热处理对STO铁电薄膜微结构的影响

Influences of annealing on the micro-structure of STO ferroelectric films

系统研究了CFA与RTA两种热处理方式以及热处理温度和时间对STO薄膜微结构的影响.STO薄膜采用脉冲激光沉积法(PLD)制备.采用原子力显微镜(AFM)和XRD分别对薄膜的表面形貌和晶粒结构进行分析.结果表明,在热处理温度650～800℃范围内,相对于CFA、STO薄膜经RTA热处理后,薄膜表面晶粒大小分布均匀、致密.两种热处理方法都使薄膜的晶粒直径随温度升高而增大,并且温度越高,薄膜的晶形越完整,同样热处理温度下,RTA与CFA相比薄膜的晶粒较小,两种热处理方法的最大晶粒尺寸都＜120nm.但XRD分析结果表明,在相同热处理温度下,CFA热处理的结晶转化率较RTA热处理要高.在一定范围内,RTA热处理时间对薄膜晶粒尺寸影响不大,热处理时间越长,晶粒更加完整,表面更加均匀平整,结晶转化率越高.

In this paper, the influences of conventional furnace annealing (CFA) and rapid thermal annealing (RTA) and annealing time on STO films were systematically studied. STO films were deposited by pulse laser depositing (PLD). Surface images and micro-structure of STO films were analyzed by atomic force microscopy (AFM) and X-ray diffractions. Compared to CFA, RTA annealed STO film grain size was more even and there was less holes than CFA annealed STO film between the annealing temperatures from 650°C to 800°C. With the increase of annealing temperature, grain size was increased both for CFA and RTA. At the same annealing temperature, RTA annealed STO film grain size was smaller than CFA annealed film. But grain size is less than 120 nm. However, at the same annealing temperature, CFA annealed STO film crystallined ratio is greater than RTA. Between the annealing temperatures from 650 to 800°C, the influence of RTA annealing time on STO film grain size can be ignored. With the increase of RTA annealing time, STO film surface was more even and crystallined ratio was increased.