Optical techniques for measuring layer thicknesses and other surface characteristics of objects such as semiconductor wafers
US6934040B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 26, 2003 |
| Grant date | Aug 23, 2005 |
| Priority date | — |
| Expiry date | Sep 30, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/4738
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A characteristic of a surface is measured by illuminating the surface with optical radiation over a wide angle and receiving radiation reflected from the surface over an angle that depends on the extend of the illumination angle. An emissivity measurement is made for the surface, and, alternatively, if a reflectivity measurement is made, it becomes more accurate. One application is to measure the thickness of a layer or layers, either a layer made of transparent material or a metal layer. A one or multiple wavelength technique allow very precise measurements of layer thickness. Noise from ambient radiation is minimized by modulating the radiation source at a frequency where such noise is a minimum or non-existent. The measurements may be made during processing of the surface in order to allow precise control of processing semiconductor wafers, flat panel displays, or other articles. A principal application is in situ monitoring of film thickness reduction by chemical-mechanical-polishing (CMP).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.