Plasma etch end point detection process
US5877407A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 22, 1997 |
| Grant date | Mar 2, 1999 |
| Priority date | — |
| Expiry date | Jul 22, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/011
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for determining the endpoint of a plasma etch process is disclosed. The endpoint of the plasma etch process is determined using an acoustic cell attached to an exhaust port on a reaction chamber of a plasma reactor. At least a portion of the gas from the reaction chamber flows into the acoustic cell during the plasma etch process. Acoustic signals are periodically transmitted through the gas flowing in the acoustic cell and a first velocity for the acoustic signals associated with etching a first material layer formed on a substrate is determined. Thereafter, the endpoint of the plasma etch step is determined when the first velocity changes to a second velocity associated with etching the first material layer through its thickness to its interface with an underlying material layer. The gas from the reaction chamber optionally flows through a compressor prior to flowing into the acoustic cell. The compressor increases the pressure of the gas that flows into the acoustic cell.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.