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Proceedings Paper

AltPSM contact hole application at DRAM 4xnm nodes with dry 193nm lithography
Author(s): Christoph Noelscher; Thomas Henkel; Franck Jauzion-Graverolle; Mario Hennig; Nicolo Morgana; Ralph Schlief; Molela Moukara; Roderick Koehle; Ralf Neubauer
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Paper Abstract

To avoid expensive immersion lithography and to further use existing dry tools for critical contact layer lithography at 4Xnm DRAM nodes the application of altPSM is investigated and compared to attPSM. Simulations and experiments with several test masks showed that by use of altPSM with suitable 0°/180° coloring and assist placement 30nm smaller contacts can be resolved through pitch with sufficient process windows (PW). This holds for arrays of contacts with variable lengths through short and long side pitches. A further benefit is the lower mask error enhancement factor (MEEF). Nevertheless 3D mask errors (ME) consume benefits in the PW and the assist placement and coloring of the main features (MF) put some constraints on the chip design. An altPSM compatible 4Xnm full-chip layout was realized without loss of chip area. Mask making showed very convincing results with respect to CDU, etch depth uniformity and defectiveness. The printed intra-field CD uniformity was comparable to attPSM despite the smaller target CDs. Room for improvement is identified in OPC accuracy and in automatic assist placement and sizing.

Paper Details

Date Published: 1 April 2008
PDF: 12 pages
Proc. SPIE 6924, Optical Microlithography XXI, 692446 (1 April 2008);
Show Author Affiliations
Christoph Noelscher, Qimonda Dresden GmbH and Co. OHG (Germany)
Thomas Henkel, Qimonda Dresden GmbH and Co. OHG (Germany)
Franck Jauzion-Graverolle, Qimonda Dresden GmbH and Co. OHG (Germany)
Mario Hennig, Qimonda Dresden GmbH and Co. OHG (Germany)
Nicolo Morgana, Qimonda Dresden GmbH and Co. OHG (Germany)
Ralph Schlief, Qimonda Dresden GmbH and Co. OHG (Germany)
Molela Moukara, Qimonda AG (Germany)
Roderick Koehle, Qimonda AG (Germany)
Ralf Neubauer, AMTC GmbH and Co. KG (Germany)

Published in SPIE Proceedings Vol. 6924:
Optical Microlithography XXI
Harry J. Levinson; Mircea V. Dusa, Editor(s)

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