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

(1)在800 ℃下，在0.1 ~ 1000 K/s的冷却速率下，用反应溅射法在Si基片上外延YSZ薄膜的C-V特性几乎没有差别，而在1 ~ 10 K/s的冷却速率下外延YSZ薄膜的击穿特性较好。(2)我们观察到在较强的等离子体辐射下沉积的YSZ薄膜的C-V特性中有较强的离子漂移。(3)发现在460和470 ℃下沉积的YSZ外延膜上的PZT膜为异质外延单斜（110）PZT膜。在300、325和3500 ℃下分步退火的单斜PZT薄膜的漏电流小于1 × 10 ^<-7>A/cm ^2。其C-V特性表现出铁电性引起的电滞回线。(4)我们在外延的（100）YSZ层上获得了异质外延的Ir薄膜。当沉积速率大于0.42nm/min和大于1.2nm/mm时，薄膜的取向分别为（100）和（111），（100）Ir外延薄膜的表面结晶质量明显优于YSZ外延薄膜。(5)我们分别在600 ℃和650 ℃下在外延（100）Ir膜和外延（111）Ir膜上获得了外延（100）和（111）PZT膜。(6)当PZT外延膜的（001）取向度变强，结晶质量变好时，反射极化变大，漏电流变小。(7)我们发现YSZ层和Si衬底之间的Si氧化层使缓冲层的介电常数降低。通过控制Zr+Y金属膜沉积工艺可以抑制该Si氧化物层的形成。

(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.