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离子束溅射、热舟和电子束法制备深紫外LaF3薄膜
DUV LaF3 thin film deposited by IBS, thermal boat and electron beam evaporation
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摘要: 为了满足深紫外光刻物镜对薄膜的要求,得到低损耗、高稳定性、长寿命的深紫外薄膜,需要选用适当的镀膜工艺方法。分别选取了离子束溅射法、热舟蒸发法和电子束蒸发法优化后的最佳工艺参量,在融石英基底上使用3种方法镀制了单层LaF3薄膜。首先,利用光度法得出3种方法镀制LaF3薄膜在185nm~800nm范围内的折射率n和消光系数k。然后,采用原子力显微镜对薄膜表面粗糙度进行了测量。最后,薄膜的微结构使用X射线衍射仪进行了分析。结果表明,离子束溅射镀制的LaF3薄膜折射率最高、表面粗糙度最低,但吸收较大;电子束蒸发法虽然吸收最小,但是折射率偏低且表面粗糙度较高;热舟蒸发法镀制的LaF3薄膜无论折射率、消光系数还是表面粗糙度都处于3种方法中间位置。综合各项指标,热舟蒸发法最适合于沉积深紫外LaF3薄膜。Abstract: In order to satisfy the requirements of coatings of deep ultraviolet(DUV) lithography objective lens and obtain coatings with low optical losses, high stability and long lifetimes, a deposition method should be confirmed first. LaF3 single layers were deposited upon fused silica by ion beam sputtering(IBS), boat and electron beam evaporation with optimized process parameters respectively. Firstly, based on spectrophotometry, the refractive index n and extinction coefficients k in 185nm~800nm of the LaF3 layer deposited with three methods were obtained. Secondly, the surface roughness of LaF3 layers was measured by means of atomic-force microscope(AFM). Finally, X-ray diffraction(XRD) was used to investigate the microstructure of LaF3 layer. Experimental results indicate that, LaF3 layer deposited by IBS has the highest refractive index and the lowest surface roughness but the highest extinction coefficients; for LaF3 layer deposited by electron beam, although its extinction coefficients is low, but the refractive index and surface roughness doesn't seem good; as for thermal boat, all parameters discussed here is intermediate between that of LaF3 layer deposited by IBS and electron beam. Finally,based on consideration with every factors, thermal boat evaporation method is most suitable for depositing DUV LaF3 film.
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Key words:
- thin films /
- LaF3 /
- thermal evaporation /
- ion beam sputtering /
- deep UV
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