Plasma formed ion beam projection lithography system
AssigneeThe Regents of the University of California
InventorsKa-Ngo Leung, Yung-Hee Yvette Lee, Vinh Ngo, Nastaran Zahir
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Abstract
A plasma-formed ion-beam projection lithography (IPL) system eliminates the acceleration stage between the ion source and stencil mask of a conventional IPL system. Instead a much thicker mask is used as a beam forming or extraction electrode, positioned next to the plasma in the ion source. Thus the entire beam forming electrode or mask is illuminated uniformly with the source plasma. The extracted beam passes through an acceleration and reduction stage onto the resist coated wafer. Low energy ions, about 30 eV, pass through the mask, minimizing heating, scattering, and sputtering.
Claims20
A plasma formed ion-beam projection lithography system, comprising:
- a plasma generator which produces ions in a plasma generation region;
- a beamlet extraction mask having a plurality of apertures in a defined pattern, the mask being positioned adjacent to the plasma generation region of the ion source for electrostatically producing a controlled pattern of micro-ion-beamlets;
- an acceleration and reduction column following the mask and having aligned apertures therethrough for accelerating and focusing the micro-ion-beamlets extracted from the plasma generation region to produce a demagnified final ion beam.
A method of producing a focused ion beam comprising a plurality of beamlets in a predetermined pattern, comprising:
- generating a plasma;
- extracting ions from the plasma through a beamlet extracting mask which produces the predetermined pattern of beamlets;
- passing the ions extracted through the mask through aligned apertures in an acceleration and reduction column.
An extraction mask for producing a pattern of an annulus around a central dot in an ion beam projection lithography system, comprising:
- a first layer formed of a conductive material and having an aperture formed therein;
- a plurality of ribs extending into the aperture in the first layer;
- a post connected to and supported by the ribs and extending out of the aperture in the first layer;
- a second layer formed of an insulator and having an aperture of the same size as the aperture in the first layer;
- a third layer formed of a conductive material and having an aperture of the same size as the apertures in the first and second layers;
- wherein the first, second and third layers are attached together in a sandwich configuration with their apertures aligned, with the post extending into the apertures of the second and third layers to define an annular channel.
Dependencies are inferred from the claim text.