Process variation monitoring (PVM) by wafer inspection tool as a complementary method to CD-SEM for mapping LER and defect density on production wafers

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

doi:10.1117/12.814063

23 March 2009 Process variation monitoring (PVM) by wafer inspection tool as a complementary method to CD-SEM for mapping LER and defect density on production wafers

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

Author Affiliations +

Proceedings Volume 7272, Metrology, Inspection, and Process Control for Microlithography XXIII; 72720O (2009) https://doi.org/10.1117/12.814063
Event: SPIE Advanced Lithography, 2009, San Jose, California, United States

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.

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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, and Toshiyuki Sekito "Process variation monitoring (PVM) by wafer inspection tool as a complementary method to CD-SEM for mapping LER and defect density on production wafers", Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72720O (23 March 2009); https://doi.org/10.1117/12.814063

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KEYWORDS

Semiconducting wafers

Line edge roughness

Wafer inspection

Finite element methods

Inspection

Polarization

Critical dimension metrology

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