Articles you may be interested inLocalized and ultrahigh-rate etching of silicon wafers using atmospheric-pressure microplasma jets

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Direct simulation Monte Carlo was used to study ion and neutral transport and reaction in a low-gas-pressure highplasma-density inductively coupled reactor with chlorine (electronegative) chemistry. Electron density and temperature were computed by a self-consistent continuum plasma code and were used as input to the direct simulation Monte Carlo code. Simulation results were compared with experimental data taken in a Gaseous Electronics Conference reference cell modified for inductive plasma operation. Data on the radial distribution of positive ion density (Cl*), negative ion density (Cl), as well as the energy distribution of ions bombarding the substrate electrode compared favorably with simulation results. In addition, the measured atomic chlorine density variations with pressure and power were captured by the simulation.

As part of a project with SEMATECH, detailed chemical reaction mechanisms have been developed that describe the gas-phase and surface chemistry occurring during the fluorocarbon plasma etching of silicon dioxide and related materials. The fluorocarbons examined are C 2 F 6 , CHF 3 and C 4 F 8 , while the materials studied are silicon dioxide, silicon, photoresist, and silicabased low-k dielectrics. These systems were examined at different levels, ranging from in-depth treatment of C 2 F 6 plasma etch of oxide, to a fairly cursory examination of C 4 F 8 etch of the low-k dielectric. Simulations using these reaction mechanisms and AURORA, a zero-dimensional model, compare favorably with etch rates measured in three different experimental reactors, plus extensive diagnostic absolute density measurements of electron and negative ions, relative density measurements of CF, CF 2 , SiF and SiF 2 radicals, ion current densities, and mass spectrometric measurements of relative ion densities. 2 AcknowledgmentsWe thank Drs.