Extreme ultraviolet soft x-ray projection lithographic method and mask devices

• Main Authors: Davis, Jr., Claude L, Hrdina, Kenneth E, Sabia, Robert, Stevens, Harrie J
• Format: Patent
• Language: English
• Published: 15.10.2002

The present invention relates generally to projection lithographic methods and systems for producing integrated circuits and forming patterns with extremely small feature dimensions. The present invention relates particularly to extreme ultraviolet soft x-ray based lithography and reflective masks which reflect extreme ultraviolet soft x-ray radiation and form pattern images that are utilized to form circuit patterns. The present invention relates to reflective masks and their use for reflecting extreme ultraviolet soft x-ray photons to enable the use of extreme ultraviolet soft x-ray radiation for lithography that surpasses current optical lithography circuit feature dimension performance. The present invention relates to reflective masks and their use for reflecting extreme ultraviolet soft x-ray photons to enable the use of extreme ultraviolet soft x-ray radiation projection lithographic methods and systems for producing integrated circuits and forming patterns with extremely small feature dimensions. The projection lithographic method includes providing an illumination sub-system for producing and directing an extreme ultraviolet soft x-ray radiation from an extreme ultraviolet soft x-ray source; providing a mask sub-system illuminated by the extreme ultraviolet soft x-ray radiation produced by the illumination sub-system and providing the mask sub-system includes providing a patterned reflective mask for forming a projected mask pattern when illuminated by radiation . Providing the patterned reflective mask includes providing a Ti doped high purity SiOglass wafer with a patterned absorbing overlay overlaying the reflective multilayer coated Ti doped high purity SiOglass defect free wafer surface that has an Ra roughness 0.15 nm. The method includes providing a projection sub-system and a print media subject wafer which has a radiation sensitive wafer surface wherein the projection sub-system projects the projected mask pattern from the patterned reflective mask onto the radiation sensitive wafer surface.