AVS 70 Session VT1-TuM: Vacuum Technology for Semiconductor

In the field of nanotechnology atomic scale processing is getting more and more advanced and requires in-depth understanding of the reaction mechanisms of deposition and etching processes. In-situ diagnostics are essential for accomplishing this. Within our group a reactor is designed and installed capable for in-depth study of atomic layer deposition (ALD) and atomic layer etching (ALE) surface reactions, with the focus on infrared spectroscopy (IR) at sub-monolayer sensitivity.

In-situ IR spectroscopy has proven itself to be a powerful tool to study the mechanism of ALD and ALE. [1,2]. To improve sensitivity into the sub-monolayer regime, the technique becomes dependent on the substrate material. Solutions can be found using pressed powder, ATR (attenuated total reflection) for dielectrics or grazing incidence RAIRS (Reflection Absorption Infra-Red Spectroscopy) for metals. The wish to be able to perform this type of diagnostics in one tool made us design a new reactor with the capability for in-situ transmission and reflection IR spectroscopy. For this versatility the back flange is designed to be able to load samples vertically (for transmission) and horizontally (for reflection).

Based on the experiences within our group and the field, the system has a hot wall reactor that is equipped with a loadlock, has the capability to bias the substrate for ion energy control and has a cabinet to mount up to eight different precursor/inhibitor bubblers. The system is pumped down using a turbo-molecular pump backed with roughening pump, to be able to reach high vacuum levels. As an extra feature the setup has the option to install up to four plasma, light or particle sources at a 45-degree angle which is to expand the research in the field of surface science and plasma physics. These ports also give the capability for extra in-situ diagnostics, e.g. optical emission spectroscopy (OES), quadrupole mass spectroscopy (QMS), quartz crystal microbalance (QCM). This contribution will outline the background, design, and capabilities of this next generation home-built reactor.

[1] Goldstein et al., J. Phys. Chem. C 112, 19530 (2008)

[2] Mameli et al., ACS Appl. Mater. Interfaces 10, 38588 (2018)

Non-selective, high-precision, plasma-assisted delayering provides a robust means for failure analysis of heterogeneously integrated devices. While chemical mechanical planarization (CMP) is often used to planarize different layers, dishing and erosion reduce the use of CMP for high-precision delayering as CMP damages the processed layer of interest. In this work, we are developing a non-selective, material-independent plasma delayering technique that is uniform over large areas, requiring only a single dry etching tool. Argon (Ar) and carbon tetrafluoride (CF4), commonly used in high-volume microchip fabrication, were selected as the etchants of dielectric and metallic surfaces. The addition of methyl acetate (MeOAc) can halt the etching process completely during etching. The relative MeOAc mass flow rate provides fine-tuned control of the precision etching with a well-defined planarization process window. In this talk, we will share our initial understanding of the mechanisms by which the acetate precursors suppress the etching process. Our goal is to scale up the dry etching process for industrial applications.

This research was developed with funding from the Defense Advanced Research Projects Agency (DARPA). The views, opinions and/or findings expressed are those of the author and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government