The effects of electrode materials, substrate temperatures, film thickness and sputtering gases on the electrical and dielectric characteristics of barium strontium titanate (Ba0.65Sr0.35TiO3) thin film capacitors
|關鍵字:||鈦酸鍶鋇;barium strontium titanate|
|摘要:||隨著高密度動態隨機存取記憶體的儲存節尺寸的縮小， 由於直接穿透效應更為顯著，使得傳統氧化矽和氮氧化矽已不再適用。所以需要高介電係數材料來保持較簡單結構的記憶單胞。常用的高介電係數材料有氧化鉭、 鈦酸鍶、鈦酸鋯鉛和鈦酸鍶鋇。鈦酸鍶鋇是一種非常適合應用在高密度動態隨機存取記憶體電容器的高介電係數材料，因為其具有較高的介電係數、漏電流低、使用壽命長及低損耗因子的特性。
As the dimensions of the charge storage node in high-density dynamic random access memory (DRAM) are scaled down. Silicon dioxide and silicon oxynitride which have been used as capacitor dielectric materials are no longer applicable because their thickness is already limited by direct tunneling. High dielectric constant materials are needed to keep a simpler cell structure. Potential dielectrics with high dielectric constant include Ta2O5, SrTiO3, Pb(Zr,Ti)O3 (PZT) and (Ba,Sr)TiO3 (BST)…etc. The BST is one of the most promising materials due to its high dielectric constant, low leakage current, a TDDB over 10 years and low dissipation factor for high density DRAM capacitor. In this work, the electrical properties of BST film deposited on Ir and Pt bottom electrode and their correlation with various substrate temperatures are studied. In addition, the physical mechanism of the stress induced leakage current for BST thin film deposited with different film thickness and various oxygen to argon ratio (OAR) were investigated in details. Finally, the effect of various OAR on dielectric relaxation and defect quantity are discussed and an equivalent circuit model for (Ba0.65Sr0.35TiO3) thin film capacitors are proposed.
|Appears in Collections:||Thesis|