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384×288 12 μm共用桥腿式非制冷红外探测器封装完成后,依据国标GB/T 13584—2011 和GB/T 17444—1998进行性能参数测试,同时与传统双层结构的相同面阵探测器进行性能比较。为研究共用桥腿结构对探测器性能的影响,共用桥腿式结构与传统双层结构相比,仅改变桥腿连接方式,不改变其他参数,即面阵大小、像元中心距、封装方式和测试参数等均相同。如表1所示为共用桥腿结构与传统双层结构的基本参数对比。
Array Pitch/μm Face area/μm2 Leg width/μm Leg length/μm Non-uniformity of Res. Package Common-leg width=0.5 μm 384×288 12 121 0.5 120 1.2% metallic Common-leg width=0.35 μm 384×288 12 121 0.35 140 0.6% metallic Regular double_layer 384×288 12 121 0.35 70 0.8% metallic Table 1. Parameter of common-leg and regular double-layer structure IRFPA detector
图8所示为两种不同宽度共用桥腿结构与传统双层结构探测器相比较的坏元分布图,探测器的盲元率均控制在0.1%以内。
图9所示为探测器的噪声分布图,噪声统计图呈很好的高斯分布,说明像元均匀性好。与传统双层结构相比,噪声图无明显变化,共用桥腿结构不会引入额外的噪声。图10所示为NETD直方图,NETD分布呈高斯分布。桥腿宽度为0.5 μm的探测器NETD在10~20 mK之间,平均为15.4 mK;桥腿宽度为0.35 μm的探测器由于桥腿长度大幅增加,其NETD在9~15 mK之间,平均为11.2 mK。传统双层结构的探测器NETD在21~41 mK之间,平均为31.5 mK。与传统双层结构探测器相比,共用桥腿结构的NETD性能指标提升了50%~64%,共用式桥腿探测器NETD性能指标优异。
图11所示为响应率直方图,探测器的响应率集中度高,响应率非均匀性为均在1.2%以内,阵列具有良好的均匀性和一致性。桥腿宽度为0.5 μm的探测器响应率均值为44.8 mV/K,响应率非均匀性为1.1%。桥腿宽度为0.35 μm的探测器响应率均值为53.9 mV/K,响应率非均匀性为0.6%。传统双层结构的探测器响应率均值为23.4 mV/K,响应率非均匀性为0.8%。与传统双层结构探测器相比,共用式桥腿结构探测器响应率提升了90%~130%。
对比图10和图11,桥腿宽度为0.35 μm的探测器性能参数优于桥腿宽度为0.5 μm的探测器。但共用桥腿宽度为0.35 μm的桥腿长度较长,其热响应时间约为16 ms,而共用桥腿宽度为0.5 μm的探测器的热响应时间约为13 ms,共用桥腿宽度为0.5 μm的探测器在快速运动场景中具有更实用优势。桥腿宽度为0.35 μm的探测器适用于成像场景不会迅速变化,但对成像画面要求较高的情况。桥腿宽度为0.5 μm的探测器可适用于快速变化场景,对成像画面要求不是特别高的情况。
Research of high-performance uncooled infrared focal plane array detector with common-leg structure
doi: 10.3788/IRLA20200330
- Received Date: 2020-09-09
- Rev Recd Date: 2020-12-01
- Available Online: 2021-05-12
- Publish Date: 2021-03-15
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Key words:
- common-leg structure /
- micro bridge structure /
- uncooled infrared /
- IRFPA
Abstract: A novel micro bridge structure for uncooled vanadium oxide infrared focal plane array (IRFPA) detector was developed. This micro bridge used common-leg structure, which was shared by column adjacent pixels. Common-leg structure greatly increased the leg length, reducing the thermal conductivity, which could effectively improve the response rate and reduced the negative electron-transfer dissociation (NETD). Furthermore, the micro bridge adopted double-layer process to increase the area of the deck and the vanadium oxide, which could improve the filling rate and the detector performance. The detector array was 384×288 with 12 μm pixels. The readout integrated circuit (ROIC) adopted rolling-shutter mode for integration and a pixel-by-pixel mode for readout. The high reliability metal vacuum package was used for the device. The results showed that the NETD of the detector was less than 15 mK, and the response rate was greater than 44 mV/K. Its performance index could meet the requirements of civil and military applications.