Apparatus and method for shielding a wafer from charged particles during plasma etching

Abstract

A plasma etch system having a wafer chuck with magnets that apply a magnetic field on the wafer to shield the wafer from charged particles. This magnetic field is parallel to the wafer and is strongest near the wafer surface. The magnetic field can be linear, or circular. In operation, electrons are deflected from the wafer by Lorentz forces, the wafer acquires a positive charge, and ions are deflected by electrostatic repulsion. Neutral nuclides are allowed to pass through the magnetic field, and they collide with the wafer. Neutral species generally provide more isotropic and material-selective etching than charged particles, so the magnetic field of the present invention tends to increase etching isotropy and material selectivity. Also, the magnetic field can protect the wafer from the polishing process designed to remove excess film from the chamber surfaces, since polishing processes typically rely on etching with charged particles.

Description

technical field [0001] The present invention generally relates to plasma etching of thin film structures such as microelectronic devices. More specifically, it relates to methods for shielding substrates from charged particles during plasma etching, to provide protection during certain process conditions, or to modulate etch anisotropy. Background technique [0002] Plasma etching is commonly used in the manufacture of microelectronic and micromechanical devices. Plasma etching is used to remove thin films, pattern thin films, or to form micromechanical features. In plasma etching, radio frequency power is applied to a gas mixture, producing charged particles that aid in the etching process. Uncharged reactive particles are also important to the plasma etch process as they provide the majority of material removal. [0003] In most plasma etching applications, it is important to control the plasma properties so that the plasma is selective for certain materials. Also, in ...

AI Technical Summary

Problems solved by technology

[0006] However it takes time to remove the wafer during photocoating and thus tends to reduce system throughput

Also, removing the coating from the wafer can damage the electrostatic chuck because the coating plasma can attack the chuck

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