AVS 64th International Symposium & Exhibition
    Plasma Science and Technology Division Wednesday Sessions
       Session PS-WeA

Paper PS-WeA1
TSV Etch Plasma Modelling from Chamber to Feature

Wednesday, November 1, 2017, 2:20 pm, Room 23

Session: Modeling of Plasmas
Presenter: Sebastian Mohr, Quantemol LTD
Authors: S. Mohr, Quantemol LTD
S. Rahimi, Quantemol LTD, UK
A. Dzarasova, Quantemol LTD, UK
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A key goal of the presented research project PowerBase is to produce new integration schemes which enable the manufacturability of 3D integrated power GaN smart systems with high precision TSV etched features. This project is a collaboration of 39 partners focused on exploring novel materials and manufacturing processes optimisation and testing. Quantemol’s contribution to the PowerBase project includes the simulation of the Rapier reactor built by SPTS presented here. This tool allows control of the homogeneity of particle fluxes to the wafer via two independently controlled coils and two independently controlled nozzles. In this project, the Rapier is used to etch through Si wafer via the BOSCH process. By combining simulation and experiment, we look for the parameter settings, which ensure homogeneous etch rates and features with a minimal amount of scalloping. This presentation includes the simulations of the reactor in both SF 6 and C 4 F 8 performed with Q-VT/HPEM as well as feature profile simulations. Due to the complicated chemistries, the non-trivial geometry of the reactor, and limited diagnostics, simulating the Rapier is an arduous task. As this presentation will show, we managed to achieve excellent agreement between experimentally and computationally obtained surface rates. The reactor simulation employs fluid techniques to calculate the particle densities and fluxes as well the electric fields and a Monte Carlo Simulation of the reactive species, both neutrals and ions, to obtain the distribution of these particles at the wafer with regards to both energy and angle (IEADFs). FInally, the IEADFs and particle fluxes are used in the feature profile model, which alternates between the polymer deposition process in C 4 F 8 and the etching process in SF 6 , which in this case is almost exclusively driven by the chemical etch of silicon by fluorine radicals. Due to the isotropic nature of the chemical etch, a certain amount of scalloping is to be expected. The simulation identified the effect of key parameters such as the ICP and rf-bias power on the feature profile, as well as the homogeneity of particle fluxes. These insights were transferred to the experiment with the final goal to achieve the optimal combination of radially homogeneous surface rates, smooth features, and process time. This presentation highlights the challenges of simulating the Rapier, comments on the agreement between simulation and experiment, and analyses the effect of parameter variations such as power and gas flow on the flux homogeneity and feature profile.