CMOS兼容的微机械热电堆红外探测器的设计

提出了一种与 CMOS 工艺兼容、高响应率、低噪声的微机械热电堆红外探测器.该结构热电偶数目为两对,材料为P/N型多晶硅,吸收层材料为TiN.采用较少热电偶对的方式来降低噪声,引入共振谐振腔结构来提高红外吸收率.阐述了探测器的基本工作原理,通过仿真得到其重要的性能参数,并给出了器件具体的工艺流程,对器件尺寸进行了优化.理论上,其响应率大于1000 V/W,探测率大于2×108 cmHz1/2W-1,噪声等效温差小于20 mK,时间常数小于10 ms,电阻值小于20 k?.     

一种与CMOS工艺兼容的热电堆红外探测器

报道了一种与CMOS工艺兼容的微机械热电堆红外探测器.提出了具有一对热电偶的两层悬浮结构,其占空因子达到80％以上,并采用P/N多晶硅作为热电偶材料,黑硅作为吸收层材料.给出了器件的工作原理,对性能优化与制作的工艺流程进行了分析,结合所选材料的基本参数,得到了优化后的结构尺寸.通过理论计算,可以获得响应率大于1000 V/W,探测率大于1×108 cmHz1/2W-1,时间常数小于40 ms,噪声等效温差小于30 mK的性能优良的热电堆红外探测器.该器件的吸收层位于结构中的顶层,金属布线位于底层,便于与后续电路集成.单元大小为25 μm×25 μm,有利于制作非制冷红外焦平面阵列.     

一种交叉式圆形MEMS热电堆红外探测器

微电子机械系统(MEMS)热电堆红外探测器是非接触测温仪、光谱仪、气体传感器等现代信息探测系统的核心工作器件。研制了一种交叉式排布的圆形热电堆结构,其热偶条形状由传统矩形调整为直角梯形以降低探测器电阻,热端通过交叉式排布延伸至中心温度集中区,同时增大冷端欧姆接触面积并覆盖反射层以降低冷端温度,有效地增大了冷热端温度梯度。测试结果显示,优化后的交叉式圆形MEMS热电堆探测器距黑体辐射面3 cm处响应电压为22.673 mV,响应率为47.5 V/W,探测率为■,相对于传统圆形热电堆探测器的18.649 mV、39.1 V/W和■分别提升了21.57%、21.48%和18.5%。给出了热电堆探测器结构设计、仿真结果、制作工艺以及测试结果,为热电堆红外探测器的优化设计提供了参考。     

一种具有高填充因子吸收层和低失调低噪声读出电路的红外探测系统

使用红外探测器及读出电路,研制成功非制冷红外探测系统.探测器用二极管作为温度传感器,使其与集成电路工艺相兼容.采用了新的器件结构,使得填充因子从20%提高到80%.器件的微机械结构面积为35μm×35μm.读出电路的失调电压为3μV.探测器的输出噪声为2μV.探测器的电压响应率为7 894.7 V/W,黑体探测率D*为1.56×109cmHz1/2/W,噪声等效温差为330 mK,响应时间为27 ms.     

偏硼酸钡热电探测器研究

本文首次报导用低温相偏硼酸钡晶体做成热电探测器,并对其性能进行了测试。结果表明:低温相偏硼酸钡热电探测器具有耐高功率辐射性能、中等探测率、宽光谱响应、介电常数小等特点,是一种大功率运用的较理想的热电探测器。器件灵敏面为φ1.5mm时,探测率D~*(500,80.1)=2×10~7cmHz~(1/2)W~(-1)。等效噪声功率NEP(500,80,2.7)=7.1×10~(-9)W。器件灵敏面为φ4及φ2mm时,采用金属衬底,在自然冷却条件下,用CO_2连续激光进行刀口调制后照射器件,器件可耐平均功率密度67W/cm~2、峰值功率密度168W/cm~2。损伤阈值为120W/cm~2(连续CO_2激光照射)。     

同时模式的中波/长波碲镉汞双色红外探测器

采用光刻胶喷涂技术,突破了碲镉汞双色探测器加工的非平面离子注入和金属化开口等工艺.基于分子束外延(MBE)和原位掺杂技术生长的p3-p2-P1型碲镉汞(Hg1-xCdxTe)多层异质结材料,通过MW光电二极管n型注入区的开口刻蚀、非平面的MW/LW同步B+注入、台面侧向钝化和爬坡金属化,得到了同时模式的128×128面阵MW/LW双色探测器.在液氮温度下,MW/LW双色探测器两个波段的光电二极管截止波长λc分别为5.10μm和10.10μm,对应的峰值探测率Dλp*分别为2.02×1011cmHz1/2/W和3.10×1010cmHz1/2/W.通过对同时模式双色探测器材料与芯片结构的优化设计,HgCdTe双色探测器MW向LW、LW向MW的光谱串音分别抑制到了3.8%和4.4%.     

InAs/GaSb台面结型器件制备工艺技术研究

随着红外探测技术的不断进步,第三代红外探测器的发展需求日渐明晰。由于带间跃迁工作原理、暗电流抑制效应以及成熟的材料制备技术基础等因素,InAs/GaSb超晶格材料已经成为了第三代红外焦平面探测器的首选制备材料。基于InAs/GaSb超晶格材料的台面结型焦平面器件制备方法主要包括湿法腐蚀技术、干法刻蚀技术以及干湿法结合技术。从文献调研结果来看,湿法腐蚀技术和干法刻蚀技术各有优缺点。湿法腐蚀技术适用于单元以及少像元面阵的制备,其中磷酸系腐蚀液的腐蚀效果最佳;干法刻蚀技术适用于大面阵、小尺寸焦平面阵列的制备,几种氯基刻蚀气体体系以及氯基与甲烷基组合的刻蚀气体体系都表现出了不错的刻蚀效果;干湿法结合技术在干法刻蚀后引入湿法腐蚀工艺以进一步消除刻蚀损伤,从而提高器件性能。对以上三种技术方案进行了介绍和分析。     

基于CMOS工艺的双层非制冷热敏电阻型红外探测器

采用0.5μm标准CMOS工艺和微机械加工工艺,设计并制作了低成本双层非制冷热敏电阻型红外探测器。探测器采用隐藏桥腿式微桥结构,使用表面牺牲层技术实现,其中包括Al、W和Si3种牺牲层材料。CMOS工艺加工完成后,双层微桥结构的微机械加工过程只需进行湿法腐蚀即可,成本较低。对双层红外探测器的热性能和光电特性进行测试,其热导为1.96×10-5 W/K,热容为2.23×10-8 J/K,热时间常数为1.14ms。当红外辐射调制频率为10Hz时,双层红外探测器的电压响应率为2.54×104 V/W,探测率为1.6×108 cm·Hz1/2/W。     

基于多层薄膜的长波红外InAs/GaSb Ⅱ类超晶格焦平面光响应调控研究

本文系统报道了基于InAs/GaSb Ⅱ类超晶格（T2SLs）的长波红外探测器的研究进展。从衬底、材料生长以及器件性能角度对比分析了基于GaSb、InAs衬底的各种器件结构的优缺点。分析结果表明,以InAs为衬底、吸收区材料为InAs/InAs_1－xSb_x、PB₁IB₂N型的结构为相对优化的器件结构设计,结合ZnS和Ge的多层膜结构设计或者重掺杂缓冲层,同时采用电感耦合等离子体（inductively coupled plasma）干法刻蚀工艺,该器件的50%截止波长可达12 μm,量子效率（quantum efficiency）可提升到65%以上,暗电流密度降低至1×10^－5 A/cm²。并归纳总结了InAs/GaSb T2SLs长波红外探测器未来的发展趋势。     

硅基热电堆真空传感器的制造技术

发展了一种与CMOS工艺完全兼容并可在商业化的1.2μm标准CMOS生产流水线上进行流片的硅基热电堆真空传感器的制造技术与流程.传感器为悬浮的多层复合薄膜结构,其上制作了n型多晶硅加热器和20对由p型多晶硅条和铝条构成的热电堆.利用标准制造工艺中铝层图形的掩蔽作用,使用干法刻蚀工艺一方面去除了传感器表面的SiNx层,使复合介质薄膜减至三层介质,即场氧化层、硼磷硅玻璃和层间介质,从而提高了传感器响应率;另一方面去除了传感器区域内腐蚀孔中的多层介质,将其中的硅衬底裸露,以便完成后续的四甲基氢氧化铵(TMAH)体硅各向异性腐蚀工艺,使传感器成为悬浮绝热结构,这种工艺具备铝保护性能,因此腐蚀中无需任何掩模.最终得到的器件尺寸为124 μm×100 μm,在空气压强为0.1 Pa～105 Pa之间的响应电压为26 mV～50 mV,响应时间为0.9 ms～1.3 ms.这种器件的制造技术具有工艺简单、成品率高、成本低、重复性好等特点.     

Thermopile Infrared Detector with Detectivity Greater Than 10<Superscript>8</Superscript> cmHz<Superscript>(1/2)</Superscript>/W

In this paper, the design, fabrication and experimental results of the thermopile infrared detector, with a single layer of low-stress SiN_x membrane, instead of thin sandwich layer membrane of SiO₂–Si₃N₄ are presented. Thermal isolation is achieved by using back etching of bulk silicon. Thermopiles are consisted of serially interconnected p-poly-Si/Al thermocouples supported by the single layer of SiN_x membrane with low stress. Au/Ti reflective coating was evaporated on the surface of cold junctions of the thermopile to block incident radiation. In the measurement, we find that infrared absorbance of SiN_x membrane to different wavelength is diverse and less than 100%, which has great influence on calculating the actual absorbing power of the detector, so the infrared (IR) transmission spectrum is measured to calibrate the actual infrared absorbing amount of the detector. The analysis result shows that only 43.72% infrared radiation is absorbed by the detector. Based on the measurement of IR transmission spectrum and output voltage of the detector, the response sensitivity of the detector is calculated as 31.65 V/W, detectivity of the detector is 1.16 × 10⁸ cmHz^(1/2)W⁻¹, and response time of the detector is 126 ms.     

A batch-fabricated silicon thermopile infrared detector

A thermopile infrared detector fabricated using silicon integrated-circuit technology is described. The device uses a series-connected array of thermocouples whose hot junctions are supported an a thin silicon membrane formed using anisotropic etching and a diffused boron etch stop. The membrane size and thickness control the speed and responsivity of the structure, which can be designed for a given application. For a 2-mm × 2-mm × 1-µm silicon membrane containing sixty bismuth-antimony couples, the structure produces a responsivity of 6 V/W and a time constant of about 15 ms. The use of polysilicon-gold couples can improve the responsivity to nearly 10 V/W while maintaining the same speed, simplifying the process, and retaining compatibility with on-chip signal processing circuitry.     

基于各向同性干法刻蚀的大面积悬空Al膜制备

热声传感器随着多孔硅的热致超声发射现象的发现越来越受到关注。热声传感器通过改变器件表面热量而在周围空气中产生交变压力,从而向外发出声波。热声传感器的关键器件是悬空金属薄膜。制备大面积悬空薄膜释放有一定的难度,需要考虑金属薄膜本身的应力与粘附效应。该文提出了两种基于各向同性干法刻蚀的制备金属薄膜的方法,利用XeF2/SF6制备悬空Al膜。由于XeF2与SF6气体刻蚀硅时对于Al有较高的选择比,XeF2对于硅是各向同性刻蚀且有很高的刻蚀速率,而通过设置感应耦合等离子体（ICP）刻蚀机的参数也可利用SF6达到各向同性刻蚀。基于上述特点制备了悬空Al膜,设计相应的制备流程,探索XeF2刻蚀机与ICP刻蚀机合适的刻蚀参数。所制备的悬空Al膜平整、无杂质,具有良好的形貌。     

Uncooled thermopile infrared detector linear arrays withdetectivity greater than 109 cmHz1/2/W

We have fabricated 63-element linear arrays of micromachined thermopile infrared detectors on silicon substrates. Each detector consists of a suspended silicon nitride membrane with 11 thermocouples of sputtered Bi-Te and Bi-Sb-Te films. At room temperature and under vacuum these detectors exhibit response times of 99 ms, zero frequency D* values of 1.4× 10⁹ cmHz^1/2/W and responsivity values of 1100 V/W when viewing a 1000 K blackbody source. The only measured source of noise above 20 mHz is Johnson noise from the detector resistance. These results represent the best performance reported to date for an array of thermopile detectors. A test procedure is described that measures many of the relevant electrical, optical, and thermal properties of the detectors without specialized test structures     

用于高灵敏度红外探测器的超薄硅膜的研制

超薄、平整的硅膜对于制作高灵敏度红外探测器是非常重要的。这种超薄硅膜的各向异性腐蚀技术，包括有机溶液EPW和无机溶液KoH及KoH IPA(异丙醇)。从腐蚀速率、腐蚀表面质量、腐蚀停特性、腐蚀边缘形貌及腐蚀工艺的角度分析比较了两种腐蚀系统，分别制作出了约1μm厚的平整超薄硅膜，并研究了不同掩膜材料在腐蚀液中的抗蚀性，为高灵敏度红外探测器的制作奠定了工艺基础。     

A silicon-thermopile-based infrared sensing array for use in automated manufacturing

This paper describes a new low-cost infrared detector array that has been realized using standard silicon MOS process technology and micromachining. This array uses thermopiles as infrared detecting elements and multiple layers of silicon oxide and silicon nitride for diaphragm windows measuring 0.4 mm × 0.7 mm × 1.3 µm. Each thermopile consists of 40 polysilicon-gold thermocouples. A high fill factor for this array structure has been achieved by using the boron etch-stop technique to provide 20-µm thick silicon support rims. The array shows a response time of less than 10 ms, a responsivity of 12 V/ W; and a broad-band input spectral sensitivity. The process is compatible with silicon MOS devices, and a 16 × 2 staggered array with on-chip multiplexers has been designed for applications in process monitoring. The array theoretically achieves an NETD of 0.9°C and an MRTD of 1.4°C at a spatial frequency of 0.2 Hz/mrad in a typical imaging system.     

Temperature-compensated film bulk acoustic resonator above 2 GHz

Two different types of temperature-compensated film bulk acoustic resonators (FBARs) are designed, fabricated, and tested. One is formed by integrating FBAR with a surface-micromachined air-gap capacitor, which passively reduces the FBAR's temperature coefficient of frequency (TCF) by about 40 ppm//spl deg/C at 2.8 GHz. With this approach, zero TCF would easily have been achieved if the FBARs were built on AlN rather than ZnO. The other type of temperature compensated FBAR is built on a surface-micromachined SiO/sub 2/ cantilever that is released by XeF/sub 2/ vapor etching of silicon. The Al-ZnO-Al-SiO/sub 2/ FBAR is measured to have a TCF of -0.45 ppm//spl deg/C (between 85/spl deg/C and 110/spl deg/C) at 4.4 GHz.     

Hydrogen fluoride vapor etching for Pre-Epi silicon surface preparation

Hydrogen fluoride vapor etching of silicon dioxide was studied for its applicability to the preparation of silicon surfaces for low temperature epitaxy. The etching behavior of hydrogen fluoride vapor with and without added water vapor was studied qualitatively by observing changes in hydrophobicity, and quantitatively using ellipsometry. Epi films grown on vapor-treated surfaces were evaluated using transmission electron microscopy and by fabricating polysilicon-emitter diodes. It was found that complete removal of the silicon dioxide monolayer closest to the wafer surface proceeded much more slowly than etching of a bulk oxide layer. A mechanism for the reaction of HF and SiO₂ is proposed, in which the etching of a bulk film takes place in a thin aqueous layer on the oxide surface, while the removal of the final monolayer of oxide takes place as a gas-solid reaction.     

微机械非制冷红外热电堆探测器

近年来,非制冷红外探测器应用和开发一直是令人关注的焦点之一,详细介绍了几种现阶段流行的非制冷热电堆探测器的工艺制作方法以及所用材料,并介绍了近几年来热电堆探测器的发展情况.