研究生: |
吳政宏 Wu, Cheng-Hung |
---|---|
論文名稱: |
以鎢、鎳為主高功函數金屬閘極之金氧半元件製程研究 Process Study for MOS Devices with Tungsten or Nickel Based High Work Function Metal Gates |
指導教授: |
張廖貴術
Chang-Liao, Kuei-Shu |
口試委員: |
趙天生
崔秉鉞 張廖貴術 |
學位類別: |
碩士 Master |
系所名稱: |
原子科學院 - 工程與系統科學系 Department of Engineering and System Science |
論文出版年: | 2011 |
畢業學年度: | 99 |
語文別: | 中文 |
論文頁數: | 129 |
中文關鍵詞: | 金屬閘極 、鎢 、鎳 |
外文關鍵詞: | Metal Gate, Tungsten, Nickel |
相關次數: | 點閱:2 下載:0 |
分享至: |
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報 |
摘要
為了改善MOSFET電晶體的性能,元件的尺寸被要求越來越小,許多新穎的研究成果已被發表出來,其中,高功函數金屬閘極的研究相當引人注目。
本論文研究的重點放在高功函數金屬閘極和微縮金屬閘極在穩定的厚度上。
第一部份為研究WN、WHfxN和WMoxN,運用在high-k介電層材料 HfAlO。根據學長的研究結果,合金式WHfxN的可靠性相當好。沉積WMoxN主要的想法是,是否合金式金屬閘極的元件可靠性都會比單層金屬閘極WN來得好,若能選用高功函數的材料摻雜,能提高元件的可靠性,又不失其高功函數的特性。由實驗結果發現,WHfxN的EOT和Jg的熱穩定性都很好。而WHfxN和WMoxN,在經過高溫退火之後,都有修補界面鍵結的現象,因此在可靠性上的表現,WHfxN和WMoxN在高溫時表現比WN還要好,WMoxN在PMA850 oC時比WN和WHfxN金屬閘極有更優秀的reliability。功函數方面,三種結構之功函數,皆相當適合於pMOS元件的應用。
第二部分為探討金屬閘極WMoxN元件結構的改善,延續第一部分,並搭配high-k介電層材料 HfAlO,致力改善元件的熱穩定性、電特性與可靠性。其一為,尋找摻雜Mo原子的最適當比例,期望能藉由合金式金屬閘極的最佳比例,進而改善元件特性。但實驗發現,降低摻雜Mo的比例,其元件電特性接近WN單層金屬閘極,沒有達到利用合金式金屬閘極高溫修補界面鍵結,抑制金屬離子擴散的效果,元件可靠性亦無法提升。其二為,在WMoxN和high-k介電層HfAlO之間,增加熱穩定性好的WHfxN,期望藉由熱穩定性佳的WHfxN當作阻障層,降低界面金屬離子的擴散,提升元件的熱穩定性、電特性與可靠性。由實驗結果發現,漏電流Jg 和Hysteresis特性都獲得改善,在元件可靠性方面,從Stress induced Vfb shift特性看出,此結構有效地改善元件的reliability,而從SILC特性得知,PMA溫度750oC、850oC下,亦有效提升元件的reliability。
第三部分探討堆疊金屬閘極Ni/TaN,並運用在high-k介電層材料 HfON。前述兩個部分的實驗,建立在高溫退火溫度約800oC~850oC,以利形成高功函數的結晶,本實驗期望能降低退火溫度,達到減緩界面金屬離子的擴散的效果,提高元件的可靠性。因此Ni金屬閘極的研究相當引人注目。但由於Ni金屬閘極在經過高溫退火之後,Ni擴散較為嚴重,所以在Ni金屬閘極和high-k介電層HfON之間,堆疊穩定的金屬閘極TaN,期望能抑制Ni擴散。並對堆疊完TaN金屬閘極後,比較TaN有無退火溫度650oC,對Ni擴散的抑制情形,並對元件進行熱穩定性、電特性與可靠性的分析。實驗發現,堆疊TaN後,先經過退火溫度650oC,再堆疊Ni後再PMA,會發現Ni比較容易向下擴散。而元件電特性和可靠性會隨著PMA溫度變高,會變差。而堆疊完成Ni/TaN金屬閘極,後再PMA,發現Ni要到PMA650oC才比較容易向下擴散,Hysteresis特性隨著PMA溫度變高,會變好。在可靠性方面,SILC為PMA550oC會最好,Stress induced Vfb shift為PMA650oC會最好。
第四部分探討微縮金屬閘極的厚度,搭配不同介電層HfAlO與HfO2,尋找微縮金屬閘極到最小厚度時,其厚度亦能保有穩定的閘極元件特性,其實驗結果,可以應用到多種CMOS元件的製程上。實驗發現,兩者在微縮TaN金屬閘極厚度至20nm時,可以保持與TaN厚度50nm,有相同的閘極元件電特性。在元件可靠性方面,TaN金屬閘極搭配介電層為HfAlO,依然必須是TaN=50nm,才會有較好的reliability。然而,TaN金屬閘極搭配介電層為HfO2,則是TaN=20nm,會有較好的reliability。
參考文獻
[1] M. S. Krishinan, et al., IEDM, pp. 571, 1998
[2] C. Hobbs, et al., IEEE Symp. On VLSI Technology Tech, Dig., 2-1, 2003.
[3] C. Hobbs, et al., IEEE Elec. Dev. Lett., vol.51(6), pp.978, 2004.
[4] Seiichiro KAWAMURA, IEEE Custom Integrated Circuits Conference, pp.467-474, 2002
[5] D. G. Park, et al., IEDM Tech. Dig., pp.671, 2001.
[6] H. Zhong, et al., Appl. Phys. Lett., vol.78, pp.1134-1136, 2001.
[7] H. Zhong, et al., J. of Electronic Materials, vol.30, pp.1493, 2001.
[8] Y. H. Kim, et al., IEDM Tech. Dig., pp.667, 2001.
[9] J. K. Schaeffer, et al., MRS spring meeting, April, 2002.
[10] I. Polishchuk, et al., IEEE Electron Device Lett., vol.22, pp.444, 2001.
[11] H. Zhong, et al., IEDM Tech. Dig., pp.467, 2001.
[12] C. Wang, et al., Appl. Phys. Lett., vol.83 (2), pp.308, 2003.
[13] C. Hobbs, et al., Symp. VLSI Tech. Dig., pp.9, 2003
[14] IEDM Short Course, Mark Rodder, Texas Instrument, 2004
[15] IEDM Short Course, Stefan De Gendt, IMEC, 2004
[16] W. Zhu, et al., Trans. Elec. Dev. Lett., vol.51 (1), pp.98, 2004.
[17] M. V. Fischetti, et al., J. Appl. Phys., vol.90 (9), pp.4587, 2001.
[18] Robert Chau, et al., Elec. Dev. Lett., vol.25 (6), pp.408, 2004
[19] H. Ono, et al., Appl. Phys. Lett., vol.73, no.11, pp.1517, 1998
[20] R. Beyers, J. of Appl. Phys., vol.56, pp.1, 1984
[21] V. Misra, et al., MRS bulletin, vol.27, no.3, pp.212, 2002
[22] C.Wang, et al., Appl.Phys.Lett.,vol.83, pp.308, 2003
[23] S. Zafar , et al., Apply Phys. Letter, vol. 80, pp. 4858-4860, 2002.
[24] Huang-Chun Wen, et al., IEEE EDL, vol.27, no.7 pp.598-601, July 2006
[25] Po-Yen. Chien, Integration of electrical characteristics for MOS devices with Molybdenum metal gate 2007, thesis in the Department of Engineering and System Science, NTHU.
[26] N. V. Nguyen, et al., Appl. Phys. Lett., 77, 3012 , 2000
[27] P. T. Gao, et al., Thin Solid Films, 377, 557 , 2000
[28] K. Kukli, et al., Thin Solid Films, 260, 135 , 1995
[29] M. Cassir, et al., Appl. Surf. Sci., 193, 120 , 2002
[30] C. M. Perkins, et al., Appl. Phys. Lett., 78, 2357 , 2001
[31] C. Chaneliere, et al., Microelectron. Reliab., 39, 261 , 1999
[32] D. D. L. Chung, et al., X-Ray Diffraction at Elevated Temperatures: A Method for In-Situ Process Analysis, Chap.1, VCH Publishers, New York ,1993
[33] Powder Diffraction File: Inorganic and Organic Data Book, PDF#19-1299, 25-0922, 25-1257, 25-1366, 27-1402, 34-1084, 42-0060, 42-1120, and 72-1088, JCPDS – International Center for Diffraction Data, American Society for Testing and Materials, Swarthmore, PA (1950-2003).
[34 ] K. Onishi, et al., Symp. VLSI Tech., pp.131, 2001.
[35] Po-Yen. Chien, Integration of electrical characteristics for MOS devices with Molybdenum metal gate 2007, thesis in the Department of Engineering and System Science, NTHU.
[36] D. K. Schroder, Semiconductor Material and Device Characterization, 2nd ed., John Wiley & Sons, New York , 1998
[37] Chih-Feng HUANG, Japanese Journal of Applied Physics Vol. 47, No. 2, pp. 872–878, 2008
[38] Integration of Metal Gate and High-k Gate Dielectric for Advanced MOS Devices H. C. Chang , 2006
[39] H. R. Gong, Kyeongjae Cho,“Electronic structure and work function of metal gate Mo–W system, ” APL 91, 092106 , 2007
[40] J. F. Kang, et al., IEEE Electron Device Lett, 26: 237-9 , 2005
[41] Heiji Watanabe, et al., APL 85, pp.449, 2004
[42] Jahan C, et al., Microelectron Reliab. 37 1529-32, 1997.
[43] Paul E. Nicollian, et al., in IRPS, pp.400-404, 1999
[44] Huei-Chi Chuang, “Electrical characteristic enhancement of MOS device with gate stack dielectrics and interfacial layer engineering ” NTHU, thesis in the Department of Engineering and System Science, 2007
[45] Kuei-Shu Chang-Liao, Yen-Ling Tseng,“Process Study for MOS Devices with Molybdenum and Tungsten Based High Work Function Metal Gates ”,2009
[46] Ting-Chou Lu, et al., “Temperature Coefficient of Poly-Silicon TFT and Its Application on Voltage Reference Circuit With Temperature Compensation in LTPS Process, ” IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 55, NO. 10, pp.2583-2589, OCTOBER 2008
[47] Chin-Lung Cheng,et al., “Device and Materials Reliability, ” IEEE Transactions on, vol.10, pp.116-122, 2010
[48] Woo Young Choi,et al., “Tunneling Field-Effect Transistors (TFETs) With Subthreshold Swing (SS) Less Than 60 mV/dec, ” IEEE ELECTRON DEVICE LETTERS, VOL. 28, NO. 8, pp.743-745, AUGUST 2007
[49] F. Fillot, S. Maitrejean ,et al., “Experimental study of the minimum metal gate thickness required to fix the effective work function in metal-oxide-semiconductor capacitors, ” APL 92 , pp.023503 1-3 , 2008