错位叠加曝光法制作楔形斜面微结构研究

Wedge-shaped bevel microstructure prepared by dislocation and superposition exposure method

本文研究了基于T公司生产的某型号正性光阻,采用错位叠加紫外曝光工艺,实现灰阶曝光效果的方法,最终得到具有特定角度的楔形斜面结构。光阻在进行紫外感光前后,对紫外光的吸收系数α会发生变化,根据朗伯比尔定律(Lambert-Beer law),将楔形斜面结构等效成台阶状结构,并通过实验计算出使该光阻发生光解反应的临界曝光能量I、光阻感光前后的吸收系数α和α′,并进一步根据等效模型结构得到错位叠加曝光过程中每步曝光所需能量大小。实验结果表明,使光阻进行分解反应的临界曝光能量I约为8 mJ,对紫外光的吸收系数α约为1.14。经过紫外感光后,光阻对紫外光的吸收系数α′降为原来20%,进一步根据计算得到的曝光能量进行实验,最终制作出所需的斜角为32°的楔形结构。错位叠加曝光的方法可以得到具有特定角度的楔形斜面微结构,而且该过程所需的曝光条件可以根据楔形角度进行计算。

A kind of exposure method of dislocation and superposition was studied,which was based on a type of positive photoresist produced by T company.It can realize the effect of gray scale exposure by the method and finally a wedge-shaped bevel microstructure with specific angle was obtained.The absorption coefficient of a photoresist can be changed after irradiated by ultraviolet light.According to the Lambert-Beer law,the bevel structure can be equivalent into step structure,and then the critical exposure energy for the photoresist to react and the absorption coefficients of the photoresist can be calculated,which was irradiated by UV before and after,as well as the exposure energy for the dislocation and superposition method.Experimental results show that the critical exposure energy for the photoresist to react is 8 mJ,and the absorption coefficientαof the photoresist for ultraviolet light is 1.14,which will reduce for 20%after irradiated by ultraviolet light.With irradiating by the energy calculated,the photoresist can form the wedge bevel structure with taper angle of 32°.A specific wedge bevel structure by the dislocation and superposition exposure method can be prepared and the energy can be calculated according to the taper angle of bevel structure.