Characterization of Cl-2/Ar high density plasmas for semiconductor etching

Chlorine-based high density plasmas, commonly used in the etching of elemen tal and compound semiconductors, are characterized using mass spectrometry, optical emission spectroscopy, and electrostatic probes. Plasma fluxes are characterized by three-dimensional Langmuir probe measurements and optical emission spectroscopy. The flux is further characterized at the substrate platen by mass spectrometry to determine its makeup in terms of charged or neutral species and atomic or molecular species. Langmuir probe investigati ons show variations in electron temperature (2-6 eV), plasma density (1 x 1 0(10) to 1 x 10(12) cm(-3)), and plasma potential (5-25 V) as process condi tions (microwave power, total pressure, and fraction of Cl-2 in Ar) and mea surement location are varied. Concurrent optical emission spectroscopy meas urements of ionized species are in general agreement with Langmuir probe re sults. Further, optical emission spectroscopy of neutral and ionized specie s provides global insight into the variation of atomic/molecular fractions in the plasma as it is transported to the substrate processing region. At t he substrate, mass spectrometric characterizations show Cl+ and Ar+ dominat ing the flux for low pressure and high powers, while Cl-2 and Ar dominate a t high pressure and low power. For Cl-2 fractions greater than 25% molecula r chlorine begins to dominate the flux to the substrate. These observations of processing space are discussed with respect to implications on semicond uctor etching and regions most suitable to high rate, anisotropic processin g conditions are identified. [S0734-2101(99)02701-3].