Video-based alignment system for x-ray lithography

R. Emmett Hughlett; Keith A. Cooper

doi:10.1117/12.47347

1 August 1991 Video-based alignment system for x-ray lithography

R. Emmett Hughlett, Keith A. Cooper

Proceedings Volume 1465, Electron-Beam, X-Ray, and Ion-Beam Submicrometer Lithographies for Manufacturing; (1991) https://doi.org/10.1117/12.47347
Event: Microlithography, 1991, San Jose, CA, United States

Abstract

The fundamental aspects and implementation of the SUSS ALX alignment system for x-ray lithography are described. This paper details the algorithm, the logic behind the alignment target design, and the real-world overlay results achieved. The system reliably achieves an overlay accuracy of 150 nanometers at 3(sigma) being the norm. Focus repeatability is +/- 0.2 microns, including zero level. Alignment calculations are performed in less than 200 msecs. Focus finding is complete in 400 msec. The ALX is a three-camera video system imaging specified mask and wafer alignment patterns to perform coarse alignment of mask and wafer to the imaging field of view, fine alignment of mask to wafer, and automatic focus. The illumination is brightfield, white light. As an auxiliary function, the ALX is used to set planarity and gap of the mask and wafer, by means of fast autofocus. This allows for completely passive (non-contact) gap setting. Both alignment and autofocus on a high SNR image profiling technique for image preprocessing and data compression, here termed 'summed projection.' This vital operation is performed in hardware in true real-time (frame rate). An optical edge detection signal processing algorithm is applied to extract position information from the compressed video input signal.

Citation Download Citation

R. Emmett Hughlett and Keith A. Cooper "Video-based alignment system for x-ray lithography", Proc. SPIE 1465, Electron-Beam, X-Ray, and Ion-Beam Submicrometer Lithographies for Manufacturing, (1 August 1991); https://doi.org/10.1117/12.47347

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available