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Proceedings Paper

High voltage CD-SEM based metrology for 3D-profile measurement using depth-correlated BSE signal
Author(s): Wei Sun; Yasunari Sohda; Hiroya Ohta; Taku Ninomiya; Yasunori Goto
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Paper Abstract

In-line metrology for measuring 3D features of the high aspect ratio (HAR) holes is becoming more challenging due to the development of semiconductor technology, particularly in memory devices. Measurements of the bottom critical dimension (CD), taper angles, and 3D profiles of the HAR holes require new imaging capabilities.

In this work, we explore backscattered electron (BSE) imaging and its applicability in 3D metrology of the HAR holes. Monte Carlo simulations were performed to estimate the BSE signals emitted from the HAR holes. The simulation results demonstrate that the BSE signal intensity decreases exponentially with increasing the depth of the irradiated location in the HAR holes. Based on the characteristics of the BSE signal intensity, an algorithm utilizing depth-correlated BSE signal intensity was proposed for the 3D metrology of the HAR holes. Furthermore, several types of holes with different taper angles and different bowing profiles were fabricated and experiments were performed to verify the feasibility of the proposed algorithm. The cross-sectional profiles of the fabricated holes which are created using the BSE profiles are matching with the as-cleaved cross section observed by X-SEM. These results demonstrate that the 3D-profile variation of the HAR holes induced by the etching processes can be identified by our approach.

Paper Details

Date Published: 26 March 2019
PDF: 8 pages
Proc. SPIE 10959, Metrology, Inspection, and Process Control for Microlithography XXXIII, 1095915 (26 March 2019); doi: 10.1117/12.2511272
Show Author Affiliations
Wei Sun, Hitachi, Ltd. (Japan)
Yasunari Sohda, Hitachi, Ltd. (Japan)
Hiroya Ohta, Hitachi High-Tech Science Corp. (Japan)
Taku Ninomiya, Hitachi High-Tech Science Corp. (Japan)
Yasunori Goto, Hitachi High-Tech Science Corp. (Japan)

Published in SPIE Proceedings Vol. 10959:
Metrology, Inspection, and Process Control for Microlithography XXXIII
Vladimir A. Ukraintsev; Ofer Adan, Editor(s)

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