Pb(Zr,Ti)O 3   강유전체 박막 이력곡선의 변형에 관한 연구

이은구; 이종국; 이재갑; 김선재; Eun Gu Lee; Jong Kook Lee; Jae Gab Lee; Sun Jae Kim

Korean Journal of Materials Research, Vol.10, No.5, 360-363, May, 2000

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Pb(Zr,Ti)O 3 강유전체 박막 이력곡선의 변형에 관한 연구

Studies on the Deformation in the Hysteresis Loop of Pb(Zr,Ti)O 3 Ferroelectric Thin Films

이은구, 이종국, 이재갑 ¹, 김선재²

조선대학교 금속재료공학부(BK 21 핵심분야 지능재료 개발 및 산업화팀)
¹국민대학교 금속재료공학과
²한국원자력연구소 원자력재료기술개발팀

Eun Gu Lee, Jong Kook Lee, Jae Gab Lee¹, and Sun Jae Kim²

Division of Metallurgical and Materials Engineering, Chosun University, Korea
¹Dept. Metallugical Materials Engineering, Kookmin University, Korea
²Advanced Nuclear Materials Development Team, Korea Atomic Energy Research Institute, Korea

초록

다양한 Zr/Ti 비율을 갖고 있는 강유전체 PZT박막을 졸-겔 법으로 증착하였고 상부 백금전극의 제조방법과 열처리온도의 변화에 따라 강유전체 특성을 측정하여 이력곡선의 변형 원인을 조사하였다. Pt/PZT/Pt 캐패시터는 상부 백금전극을 반응성 이온 식각(RIE) 하는 과정에서 생성된 dc plasma 전압에 의하여 양의 방향으로 분극되었고 도메인 계면에 포획된 전하에 의해 내부전장이 발생되었다. PZT 박막은 sputtering으로 상부전극을 증착하는 과정에서 이력곡선의 중간에 잘룩하게 되는 시효현상이 관찰되었다. 상부전극을 제작한 후 열처리는 포획된 전하흫 제거시켜 양호한 이력곡선 특성을 되찾게 하였다. Zr/Ti 비율이 감소함에 따라 내부전장이 증가하였으며 내부전장이 없어지는 열처리온도가 증가하였다.

Deformation in the hysteresis loop of Pb(Zr,Ti)O 3 (PZT) thin films with various Zr/Ti ratios has been studied by varying the top electrode preparation method and the annealing temperature. Pt/PZT/Pt capacitors was found to be positively poled due to dc plasma potential generated during reactive ion etch (RIE) of Rt. Internal field is formed by space charges trapped at domain boundaries. Aging phenomenon such as constriction in the middle of the hysteresis loop was observed in the PZT film with top electrode deposited by sputtering. Top electrode annealing restores the hysteresis loop by removing the space charges. As Zr/Ti ratio decrease, voltage shift increases and an-nealing temperature at which internal field disappears also increases.

Keywords:sol-gel;aging;ferroelectricity;thin films

[References]

Scott JD, Araujo CA, Science, 246, 1400 (1989)
Moazzami R, Maniar PD, Jones RE, Jr., Campbell AC, Mogab CJ, IEDM Tech. Dig., IEEE, 973 (1992)
Lee J, Johnson L, Safari A, Ramesh R, Sands T, Gilchrist H, Keramidas VG, Appl. Phys. Lett., 63, 27 (1993)
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Shihara K, Ishikawa T, Hamada K, Onishi S, Kudo J, Sakiyama K, Integrated Ferroelectrics, 6, 301 (1995)
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Robels U, Calderwood JH, Arlt G, J. Appl. Phys., 77, 4002 (1995)
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[Related Articles]

[1] Scott JD, Araujo CA, Science, 246, 1400 (1989)

[2] Moazzami R, Maniar PD, Jones RE, Jr., Campbell AC, Mogab CJ, IEDM Tech. Dig., IEEE, 973 (1992)

[3] Lee J, Johnson L, Safari A, Ramesh R, Sands T, Gilchrist H, Keramidas VG, Appl. Phys. Lett., 63, 27 (1993)

[4] Ramesh R, Ichrist H, Sands T, Keramidas VG, Haakenaaen R, Fork DK, Appl. Phys. Lett., 63, 27 (1993)

[5] Dat R, Lichtenwalner DJ, Auciello O, Kingon AI, Appl. Phys. Lett., 64, 2673 (1994)

[6] Lefkowitz I, Mitsui T, J. Appl. Phys., 30, 269 (1959)

[7] Naik IK, Sanchez LE, Wu SY, Maderie BP, Integrated Ferroelectrics, 2, 133 (1992)

[8] Shihara K, Ishikawa T, Hamada K, Onishi S, Kudo J, Sakiyama K, Integrated Ferroelectrics, 6, 301 (1995)

[9] Mihara T, Yoshimori H, Watanabe H, Araujo CA, Jpn. J. Appl. Phys., 34, 5233 (1955)

[10] Reaney IM, Brooks K, Klissurska R, Pawlaczyk C, Setter N, J. Am. Ceram. Soc., 77, 1209 (1994)

[11] Robels U, Calderwood JH, Arlt G, J. Appl. Phys., 77, 4002 (1995)

[12] Warren WL, Dimos D, Tuttle BA, Nasby RD, Pike GE, Appl. Phys. Lett., 65, 1018 (1994)

[13] Prokopalo OI, Sov. Phys. Solid State, 21, 1768 (1980)

[14] Warren WL, Dimos D, Pike GE, Vanheusden K, Ramesh R, Appl. Phys. Lett., 67, 1689 (1995)

[15] Okazaki K, Nagata K, J. Am. Ceram. Soc., 56, 82 (1973)