Colorado School of Mines

Film Sense In Situ Ellipsometer Integration

The Film Sense FS-1 provides in situ measurements of film thickness, with excellent precision to the sub-nm level, to complement their in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy capabilities. The ATR-FTIR measurements provide information about the chemical bonding on the surface, using a custom ZnSe trapezoid in the ATR configuration. The FS-1 ellipsometer measurements of film thickness are performed on an adjacent Si wafer, and provide the growth (or etch) per cycle, which in turn can confirm if a process is proceeding in a surface-limited mode. Combining the data from these two in situ diagnostic techniques provides a comprehensive characterization of new ALD and ALE chemistries and processes, and enables efficient process optimization. For typical examples, please see these references:

  • “Atomic Layer Deposition of SiC x N y Using Si 2 Cl 6 and CH 3 NH 2 Plasma”, Rafaiel A. Ovanesyan, Noemi Leick, Kathryn M. Kelchner, Dennis M. Hausmann, and Sumit Agarwal, Chem. Mater. 2017, 29, 6269−6278 (
  • “Surface Phenomena During Plasma-Assisted Atomic Layer Etching of SiO 2 ”, Ryan J. Gasvoda, Alex W. van de Steeg, Ranadeep Bhowmick, Eric A. Hudson, and Sumit Agarwal, ACS Appl. Mater. Interfaces 2017, 9, 31067−31075 (
In Situ Ellipsometer Integration - Image Credit Colorado School Of Mines Facebook Page

Dr. Agarwal chose the FS-1 for his lab because it was affordable and easy to integrate with his existing custom ALD reactor, while still providing the thin film thickness resolution required to characterize his processes. A second FS-1 was purchased in July 2018 to support measurements on the multiple ALD/ALE chambers in the lab.

“When I was setting up my laboratory in 2005, I had always envisioned a reactor with both infrared and ellipsometry capabilities. In fact, both of our reactors were designed with ports for ellipsometry. However, due to limited resources, we were only able to install the ATR-FTIR setup since we could use the same spectrometer for both reactors. When I saw the Film Sense ellipsometer at the vendor exhibit at an MRS meeting, it immediately seemed like a very good alternative to a full spectroscopic ellipsometer. These FS-1 ellipsometers are one of the best upgrades to our atomic layer processing reactors, and have now become an integral part of all our experiments on ALD and ALE.”

In Situ Ellipsometer Integration
In Situ Ellipsometer Integration - FS-1 Compact Footprint Ellipsometer

Film Sense In Situ Application Examples

The FS-1 has been installed for in situ measurements on many different ALD reactors, including custom designs, and commercial reactors from the companies below.

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