Development of Low-Temperature MOCVD Technology for Ferroelectric Thin Films

铁电薄膜低温MOCVD技术的发展

基本信息

批准号：
11555085
负责人：
TOKUMITSU Eisuke
金额：
$ 7.55万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The objective of this research project is to develop a low-temperature MOCVD (metalorganic chemical vapor deposition) technology for ferroelectric thin films which will be used for future nonvolatile memory applications. In this research project, we introduced RF plasma in the growth of ferroelectric SrBi_2Ta_2O_9 (SBT) films by liquid-delivery MOCVD to reduce the crystallization temperature. We first used Sr[Ta(OC_2H_5)_6]_2 as a Sr-Ta source and showed that low-temperature (350℃) deposition of the film followed by high-temperature (750℃) crystallization annealing is necessary to obtain ferroelectric SrBi_2Ta_2O_9 (SBT) films. This is because Sr[Ta(OC_2H_5)_6]_2 can be easily decomposed at high temperatures, which makes the composition control difficult. Hence, we next used a novel Sr-Ta source precursor, Sr[Ta(OC_2H_5)_5(OC_2H_4OCH_3)]_2, which is more thermally stable than the conventional source, to overcome this problem. Using the Sr[Ta(OC_2H_5)_5(OC_2H_4OCH_3)]_2, we grew good ferroelectric SBT films with a remanent polarization of 6.2 μC/cm^2 and a coercive field of 62 kV/cm at 750℃ without RF plasma. By applying the RF plasma during the growth, we succeeded in reducing the crystallization temperatures to as low as 615℃. This temperature is about 150℃ lower than the temperature required in the conventional techniques. Remanent polarization of the ferroelectric SBT film grown by the plasma-assisted MOCVD technique at 615℃ with an RF power of 20W was 5.8 μC/cm^2, which is comparable to the remanent polarization obtained by the conventional techniques around 750℃.

该研究项目的目的是开发用于铁电薄膜的低温MOCVD（金属有机化学蒸气沉积）技术，该技术将用于将来的非挥发性记忆应用。在该研究项目中，我们通过液体传递MOCVD引入了铁电srbi_2ta_2o_9（SBT）膜的生长中的RF等离子体，以降低结晶温度。我们首先使用Sr [TA（OC_2H_5）_6] _2作为SR-TA源，并表明膜的低温（350℃）沉积，然后是高温（750℃）结晶退火是获得Ferroelectric SRBI_2TA_2O_2O_9（SBT）的胶片。这是因为SR [TA（OC_2H_5）_6] _2可以在高温下轻松分解，这使得组成控制变得困难。因此，我们接下来使用了一种新颖的SR-TA源前体，SR [TA（OC_2H_5）_5（OC_2H_4OCH_3）] _ 2，它比常规源更热稳定，以克服这个问题。使用sr [TA（OC_2H_5）_5（OC_2H_4OCH_3）] _ 2，我们生长出良好的铁电SBT膜，其不含6.2μc/cm^2的remanent极化和一个62 kV/cm的强制性在没有RF等离子的情况下为62 kV/cm。通过在生长过程中应用RF血浆，我们成功地将结晶温度降低到低至615℃。该温度比传统技术所需的温度低约150℃。在615℃时等血浆辅助MOCVD技术生长的铁电SBT膜的离近极化为20W的RF功率为5.8μc/cm^2，可与传统技术在750左右的传统技术获得的远期极化相媲美。