhanced ALD of Ru thin films performed using an alternate supply of bis(ethylcyclopentadienyl)ruthenium and NH3 plasma, where NH3 plasma acted as an effective reducing agent for bis(ethylcyclopentadienyl)ruthenium.  The process exhibited no carbon or nitrogen impurities in the film as determined by elastic recoil detection time of flight analysis and the film density was found to be higher than that found in conventional oxygen based ALD.


More than fifty years of experience in manufacturing inorganic and organometallic chemicals has enabled Strem to expand its product offering of MOCVD, CVD, and ALD precursors to continually add new products in support of this dynamic and exciting field.  Strem’s CVD & ALD product range includes:


  • Metal Alkyls
  • Metal alkylamides and alkylimides
  • Metal amidinates
  • Metal alkoxides
  • Metal β-diketonates
  • Metal cyclopentadienyls
  • Metal halides
  • Volatile organometallics
  • Volatile metal carbonyls
  • Fluorinated derivatives
  • Electronic grade chemicals
  • Single source precursors for mixed metal oxides


**This blog had been researched, produced and written by Jonas Sunquist.  It is reposted from BALD Engineering's blog on April 10, 2019.  Original blog:  **


For more information about our CVD/ALD Precursors and Equipment please visit the links below:

MOCVD, CVD & ALD Precursors Booklet


Products mentioned in this blog:

44-0040: Bis(ethylcyclopentadienyl)ruthenium(II), 98% (99.9%-Ru)  [32992-96-4]

98-4009:  Bis(ethylcyclopentadienyl)ruthenium(II), 98% (99.9%-Ru), 44-0040, contained in 50ml Swagelok® cylinder (96-1070) for CVD/ALD  [32992-96-4]

98-4067: Bis(ethylcyclopentadienyl)ruthenium(II), 98% (99.9%-Ru), 44-0040, contained in high-temp 50ml Swagelok® cylinder (96-1071) for CVD/ALD  [32992-96-4]



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