热ALD和等离子增强ALD沉积HfO2薄膜的比较（英文）

Comparison of Thermal and Plasma Enhanced Atomic Layer Deposition of HfO2 Thin Films

以四(甲乙胺)铪(TEMAHf)作为前驱体,采用热原子层沉积(TALD)技术和等离子体增强原子层沉积(PEALD)技术分别在硅衬底上沉积二氧化铪(HfO2)薄膜。分别研究了水和臭氧作为共反应物对TALD HfO2薄膜性能的影响及采用电容耦合等离子体(CCP)PEALD HfO2薄膜的最佳工艺条件。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和光电子能谱(XPS)对不同工艺制备的HfO2薄膜的微观结构、表面形貌进行了表征。结果表明,反应温度为300℃时,TALD 50 nm厚的HfO2薄膜为单斜相晶体;PEALD在较低反应温度(150℃)下充分反应,所沉积的50 nm厚的HfO2薄膜杂质含量较低,薄膜未形成结晶态;PEALD工艺得到的HfO2薄膜的界面层最厚,主要为硅的亚氧化物或铪硅酸盐。电流-电压(I-V)和电容-电压(C-V)测试结果表明,以水作为氧源且反应温度300℃的TALD工艺所得到的HfO2薄膜,其金属-绝缘体-半导体(MIS)器件的漏电流及电滞回线最小。

HfO2 thin films were deposited on silicon substrate by thermal atomic layer deposition(TALD)and plasma enhanced atomic layer deposition(PEALD)techniques respectively,with the tetrakis(ethylmethylamino)hafnium(TEMAHf)as the precursor.The effects of water and ozone,which acted as the co-reactants,on properties of TALD HfO2 thin films were studied respectively.The optimum capacitive coupled plasma(CCP)PEALD process condition was studied.The microstructures and surface morphologies of the HfO2 thin films deposited by different techniques were characterized by the X-ray diffraction(XRD),scanning electron microscope(SEM)and X-ray photoelectron spectroscopy(XPS).The results show that the HfO2 thin films with the thickness of 50 nm deposited by the TALD at the reaction temperature of 300℃crystallize into monoclines.Compared with TALD,PEALD fully reacts at a lower temperature(150℃),and the deposited HfO2 thin film with the thickness of 50 nm have low impurity and no crystalline state.The interface layers of the HfO2 thin film obtained by PEALD process is the thickest,which are mostly Si sub-oxides or the Hf silicate.The current-voltage(I-V)and capacitance-voltage(C-V)measurements show that the leakage current and C-V hysteresis of the metal-insulator-semiconductor(MIS)structure with HfO2 thin film,obtained by TALD with H2O as the oxygen source at the reaction temperature of 300℃,are the minimum.