Equilibrium profiles for RF-plasma sources with ponderomotive forces

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · IEEE Transactions on Plasma Science

DOI:https://doi.org/10.1109/27.467974· OSTI ID:118899

DiPeso, G; Rognlien, T D; Vahedi, V; Hewett, D W ^[1]

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1. Lawrence Livermore National Lab., CA (United States)

Inductively coupled radio frequency (RF) plasmas have been recently applied as sources in semiconductor processing because plasma density and ion etching energy can be controlled independently, and the discharge can operate at lower pressures to improve etching anisotropy. In addition to plasma density,ion energy, and discharge pressure, the uniformity of the etching over the wafer surface and the uniformity of the etching over the wafer surface and damage to the dielectric window by a high ion flux are important considerations. An analysis is given of the influence of the electron ponderomotive force on the equilibrium plasma profiles of partially ionized, radio frequency discharge sources. The ponderomotive force can be written as a gradient of a potential varying with the square of the RF field in the plasma and is largest for electrons. The impact of this electron ponderomotive force on density and electrostatic potential profiles is demonstrated using a one-dimensional analytic model with supporting numerical solutions and a two dimensional fluid simulation. For nearly collisionless plasmas, the ponderomotive force is valid when {omega}{sub ce}{sup h}/{omega}<1 where w{sub ce}{sup h} is the electron cyclotron frequency due to the RF magnetic field and {omega} is the RF driving frequency. In processing plasmas with parameters that satisfy this validity criteria, the equilibrium density profiles are weakly modified. For nearly collisionless processing plasmas with parameters such that {omega}{sub ce}{sup h}/{omega}>1, the ponderomotive force, is modified by other nonlinear force terms that need to be evaluated.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 118899
• Journal Information: IEEE Transactions on Plasma Science, Journal Name: IEEE Transactions on Plasma Science Journal Issue: 4 Vol. 23; ISSN ITPSBD; ISSN 0093-3813
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COLLISIONLESS PLASMA
ETCHING
PLASMA DENSITY
PLASMA FLUID EQUATIONS
PLASMA POTENTIAL
PLASMA PRODUCTION
PLASMA SIMULATION
PONDEROMOTIVE FORCE
RF SYSTEMS
SEMICONDUCTOR MATERIALS