Overlay and critical dimension control in 100-nm ULSI processes using TaBN x-ray masks and the XRA x-ray stepper

Kiyoshi Fujii; Yuusuke Tanaka; Toshiyuki Iwamoto; Shinji Tsuboi; Hiroaki Sumitani; Takao Taguchi; Katsumi Suzuki; Yasuji Matsui

doi:10.1117/12.436645

20 August 2001 Overlay and critical dimension control in 100-nm ULSI processes using TaBN x-ray masks and the XRA x-ray stepper

Kiyoshi Fujii, Yuusuke Tanaka, Toshiyuki Iwamoto, Shinji Tsuboi, Hiroaki Sumitani, Takao Taguchi, Katsumi Suzuki, Yasuji Matsui

Author Affiliations +

Proceedings Volume 4343, Emerging Lithographic Technologies V; (2001) https://doi.org/10.1117/12.436645
Event: 26th Annual International Symposium on Microlithography, 2001, Santa Clara, CA, United States

Abstract

We developed highly precise x-ray masks and used them to fabricate 100-nm-rule gate and contact-hole (C/H) level masks for 4-Gb DRAM test processes. The masks consisted of 350-nm-thick TaBN absorbers, 3-micrometers -thick SiC membranes, 1- mm-thick Si substrates and 6.63-mm-thick Pyrex glass frames. The membranes and absorbers were deposited in facilities at Hoya Corporation. The frames were bonded to the Si substrates using anodic bonding resulting in a convex surface. An EB-X3 high-precision 100-kV electron-beam writer was used to delineate the patterns. The image placement (IP) accuracy was within +/- 15 nm in both the gate- and C/H-level masks. The critical dimension (CD) variations for 100 nm features measured in a 24 mm square chip area were within +/- 6 nm in the best case. The x-ray masks were used for overlay and CD control evaluating of he XRA mass production x-ray stepper developed by Canon, Inc. The overlay evaluation was done using a double exposure method. The C/H layer was exposed aligning to the gate marks by using the advanced dual grating lens (ADGL) method in global-alignment mode. The total overlay accuracy between the gate and C/H levels was better than +/- 30 nm, including the intra-chip IP errors caused by mask distortion. The overall CD variation for the resist patterns was within +/- 13.1 nm in the gate level and +/- 8.2 nm in the C/H level.

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Kiyoshi Fujii, Yuusuke Tanaka, Toshiyuki Iwamoto, Shinji Tsuboi, Hiroaki Sumitani, Takao Taguchi, Katsumi Suzuki, and Yasuji Matsui "Overlay and critical dimension control in 100-nm ULSI processes using TaBN x-ray masks and the XRA x-ray stepper", Proc. SPIE 4343, Emerging Lithographic Technologies V, (20 August 2001); https://doi.org/10.1117/12.436645

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