Diffractive phase-shift lithography photomask operating in proximity printing mode

Author(s)

Cirino, Giuseppe A. ^[1] ; Mansano, Ronaldo D. ^[2] ; Verdonck, Patrick ^[3] ; Cescato, Lucila ^[4] ; Neto, Luiz G. ^[5]

Affiliation

^[1] Univ Fed Sao Carlos, CCET, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, PSI, BR-05508970 Sao Paulo - Brazil

^[3] IMEC, B-3001 Louvain - Belgium

^[4] Univ Estadual Campinas, IFGW, BR-13083970 Campinas, SP - Brazil

^[5] Univ Sao Paulo, EESC, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Optics Express; v. 18, n. 16, p. 16387-16405, AUG 2 2010.
• Web of Science Citations: 6

Abstract

A phase shift proximity printing lithographic mask is designed, manufactured and tested. Its design is based on a Fresnel computer-generated hologram, employing the scalar diffraction theory. The obtained amplitude and phase distributions were mapped into discrete levels. In addition, a coding scheme using sub-cells structure was employed in order to increase the number of discrete levels, thus increasing the degree of freedom in the resulting mask. The mask is fabricated on a fused silica substrate and an amorphous hydrogenated carbon (a:C-H) thin film which act as amplitude modulation agent. The lithographic image is projected onto a resist coated silicon wafer, placed at a distance of 50 mu m behind the mask. The results show a improvement of the achieved resolution - linewidth as good as 1.5 mu m - what is impossible to obtain with traditional binary masks in proximity printing mode. Such achieved dimensions can be used in the fabrication of MEMS and MOEMS devices. These results are obtained with a UV laser but also with a small arc lamp light source exploring the partial coherence of this source. (C) 2010 Optical Society of America (AU)

• FAPESP's process: 08/57858-9 - National Institute for Optics and Photonics
• Grantee: Vanderlei Salvador Bagnato
• Support type: Research Projects - Thematic Grants