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Attenuated Phase Shift Mask Method Disclosure Number: IPCOM000006142D
Original Publication Date: 2001-Dec-06
Included in the Prior Art Database: 2001-Dec-06
Document File: 1 page(s) / 21K

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Karl Mautz: AUTHOR [+1]


Attenuated Phase Shift Mask Method

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Attenuated Phase Shift Mask Method

Karl Mautz and John Maltabes

Reticle manufacturing is challenged by the reduction of feature size variation, increased resolution, and improved overlay control for positioning of features on the reticle substrate.  These become increasingly difficult in manufacturing reticles for sub-0.35um device technologies.  Other reticle manufacturing techniques such as optical proximity correction or phase shift masks adds additional complexity and cost to the reticles.

Phase shift masks are difficult to produce due to the custom manufacturing procedures on the substrate and masking materials.  The masking materials include molybdenum and chrome materials on quartz substrate plates.  Attenuation plates are used to lower the intensity of the radiation going through the mask.  Combining these two masks produces an effect that can uniformly adjust the CD (critical dimensions) produced by the mask combination.  By changing the attenuation plate, variation in the CDs without either:  1) adjusting the lithography tool exposure energy (that can lead to scumming or overexposure effects if the adjustment is outside the control zone of the Bolson curve), or 2) by producing another reticle with a different CD feature sizing.  This allows experimentation on the process and tool capabilities without producing many expensive reticles to test this.  Reticles typically are expensive to produce ($50,000) and can take 2-4 weeks to complete.

This method is done by adding removab...