衍射光学元件制作中的基片涂胶方法

在基片上涂布一层厚度均匀的光刻胶层,是衍射光学元件制作中的一个重要步骤。介绍了目前用于衍射光学元件制作的两种主要涂胶方法———提拉法和旋转法,分析了这两种方法的特点和影响胶层厚度的主要因素,尤其是对其均匀性的影响,并提出了获得均匀胶厚的途径。对于提拉涂胶,选择粘度较高的光刻胶溶液与合适的提拉速度将有助于减小Marangoni流动和Van derWaals力对膜厚均匀性的影响;对于旋转涂胶,可以通过密封基片所在空间,或者通过气流控制器使基片上方空气流动处于层流状态来获得均匀一致的溶剂挥发速率,从而提高胶层的均匀性。

Techniques of Coating Wafers Used for Fabrication of Diffraction Optical Elements

It is an important step to deposit uniform photoresist coatings on substrates in the process of manufacturing diffraction optical elements.Two coating techniques,dip coating and spin coating,which have been broadly used at present,were introduced.Their properties and influences on the thickness of coatings were analyzed.Especially,the main factors of influences on the uniformity of coatings were analyzed in detail and some methods of obtaining maximum uniformity of coatings were proposed.For the dip-coating,it is a good idea to select a photoresist solution with a high viscous coefficient and withdraw the substrate at a proper speed out from high viscous solution because the methods can reduce the effects of marangoni flow and van der Waals force on the uniformity of coatings.When the spin-coating is employed,it is recommended that the coating chamber should be airproofed or an air-controller should be used to make air keep a laminar flow so that the solution can be uniformly evaporated and the uniformity of the coating is increased.