Application of Pulsed Chemical Vapor Deposited Tungsten Thin Film as a Nucleation Layer for Ultrahigh Aspect Ratio Tungsten-Plug Fill Process

Byeonghyeon Jang; Soo-Hyun Kim

Korean Journal of Materials Research, Vol.26, No.9, 486-492, September, 2016

DOI10.3740/MRSK.2016.26.9.486 Export Citation

Application of Pulsed Chemical Vapor Deposited Tungsten Thin Film as a Nucleation Layer for Ultrahigh Aspect Ratio Tungsten-Plug Fill Process

Byeonghyeon Jang, and Soo-Hyun Kim^†

School of Materials Science and Engineering, Yeungnam Universitsy, 280 Daehak-ro, Gyeongsan, Gyeongbuk 38541, Republic of Korea

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Tungsten (W) thin film was deposited at 400 °C using pulsed chemical vapor deposition (pulsed CVD); film was then evaluated as a nucleation layer for W-plug deposition at the contact, with an ultrahigh aspect ratio of about 14~15 (top opening diameter: 240~250 nm, bottom diameter: 98~100 nm) for dynamic random access memory. The deposition stage of pulsed CVD has four steps resulting in one deposition cycle: (1) Reaction of WF6 with SiH4. (2) Inert gas purge. (3) SiH4 exposure without WF6 supply. (4) Inert gas purge while conventional CVD consists of the continuous reaction of WF6 and SiH4. The pulsed CVD-W film showed better conformality at contacts compared to that of conventional CVD-W nucleation layer. It was found that resistivities of films deposited by pulsed CVD were closely related with the phases formed and with the microstructure, as characterized by the grain size. A lower contact resistance was obtained by using pulsed CVD-W film as a nucleation layer compared to that of the conventional CVD-W nucleation layer, even though the former has a higher resistivity (~100 μΩ-cm) than that of the latter (~25 μΩ-cm). The plan-view scanning electron microscopy images after focused ion beam milling showed that the lower contact resistance of the pulsed CVD-W based W-plug fill scheme was mainly due to its better plug filling capability.

Keywords:tungsten(W);pulsed chemical vapor deposition;W-plug;nucleation layer;contact resistance

[References]

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[1] Schmitz JEJ, Chemical vapor deposition of tungsten and tungsten silicide, Noyes, Park Ridge, New Jersey (1992).

[2] Broadbent EK, Ramiller CL, J. Electrochem. Soc., 131, 1427 (1984)

[3] McConica CM, Krishnamani K, J. Electrochem. Soc., 133, 2542 (1986)

[4] McInerney EJ, Mountsier TW, Chin BL, Broadbent EK, J. Vac. Sci. Technol. B, 11, 734 (1993)

[5] Herner SB, Desai SA, Nak A, Ghanayem SG, Electrochem. Solid State Lett., 2, 398 (1999)

[6] Nicolet MA, Appl. Surf. Sci., 91, 269 (1995)

[7] Omstead T, D’Couto GC, Lee SH, Wongsenkaum P, Collins J, Levy K, Solid State Technol., 51, 45 (2002)

[8] International Technology Roadmap for Semiconductors (ITRS), 2011 Edition, Interconnect Summary.

[9] Suntola T, Handbook of Crystal Growth, edited by Hurle DTJ, (Elsevier Science B. V., 1994), Vol. 3, Chapter 14.

[10] Klaus JW, Ferro SJ, George SM, Thin Solid Films, 360(1-2), 145 (2000)

[11] Lee SH, Gonzalez L, Collins J, Ashitani K, Levy K, Conference Proceedings ULSI XVII, 649 Materials Research Society (2002).

[12] Okubo K, Ishizuka H, Suzuki K, Sato K, Tachibana M, Conference Proceedings ULSI XVII, 661 Materials Research Society (2002).

[13] Yang M, Chung H, Yoon A, Fang H, Zhang A, Knepfler C, Jackson R, Byun JS, Mak A, Eizenberg M, Xi M, Kori M, Sinha AK, Conference Proceedings ULSI XVI, 655 Materials Research Society (2002).

[14] Kim SH, Hwang ES, Han SY, Pyi SH, Kawk N, Sohn H, Kim J, Choi GB, Electrochem. Solid State Lett., 7(9), G195 (2004)

[15] Kim SH, Hwang ES, Ha SC, Pyi SH, Sun HJ, Lee JW, Kawk N, Kim JK, Sohn H, Kim J, J. Electrochem. Soc., 152(6), C408 (2005)

[16] Tanaka Y, Kim E, Forster J, Xu Z, J. Vac. Sci. Technol. B, 17(2), 416 (1999)

[17] Petroff PM, Sinha AK, Sheng TT, Levinstein HJ, Alexander FB, J. Appl. Phys., 44, 2545 (1973)