在本次研究中，我們製作出鋁(Al)/鐵酸鉍(BFO)/氧化釔(Y2O3)/半導體結構的電容器與場效電晶體。在電容器方面，為了探討BFO薄膜在不同溫度下退火的效果，我們分別施以500 ℃和600 ℃的退火處理並對其作比較。結果顯示，500 ℃的退火溫度在電性上的結果優於600 ℃，退火溫度500 ℃的最大記憶窗約0.91 V，而漏電流在5 V下約2 x 10-7 A/cm2。
　　另外，我們也使用表面處理的方法試圖改善絕緣層與半導體間的介面特性，進而降低漏電流。在沉積絕緣層前先將晶圓浸泡H2O2，並且在沉積絕緣層後再以稀釋的鹽酸溶液沖洗晶圓。在表面處理後，漏電流從原先的2 x 10-7 A/cm2 降低到 4 x 10-9 A/cm2。
　　在電晶體方面，我們得到不錯的IDS-VDS與IDS-VGS特性，從量測到的資料來分析，次臨界斜率約155 mV/dec，最大電荷遷移率155 cm2/V-s，IDS-VGS的開關電流比值在4個數量級左右。而記憶體特性量測上，IDS-VGS記憶窗最大值約0.93 V左右，至於電荷保持時間在經過10000秒之後仍然保有3個數量級的IDS電流比值。
　　從以上的結果我們可以歸納出，鋁(Al)/鐵酸鉍(BFO)/氧化釔(Y2O3)/半導體結構的電容器與場效應電晶體在非揮發性記憶體的應用上，是很適合的選擇。

Al/ BiFeO3 (BFO)/ Y2O3/ p-Si metal ferroelectric insulator semiconductor (MFIS) capacitors and transistors were fabricated. To compare the effect of different annealing temperature, the BFO thin films were annealed at 500 ℃ and 600 ℃. The BFO films annealed at 500 ℃ show better electrical properties than those at 600 ℃. The maximum C-V memory window was 0.91 V at the annealing temperature of 500 ℃. The corresponding leakage current density was 2 x 10-7 A/cm2 at a bias voltage of 5 V.
In addition, a surface treatment method was also used to passivate the Y2O3/Si interface and to reduce the leakage current. The wafers were given a H2O2 pre-treatment before Y2O3 deposition and a HCl post-treatment after deposition. The leakage current density at a bias voltage of 5 V was reduced from 2 x 10-7 A/cm2 to 4 x 10-9 A/cm2.
The fabricated MFIS transistors (MFIS-FET) show good transistor characteristics. The subthreshold swing (St) was about 155 mV/dec. The IDS-VGS on-off ratio was approximately 4 orders of magnitude. The maximum electron mobility was 155 cm2/V-s. To measure the memory properties, the shift of IDS-VGS curves was observed. The maximum IDS-VGS memory window was 0.93 V. The drain current on/off ratio was more than 3 orders of magnitude after applying poling voltages of ± 7 V with duration of 10 μs. The IDS maintains an on/off ratio of more than 3 orders after an elapsed time of 104 sec.
These results show that the Al/BFO/Y2O3/p-Si structure has great potential for nonvolatile memory applications.

Chapter 1
[1] 賴明駿, “極大型積體電路之鐵電材料”, 電子月刊, 第五卷第六期, p. 94. 1996.
[2] B. W. Shen, G. Chung, I. C. Chen, D. J. Coleman, P. S. Ying, R. McKee, M. Yashiro, and C. W. Teng, “Scalability of a trench capacitor cell for 64 Mbit.,” IEDM Tch. Dig., pp. 27, 1989.
[3] 何彬明, “FeRAM產品化的崎嶇道路,” 電子月刊, 第五卷第三期, p.166. 1996.
[4] T. Eimori and B. Desu, “A newly designed planar stacked capacitor cell with high dielectric constant film for 256Mbit DRAM,” IEEE IEDM, pp.631-634, 1993.
[5] T. Sumi and P. D. Maniar, “Ferroelectric nonvolatile memory technology and its applications,” Jpn. J. Appl. Phys., vol. 35, pp.1516-1520, 1996.
[6] S. L. Miller and P. J. McWhorter, “Physics of the ferroelectric nonvolatile memory field effect transistor,” J. Appl. Phys., vol. 72, pp.5999-6010, 1992.
[7] R. Moazzami, C. Hu, and W.H. Shepherd, “A ferroelectric DRAM cell for high-density NVRAM’s,” IEEE Electron Device Lett., pp.454-456, 1990.
[8] 李雅明, 吳世明, 陳宏名, “鐵電記憶元件”, 電子月刊, 9月號, 1996.
[9] S. Sinharoy, H. Buhay, D. R. Lampe, and M. H. Francombe, “Integration of ferroelectric thin films into nonvolatile memories,” Journal of Vacuum Science & Technology A., vol. 10, pp.1554-1561, 1992.
[10] T. Nakamur and Y. Fujimor, “Fabrication technology of ferroelectric memories,” Jpn. J. Appl. Phys. part. 1, vol. 37, pp.1325-1327, 1998.
[11] K. H. Kuo and M. J. Sun, “Metal-ferroelectric-semiconductor (MFS) FET’s using LiNbO3/Si (100) structures for nonvolatile memory Application,” IEEE Electron Device Lett., vol. 19, pp.204-206, 1998.
[12] K. Sugibuchi, Y. Kurogi, and N. Endo, “Ferroelectric field-effect memory device using Bi4Ti3O12 film,” J. Appl. Phys., vol. 46, pp.2877-2881, 1975.
[13] N. A. Basit and H. K. Kim, “Growth of highly oriented Pb(Zr,Ti)O3 films on MgO-buffered oxidized Si Substrates and its application to ferroelectric nonvolatile memory field-effect transistors ,” Appl. Phys. Lett., vol. 73, no. 26, pp. 3941-3943, 1998.
[14] H. N. Lee, M. H. Lim, and Y. T. Kim, “Characteristics of metal/ferroelectric/insulator/semiconductor field effect transistors using a Pt/SrBi2Ta2O9 /Y2O3 /Si structure,” Jpn. J. Appl. Phys., vol. 37, part 1, no.3B, pp.1107-1109, 1998.
[15] N. A. Basit and H. K. Kim, “Growth of highly oriented Pb(Zr,Ti)O3 films on MgO-buffered oxidized Si Substrates and its application to ferroelectric nonvolatile memory field-effect transistors ,” Appl. Phys. Lett., vol. 73, no. 26, pp.3941-3943, 1998.
[16] H. Ishiwara, M. Okuyama, and Y. Arimoto, “Ferroelectric Random Access Memories”, Springer-Verlag, Berlin, Heidelberg, p. 3-4, 2004.
[17] W. I. Kinney, W. Shepherd, W. Miller, J. Evans and R. Womack, “A non-volatile memory cell based on ferroelectric storage capacitors”, IEEE IEDM, 87, 850, 1987.
[18] June-Mo Koo, B. S. Seo, S. Kim, S. Shin, J. H. Lee, H. Baik, J. H. Lee, J. H. Lee, B. J. Bae, J. E. Lim, D. C. Yoo, S. O. Park, H. S. Kim, H. Han, S. Baik, J. Y. Choi, Y. J. Park, and Y. Park, “Fabrication of 3D trench PZT capacitors for 256Mbit FRAM device application”, IEEE IEDM, 2005.
[19] J. H. Kim, D. J. Jung, S. K. Kang, Y. M. Kang, H. H. Kim, J. Y. Kang, E. S. Lee, W. W. Jung, H. J. Joo, J. Y. Jung, J. H. Park, H. Kim, D. Y. Choi, S. Y. Lee, H. S. Jeong, and K. Kim, “Manufacturing Technologies for a Highly Reliable, 0.34μm2–Cell, 64Mbit, and 1T1C FRAM”, IEEE IEDM, 2006.
[20] Y. M. Kang, H. J. Joo, J. H. Park, S. K. Kang, J. H. Kim, S. G. Oh, H. S. Kim, J. Y. Kang, J. Y. Jung, D. Y. Choi, E. S. Lee, S. Y. Lee, H. S. Jeong, and K. Kim, “World Smallest 0.34μm2 COB Cell 1T1C 64Mb FRAM with Sensing Architecture and Highly Reliable MOCVD PZT Integration Technology”, IEEE VLSI, 124-125, 2006.
[21] O. Hidaka, T. Ozaki, H. Kanaya, Y. Kumura, Y. Shimojo, S. Shuto, Y. Yamada, K. Yamakawa, S. Yamazaki, D. Takashima, T. Miyakawa, S. Shiratake, S. Ohtsuki, I. Kunishima, and A. Nitayama, “High Density and High Reliability Chain FeRAM with Damage-robust MOCVD-PZT Capacitor with SrRuO3/IrO2 Top Electrode for 64Mb and Beyond”, IEEE VLSI, 126-127, 2006.
[22] Y. K. Hong, D. J. Hong, S. K. Kang, H. S. Kim, J. Y. Jung, H. K. Koh, J. H. Park, D. Y. Choi, S. E. Kim, W. S. Ann, Y. M. Kang, H. H. Kim, J.-H. Kim, W. U. Jung, E. S. Lee, S. Y. Lee, H. S. Jeong, and Kinam Kim, “130 nm –technology, 0.25μm2, 1T1C FRAM Cell for SoC (System-on-a-Chip)-friendly Applications”, IEEE VLSI, 130-131, 2007.
[23] Y. Kato, Y. Kaneko, H. Tanaka, K. Kaibara, S. Koyama, K. Isogai, T. Yamada, and Y. Shimada, “Overview and Future Challenge of Ferroelectric Random Access Memory Technologies”, Jpn. J. Appl. Phys., vol. 46, no. 4B, pp.2157-2163, 2007.
[24] S. Y. Wu, “A new ferroelectric memory device MFS transistor”, IEEE Trans. Electron Devices, vol. ED-21, no. 8 , p499, 1974.
[25] T. P. Ma and J. P. Han, “Why is nonvolatile ferroelectric memory field-effect transistor still elusive,” IEEE Electron Device Letters, vol. 23, no. 7, pp. 386-388, 2002.
[26] K. Aizawa, B. E. Park, Y. Kawashima, K. Takahashi, and H. Ishiwara, “Impact of HfO2 buffer layers on data retention characteristics of ferroelectric-gate field-effect transistors,” Appl. Phys. Lett., vol. 85, no. 15, pp. 3199-3201, 2004.
[27] M. Takahashi, and S. Sakai, “Self-Aligned-Gate Metal/ Ferroelectric/ Insulator/ Semiconductor Field-Effect Transistors with Long Memory Retention”, Jpn. J. Appl. Phys., vol. 44, no. 25, pp. L800-L802, 2005.
[28] P. Cappelletti, C. Golla, P. Olivo, and E. Zanoni, “Flash Memories”, Kluwer Academic, 1999.
[29] 沈士傑, “淺談快閃式記憶體(Flash Memory)之發展”, 電子月刊, 9月號, 1996.
[30] V. R. Palkar, J. John, and R. Pinto, “Observation of saturated polarization and dielectric anomaly in magnetoelectric BiFeO3 thin films”, Appl. Phys. Lett., Vol. 80, no. 9, p.1628-1630, 2002.
[31] Y. W. Chiang and J. M. Wu, “Characterization of metal-ferroelectric (BiFeO3) -insulator (ZrO2)- silicon capacitors for nonvolatile memory applications”, Appl. Phys. Lett, vol. 91, 142103, 2007.

Chapter 2
[32] H. M. Dulker, P. D. Beal, and J. F. Scott, “Fatigue and switching in ferroelectric memories: theory and experiment,” J. Appl. Phys., vol. 68, pp. 5783-5791, 1990.
[33] G. W. Dietz, M. Schumacher, and R. Waser, “Leakage current in Ba0.7Sr0.3TiO3 thin films for ultrahigh-density dynamic random access memories,” J. Appl. Phys., vol. 82, no. 5, pp. 2359-2361, 1997.
[34] Y. N. Venevtsev, G. Zhadanov and S. Solon’ev, Sov. Phys. Crystallogr., vol. 4, 538, 1960.
[35] G. Smolenskii, V. Isupov, A. Agranovskaya and N. Kranik, “New Ferroelectrics of Complex Composition IV”, Sov. Phys. - Solid State, vol. 2, pp. 2651-2654, 1961.
[36] E. Ascher, H. Rieder, H. Schmid, and H. Stossel, “Some Properties of Ferromagnetoelectric Nickel-Iodine Boracite, Ni3B7O13I”, J. Appl. Phys., vol. 37, no. 3, p. 1404-1405, 1966.
[37] G. A. Smolensky, V. A. Isupov, N. N. Krainik, and A. I. Agranovskaya, “Concerning the Coexistance of the Ferroelectric and Ferrimagnetic States”, Isv. Akad. Nauk SSSR, Ser Fiz. 25, 1333, 1961.
[38] Y. N. Venevtsev, V. Gagulin, and I. D. Zhitomirsky, “Material Science aspects of Seignette-Magnetism Problem”, Ferroelectrics, 73, 221, 1987.
[39] C. Michael, J. M. Moreau, G. D. Achenbach, R. Gerson, and W. J. James, “The atomic structure of BiFeO3”, Solid State Commun., 7, 701, 1969.
[40] B. Ruette, S. Zvyagin, A. Pyatakov, A. Bush, J. F. Li, V. I. Belotelov, A. K. Zvezdin, and D. Viehland, “Magnetic-field-induced phase transition in BiFeO3 observed by high-field electron spin resonance: Cycloidal to homogeneous spin order”, Phys. Rev. B, 69, 064114, 2004.
[41] J. Wang, J. Neaton, H. Zheng, V. Nagarajan, S. B. Ogale, B. Liu, D. Viehland, V. Vaithyanathan, D. G. Schlom, U. V. Waghmare, N. A. Spaldin, K. M. Rabe, M. Wuttig, and R. Ramesh, “Epitaxial BiFeO3 Multiferroic Thin Film Heterostructures”, Science, 299, 1719, 2003.
[42] K. Y. Yun, D. Ricinschi, T. Kanashima, M. Noda, and M. Okuyama, “Giant Ferroelectric Polarization Beyond 150 μC/m2 in BiFeO3 Thin Film”, Jpn. J. Appl. Phys., vol. 43, no. 5A, pp. L647-L648, 2004.
[43] S. K. Singh and H. Ishiwara, “Reduced Leakage Current in BiFeO3 Thin Films on Si Substrates Formed by a Chemical Solution Method”, Jpn. J. Appl. Phys., vol. 44, no. 23, pp. L734-L736, 2005.
[44] C. C. Lee and J. M. Wu, “Effect of film thickness on interface and electric properties of BiFeO3 thin films”, Appl. Surf. Science, 253, 7069-7073, 2007.
[45] J. R. Teague, R. Gerson, and W. J. James, “Dielectric hysteresis in single crystal BiFeO3”, Solid State Commun., 8, 1073, 1970.
[46] H. Uchida, R. Ueno, H. Nakaki, H. Funakubo, and S. Koda, “Ion Modification for Improvement of Insulating and Ferroelectric Properties of BiFeO3 Thin Films Fabricated by Chemical Solution Deposition”, Jpn. J. Appl. Phys., vol. 44, no. 18, pp. L561-L563, 2005.
[47] C. Wang, M. Takahashi, H. Fujino, X. Zhao, E. Kume, T. Horiuchi, and S. Sakai, “Leakage current of Multiferroic (Bi0.6Tb0.3La0.1)FeO3 thin films grown at various oxygen pressures by pulsed laser deposition and annealing effect”, J. Appl. Phys., 99, 054104, 2006.
[48] V. A. Khomchenko, D.A. Kiselev, J. M. Vieira, L. Jian, A. L. Kholkin, A. M. L. Lopes, Y. G. Pogorelov, J. P. Araujo, and M. Maglione, “Effect of diamagnetic Ca, Sr, Pb, and Ba substitution on the crystal structure and Multiferroic properties of the BiFeO3 perovskite”, J. Appl. Phys., 103, 024105, 2008.
[49] X. Qi, J. Dho, R. Tomov, M. G. Blamire, and J. L. MacManus-Driscoll, “Greatly reduced leakage current and conduction mechanism in aliovalent-ion-doped BiFeO3”, Appl. Phys. Lett., 86, 062903, 2005.
[50] J. K. Kim, A. S. Kim, and W. J. Kim, “Enhanced ferroelectric properties of Cr-doped BiFeO3 thin films grown by chemical solution deposition”, Appl. Phys. Lett., 88, 132901, 2006.
[51] C. F. Chung, J. P. Lin, and J. M. Wu, “Influence of Mn and Nb dopants on electric properties of chemical-solution-deposited BiFeO3 films”, Appl. Phys. Lett., 88, 242909, 2006.
[52] K. Ueda, H. Tabata, and T. Kawai, “Coexistence of ferroelectricity and ferromagnetism in BiFeO3-BaTiO3 thin films at room temperature”, Appl. Phys. Lett., vol. 75, no. 4, 555-557, 1999.
[53] J. Cheng, S. Yu, J. Chen, Z. Meng, and L. E. Cross, “Dielectric and magnetic enhancements in BiFeO3-PbTiO3 solid solutions with La doping”, Appl. Phys. Lett., 89, 122911, 2006.
[54] J. S. Kim, C. I. Cheon, Y. N. Choi, and P. W. Jang, “Ferroelectric and ferromagnetic properties of BiFeO3-PrFeO3-PbTiO3 solid solutions”, J. Appl. Phys., vol. 93, no. 11, 9263-9270, 2003.
[55] C. C. Lee and J. M. Wu, “Thickness-dependent retention behaviors and ferroelectric properties of BiFeO3 thin films on BaPbO3 electrodes”, Appl. Phys. Lett., 91. 102906, 2007.
[56] Y. H. Lee, J. M. Wu, Y. L. Chueh, and L. J. Chou, “Low-temperature growth and interface characterization of BiFeO3 thin films with reduced leakage current”, Appl. Phys. Lett., 87, 172901, 2005.
[57] S. K. Singh, N. Menou, H. Funakubo, K. Maruyama, and H. Ishiwara, “(111)-textured Mn-substituted BiFeO3 thin films on SrRuO3/Pt/Ti/SiO2/Si structures”, Appl. Phys. Lett., 90, 242914, 2007.
[58] J. F. Scott, “Ferroelectric Memories” Berlin, Germany: Springer-Verlag, 2001.
[59] H. Hu and S. B. Ktupanidhi, “Current-voltage characteristics of ultrafine-grained ferroelectric Pb(Zr,Ti)O3 thin film”, J. Mater. Res., vol. 9, no. 6, 1994.
[60] J. F. Scott, C. A. Araujo, B. M. Melnick, and L. D. McMillan, “Quantitative measurement of space-charge effects in lead zirconate-titanate memories”, J. Appl. Phys., vol. 70, no. 1, pp. 382-388, 1991.
[61] C. Sudhama, A. C. Campbell, P. D. Maniar, R. E. Jones, R. Moazzami, and C. J. Mogab, “A model for electrical conduction in metal-ferroelectric-metal thin film capacitor”, J. Appl. phys., vol. 75, no. 2, pp. 1014-1022, 1994.
[62] N. Inoue and Y. Hayashi, “Effect of imprint on operation and reliability of ferroelectric random access memory (FeRAM)”, IEEE Transactions on Electron Devices, vol. 48, pp. 2266-2272, 2001.

Chapter 3
[63] R. Ueno, S. Okaura, H. Funakubo, and K. Saito, “Crystal Structure and Electrical Properties of Epitaxial BiFeO3 Thin Films Grown by Organic Chemical Vapor Deposition”, Jpn. J. Appl. Phys., vol. 44, no. 39, pp. L1231-L1233, 2005.

Chapter 4
[64] 汪建民, “材料分析,”中國材料科學學會, 1998.
[65] G. Binnig and C. F. Quate, “Atomic Force Microscope”, Phys. Rev. Lett. 56, pp. 930-933, 1986.
Chapter 5
[66] J. P. Han, S. M. Koo, C. A. Richter, and E. M. Vogel, “Influence of buffer layer thickness on memory effects of SrBi2Ta2O9/SiN/Si structures”, Appl. Phys. Lett., vol. 85, no. 8, pp. 1439-1441, 2004.
[67] T. F. Tseng, R. P. Yang, and K. S. Liu, “Ferroelectric properties of PLZT films deposited on Si3N4-coated Si substrates by pulsed laser deposition process”, Appl. Phys. Lett., vol. 70, no. 1, pp. 46-48, 1997.
[68] H. Nakasima and Y. Fujimor, “Electrical properties for capacitors of dynamic random access memory on PLZT thin films by metaorganic chemical vapor deposition”, Jpn. J. Appl. Phys., vol. 33, no. 9B, pp. 5139-5142, 1994.
[69] C. M. Foster and H. K. Kim, “Single-crystal PZT thin films prepared by metal-organic chemical vapor deposition: Systematic compositional variation of electronic and optical properties”, J. Appl. Phys., vol. 81, no. 5, pp. 2349-2357, 1997.
[70] H. Miki and Y. Ohji, “Uniform ultra-thin Pb(Zr,Ti)O3 films formed by metal-organic chemical vapor deposition and their electrical characteristics”, Jpn. J. Appl. Phys., vol. 33, no. 9B, pp. 5143-5146, 1994.
Chapter 6
[71] Y. D. Su, W. C. Shih, and J. Y. M. Lee, “The effect of band offset on the retention properties of metal-ferroelectric (PbZr0.53Ti0.47O3)-insulator (Dy2O3, Y2O3)-semiconductor capacitors and field effect transistors”, Appl. Phys. Lett., 91, 122902, 2007.
[72] C. T. Black, C. Farrell, and T. J. Licata, “Suppression of ferroelectric polarization by an adjustable depolarization field”, Appl. Phys. Lett., vol. 71, pp. 2041-2043, 1997.