Multi-probe grouping system with nonlinear error correction
US4910453A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1987 |
| Grant date | Mar 20, 1990 |
| Priority date | — |
| Expiry date | Oct 15, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B7/08
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An error compensated thickness measuring system utilizing first and second probes placed on opposite sides of a semiconductor wafer whose thickness is to be measured. The output of the probes is linearized and electronically processed to provide a signal representative of the thickness of the semiconductor wafer. The electronic processing includes an error compensating circuit which removes higher order error in the thickness signal attributable to the wafer being other than precisely centered between the two probes. The error compensating circuitry operates to produce a scaled higher order representation of the displacement of the wafer from the centered condition to combine this with the thickness signal to produce an error compensated signal. The present invention finds particular application in the thickness gauging of semiconductor wafers which represent a substantial impedance to circuit common and in which compensating circuitry is utilized to adjust for or control the potential of the ungrounded object.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.