Reduction of semiconductor structure damage during reactive ion etching
US5880034A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 29, 1997 |
| Grant date | Mar 9, 1999 |
| Priority date | — |
| Expiry date | Apr 29, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/3341
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Uniformity of plasma density and potential are increased by reducing plasma confinement through use of a non-uniform, graded magnetic field by asymmetric energization of electromagnets with a waveform including harmonics of a fundamental frequency. The magnetic field strength or intensity decreases in the direction of ExB drift of energetic electrons within the plasma which tends to cause additional ionization in the plasma and a gradient of plasma density and potential. Thus, increase in ionization due to ExB drift is balanced by reduction of plasma confinement. Uniformity of average exposure to the plasma is further increased by rotation of the magnetic field. Uniformity of plasma potential or wafer bias is further improved by modulation of the radio frequency (RF) power used to form the plasma in synchronism with decreases in the magnetic field during switching for magnetic field rotation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.