Chun-Te Lin

Investigation of the hysteresis phenomenon of a silicon-based piezoresistive pressure sensor

At present, the silicon piezoresistive pressure sensor is a mature technology in the industry, and its measurement accuracy is more rigorous in many advanced applications. Micro piezoresistive pressure sensor is fabricated by a MEMS process, and its main operational principle is that the external pressure loading causes the deflection, strain, and stress which occur on the silicon membrane. The environmental temperature, the humidity, and the pressure will reduce its performance. Moreover, the drifts of output voltage in the same temperature caused by the residual stress on the aluminum trace under thermal cycle loading also influence the performance of the piezoresistive pressure sensor. This is called the thermal hysteresis phenomenon, and the variation of output voltage is called the thermal hysteresis voltage. Among the critical issues of silicon piezoresistive pressure sensor, the hysteresis phenomenon should be deeply paid attention to obtain better sensor accuracy. For this reason, this research would like to investigate the effect of the external loading on the output voltage of a pressure sensor. Based on the process of pressure sensors, this research adopts the concept of pseudo temperature combined with a finite element method (FEM) to obtain the thermal hysteresis voltage. After several numerical analysis of thermal hysteresis voltage, the experiment is then performed to validate the simulation results. After being validated with the experimental results, the variation of thermal hysteresis voltage under a different trace layout is analyzed. Based on simulation results of a different trace layout, it is found that the trace line layout plays an important role in the thermal hysteresis performance of a pressure sensor, which indicates that the longer aluminum trace increases the hysteresis voltage. The uniform and symmetrical layout of aluminum trace can reduce the variation of resistance change and decrease the hysteresis voltage. Furthermore, the trace layout which is far away from the silicon membrane and piezoresistance is suggested to reduce the hysteresis voltage.

Investigation of Thermal Effect of Packaged CMOS Compatible Pressure Sensor

In this study, a packaged silicon base piezoresistive pressure sensor with thermal stress buffer is designed, fabricated, and measured. A finite element method (FEM) is adopted for design and experimental validation of the sensor performance. Thermal and pressure loading on the sensor is applied to make a comparison between sensor experimental and simulation results. Furthermore, a method that transfers simulation stress data into output voltage is proposed in this study, the results indicate that the experimental result coincides with simulation data.Copyright

Analysis and Validation of Thermal and Packaging Effects of a Piezoresistive Pressure Sensor

Abstract In this study, a packaged silicon base piezoresistive pressure sensor with thermal stress buffer is designed, fabricated, and studied. A finite element method (FEM) is adopted for designing and optimizing the sensor performance. Thermal and pressure loading on the sensor is applied to make a comparison between experimental and simulation results. Furthermore, a method that transforms simulation stress data into output voltage is proposed in this study, and the results indicate that the experimental result coincides with the simulation data. In order to achieve better sensor performance, a parametric analysis is performed to evaluate the system sensitivity, as well as thermal and packaging effects of the pressure sensor. The design parameters of the pressure sensor include membrane size, sensor chip size, glass thickness, adhesive layer thickness, PCB thickness/material, etc. The findings show that proper selection of the sensor structure and material not only enhances the sensor sensitivity but also reduces the thermal effects as well as the packaging influence.

Analysis and Validation of Sensing Sensitivity of a Piezoresistive Pressure Sensor

In this study, a packaged silicon based piezoresistive pressure sensor is designed, fabricated, and studied. A finite element method (FEM) is adopted for designing and optimizing the sensor performance. Thermal as well as pressure loading on the sensor is applied to make a comparison between experimental and simulation results. Furthermore, a method that transfers the simulation stress data into output voltage is proposed in this study, and the results indicate that the experimental result coincides with the simulation data. In order to achieve better sensor performance, a parametric analysis is performed to evaluate the system output sensitivity of the pressure sensor. The design parameters of the pressure sensor include membrane size/shape and the location of piezoresistor. The findings depict that proper selection of the membrane geometry and piezoresistor location can enhance the sensor sensitivity.Copyright

Development of double-sided with double-chip stacking structure using panel level embedded wafer level packaging

In recent years, consumer electronics demand has been geared towards lightweight, high capacity, and high efficiency small form factor devices. These characteristics can be achieved by using three-dimensional (3D) integrated circuit (IC) technology. This study proposes a double-chip stacking structure in an embedded fan-out wafer level packaging (WLP) with double-sided interconnections. This structure consists of two or more thin dies, chip carriers, through mold vias (TMV), and interconnection structures. The thermal performance of the proposed packaging structure is examined and discussed by using finite element (FE) analysis. An FE model of the WLP is also established to compare the thermal performance of conventional WLP and the proposed packaging structure. The proposed packaging structure has a larger size and silicon carrier, which reduces its thermal resistance from 49 °C/W to 39 °C/W. By adopting the proposed design guidelines, including carrier material selection, and designating thermal vias and chip/package size ratios, FE analysis determined that the thermal performance of the proposed packaging structure can be further improved, thereby enhancing its suitability for applications with high power density.

A New Nano-Probe Using Micro Assembly Transfer

This paper demonstrates a new force sensing nano-probe that allows a cost effective nano-tip to be easily assembly on a tuning fork sensor. By taking advantages of surface micromachined tip fabrication, the subsequent assembly-transfer procedures are able to minimize the mass load effect of a tuning fork based atomic force microscopy (AFM). Furthermore, the micro assembly transfer of nano-probes can also be achieved to manufacture devices in an easy way and to mount the probe precisely. This approach is compatible with CMOS process and able to integrate micromachined probes into an alternative host chip

Investigation of Nano-Scale Single Crystal Silicon Using the Atomistic-Continuum Mechanics with Stillinger-Weber Potential Function

This research proposes a novel atomistic-continuum method (ACM) based on the finite element method (FEM) to investigation the mechanical behavior of nano-scale single crystal silicon under uniaxial tensile loading. The FEM is widely used to model and simulate the mechanical behaviors of solid structure, it is a mature technology after decades of development. The ACM could be reduced efficiently the computational time and maintained the simulation accuracy. Since, the ACM developed the bonding force between the two silicon atoms to the two kinds of the nonlinear spring element. Moreover, due to the FEM considered the minimization of the total potential energy, which includes strain energy and the potential energy possessed by applied loads of SCS, a robust FEM is applied to solve the numerical model based on ACM. Therefore, this study combines FEM and interatomic potential function to explore the mechanical properties of nano-scale single crystal silicon. A general form of Stillinger-Weber potential function was used for interaction between the silicon atoms in the simulations. Simulation results showed that the Young’s modulus of single crystal silicon were 121.8, 153 and 174.6 GPa along the

The effects of silica content, sintering temperature and sintering time on a Ni‐Zn ferrite

Abstract In this experiment the effects of silica content, sintering time, and sintering temperature on the microstructure and magnetic properties of a ferrite, Ni032Zn068Fe2O4, were studied. The initial permeability is reduced only slightly when the silica content is less than 0.2 wt %. The Q value is proportional to the silica content approximately. The peak value of μ iQ product is about constant when the silica content is less than 0.2 wt %. The best sintering temperature is between 1175°C and 1200°C. The addition of silica (<0.2 wt%) enhances the rate of densification, but the control of sintering time has to be more precise because the addition of silica makes the shape of μ iQ product peak become sharper and narrower.

Validation of Mechanical Properties of Single Crystal Silicon by Atomic-Level Numerical Model

In this research, an atomistic-continuum mechanics (ACM) based on the finite element method (FEM) is applied to investigate the elastic constant of the nanoscale single crystal silicon in different crystallography planes of (100), (110), and (111) under uniaxial tensile loading and modal analysis.

Investigation of Packaging Effect of Silicon-Based Piezoresistive Pressure Sensor

The silicon-based pressure sensor is one of the major applications in the MEMS device. Nowadays, the silicon piezoresistive pressure sensor is a mature technology in industry and its measurement accuracy is more rigorous in many advanced applications. In order to operate the piezoresistive pressure sensor in harsh environment, the silicone get is usually used to protect the die surface and wire bond while allowing the pressure signal to be transmitted to the silicon diaphragm. The major factor affecting the high performance applications of the piezoresistive pressure sensor is the temperature dependence of its pressure characteristics. Therefore, the thermal and packaging effects caused by the silicone gel behaviors should be taken into consideration to obtain better sensor accuracy and sensitivity. For this reason, a finite element method (FEM) is adopted for the sensor performance evaluation, and the thermal and pressure loading is applied on the sensor to study the output signal sensitivity as well as the packaging-induced signal variation, thermal/packaging effect reduction, and output signal prediction for the pressure sensors. The design parameters include silicon die size, silicone gel geometry and its material properties. The simulation results show that the smaller die size and the thicker die thickness can reduce the packaging-induced thermal effect. Furthermore, the different geometry of silicone gel also influences the sensitivity of pressure sensor.Copyright