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A large area plasma source based on 12 multi-dipolar ECR plasma cells arranged in a 3 × 4 matrix configuration was built and optimized for silicon etching by negative ions. The density ratio of negative ions to electrons has exceeded 300 in Ar/SF6 gas mixture when a magnetic filter was used to reduce the electron temperature to about 1.2 eV. Mass spectrometry and electrostatic probe were used for plasma diagnostics. The new source is free of density jumps and instabilities and shows a very good stability for plasma potential, and the dominant negative ion species is F-. The magnetic field in plasma volume is negligible and there is no contamination by filaments. The etching rate by negative ions measured in Ar/SF6/O2 mixtures was almost similar with that by positive ions reaching 700 nm/min. [ABSTRACT FROM AUTHOR]

A method that allows easy and inexpensive detection of negative ions is introduced. The method is based upon the electrostatic lens effect of the sheath layer evolving to a positively biased planar probe that focuses the negative charges to distinct regions on the surface. Trajectories of negative ions inside the sheath are obtained after computing the potential and electric field distribution by solving in three dimensions the nonlinear Poisson equation. The negative ions’ flux to square and disk probes is developed in Ar/SF[sub 6] and O[sub 2] plasmas. The method allows negative ion detection with sensitivity higher than that of Langmuir probes. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A method to detect the parameters of electronegative plasmas with bi-Maxwellian electrons using a Langmuir probe is proposed by applying the test function. The radial model for the positive ion collection is extended and found to be more appropriate for density detection than the orbital motion limited model. The parameters of a diffused Ar/SF[sub 6] plasma are obtained by cylindrical and spherical probes for various Ar/SF[sub 6] ratios over a pressure range from 0.5 to 10 mTorr. The density ratio of bulk to hot electrons decreases from about 50 in Ar plasma to less than one for Ar/SF[sub 6], of which the SF[sub 6] flow is 0.05 standard cubic centimeters per minute. The hot electron group cannot be neglected for density ratios of negative ions to electrons lower than 100, though approximation of Maxwellian electrons is valid for larger density ratios. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study which the describes a test function for negative ion and electron parameters in plasma. Description of the numerical procedures for the processing of the Langmuir probe characteristics; Type of device the experiments were conducted in.

A thermal probe for plasma diagnostics is introduced. The method is based upon measuring the equilibrium temperature of a conducting sphere as a function of its applied bias. The resulting temperature–voltage characteristic is processed using a theoretical model that accounts for charge and thermodynamic balance. The thermal probe is capable of detecting negative ions and shows sensitivity to certain chemical reactions. Measurements performed in Ar, Ar/SF[sub 6], and O[sub 2] show good agreement among the plasma parameters using thermal and Langmuir probes. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]