Effect of SiC x-ray masks on alignment accuracy of heterodyne alignment

Hajime Aoyama; Fumiaki Kumasaka; Yoshihisa Iba; Takao Taguchi; Masayuki Takeda; Masaki Yamabe; Makoto Fukuda; Masanori Suzuki; Kimiyoshi Deguchi

doi:10.1117/12.275796

7 July 1997 Effect of SiC x-ray masks on alignment accuracy of heterodyne alignment

Hajime Aoyama, Fumiaki Kumasaka, Yoshihisa Iba, Takao Taguchi, Masayuki Takeda, Masaki Yamabe, Makoto Fukuda, Masanori Suzuki, Kimiyoshi Deguchi

Author Affiliations +

Proceedings Volume 3048, Emerging Lithographic Technologies; (1997) https://doi.org/10.1117/12.275796
Event: Microlithography '97, 1997, Santa Clara, CA, United States

Abstract

This paper describes the results of a study to investigate the applicability of silicon carbide (SiC) x-ray masks to an optical-heterodyne alignment technique. SiC was deposited at a thickness of 2 micrometer on a 4 inch silicon (Si) wafer. Its surface roughness was improved from 15 nm Ra (geometrical average) to 0.2 nm Ra using a polishing method. Using this SiC material, x-ray masks with Ta absorber patterns for alignment marks and overlay measurement were fabricated. To obtain a high overlay repeatability, we have deposited an anti- reflection coating (ARC) on both sides of the x-ray mask, which increased an optical transmission at a wavelength of 785 nm from 37% to 73%. We have also deposited an opaque coating (OPC) on the mask alignment mark. Using the x-ray mask, the overlay repeatability by mix-and-match method was evaluated. The overlay repeatability near the X, Y and (theta) alignment marks was 21 nm, 21 nm, and 49 nm (3 sigma) for the corresponding axes. The overlay repeatability of the X and Y directions was 61 nm and 54 nm (3 sigma) in a wafer. These results are equivalent to the results obtained using SiN x-ray masks. From these results, we consider that SiC x-ray masks are applicable to optical heterodyne alignment, and can also be used in practical x-ray lithography.

Citation Download Citation

Hajime Aoyama, Fumiaki Kumasaka, Yoshihisa Iba, Takao Taguchi, Masayuki Takeda, Masaki Yamabe, Makoto Fukuda, Masanori Suzuki, and Kimiyoshi Deguchi "Effect of SiC x-ray masks on alignment accuracy of heterodyne alignment", Proc. SPIE 3048, Emerging Lithographic Technologies, (7 July 1997); https://doi.org/10.1117/12.275796

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