In:
Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena, American Vacuum Society, Vol. 6, No. 6 ( 1988-11-01), p. 2135-2138
Abstract:
A prototype synchrotron radiation (SR) stepper for quarter-micron devices has been developed and installed at the Photon Factory in the National Laboratory for High Energy Physics, Japan. The stepper features are, (i) exposure in an atmospheric environment, (ii) large exposure area (25-mm sq), and (iii) alignment error detection at all times, including during exposure. The stepper consists of an SR extracting chamber, precision mechanical stages, and an alignment error detection system. An SR beam in UHV goes through a beryllium window into an atmospheric environment, and covers the 25-mm sq exposure area by using an oscillating mirror. Patterns on a mask are imprinted onto a wafer. Mask and wafer are, respectively, held in place with vacuum chucks. Their subsequent positioning movements are driven in 6 degrees of freedom by piezoelectric actuators for fine alignment and gap setting. The alignment system, based on the previous Fresnel lens optical system, newly employs a differential mode linear Fresnel zone plate alignment method. As the optical system for this method is located at the outside of an SR beam, it can detect an alignment error between a mask and a wafer at all times, including during exposure. Patterns measuring 0.2 μm were completely successfully imprinted on a wafer. Until now, 0.03-μm (3σ) positioning accuracy and 0.2-μm (3σ) overlay accuracy were achieved.
Type of Medium:
Online Resource
ISSN:
0734-211X
,
2327-9877
Language:
English
Publisher:
American Vacuum Society
Publication Date:
1988
detail.hit.zdb_id:
3117331-7
detail.hit.zdb_id:
1475429-0
