Integration of BaxSr1-xTiO3 thin film for DRAM application

Keiichiro Kashihara; Tomonori Okudaira; Yoshikazu Tsunemine; Yoshikazu Ohno; Hiromi Itoh; Tadashi Nishimura; Makoto Hirayama; Tsuyoshi Horikawa; Teruo Shibano; Kazuo Horie

doi:10.1117/12.221125

15 September 1995 Integration of Ba_xSr_1-xTiO₃ thin film for DRAM application

Keiichiro Kashihara, Tomonori Okudaira, Yoshikazu Tsunemine, Yoshikazu Ohno, Hiromi Itoh, Tadashi Nishimura, Makoto Hirayama, Tsuyoshi Horikawa, Teruo Shibano, Kazuo Horie

Author Affiliations +

Proceedings Volume 2636, Microelectronic Device and Multilevel Interconnection Technology; (1995) https://doi.org/10.1117/12.221125
Event: Microelectronic Manufacturing '95, 1995, Austin, TX, United States

Abstract

This paper presents a newly developed process technology to integrate the Ba_xSr_1-xTiO₃(BST) thin film prepared by an rf magnetron sputtering. Evaluations of the integrated BST capacitors on a test element group (TEG) structure revealed some of key issues for a successful integration. A two-step sputtering method comprising the first step to form a nucleation layer and the second step to form the main part of the BST film was found to be useful for preventing the dielectric properties of the integrated BST thin film from the degradation. A careful control of the shape of the lower structures such as the edge of the bottom electrode or the poly Si plug of the storage node turned to be indispensable to obtain the reliable capacitor and this recommends the extensive use of the process that can provide a flush surface such as the Chemical Mechanical Polishing (CMP) in the future integration. The interlevel dielectrics over the BST capacitor was shown to seriously affect the leakage characteristics and an undoped SiO₂ film was most suitable for the integrity, implying the needs for another planarization technique instead of the glass reflow. Finally, a preliminary evaluation of the reliability and the normal bit function of a 4 Mbits DRAM, made of fully flat BST stacked capacitors, demonstrated the utility of the developed integration technology.

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Keiichiro Kashihara, Tomonori Okudaira, Yoshikazu Tsunemine, Yoshikazu Ohno, Hiromi Itoh, Tadashi Nishimura, Makoto Hirayama, Tsuyoshi Horikawa, Teruo Shibano, and Kazuo Horie "Integration of Ba_xSr_1-xTiO₃ thin film for DRAM application", Proc. SPIE 2636, Microelectronic Device and Multilevel Interconnection Technology, (15 September 1995); https://doi.org/10.1117/12.221125

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