University of Cincinnati

Plasma Quest Limited

Thomas D Mantei

John E Spencer

Robert Westmoreland

A plasma producing device is furnished with a half height waveguide that transmits microwave energy through a window into an evacuated chamber, adjustable spacers controlling the distance between an opening of the waveguide and the window, and/or a return piece adjacent a permanent magnet producing the required magnetic field, preferably including sidewalls encompassing the permanent magnet. The improvements promote plasma uniformity at the workpiece by allowing smaller magnets to be employed, reducing stray magnetic fields outside the resonance zone, and facilitating transition of the microwaves from a rectangular transmission mode to a circular transmission mode outside the chamber. Facilitating transistion in this manner improves tuning or impedance matching.

Plasma producing structure

An apparatus is provided for the production of plasma. An evacuable chamber is operatively connected to a microwave waveguide, down which microwave energy at approximately 2.45 GHz is transported. The microwave energy enters the evacuable chamber through an opening in the upper wall of the chamber covered by microwave transparent material. Centrally located above the opening in the upper wall of the chamber and outside the waveguide, a permanent magnet is provided. The strong downward magnetic field of the magnet enters the chamber in the same direction as the propagation path of the microwaves. The downward magnetic field component is at a right angle to the electric field associated with the microwaves. A working gas is introduced to the chamber by a plurality of gas inlets operatively connected to the chamber. At some point within the vacuum of the chamber, the electrons rotating about the downward magnetic field component are in phase with the electric field of the microwaves. These electrons acquire sufficient energy at this point to dissociate molecules of the working gas into atoms and to remove electrons from atoms to form ions and free electrons. This plasma of ions, electrons and atoms is then used to perform work on a workpiece provided on a support with the chamber.

Magnetic plasma producing device with adjustable resonance plane

A method and apparatus for plasma etching a substrate, such as a semiconductor wafer, utilizing a multipole surface magnetic field confining within an etching chamber an etching plasma of substantially uniform density throughout its volume. The plasma is produced and maintained by subjecting a gas such as CF.sub.4 to an ionizing discharge within the chamber. Only DC power sources are used for the discharge, so that there is virtually no perturbing radio frequency interference produced. The wafer is consequently easily biased relative to the plasma for controlled fine-scale etching. Low gas pressures permitted by the surface magnetic field result in substantially anisotropic etching of the substrate by dense plasma concentrations.

Growing community of inventors

Cincinnati, OH, United States of America

Thomas D Mantei