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Proceedings Paper

Highly anisotropic etching of phase-shift masks using ICP of CF4-SF6-CHF3 gas mixtures
Author(s): Se-Jong Choi; Han-Sun Cha; Si-Yeul Yoon; Yong-Dae Kim; Dong-Hyuk Lee; Jin-Min Kim; Jin-Su Kim; Dong-Soo Min; Pil-Jin Jang; Byung-Soo Chang; Hyuk-Joo Kwon; Boo-Yeon Choi; Sang-Soo Choi; Soo Hong Jeong
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Paper Abstract

There is considerable interest in phase shift masks as a route to extending the resolution, contrast, and depth of focus of lithographic tools beyond what is achievable with the normal chrome mask technology. A problem that has so far hindered the introduction of phase shift masks has been the difficulty of phase and transmittance control when a phase shift mask is applied to practical use. Also, to apply phase shift layer (MoSiON), it remains that effects several critical mask parameters including sidewall slope, surface roughness, and critical dimension. For these reasons, this process requires a high degree of control of the etch process of shift layer. So in this paper, we described a technique for the fabrication of phase shift masks by etch rate of a MoSiON layer. Etching experiments of MoSiON were performed using different fluorinated gas mixtures. Four of them, CF4/O2/He, SF6/O2/He, CHF3/O2/He and Cl2/CF4/O2/He were chosen for high etch rate, sidewall slope, and surface morphology. Each added gases had a unique property on the etch rate, anisotropy, surface roughness and sidewall morphology. Result indicates that vertical slope and smooth surface are obtained using the Cl2/ CF4/O2/He and SF6/O2/He mixture. With increasing O2 flow rate to the SF6/O2/He Plasma and added Cl2 gas to the CF4/O2/He Plasma, the MoSiON etching profile becomes anisotropic without undercutting and trench profile. It is probably due to both increasing etch rate and sidewall passivation of Cl2 ion flux. When Cl2 gas was added to the CF4/O2/He Plasma, the small addition of chlorine was enough to protect the exposed sidewall of the undercutting, therefore, higher flow rate of chlorine had to be added to protect the sidewall of the undercutting by forming a sidewall passivation layer. These results show that both increasing O2 flow rate to the SF6/O2/He Plasma and the addition of Cl2 to the CF4/O2/He plasma are necessary in order to achieve a vertical profile and a smooth surface morphology.

Paper Details

Date Published: 1 August 2002
PDF: 9 pages
Proc. SPIE 4754, Photomask and Next-Generation Lithography Mask Technology IX, (1 August 2002); doi: 10.1117/12.476984
Show Author Affiliations
Se-Jong Choi, PKL (South Korea)
Han-Sun Cha, PKL (South Korea)
Si-Yeul Yoon, PKL (South Korea)
Yong-Dae Kim, PKL (South Korea)
Dong-Hyuk Lee, PKL (South Korea)
Jin-Min Kim, PKL (South Korea)
Jin-Su Kim, PKL (South Korea)
Dong-Soo Min, PKL (South Korea)
Pil-Jin Jang, PKL (South Korea)
Byung-Soo Chang, PKL (South Korea)
Hyuk-Joo Kwon, PKL (South Korea)
Boo-Yeon Choi, PKL (South Korea)
Sang-Soo Choi, PKL (South Korea)
Soo Hong Jeong, PKL (South Korea)

Published in SPIE Proceedings Vol. 4754:
Photomask and Next-Generation Lithography Mask Technology IX
Hiroichi Kawahira, Editor(s)

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