Method and apparatus for measuring values of physical property
US6823724B1 · kind B1 · utility
Assignees
Inventors
Key dates
| Filing date | Mar 25, 2003 |
| Grant date | Nov 30, 2004 |
| Priority date | — |
| Expiry date | Mar 25, 2023 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S977/852
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of detecting the distribution of values of a physical property such as the dopant concentration of a semiconductor without being adversely affected by stray capacitance is offered. A scanning probe microscope capable of implementing this method is also offered. The method starts with applying an AC voltage of angular frequency &ohgr; between a probe and a sample from a fixed oscillator. The output from the oscillator is supplied to a piezoelectric device that drives the cantilever. The cantilever produces a deflection signal corresponding to forces corresponding to interactions between the probe and sample. A signal regarding the amplitude is extracted from the deflection signal. This signal is fed back to a means for controlling the distance between the probe and sample and supplied to a display device. As a result, an image of the surface topography of the sample is obtained. A harmonic component having a frequency higher than the triple or more of the angular frequency &ohgr; and contained in the cantilever deflection signal is extracted by a lock-in amplifier. As a result, information representing an image of differential capacitance (∂C/∂V) is obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.