Dynamic focus adjustment with optical height detection apparatus in electron beam system
US8791414B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 21, 2010 |
| Grant date | Jul 29, 2014 |
| Priority date | — |
| Expiry date | Oct 4, 2032 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/2487
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention generally relates to dynamic focus adjustment for an image system. With the assistance of a height detection sub-system, present invention provides an apparatus and methods for micro adjusting an image focusing according the specimen surface height variation by altering the field strength of an electrostatic lens between objective lens and sample stage/or a bias voltage applied to the sample surface. Merely by way of example, the invention has been applied to a scanning electron inspection system. But it would be recognized that the invention could apply to other system using charged particle beam as observation tool with a height detection apparatus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.