基于nc-Si：H TFTs的加速度传感器特性研究

发布时间：2018-06-30 09:37

本文选题：加速度传感器 + nc-Si:H　；参考：《黑龙江大学》2016年博士论文

【摘要】：加速度传感器是微型惯性组合测量系统的核心器件。采用微机械加工技术制作的加速度传感器广泛应用于导航系统、自动控制、汽车、地震测量、军事和空间系统等方面。加速度传感器种类多样,其中压阻式加速度传感器具有体积小、频率范围宽、测量加速度的范围大、直接输出电压信号、接口电路简单、适合大批量生产,与标准IC工艺兼容等特点。本课题研究基于nc-Si:H TFTs的加速度传感器,为纳米硅薄膜在传感器领域进一步应用以及传感器高灵敏度、小型化和多功能化研究奠定基础。主要内容包括:1.基于nc-Si:H TFTs的加速度传感器基本结构与工作原理采用CMOS工艺在自由端带有质量块的悬臂梁根部制作四个纳米硅薄膜晶体管(nc-Si:H TFTs),形成惠斯通电桥结构,其中两个nc-Si:H TFTs沿011晶向制作,而另外两个nc-Si:H TFTs沿011晶向制作,以实现基于nc-Si:H TFTs的加速度传感器。在外加加速度作用下,悬臂梁受到弯矩作用而发生弯曲。由于悬臂梁根部受应力作用,在根部制作的四个nc-Si:H TFTs沟道等效电阻的阻值将发生变化,沿011晶向制作的两个nc-Si:H TFTs沟道电阻的相对变化量是正值,而沿011晶向制作的两个nc-Si:H TFTs沟道电阻的相对变化量是负值,使得惠斯通电桥两臂不平衡,产生输出电压,从而将非电量信号加速度转换为电信号输出。针对基于nc-Si:H TFTs的加速度传感器工作过程中悬臂梁根部nc-Si TFTs所受应力作用,根据压阻理论从外加压力P=0和P≠0两方面对I-V特性进行详述。2.基于nc-Si:H TFTs的加速度传感器仿真研究、芯片设计、制作和封装为了研究nc-Si:H TFTs的特性并实现高性能基于nc-Si:H TFTs的加速度传感器设计制作,通过仿真软件SILVACO和ANSYS分别对nc-Si:H TFT和加速度传感器进行仿真研究。当nc-Si:H TFT的沟道长度缩小到10μm,采用ATLAS建立二维仿真模型,根据热载流子能量平衡输运原理,在VGS=3V、6V和9V条件下,nc-Si:Htft仿真模型的ids-vds特性出现负阻现象。通过栅氧化层与纳米硅薄膜界面处的载流子复合率、平行于沟道表面方向的横向电场强度和沿纳米硅薄膜与栅氧化层界面处的纵向电场强度分布分析在夹断区内热载流子输运对负阻特性的影响。利用有限元仿真工具ansys,建立加速度传感器有限元模型,该芯片尺寸为10mm×10mm×500μm(厚),悬臂梁的尺寸为6000μm(长)×1500μm(宽)×62μm(厚)。对加速度传感器静态分析表明在距离悬臂梁根部150μm处δxx和δyy达到最大值,选择压阻效应最大区域,确定由4个nc-si:htfts构成的惠斯通电桥结构的最佳位置,优化基于nc-si:htfts的加速度传感器芯片设计,以求加速度传感器性能的最佳条件。在静态分析的基础上,对有限元仿真模型进行模态分析以及谐响应特性分析,从而实现高灵敏度加速度传感器的制作。在仿真研究的基础上,详细论述基于nc-si:htfts的加速度传感器设计、制作工艺和芯片封装。在n型100晶向高阻(ρ100Ω·cm)单晶硅衬底上,采用cmos工艺在悬臂梁根部制作四个长宽比l/w=80μm/40μm的nc-si:htfts,构成惠斯通电桥结构,其中两个nc-si:htfts沿011晶向制作,而另外两个nc-si:htfts沿011晶向制作。采用icp刻蚀的方法制作长和宽分别为6000μm和1500μm的悬臂梁,并形成位于悬臂梁自由端的质量块,从而实现基于nc-si:htfts的加速度传感器制作,芯片面积为10mm×10mm。3.加速度传感器输出信号的存储电路为实现基于nc-si:htfts的加速度传感器输出信号的数字化存储,本课题进一步探讨加速度传感器模数转换及存储问题。设计并制作了基于双稳态电阻开关ito/pvk/al的1t-1r一位存储单元电路,提出传感器数字化存储的新技术方案。在加速度传感器模数转换的基础上,采用非共轭聚合物材料聚乙烯咔唑(poly(n-vinylcarbazole),pvk)纳米膜作为存储层,研究双稳态电阻开关ito/pvk/al以及n-mosfet与双稳态电阻开关ito/pvk/al组成的1t-1r一位存储单元电路特性。采用存储材料pvk所制作的ito/pvk/al表现出非挥发双稳态电阻开关特性,开启电压为-1v,on/off电流开关比接近104。在常温下,由该有机电阻开关与n-mosfet组成的一位存储单元电路在104s的编程时间里,具有较高的稳定性,提出基于有机存储材料实现加速度传感器输出数据数字化存储的可行性方案,为实现压阻式加速度传感器输出从模拟信号到数字信号的数据存储奠定基础。4.基于nc-Si:H TFTs的加速度传感器特性研究采用XRD、拉曼光谱、AFM和SEM对LPCVD法制备的纳米硅薄膜进行表征。并对采用该方法制备的L/W=80μm/40μm、L/W=160μm/40μm和L/W=240μm/40μm的nc-Si:H TFT s进行IDS-VDS特性测试。在基于nc-Si:H TFTs的加速度传感器频率特性测试中,对于纳米硅薄膜厚度达到90nm的加速度传感器,悬臂梁厚度由62μm增加到160μm导致加速度传感器共振频率由458.72Hz增加到1054.06Hz;对于悬臂梁厚度为160μm的基于nc-Si:H TFTs的加速度传感器,随着质量块质量的增加,共振频率由1054.06Hz减小到458.71Hz,但输入与输出信号之间产生1.08ms的延迟;加速度传感器的共振频率与所受外部振动信号的频率有关,而与输入振动波形无关。对已经测试频率特性的悬臂梁厚度为160μm且质量块质量增加的加速度传感器进行灵敏度测试,传感器输出信号经仪表放大器放大,灵敏度为0.198V/g/5V。
[Abstract]:Acceleration sensors are the core components of the micro inertial measurement system. The accelerometers made with micromachining technology are widely used in the navigation system, automatic control, automobile, seismic measurement, military and space systems. The variety of accelerometers, in which the piezoresistive accelerometer has small volume and frequency. Wide range, wide range of measurement acceleration, direct output voltage signal, simple interface circuit, suitable for large mass production and compatible with standard IC technology. This subject studies the acceleration sensor based on nc-Si:H TFTs, further application of nano silicon film in the field of sensor, and sensor's high sensitivity, miniaturization and multi-function research The main contents are as follows: 1. based on the basic structure and working principle of the nc-Si:H TFTs acceleration sensor, four nanoscale silicon thin film transistors (nc-Si:H TFTs) are produced at the root of the cantilever beam with mass block at the free end, forming the structure of the Wheatstone bridge, of which two nc-Si:H TFTs are made along the 011 crystal, and the other two. The nc-Si:H TFTs is made along the 011 crystal direction to realize the acceleration sensor based on nc-Si:H TFTs. Under the action of acceleration, the cantilever beam is flexed by the bending moment. As the root of the cantilever beam is subjected to stress, the resistance value of the equivalent resistance of the four nc-Si:H TFTs channels produced in the root will change, and the two NC made along the 011 crystal will be changed. The relative variation of the -Si:H TFTs channel resistance is positive, while the relative variation of the resistance of the two nc-Si:H TFTs channel along the 011 crystal is negative, making the two arms of the Wheatstone bridge unbalanced and producing the output voltage, thus converting the acceleration of the non electric signal to the electrical signal output. For the acceleration sensor based on nc-Si:H TFTs, the acceleration sensor works. In the course of the stress action of the nc-Si TFTs of the cantilever beam root, according to the piezoresistive theory from the external pressure P=0 and P 0, the acceleration sensor simulation of.2. based on nc-Si:H TFTs is detailed. The chip design, fabrication and encapsulation are used to study the characteristics of nc-Si:H TFTs and achieve high performance based on the acceleration transmission of nc-Si:H TFTs. The sensor is designed and made. The simulation study of nc-Si:H TFT and acceleration sensor is carried out by simulation software SILVACO and ANSYS. When the channel length of nc-Si:H TFT is reduced to 10 mu m, a two-dimensional simulation model is established with ATLAS. The nc-Si:Htft simulation model is based on the principle of the energy balance of the hot carrier and under the VGS=3V, 6V and 9V conditions. The effect of the carrier recombination at the interface between the gate oxide layer and the nano silicon film, the transverse electric field strength parallel to the channel surface and the distribution of the longitudinal electric field along the interface between the nanoscale film and the gate oxide layer at the interface between the nanoscale silicon film and the gate oxide layer influence the negative resistance characteristics of the hot carrier transport in the pinch zone. With ANSYS, a finite element model of the acceleration sensor is set up, the size of the chip is 10mm x 10mm x 500 mu m (thick), the size of the cantilever beam is 6000 m (long) * 1500 mu m (wide) x 62 mu m (thick). The static analysis of the acceleration sensor shows that the maximum value is reached at the 150 u m of the cantilever beam at the root of the cantilever beam, and the maximum area of the piezoresistive effect is selected and the 4 nc-Si is determined. The best position of the structure of the Wheatstone bridge is made up of htfts, optimizing the design of the acceleration sensor chip based on nc-si:htfts to optimize the performance of the acceleration sensor. On the basis of static analysis, the modal analysis and the harmonic response characteristic analysis of the finite element simulation model are carried out to realize the high sensitivity acceleration sensor. On the basis of simulation research, the design of acceleration sensor based on nc-si:htfts, fabrication process and chip packaging are discussed in detail. On the N type 100 crystal to high resistance (rho 100 Omega cm) single crystal silicon substrate, CMOS technology is used to produce four nc-si:htfts of long and wide ratio l/w=80 u m/40 mu m in the root of the cantilever beam, which constitutes the structure of the Wheatstone bridge, of which two Nc-si:htfts is made along the 011 crystal, while the other two nc-si:htfts are made along the 011 crystal. The cantilever beam with long and wide width of 6000 mu m and 1500 mu m is made by ICP etching, and the mass block at the free end of the cantilever beam is formed, thus the acceleration sensor based on nc-si:htfts is made. The chip area is 10mm x 10mm.3. acceleration sensing. The storage circuit of the output signal of the device is to realize the digital storage of the output signal of the acceleration sensor based on nc-si:htfts. This topic further discusses the problem of the analog conversion and storage of the acceleration sensor. A 1t-1r one bit storage unit based on the bistable resistance switch ito/pvk/al is designed and produced, and the digital storage of the sensor is put forward. On the basis of the modulus conversion of acceleration sensor, the non conjugated polymer material polythene carbazole (poly (N-vinylcarbazole), PVK) nano film is used as the storage layer to study the circuit characteristics of a 1t-1r one bit memory unit composed of bistable resistance switch ito/pvk/al and n-MOSFET and bistable resistor switch ito/ pvk/al. The ito/pvk/al produced by the storage material PVK shows the non volatile bistable resistance switch characteristic, the opening voltage is -1v, the on/off current switch ratio is close to 104. at normal temperature. A memory unit circuit composed of the organic resistor switch and n-MOSFET has high stability in the programming time of 104s, and it is proposed based on the organic storage material. The feasibility of the digital storage of the output data of the acceleration sensor is used to lay the foundation for the output of the piezoresistive acceleration sensor from the analog signal to the digital signal. The.4. based acceleration sensor based on the nc-Si:H TFTs is used to characterize the nano silicon thin film prepared by the LPCVD method by the XRD, the Raman spectra, the AFM and the SEM. The characteristics of the L/W=80 mu m/40 mu m, L/W=160 mu m/40 mu m and L/W=240 mu m/40 mu m nc-Si:H TFT s are tested. In the acceleration sensor based on the acceleration sensor, the cantilever beam thickness is increased from 62 to 160 Mu to the acceleration sensor. The resonant frequency of the sensor is increased from 458.72Hz to 1054.06Hz, and for the acceleration sensor based on nc-Si:H TFTs for the thickness of the cantilever beam 160 m, the resonance frequency decreases from 1054.06Hz to 458.71Hz with the mass of mass increase, but the delay between the input and output signals produces 1.08ms; the resonance frequency of the acceleration sensor and the outside of the acceleration sensor The frequency of the vibration signal is related to the input vibration wave. The sensitivity test for the acceleration sensor with the thickness of the cantilever beam of 160 mu m and the mass increase of the mass is tested. The sensor output signal is amplified by the instrument amplifier, and the sensitivity is 0.198V/g/ 5V.
【学位授予单位】：黑龙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP212

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