AVS 63rd International Symposium & Exhibition
    Plasma Science and Technology Wednesday Sessions
       Session PS-WeM

Paper PS-WeM5
Customizing Ion Energy Distributions in Pulsed Plasmas with Chirped Bias Power

Wednesday, November 9, 2016, 9:20 am, Room 104B

Session: Plasma Sources and Novel Mechanisms for Generating Plasmas
Presenter: Steven Lanham, University of Michigan
Authors: S.J. Lanham, University of Michigan
M.J. Kushner, University of Michigan
Correspondent: Click to Email
Control of the ion energy distribution (IED) in plasma material processing reactors is necessary to maintain the critical dimensions (CD) needed to produce modern microelectronic devices. An effective way to customize IEDs is using pulsed power. For example, electronegative (e.g. halogen) plasmas used in etching processes form ion-ion plasmas during the power off period, where low energy ions can be preferentially extracted. This also allows for extraction of negative ions during the afterglow, which can help negate charge induced damage. Pulsed power parameters such as duty cycle and pulse repetition frequency need to be optimized for different electronegative plasmas chemistries due to varying attachment rates and heavy particle reaction mechanisms. The choice of frequency for the bias is a first-order decision in forming the IED, even in pulsed systems, which has in turn resulted in multi-frequency biases to aid in further customization. The use of multi-frequency biases brings additional complexity to pulsed systems.

In this work, based on a computational investigation, we discuss methods to produce customized IEDs in pulsed, electronegative inductively coupled plasmas. A 2-dimensional model, the Hybrid Plasma Equipment Model (HPEM), was used for this study. For pulsed biases in inductively coupled plasmas, IEDs will be discussed for various halogen plasma chemistries. Chirped biases in which the frequency is ramped during a pulsed period are discussed as a means to replicate IEDs that can otherwise only be formed in dual or triple frequency systems.

Work was supported by the Department of Energy Office of Fusion Energy Science and the National Science Foundation.