Noncontact conductivity measuring instrument
US7309995B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 5, 2004 |
| Grant date | Dec 18, 2007 |
| Priority date | — |
| Expiry date | Nov 5, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/2648
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention relates to measurement of conductivity. A microwave oscillated by an oscillator using a Gunn diode is applied through an isolator, a circulator, and a horn antenna to a silicon wafer. The isolator is used for reducing the standing wave influencing the operation of the instrument. The reflected wave is received by the same horn antenna, detected by a detector connected to the circulator, and outpufted in the form of a voltage. The detector produces an output voltage proportional to the square of the amplitude of an electric field. Since the amplitude of the reflected wave from a silicon wafer is proportional to the absolute value of the reflectance, the output voltage is also proportional to the square of the absolute value of the reflectance. The reflectance is in a certain relationship with the conductivity, the conductivity of the silicon wafer can be determined.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.