Overlay accuracy evaluation in step-and-repeat X-ray lithography

Overlay accuracy in step-and-repeat X-ray lithography is evaluated through MOS device fabrication using an X-ray stepper applied to four lithography levels. Though relatively good overlay accuracies of 0.15 µm (σ) between two levels are obtained, these values are not satisfactory for sub-half-microm...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 1988-07, Vol.27 (7), p.1275-1280
Main Authors: DEGUCHI, K, KOMATSU, K, HORIUCHI, T, HIRATA, K
Format: Article
Language:English
Subjects:
Applied sciences
Design. Technologies. Operation analysis. Testing
Electronics
Exact sciences and technology
Integrated circuits
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
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Summary:Overlay accuracy in step-and-repeat X-ray lithography is evaluated through MOS device fabrication using an X-ray stepper applied to four lithography levels. Though relatively good overlay accuracies of 0.15 µm (σ) between two levels are obtained, these values are not satisfactory for sub-half-micrometer ULSI fabrication. To improve overlay accuracy, error factors are investigated. It is found that overlay errors are strongly affected by mask pattern placement errors. The standard deviation of mask errors is as high as 0.1 µm. These errors are introduced by e-beam writing errors and pattern displacement caused by stress relief of absorber and membrane layers in the etching process. The influence of these error factors on pattern placement accuracy is discussed.
ISSN:0021-4922
1347-4065
DOI:10.1143/jjap.27.1275