Apparatus and methods for inspecting wafers and masks using multiple charged-particle beams
US5892224A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 9, 1997 |
| Grant date | Apr 6, 1999 |
| Priority date | — |
| Expiry date | May 9, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/2817
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus and methods are disclosed for inspecting masks, reticles, and other patterned samples used in microlithography. The apparatus and methods are useful for detecting, at high speed and high accuracy, any defects in the pattern defined by the sample. Multiple charged-particle beams (e.g., electron beams) scannably irradiated simultaneously on respective loci in an irradiation region of a surface of the sample. A charged-particle detector is situated so as to detect charged particles propagating, during the irradiation, from the loci. The charged-particle detector produces data on whether or not the pattern in the irradiated region has any defects compared to a reference pattern. The detectors can be situated so as to receive charged particles reflected from the irradiated region, charged particles passing through the irradiated region, or secondary electrons produced from irradiating the loci. An electrode plate, preferably defining multiple apertures each dedicated to receiving charged particles originating at a respective locus, is used to attract the charged particles toward the detectors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.