| AVS 63rd International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS+TF-WeA |
| Session: | Plasma Deposition and Plasma Assisted ALD |
| Presenter: | Tahsin Faraz, Eindhoven University of Technology, The Netherlands |
| Authors: | T. Faraz, Eindhoven University of Technology, The Netherlands H.C.M. Knoops, Oxford Instruments Plasma Technology, UK D.M. Hausmann, Lam Research Corporation J. Henri, Lam Research Corporation W.M.M. Kessels, Eindhoven University of Technology, The Netherlands |
| Correspondent: | Click to Email |
Ion-surface interactions during plasma-enhanced atomic layer deposition (PEALD) can influence the physical and chemical properties of the growing material. The limit to which ion-surface interactions can influence the deposition process depends on the energy and flux of the ions which are governed, in principle, by various process parameters. In a low pressure, remote inductively-coupled-plasma (ICP) reactor (e.g., Oxford Instruments FlexAL) capable of producing a wide range of ion fluxes, the ion energy can be controlled independently of the ion flux if equipped with substrate biasing. Previously, our group demonstrated that the material properties of thin films deposited on planar substrates using remote plasma-ALD can be tailored by controlling the energy of the impinging ions through substrate biasing.1
In this contribution, we will investigate the role of the ion energy via substrate biasing during remote plasma-ALD on both planar and 3D topologies. An upgrade to enable substrate biasing (up to 100 W, 13.56 MHz RF power, -500 V resulting DC bias) has been implemented in the FlexAL system in our laboratory. PEALD processes for SiNx, a material used as gate spacers and hard masks during CMOS fabrication, were developed using aminosilane precursors and N2 plasma.2 The processes were modified by incorporating a tunable RF bias signal on the substrate table during the N2 plasma exposure step which enabled control over the energy of the nitrogen ions impinging on the growing film. SiNx films were simultaneously deposited on planar Si wafers and 3D trench nanostructures (AR ~ 4.5 : 1) using bias powers upto 10 W (~ -65 V resulting DC bias). The planar films deposited with biasing typically exhibited lower refractive indices and densities (~ 1.71 and 2.75 g/cm3 respectively for -65V) compared to those deposited without biasing (~ 1.93, 3.13 g/cm3). A 30s dilute HF etch treatment was performed on the films deposited on 3D trench nanostructures. Horizontal SiNx film regions located at the top and bottom surfaces of the trench exhibited very high wet etch rates (WER) and were completely removed after the etch. However, vertical SiNx film regions exhibited very low WERs (~ 3 nm/min) and remained selectively at the trench sidewalls post-etch. It will be discussed that the results observed could hold potential applications in multiple patterning and area-selective processing techniques, relevant for the fabrication of state-of-the-art FinFETs and next-generation “gate-all-around” FETs.
1 Profijt, Van de Sanden, Kessels., J. Vac. Sci. Technol. A 31, 01A106 (2013)
2 Knoops, Braeken, de Peuter, Potts, Haukka, Pore, Kessels, ACS App. Mat. Interfaces 7, 19857 (2015)