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Proceedings Paper

Quantitative measurement of voltage contrast in SEM images for in-line resistance inspection of wafers manufactured for SRAM
Author(s): Miyako Matsui; Takahiro Odaka; Hiroshi Nagaishi; Koichi Sakurai
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Paper Abstract

An in-line inspection method for partial-electrical measurement of defect resistance, which is quantitatively estimated from the voltage contrast formed in an SEM image of an incomplete-contact defect, was developed. This inspection method was applied to wafers manufactured for an SRAM device. That is, the gray scales of the defect images captured on an SRAM plug pattern were quantitatively analyzed. Accordingly, the gray scales of defective plugs formed for shared contact patterns were classified as two levels. The higher contrasts, which were calculated from the grayscales of the darker defects, were about 100%; the lower contrasts, which were calculated from the grayscales of the other defects, were from 38% to 60%. The resistances of these defects were estimated from a calibration curve obtained from the grayscales of the SEM images and the resistances of deliberately formed failures on standard wafers for voltage-contrast estimation. The estimated resistances of the lower-contrast defects (with an accuracy of about an order of magnitude) agree well with the resistances measured by nano-prober. It is concluded that this in-line inspection method for partial-electrical measurement is a useful technique for defect classification based on defect resistance and defect mode.

Paper Details

Date Published: 23 March 2009
PDF: 8 pages
Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72721D (23 March 2009); doi: 10.1117/12.812949
Show Author Affiliations
Miyako Matsui, Hitachi, Ltd. (Japan)
Takahiro Odaka, Hitachi, Ltd. (Japan)
Hiroshi Nagaishi, Renesas Technology Corp. (Japan)
Koichi Sakurai, Renesas Technology Corp. (Japan)


Published in SPIE Proceedings Vol. 7272:
Metrology, Inspection, and Process Control for Microlithography XXIII
John A. Allgair; Christopher J. Raymond, Editor(s)

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