Browsing by Author "Lai, MJ"

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Effect of rapid thermal annealed TiN barrier layer on BST capacitors prepared by RF magnetron cosputter system at low substrate temperatures
(2000-12-01)
Hwang, CC
;
Jaing, CC
;
Lai, MJ
;
Chen, JS
;
Huang, S
This work reports on rapid-thermal-annealed TiN as a barrier for Pt/BST/Pt/TiN/Ti/Si capacitors. Experimental results indicate that the diffusion of Ti and Si from the Ti adhesion layer and Si plug, respectively, degrade the capacitor for the gigabit dynamic random access memories (DRAMs) using barium strontium titanate (BST) as a dielectric material. Although the diffusion barrier TiN between the bottom electrode Pt and Ti adhesion layer has been conventionally used to release the issue, the interdiffusion of Ti and Si occurs due to the thermal budget of the BST deposition. A rapid thermal annealing process is applied to the as-deposited TiN barrier against the interdiffusion. Excellent electrical characteristics, including high dielectric constant (epsilon (r) = 320), low leakage current (1.5 x 10(-8) A/cm(2)) under 0.1 MV/cm, and a lifetime greater than 10 years under 1.5 MV/cm are obtained. Our results further demonstrate that the proposed technique is highly promising for future high-density DRAMs. (C) 2000 The Electrochemical Society. S1099-0062(00)07-005-X. All rights reserved.
Effect of rapid-thermal-annealed TiN barrier layer on the Pt/BST/Pt capacitors prepared by RF magnetron co-sputter technique at low substrate temperature
(2001-01-01)
Hwang, CC
;
Juang, MH
;
Lai, MJ
;
Jaing, CC
;
Chen, JS
This investigation reports the effect of rapid-thermal-annealing (RTA) on metallic barrier TiN against the interdiffusions of Ti and Si into barium strontium titanate (BST) in Pt/BST/Pt/TiN/Ti/Si capacitors. In the integration of BST capacitors, the thermal budget of the BST deposition would cause the inter-diffusions of Ti and Si from Ti adhesion layer and Si plug respectively. This event would degrade the BST capacitors. To address this issue. rapid-thermal-annealed TiN barriers were deposited between the bottom electrode Pt and adhesion layer Ti. Optimal RTA condition for TiN were found ill this: experiment. Excellent electrical characteristics of Pt/BST/Pt/TiN/Ti/Si capacitors. including high dielectric constant (epsilon (r) = 320). low leakage current (1.5 x 10(-8) A/cm(2)) under 0.1 MV/cm, and greater than 10 year lifetime under 1.6 MV/cm were obtained with Ar + O-2 mixed ambient at a low substrate temperature (300 degreesC). (C) 2001 Elsevier Science Ltd. All rights reserved.
Effect of TiN treated by rapid thermal annealing on properties of BST capacitors prepared by RF magnetron co-sputter system at low substrate temperature
(2000)
Teng, TH
;
Hwang, CC
;
Lai, MJ
;
Huang, SC
;
Chen, JS
In this work, (Ba0.7Sr0.3)TiO3 thin films on Pt/TiN/Ti/Si substrate were deposited by an RF magnetron co-sputter system at 300 degrees C in an Ar+O-2 mixed ambient. In the integration of BST capacitors, the diffusion barrier (TiN) under bottom electrodes is one of the key issues. To obtain a stable and excellent diffusion barrier against inter-diffusion between Pt and Si, as well as against being oxidized during BST deposition, TiN was treated by a rapid thermal annealing (RTA) process. Experimental results indicated that proper RTA treatments resulted in a superior TiN barrier layer. In addition, low substrate temperature during BST deposition suppressed the phenomena of inter-diffusion and barrier oxidation. Furthermore, Pt hillocking, another problem during BST deposition because of high thermal budget, was also solved by reducing substrate temperature during BST deposition. The MIM (Pt/BST/Pt) structure was used in the experiments for electrical properties measurement. High dielectric constant (epsilon (r)=300), low leakage current (1.5x10(-8) A/cm(2)) under 0.1MV/cm, and 10 year lifetime under 1.6MV/cm were achieved with an Ar+O-2 mixed ambient at a low substrate temperature (300 degrees C).
Effects of post-oxygen plasma treatment on Pt/(Ba,Sr)TiO3/Pt capacitors at low substrate temperatures
(2003-02-01)
Shye, DC
;
Hwang, CC
;
Lai, MJ
;
Jaing, CC
;
Chen, JS
We investigated how oxygen plasma post-treatment improves leakage characteristics of Pt/(Ba,Sr)TiO3 (BST)/Pt capacitors prepared by the radio-frequency (RF) cosputtering technique. Experimental results indicate that oxygen plasma treatment can effectively passivate the oxygen vacancies of (Ba,Sr)TiO3 (BST) films, thus decreasing the electric conduction paths of leakage currents. By this low-temperature (250degreesC), and short-duration (similar to5 min) process, the leakage current is reduced by as many as two orders of magnitude. The reliability characteristics of time-dependent dielectric breakdown (TDDB) are improved as well. However, the usage of oxygen plasma treatment is not unrestricted. Plasma treatment for an extended period (more than 10 min) degrades both the leakage and reliability characteristics, due to plasma damage. Excellent electrical characteristics, including low leakage current (1.5 x 10(-8) A/cm(2)) under 0.1 MV/cm, high dielectric constant (288), and a lifetime longer than 10 years under 2 MV/cm can be achieved. Therefore, the proposed technique for as-deposited BST films is a highly promising means of improving the electrical characteristics of BST thin films.
Low temperature radio-frequency-sputtered (Ba, Sr)TiO3 films on Pt/TiN/Ti/Si substrates with various oxygen/argon mixing ratios
(2003-02-01)
Shye, DC
;
Chiou, BS
;
Lai, MJ
;
Hwang, CC
;
Jiang, CC
(Ba, Sr) TiO3 (BST) films were fabricated on Pt/TiN/Ti/Si substrates by low temperature radio frequency magnetron cosputtering at 300degreesC. Material and electrical properties of BST films sputtered at low temperatures are significantly affected by the O-2/(Ar + O-2) mixing ratio (OMR). Plasma emission spectra indicate that the deposition rate declines at a higher OMR due to oxide formation on the target surface. The dielectric constant of the BST films can reach a maximum of 364 at 5% OMR. The ten-year lifetime of the time-dependent dielectric breakdown implies that the reliability of the capacitor can be enhanced at a higher OMR due to compensation of oxygen vacancies and smaller grain sizes. Current-voltage analysis indicates that the leakage current of the Pt/BST/Pt capacitor is limited by Schottky emission (SE)/Poole-Frenkel emission (PF) at a lower/higher applied field. The applied field boundary between SE and PF shifts toward higher field as OMR increases. Moreover, an energy band model was proposed and this leakage mechanism was discussed. (C) 2003 The Electrochemical Society.
Low-temperature process to improve the leakage current of (Ba, Sr)TiO3 films on Pt/TiN/Ti/Si substrates
(2000-12-15)
Hwang, CC
;
Lai, MJ
;
Jaing, CC
;
Chen, JS
;
Huang, S
In this study, we employed an oxygen plasma post-treatment to improve the leakage characteristics of Pt/(Ba, Sr)TiO3(BST)/Pt capacitors prepared by the RF cosputtering technique. Applying oxygen plasma treatment to BST thin films can effectively passivate the oxygen vacancies of the BST films, thus decreasing the electric conduction paths of leakage current. The leakage current is reduced by as many as two orders of magnitude by this low-temperature (250 degreesC) and short duration (similar to5 min) process. However, the usage of oxygen plasma treatment is not unrestricted. Plasma treatment over a long time (more than 10 min) degrades the leakage characteristics, due to plasma damage. Therefore, a proper oxygen plasma treatment for as-deposited BST films is desired to improve leakage characteristics of BST thin films.