大高宽比光栅的摇床式辅助显影工艺

针对大高宽比微结构显影过程中由显影液的对流传质严重受限、光刻胶层厚、显影时间长带来的显影不均匀问题,提出了基于翘板式摇床辅助的显影方法。利用有限元法模拟了摇床工作时整个样品表面的流场分布以及显影液在不同高宽比微结构光栅表面的流场分布。模拟结果表明,通过摇床摆动可以实现显影液均匀流动。然后,提出了快速的显影参数确定方法,并通过实验给出了沟槽深宽比和显影速率之间的关系,提供了可参考的显影工艺参数,并验证了工艺参数的合理性。在显影时间为10~12 min,显影速率为0.21~0.23 m/s,沟槽深宽比为2.5,光刻胶厚度为200μm的光栅的显影均匀性优于96%。该方法可以实现大高宽比微结构的均匀显影,满足高质量大高宽比光栅的制作要求。

Optimization of development process for fabrication of high aspect ratio gratings

In the development process of high aspect ratio microstructures, the convective mass transfer of the developer is severely limited in the very thick photoresist layer. To improve the uniformity of the development, we have developed a rocker-type shaker-assisted development method that uses the up and down swing of the rocker-type shaker to achieve a uniform flow of the developer. Finite element method is used to simulate the flow field distribution on the surface of the substrate and the different aspect ratios of the microstructure gratings. The simulation results show that the up and down swing of the rocker-bed can achieve a uniform flow in the developer. Furthermore, we propose a rapid development parameter determination method to efficiently define suitable development parameters. The experiments show the relationship between the aspect ratios of the trenches and the development rates, and provide suitable development process parameters. The experimental results verified the rationality of the process parameters. When the development time is 10-12 min and the development rate is 0.21-0.23 m/s, the development uniformity of the grating having a photoresist thickness of 200 μm can be 96% when the aspect ratio of the trenches is 2.5. The simulations and experimental results show that this development method can achieve uniform development of high aspect ratio microstructures and meet the requirements of fabricating high-quality gratings with high aspect ratios.