Hoteroepitaxial growth of ferroelectric thin film on Si substrate by controlling the interface

(1)在800ﾟC下，用反应溅射的方法在硅衬底上沉积的YSZ外延薄膜的C-V特性几乎没有观察到差别，但在1~10K/S的冷却速率下生长的薄膜具有良好的击穿特性。(2)我们观察到在较大的等离子体辐射下沉积的硅基YSZ外延薄膜的C-V特性有较强的离子漂移。(3)我们发现在460和470ﾟC沉积的YSZ外延薄膜是异质外延的单斜(110)PZT薄膜。单斜晶系PZT薄膜在300℃、325℃和3500℃分步退火后的漏电流均小于1×10~(-7)A/cm~2，其C-V特性表现出铁电特性所致的磁滞回线。(4)在(100)YSZ外延层上获得了异质外延薄膜。当沉积速率大于0.42 nm/m in和大于1.2 nm/mm时，Ir薄膜的择优取向分别为(100)和(111)，发现(100)Ir外延薄膜的表面结晶质量明显好于YSZ外延薄膜。(5)在600ﾟC和650ﾟC下分别在(100)Ir外延薄膜和(111)Ir外延薄膜上获得了(100)和(111)PZT外延薄膜，(6)外延PZT薄膜的(001)取向程度越强，结晶质量越好，剩余极化越大，漏电流越小。(7)我们发现YSZ层与Si衬底之间的氧化硅层使得缓冲层的介电常数降低。通过控制Zr+Y金属膜的沉积过程，可以抑制这种硅氧化层的形成。

(1) We hardly observed the difference on the C-V characteristics of the epitaxial YSZ films on Si substrates deposited by reactive sputtering with the cooling rates of 0.1 to 1000K/s at 800ﾟC.However, the break down characteristics were good for the films produced with the cooling rates of 1 to 10 K/s.(2) We observed that the stronger ion drift in the C-V characteristics of the epitaxial YSZ films on Si deposited with heavier plasma radiation.(3) It was found that the PZT films on epitaxial YSZ films deposited at 460 and 470ﾟC were heteroepitaxial monoclinic (110) PZT films. The leakage current of the monoclinic PZT film step-annealed at 300, 325 and 3500 C was less than 1X10^<-7> A/cm^2. Its C-V characteristics showed the hysteresis loop due to the ferroelectric property.(4) We obtained the heteroepitaxial Ir films on epitaxial (100) YSZ layers. When the deposition rates were later than 0.42 nm/min and faster than 1.2 nm/mm, the orientation of the deposited Ir films were (100) and (111), respectively, It was found that the surface crystalline quality of the epitaxial (100) Ir film was much better than that of the epitaxial YSZ film.(5) We obtained the epitaxial (100) and (Ill) PZT films on the epitaxial (100) Ir film at 600ﾟC and the epitaxial (111) Ir film at 650ﾟC, respectively.(6) When the degree of the (001) orientation of the epitaxial PZT film became stronger and the crystalline quality became better, the remanent polarization became larger and the leakage current became lower.(7) We found that the Si oxide layer between the YSZ layer and the Si substrate made the dielectric constant of the buffer layer decrease. This Si oxide layer formation can be suppressed by controlling the Zr+Y metal film deposition process.