退火工艺对磁控溅射LiCoO2薄膜形貌与力学性能的影响

Effects of annealing process on morphology and mechanical properties of magnetron sputtered LiCoO2 thin films

采用磁控溅射方法在单晶Si(100)上制备LiCoO2薄膜并选择不同退火温度、保温时间和退火气氛对薄膜进行热处理,研究不同退火条件对LiCoO2薄膜形貌、组成、晶体结构和力学性能的影响。结果表明:退火过程将LiCoO2薄膜表面粗糙度从11.63 nm降低至6.13 nm,且退火气氛对LiCoO2薄膜表面形貌影响最大;LiCoO2薄膜退火产生Li2O、CoO、Co3O4等副产物,薄膜组成被破坏;任一退火条件均能使LiCoO2薄膜结晶,平均晶粒尺寸约为30 nm,退火温度对LiCoO2薄膜晶粒尺寸和残余应力影响最大;LiCoO2薄膜退火后,其硬度H、杨氏模量Er增大一个数量级,最优退火工艺下(600℃,60 min,纯O2气氛),H3/Er 2比例为0.03 GPa,抵抗塑性变形能力好。

LiCoO2 thin films were prepared on single crystal Si(100)by magnetron sputtering method and then annealed by different annealing temperatures,holding times and atmospheres.The effects of annealing processes on the surface morphologies,compositions,crystal structures and mechanical properties of LiCoO2 films were investigated.The results show that the surface average roughness of LiCoO2 film is reduced from 11.63 nm to 6.13 nm;annealing atmosphere has the greatest influence on the surface morphologies of LiCoO2 films.The LiCoO2 film composition is destroyed due to Li2O,CoO,Co3O4 by-products formed during annealing process.LiCoO2 film are crystallized under any annealing conditions,the average grain size is about 30 nm,annealing temperature has the greatest influence on the grain size and residual stress.After annealing,the hardness and young's modulus of LiCoO2 films are increased by an order of magnitude.Under the optimal annealing process(600℃,60 min,pure O2 atmosphere),the ratio of H3/Er 2 is 0.03 GPa,which shows excellent resistance to plastic deformation.