刘伟, 何兵, 马特, 刘刚. 微测辐射热计器件工艺开发和特性评估[J]. 红外与激光工程, 2023, 52(1): 20220279. DOI: 10.3788/IRLA20220279
引用本文: 刘伟, 何兵, 马特, 刘刚. 微测辐射热计器件工艺开发和特性评估[J]. 红外与激光工程, 2023, 52(1): 20220279. DOI: 10.3788/IRLA20220279
Liu Wei, He Bing, Ma Te, Liu Gang. Process development and characteristic evaluation of micro-bolometer device[J]. Infrared and Laser Engineering, 2023, 52(1): 20220279. DOI: 10.3788/IRLA20220279
Citation: Liu Wei, He Bing, Ma Te, Liu Gang. Process development and characteristic evaluation of micro-bolometer device[J]. Infrared and Laser Engineering, 2023, 52(1): 20220279. DOI: 10.3788/IRLA20220279

微测辐射热计器件工艺开发和特性评估

Process development and characteristic evaluation of micro-bolometer device

  • 摘要: 依托半导体生产线开发了基于MEMS微桥结构的微测辐射热计(micro-bolometer)器件,其中,使用化学气相沉积(CVD)技术开发了非晶硅(α-Si)薄膜工艺,并将其用作微测辐射热计器件的敏感层材料,该材料在1000 Å厚度下的膜厚均匀性可以控制在2%以内(1-sigma,within wafer),电阻均匀性可以控制在2%以内(1-sigma,within wafer),其室温下的电阻温度系数(TCR)可以达到−2.5%左右;采用先刻沟槽工艺技术开发了MEMS微桥结构的接触模块,以无支撑柱结构实现了其支撑和电连接结构;使用Ti/TiN薄金属薄膜作为电极层,并利用电极层图形实现该敏感层电阻器件的电连接和图形定义;开发了高性能敏感层电阻工艺技术,实现了对敏感层材料工艺损失和电极层侧面腐蚀的良好工艺控制。在完成微测辐射热计器件工艺开发后,对其进行了器件级测试和评估,结果表明:该器件室温电阻值在250 kΩ左右,且具有优异的欧姆接触特性;室温下器件级TCR在−2%左右,略低于非晶硅薄膜材料TCR的测试值;同时,对该器件进行的升温和降温测试结果表明,文中开发的敏感层材料没有滞回效应。最后,对该器件进行释放工艺处理形成悬空的MEMS微桥结构,经扫描电镜(SEM)和光学显微镜测试评估,其微桥表面呈现良好的平坦度和均匀性,能够很好地满足微测辐射热计及相应的非制冷红外探测器产品的技术需求。

     

    Abstract: Based on MEMS micro-bridge structure, micro-bolometer device was developed on standard semiconductor production line. Chemical Vapor Deposition (CVD) technology was used to deposit amorphous silicon (α-Si) film as sensing material. The within wafer thickness uniformity and the resistance uniformity of 1000 Å α-Si film can be controlled to be less than 2%, and the Temperature Coefficient of Resistance (TCR) of 1000 Å α-Si film can reach at about −2.5%. Contact module of MEMS micro-bridge structure was developed by trench first approach, and electrical connection between MEMS and readout circuit was achieved by thin electrode layer on sidewall and bottom of the anchor and contact structure. Ti/TiN thin metal layer was used as electrode layer, and sensing resistor device was defined by the electrode layer patterns. Sensing material resistor device was fabricated by optimized integration scheme, which can achieve better process control on the sensing material loss and electrical layer sidewall recess etch amount. After device fabrication, room temperature resistance of device was about 250 kΩ with good ohmic contact. Device level TCR was measured at about −2%, and slightly lower than the data of thin film on blanket wafer. And the resistance data during the temperature raising up and down indicated that there was no hysteresis effect. Finally the MEMS device was released, and the optical and SEM data showed good physical performance, which can match the technical requirements of micro-bolometer production.

     

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