Mercury-vapor high-pressure short-arc discharge lamp, and method and apparatus for exposure of semiconductor wafers to radiation emitted from said lamp
US5608227A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 22, 1995 |
| Grant date | Mar 4, 1997 |
| Priority date | — |
| Expiry date | Aug 22, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J61/35
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
To essentially eliminate short ultraviolet (UV) radiation from a mercury high-pressure short-arc discharge lamp, that is, wavelengths below the radiation band of 365 nm, the lamp includes a discharge vessel of quartz glass which is coated with a selectively reflective outer coating (2a) and, at the inside, with a selectively absorbing inner coating (2b). The outer coating (2a) is formed by a multi-layer interference reflection filter which preferentially reflects wavelengths between about 240 and 300 nm with a filter cut-off, corresponding to 50% transmission, in the wavelength region between about 290 and 330 nm. The inner coating (2b) is a titanium dioxide coating which, preferentially, absorbs radiation below about 250 nm, with a 50% transmission at about 240 nm. In accordance with a preferred feature of the invention, a radiation absorbing titanium dioxide/silicon dioxide mixed-layer coating (2c) is applied at the outside over the multi-layer interference reflection filter (2a). The outer absorbing coating preferentially absorbs radiation below about 280 nm. Preferably, the multi-layer interference reflection filter is formed by at least 8 alternating ZrO.sub.2 and SiO.sub.2 in…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.