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Proceedings Paper

Process variation monitoring (PVM) by wafer inspection tool as a complementary method to CD-SEM for mapping LER and defect density on production wafers
Author(s): Saar Shabtay; Yuval Blumberg; Shimon Levi; Gadi Greenberg; Daniel Harel; Amiad Conley; Doron Meshulach; Kobi Kan; Ido Dolev; Surender Kumar; Kalia Mendel; Kaori Goto; Naoaki Yamaguchi; Yasuhiro Iriuchijima; Shinichi Nakamura; Shirou Nagaoka; Toshiyuki Sekito
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Paper Abstract

As design rules shrink, Critical Dimension Uniformity (CDU) and Line Edge Roughness (LER) constitute a higher percentage of the line-width and hence the need to control these parameters increases. Sources of CDU and LER variations include: scanner auto-focus accuracy and stability, lithography stack thickness and composition variations, exposure variations, etc. These process variations in advanced VLSI manufacturing processes, specifically in memory devices where CDU and LER affect cell-to-cell parametric variations, are well known to significantly impact device performance and die yield. Traditionally, measurements of LER are performed by CD-SEM or Optical Critical Dimension (OCD) metrology tools. Typically, these measurements require a relatively long time and cover only a small fraction of the wafer area. In this paper we present the results of a collaborative work of the Process Diagnostic & Control Business Unit of Applied Materials® and Nikon Corporation®, on the implementation of a complementary method to the CD-SEM and OCD tools, to monitor post litho develop CDU and LER on production wafers. The method, referred to as Process Variation Monitoring (PVM), is based on measuring variations in the light reflected from periodic structures, under optimized illumination and collection conditions, and is demonstrated using Applied Materials DUV brightfield (BF) wafer inspection tool. It will be shown that full polarization control in illumination and collection paths of the wafer inspection tool is critical to enable to set an optimized Process Variation Monitoring recipe.

Paper Details

Date Published: 23 March 2009
PDF: 10 pages
Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72720O (23 March 2009); doi: 10.1117/12.814063
Show Author Affiliations
Saar Shabtay, Applied Materials (Israel)
Yuval Blumberg, Applied Materials (Israel)
Shimon Levi, Applied Materials (Israel)
Gadi Greenberg, Applied Materials (Israel)
Daniel Harel, Applied Materials (Israel)
Amiad Conley, Applied Materials (Israel)
Doron Meshulach, Applied Materials (Israel)
Kobi Kan, Applied Materials (Israel)
Ido Dolev, Applied Materials (Israel)
Surender Kumar, Applied Materials (Israel)
Kalia Mendel, Applied Materials (Israel)
Kaori Goto, Applied Materials Japan, Inc. (Japan)
Naoaki Yamaguchi, Applied Materials Japan, Inc. (Japan)
Yasuhiro Iriuchijima, Nikon Corp. (Japan)
Shinichi Nakamura, Nikon Corp. (Japan)
Shirou Nagaoka, Nikon Corp. (Japan)
Toshiyuki Sekito, Nikon 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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