Methods and apparatus for cleaning objects in a chamber of an optical instrument by generating reactive ions using photon radiation
| DWPI Title: Optical instrument e.g. mask inspection system comprises object such as lens exposed to chamber, source of low-pressure molecular gas; low voltage source; and extreme/vacuum ultra violet light source to direct light on object |
| Abstract: An optical instrument, including a chamber, an object exposed to an interior of the chamber, a source of low-pressure gas, the gas comprising at least one of low-pressure molecular hydrogen gas, low-pressure molecular oxygen and a low-pressure noble gas, the source of low pressure gas being fluidly coupled to the chamber, a low voltage source electrically coupled between the object and a remaining portion of the instrument that is exposed to the interior of the chamber so as to maintain the object at a low voltage relative to the remaining portion, and an EUV/VUV light source adapted to direct EUV/VUV light through the low pressure gas in the chamber onto the object. In such a system, when the EUV/VUV light source is activated ions of the low-pressure gas are formed and directed to the object. The ions may be ions of Hydrogen, Oxygen or a noble gas. |
| Use: For contamination protection in optical instruments such as mask inspection systems or lithographic systems or metrology systems (claimed). |
| Advantage: The present optical instrument have cleaning capabilities including an ability to generate hydrogen ions produced using EUV light and/or VUV light. By using EUV/VUV light, the system allows in situ cleaning of optical components of system, some portion of a chamber wall of the system, mechanical component e.g. holder or stage, or other objects of the instrument. In the presence of ionizing radiation such as EUV/VUV light, hydrogen molecule emits a photoelectron and ultimately produces hydrogen ions in high yield. |
| Novelty: Optical instrument (100) comprises chamber (110); object exposed to interior of chamber; source of low-pressure molecular gas (140) connected to chamber and comprising hydrogen gas, oxygen gas or noble gas; low voltage source (150) connected between object and instrument which is exposed to interior of chamber to maintain the object at low voltage; and extreme ultra violet (EUV)/vacuum ultra violet (VUV) light source (160) adapted to direct EUV/VUV light through low pressure gas on object, where when light source is activated, ions of low-pressure gas are formed and directed to object. |
| Filed: 9/10/2014 |
| Application Number: US14482510A |
| Tech ID: SD 12783.2 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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