Monochromator for charged particle beam apparatus
US8274046B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 2011 |
| Grant date | Sep 25, 2012 |
| Priority date | — |
| Expiry date | May 19, 2031 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/153
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
This invention provides a monochromator for reducing energy spread of a primary charged particle beam in charged particle apparatus, which comprises a beam adjustment element, two Wien-filter type dispersion units and an energy-limit aperture. In the monochromator, a double symmetry in deflection dispersion and fundamental trajectory along a straight optical axis is formed, which not only fundamentally avoids incurring off-axis aberrations that actually cannot be compensated but also ensures the exit beam have a virtual crossover which is stigmatic, dispersion-free and inside the monochromator. Therefore, using the monochromator in SEM can reduce chromatic aberrations without additionally incurring adverse impacts, so as to improve the ultimate imaging resolution. The improvement of the ultimate imaging resolution will be more distinct for Low-Voltage SEM and the related apparatuses which are based on LVSEM principle, such as the defect inspection and defect review in semiconductor yield management. The present invention also provides two ways to build a monochromator into a SEM, one is to locate a monochromator between the electron source and the condenser, and another is to locat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.