BST薄膜电容器的制备及其调谐性能研究

Fabrication and Tuning Properties of Ba_(0.8)Sr_(0.2)TiO_3 Thin-film Capacitors on SiO_2/Si Substrate

利用氩离子束溅射技术在SiO2/Si衬底上淀积Ba0.8Sr0.2TiO3(BST)薄膜,该薄膜在氧气气氛中500℃退火处理30 min,然后利用集成电路平面工艺将薄膜制作成叉指结构电容器。X-射线衍射仪(XRD)和扫描电镜(SEM)分析表明,BST薄膜具有钙钛矿结构,薄膜表面光滑,晶粒致密且分布均匀。调谐性能测试结果表明,该电容器具有较高的电容调谐率,在室温100 kHz频率下,对于2 V的直流偏压,其调谐率和损耗因子分别为62%和0.02。这说明具有此结构的BST薄膜电容器可望应用于微波集成电路。

Barium strontium titanate （B ST） thin films deposited on a SiO2/Si substrate by argon ion-beam sputtering technique were annealed at 500 ℃ in oxygen atmosphere for 30 min, and then were fabricated integrated capacitors with interdigital structure by standard integrated-circuit technology. The structure and micrograph of the BST thin films were characterized by glancing incidence X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The structure of the film is a cubic perovskite phase structure, and micrograph exhibits fully grown BST grains with well-defined grain boundaries and crack-free smooth surface. The capacitor shows a relatively high tunability, and a tunalility of 62% and a loss factor of 0. 02 are achieved at an applied DC bias voltage of 2 V and the frequency of 100 kHz at room temperature. These results suggest that the Ba0.8Sr0.2TiO2 thin-film capacitors are promising candidates to be developed as tunable microwave elements and integrated capacitor.