基于标准CMOS工艺的微测辐射热计研究

发布时间：2018-08-26 13:46

【摘要】：非制冷红外探测器具有工作无需制冷、成本低、功耗小、重量轻、体积小、启动快、使用方便等优点,得到了广泛关注。其中,微测辐射热计为应用最为广泛的非制冷红外探测,它的发展主要依托于军事应用,但随着红外技术的发展和市场的需要,应用于商业领域和民用领域的基于标准CMOS工艺的低成本微测辐射热计成为研究热点。本文从结构设计、制作工艺以及性能测试等方面,对基于标准0.5μm CMOS工艺(两层多晶硅、三层金属铝)的微测辐射热计进行系统的研究。着眼于低成本大批量生产,根据标准CMOS工艺,设计并制作了两种基于单层微桥结构的单牺牲层微测辐射热计。其微桥结构采用表面牺牲层技术实现,不需要任何额外的光刻和沉积工艺。标准CMOS工艺中的金属1层与金属2层间的钨通孔2层以及金属3层分别作为热敏电阻材料,多晶硅2层和金属2层分别作为牺牲层材料,多晶硅牺牲层的腐蚀采用不腐蚀铝的TMAH溶液配方,金属2层牺牲层腐蚀采用磷酸溶液配方。测试结果表明,单牺牲层钨微测辐射热计的电压响应率为139.95V/W,探测率为8.19×107cmHz1/2/W,单牺牲层铝微测辐射热计的电压响应率为643.6VAW,探测率为3.44×108cmHz1/2/W。为进一步提高性能指标,设计并制作了基于单层微桥结构的双牺牲层铝微测辐射热计。其微桥结构采用表面牺牲层技术实现,不需要任何额外的光刻和沉积工艺。标准CMOS工艺中的金属3层作为热敏电阻材料,金属1层和金属2层间的通孔钨以及金属2层作为双牺牲层材料,牺牲层腐蚀分别采用过氧化氢溶液配方和磷酸溶液配方。同单牺牲层相比,双牺牲层形成的空腔可以进一步降低近场热辐射现象,并且其对于3～51μm的红外辐射可形成光学谐振腔,增强红外吸收。测试结果表明,双牺牲层铝微测辐射热计的电压响应率1751V/W,探测率为8.37×108cmHz1/2/W。为解决像元尺寸进一步减小时单层微桥结构的热隔离性能与填充因子的矛盾,设计并制作了基于双层微桥结构的多牺牲层铝微测辐射热计。其双层微桥结构采用隐藏桥腿式设计,由表面牺牲层技术实现,不需要任何额外的光刻工艺。标准CMOS工艺中的金属3层作为热敏电阻材料,多晶硅2层、多晶硅2层与金属1层间的过孔材料钨、金属1层、金属1层与金属2层间的过孔材料钨层以及金属2层作为多牺牲层材料,牺牲层腐蚀分别采用TMAH溶液配方、过氧化氢溶液配方和磷酸溶液配方。同单层微桥结构相比,双层微桥结构可以获得最大的填充因子,更适合制作小尺寸的微测辐射热计单元。测试结果表明,多牺牲层双层铝微测辐射热计的电压响应率863.96V/W,探测率为6.39×108cmHz1/2/W。为实现单片集成化,进行了铝微测辐射热计阵列与读出电路集成的初步研究。阵列单元采用单牺牲层铝微测辐射热计结构,并对其支撑腿进行优化设计,读出电路可以集成在微桥结构正下方,节省流片面积。测试结果表明,铝微测辐射热计阵列单元的电压响应率1206V/W,探测率为5.98×108cmHz1/2/W。阵列电阻分布均匀,成品率高,集成读出电路工作正常,可行性好,为制作低成本、大规模、高集成度的微测辐射热计阵列奠定了基础。
[Abstract]:Uncooled infrared detectors have attracted much attention due to their advantages such as low cost, low power consumption, light weight, small size, fast start-up and easy operation. Among them, microcalorimeter is the most widely used uncooled infrared detector, and its development mainly depends on military applications. However, with the development of infrared technology and market demand Low-cost microbolometers based on standard CMOS process for commercial and civilian applications have become a research hotspot. This paper systematically studies the microbolometers based on standard 0.5 micron CMOS process (two-layer polycrystalline silicon, three-layer metallic aluminum) from the aspects of structure design, fabrication process and performance testing. According to the standard CMOS process, two kinds of single sacrificial layer microbolometers are designed and fabricated. The micro-bridge structure is realized by surface sacrificial layer technology without any additional lithography and deposition process. As thermistor material, polycrystalline silicon 2 layer and metal 2 layer are sacrificial layer material, polycrystalline silicon sacrificial layer is corroded by TMAH solution without corrosive aluminum, and metal 2 layer is corroded by phosphoric acid solution. The voltage response rate of the single sacrificial layer aluminum microbolometer is 643.6 VAW and the detection rate is 3.44 In standard CMOS process, three layers of metal are used as thermistors, tungsten and two layers of metal are used as double sacrificial layers, and hydrogen peroxide solution and phosphoric acid solution are used for sacrificial layer corrosion respectively. The results show that the voltage response rate of the double sacrificial layer aluminum microbolometer is 1751V/W, and the detection rate is 8.37 *108cmHz 1/2/W. The thermal isolation performance and filling factor of the single-layer micro-bridge structure are solved when the pixel size is further reduced. A double-deck micro-bridge structure is designed and fabricated based on a double-deck micro-bridge structure. The double-deck micro-bridge structure is designed with hidden bridge legs and is realized by surface sacrificial layer technology without any additional lithography process. The metal three layers in the standard CMOS process are used as thermistor materials, polysilicon two layers, polysilicon two layers and gold. The tungsten layer, metal layer, metal layer and metal layer are used as multi-sacrificial layers. The TMAH solution, hydrogen peroxide solution and phosphoric acid solution are used for sacrificial layer corrosion respectively. The results show that the voltage response rate of the multi-sacrificial double-layer aluminum microbolometer is 863.96V/W and the detection rate is 6.39 *108cmHz 1/2/W. In order to realize the monolithic integration, the integration of the aluminum microbolometer array and the readout circuit is studied. The readout circuit can be integrated directly below the micro-bridge structure to save the chip area. The test results show that the voltage response rate of the array unit is 1206V/W, the detection rate is 5.98 *108cmHz 1/2/W. It works well and has good feasibility, which lays a foundation for fabricating low cost, large scale and high integration microbolometer array.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN215

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