热蒸发HfO_2薄膜光学常数表征

Characterization of Optical Constants of HfO_2 Films by Thermal Evaporation

薄膜材料库中的光学常数与实际制备的相比有很大差别,精确求解在特定工艺条件下的光学常数对设计和制备多层薄膜具有重要意义。在熔融石英(JGS1)基底上,采用热蒸发沉积方法制备了厚度为330nm的单层HfO_2薄膜,利用分光光度计测量薄膜的透射率和反射率,并采用包络法和光度法分别计算得到230nm^800nm范围内折射率n和消光系数k的色散曲线。两种方法确定的HfO_2薄膜厚度分别为331.22nm和331.03nm,两者偏差为0.057%;在266nm处两种方法确定的折射率相差0.011,消光系数相差10-5量级。结果表明,运用包络法和光度法确定HfO_2薄膜光学常数的拟合结果吻合较好,能够相互验证且避免了单一方法求解过程中所产生的误差。

The optical constants in the material library of thin films are different from that we prepared. So accurate solution of optical constants by using special process conditions is great important for the design and preparation of multilayer films. To obtain the precise optical constants of thin films,HfO2 thin films of 330 nm thickness are deposited by thermal evaporation on fused silica（JGS1）. Refractive index n and extinction coefficients k are obtained from the measured transmittance and reflectance spectral curves in the range of 230nm～800nm.There are two methods to ensure the optical constants, they are envelope method and spectrophotometry. HfO2 thin films thickness calculated as 331.22 nm and 331.03 nm respectively,the deviation between the two methods are 0.057%. The two methods determine the n and k different of 0.11 and 10-5magnitude at 266 nm. The results show that optical constants fitting curves of thin films are good by using envelope method and spectrophotometry,avoid errors which produced in a single method of solving the process.