HfO_2栅介质薄膜的结构和介电性质研究

Structure and Dielectric Properties of HfO_2 Thin Films

采用脉冲激光沉积方法(PLD)在Si(100)衬底上生长了HfO2栅介质薄膜.利用X射线衍射(XRD)和扩展X射线吸收精细结构(EXAFS)对其结构进行了表征,利用远红外光谱对其声子振动模式和介电性质进行了研究.结果表明,室温下制备薄膜为非晶,衬底温度400℃时已经形成单斜相的HfO2薄膜,1000℃退火后薄膜更趋向于(1-11)晶面取向,且结晶质量改善.薄膜的局域结构研究显示低衬底温度下生长的样品具有更短的Hf-O键长和更高的无序度.薄膜结构和薄膜质量影响其远红外声子模式,使得一些低频红外声子模式消失,造成其介电常数相对体材料有所降低,但由于影响介电常数的主要远红外声子模式依然存在,晶态薄膜仍然能保持一定的介电常数值.

HfO2 dielectric thin films were deposited on Si（100） substrate by pulsed laser deposition（PLD） method.The structure of films was characterized by X-ray diffraction（XRD） and extended X-ray absorption fine structure spectroscope（EXAFS）.The phonons modes and dielectric properties were investigated by far infrared spectroscope.These results show that the thin films deposited at room temperature and 400℃ are amorphous and monoclinic phase,respectively.The crystallization quality of the film is improved after annealing at 1000℃.The HfO2 thin film has shorter Hf-O bonding length and higher disorder than those of HfO2 powder.Some far infrared phonon modes disappear due to the higher disorder and worse crystalline quality of thin film,which causes the dielectric constant of thin film smaller than that of powder sample.However,main infrared phonon modes are preserved and the crystallized thin film still has enough value of dielectric constant.