Method and system for gas flow mitigation of molecular contamination of optics
US9874512B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Aug 22, 2014 |
| Grant date | Jan 23, 2018 |
| Priority date | — |
| Expiry date | Jul 8, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/151
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A computer-implemented method for determining an optimized purge gas flow in a semi-conductor inspection metrology or lithography apparatus, comprising receiving a permissible contaminant mole fraction, a contaminant outgassing flow rate associated with a contaminant, a contaminant mass diffusivity, an outgassing surface length, a pressure, a temperature, a channel height, and a molecular weight of a purge gas, calculating a flow factor based on the permissible contaminant mole fraction, the contaminant outgassing flow rate, the channel height, and the outgassing surface length, comparing the flow factor to a predefined maximum flow factor value, calculating a minimum purge gas velocity and a purge gas mass flow rate from the flow factor, the contaminant mass diffusivity, the pressure, the temperature, and the molecular weight of the purge gas, and introducing the purge gas into the semi-conductor inspection metrology or lithography apparatus with the minimum purge gas velocity and the purge gas flow rate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.