Zhang Yanfeng, Li Yunxiao, Liu Lin, Yang Chunchuan, Chen Yujie, Yu Siyuan
Opt Express. 2017 Jun 26;25(13):15572-15580. doi: 10.1364/OE.25.015572.
Diamond is a promising platform for quantum information technologies (QITs) mainly due to the properties of color centers including spin read-out, magnetic field sensing, and entanglement between different nitrogen-vacancy (NV) centers. High photon collection efficiency is essential for a high fidelity optical single-shot readout of electronic spin in the color center. To avoid total internal reflection, sculpting solid immersion lenses in the diamond surface is an ideal natural choice. Three-dimensional (3D) microstructures can be made in a photoresist material by a special lithography method. These structures can be subsequently transferred into silicon, diamond or other semiconductors by plasma etching with appropriate selectivity. However, this method cannot be directly implemented into making large height diamond microlenses where the selectivity between diamond and the photoresist is very low. In this work, we propose and demonstrate a dual mask method to achieve an overall high selectivity between diamond and photoresist via the interlayer of single crystalline silicon. By tuning the process parameters of the two etching steps, diamond micro-lenses with large variable height are successfully demonstrated..
金刚石是量子信息技术（QITs）中一个很有前景的平台，这主要归功于色心的特性，包括自旋读出、磁场传感以及不同氮空位（NV）中心之间的纠缠。高光子收集效率对于色心中电子自旋的高保真光学单次读出至关重要。为了避免全内反射，在金刚石表面雕刻固体浸没透镜是一种理想的自然选择。三维（3D）微结构可以通过特殊的光刻方法在光刻胶材料中制作。随后，这些结构可以通过具有适当选择性的等离子体蚀刻转移到硅、金刚石或其他半导体中。然而，这种方法不能直接用于制作大高度的金刚石微透镜，因为金刚石和光刻胶之间的选择性非常低。在这项工作中，我们提出并展示了一种双掩膜方法，通过单晶硅中间层实现金刚石和光刻胶之间的整体高选择性。通过调整两个蚀刻步骤的工艺参数，成功展示了具有大可变高度的金刚石微透镜。
