Electrical and reliability properties of PZT thin films for ULSI DRAM applications

Abstract

The electrical and reliability characteristics of ferroelectric capacitors fabricated using sol-gel derived 50/50 lead-zirconate-titanate (PZT) thin films have been examined for ULSI DRAM (dynamic random access memory) applications. Various electrode materials, film thicknesses (200 nm to 600 nm) and capacitor areas were used. A large stored-energy density (Q(c)) of 15 muC/cm(2) (at 125 kV/cm) was measured using different methods. The results indicate that PZT thin films exhibit material properties which might satisfy the requirements of ULSI DRAMs.

An investigation on the leakage current and time dependent dielectric breakdown of ferroelectric lead–zirconate–titanate thin film capacitors for memory device applications

“…[9][10][11] The TDDB of ferroelectric capacitors has been mentioned by only a few reports. 1,12 TDDB in dielectric films such as silicon dioxide is usually explained by the mechanism of impact ionization. 13 The electron-hole pairs generated in the impact ionization process will be subjected to traps in the films.…”

“…The TDDB of PZT has been studied by only a few authors. 1,12 The time to breakdown ͑ t BD ͒ is measured by applying a voltage from 20 to 30 V until dielectric breakdown. It is usually assumed that the t BD is a function of a͒ Electronic mail: ymlee@ee.nthu.edu.tw the total number of carriers passing through the films.…”

The temperature dependence of the transient current in ferroelectric Pb(ZrxTi1−x)O3 thin films for memory devices applications

“…3,4 However, there are still a few remaining reliability issues, such as leakage current, 5,6 fatigue, 7 aging, 8 imprint property, 9,10 and time dependent dielectric breakdown ͑TDDB͒. 2,11 It is known that space charges in the ferroelectric thin film play an important role in the understanding of these problems. The influence of the trap states on the electrical properties of dielectrics has been extensively studied for traditional materials like SiO 2 .…”

Orientation of Bi3.2La0.8Ti3O12 ferroelectric thin films with different annealing schedules

“…It is important in these applications that the films have a low coercive field, high remanent polarization, low leakage current and low polarization fatigue [2] . To enhance the fatigue resistance and remanent polarization 2Pr of Bi 4 Ti 3 O 12 thin film, substitution of bismuth ion (Bi 3+ ) with ions such as lanthanum (La 3+ ) [3][4][5][6] , neodymium (Nd 3+ ) [5,[7][8][9][10] , samarium (Sm 3+ ) [5,11] or yttrium (Y 3+ ) [12] were studied.…”