Dual beam symmetric height systems and methods
US6597006B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 9, 2001 |
| Grant date | Jul 22, 2003 |
| Priority date | — |
| Expiry date | Jan 9, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0625
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Systems and methods for determining the height of a surface of a specimen, such as a surface of a semiconductor device wafer are provided. A system may be configured to generate a comparison signal that may used to alter a Z-axis fine height adjustment of the system. The system may include for example, a processing tool, a metrology tool, or an inspection tool that may be used in semiconductor device fabrication. In this manner, the system may be configured to maintain a constant working distance between the wafer surface and an optical column of the system. A system may include an off-axis dual beam symmetric height sensor due to mechanical constraints of the system. The dual beam symmetric height sensor may provide automatic focusing of the wafer with high precision by substantially eliminating wafer pattern-induced error in comparison signals generated by the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.