用于热释电探测器的红外微透镜阵列的设计与制作

发布时间：2018-12-26 16:56

【摘要】：非制冷红外焦平面阵列可用于对红外目标的凝视成像。由于其无需制冷装置,因而重量轻、功耗小、成本低,在军用和民用领域都得到了广泛应用。对于热释电型非制冷红外焦平面阵列而言,像元间的热串扰是制约其性能的重要因素,因而通常需对其像元进行热隔绝。然而,这会降低探测器的填充因子,进而导致光能利用率下降。而将微透镜阵列和探测器集成则可有效解决这一问题,这种方法使用微小透镜单元将入射到整个像元上的红外辐照汇聚到像元中间的光敏区内。总的来说,集成微透镜阵列可显著提高热释电探测器的灵敏度、信噪比等性能。从上述具体应用出发,本论文研究了红外微透镜阵列的设计和制作。为了得到大F数、高面形精度红外微透镜阵列,本论文对所用的热回流、离子束刻蚀制作工艺进行了重点研究。具体来说,本文主要取得了以下成果:1.明确了热释电探测器上的具体应用对红外微透镜阵列的设计所提出的要求。2.针对传统热回流法难以制作大F数微透镜的问题,深入研究了热回流的理、化机理和动态过程。研究发现光刻胶分子热交联和重力是制约传统热回流法获得大F数微透镜的重要因素。在此基础上,提出二次曝光和倒置热回流相结合的方法,该方法可将光刻胶微透镜的F数上限由2.4提高至9.7。此外,还可以通过调节二次曝光的剂量对微透镜的面形进行精确控制。3.为实现光刻胶微透镜向硅基底的保形转移,研究了离子束刻蚀过程中的面形演化机制以及刻蚀选择比、刻面效应和槽底开沟对图形转移的影响。在此基础上,通过优化离子束刻蚀角度消除了刻面效应和槽底开沟对微透镜图形转移的不利影响。研究发现当离子束以40度角倾斜入射时,可将实际面形和理想球面的最大误差控制在0.27微米以内,并且刻蚀得到的硅微透镜表面光滑、均匀性良好。
[Abstract]:Uncooled infrared focal plane arrays can be used for staring imaging of infrared targets. Because of its light weight, low power consumption and low cost, it is widely used in military and civil fields. For pyroelectric uncooled infrared focal plane arrays, thermal crosstalk between pixels is an important factor that restricts their performance, so it is usually necessary to thermal insulate their pixels. However, this reduces the fill factor of the detector, which in turn leads to a decrease in the utilization rate of light energy. The integration of microlens array and detector can effectively solve this problem. In this method, the infrared radiation incident to the whole pixel can be converged into Guang Min region in the middle of the pixel by using the micro lens element. In general, integrated microlens arrays can significantly improve the sensitivity, signal-to-noise ratio and other performance of pyroelectric detectors. Based on the above application, the design and fabrication of infrared microlens array are studied in this paper. In order to obtain a large F number and high precision infrared microlens array, the fabrication process of thermal reflux and ion beam etching is studied in this paper. Specifically, the main achievements of this paper are as follows: 1. The requirements for the design of infrared microlens arrays for the specific applications of pyroelectric detectors are clarified. 2. In order to solve the problem that it is difficult to fabricate large F-number microlens by traditional heat reflux method, the mechanism and dynamic process of thermal reflux are studied. It is found that thermal crosslinking and gravity of photoresist molecules are important factors restricting the traditional thermal reflux method to obtain large F-number microlenses. On this basis, a method of combining secondary exposure and inverted heat reflux is proposed, which can increase the upper limit of F number of photoresist microlens from 2.4 to 9.7. In addition, the surface shape of the microlens can be precisely controlled by adjusting the dose of secondary exposure. In order to realize the conformal transfer of photoresist microlens to silicon substrate, the mechanism of surface shape evolution during ion beam etching and the influence of etching selection ratio, etch effect and groove opening on the pattern transfer were studied. On this basis, the negative effects of surface effect and groove opening on the pattern transfer of microlens were eliminated by optimizing the ion beam etching angle. It is found that the maximum error between the real surface and the ideal sphere can be controlled within 0.27 渭 m when the ion beam is tilted at an angle of 40 degrees, and the surface of the etching silicon microlens is smooth and the uniformity is good.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN215

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