1 August 1989 Preliminary Testing Results For A New X-Ray Stepper
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Abstract
Preliminary testing results for a new, commercially available soft x-ray proximity stepper are presented. Total system performance (i.e., overlay precision, alignment precision, and critical dimension control) is under investigation using electrical probe structures and scanning electron microscopy (SEM). Preliminary results indicate that the total system performance is consistent with that required for 0.5 μm device design rules. Process latitude data will be presented for several conventional novolak-based resists as well as for an e-beam novolak-based resist. Sensitivities have been obtained over the range of 5 to 400 mJ/cm2. The absence of measurable reflectivity coefficients for nearly normal incident soft x-rays allows one to perform stepper testing with nonstandard substrates. The stable source, large process latitude for conventional resists, and substrate insensitivity allow stepper use without the need to run "send ahead" wafers. The high "MTF" and lack of imaging aberrations allow the use of unbiased reticle patterns with excellent pattern replication on a variety of substrates. Preliminary performance of the alignment system, stage, and gap control imply that overlay consistent with 0.50 μm design rules is achievable.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stephen M. Preston, Darryl W. Peters, David N. Tomes, "Preliminary Testing Results For A New X-Ray Stepper", Proc. SPIE 1089, Electron-Beam, X-Ray, and Ion-Beam Technology: Submicrometer Lithographies VIII, (1 August 1989); doi: 10.1117/12.968525; https://doi.org/10.1117/12.968525
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KEYWORDS
Semiconducting wafers

Optical alignment

X-rays

Reticles

Lithography

Photoresist processing

X-ray lithography

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