陳炳煇臺灣大學：機械工程學研究所Kuo, Jin-ShunJin-ShunKuo2007-11-282018-06-282007-11-282018-06-282005http://ntur.lib.ntu.edu.tw//handle/246246/61241The purpose of this dissertation is to design a novel microdevice for measuring the thermal conductivity of a liquid droplet in small amounts. The CMOS chip is fabricated by VIS 0.5 μm 2P3M CMOS process and post-CMOS micromachining processes are proceeded. The CMOS chip consists of a thin film of polysilicon that covers a cavity of the substrate. The thin film has a rectangular centered heater and four temperature sensors that are located at different locations from the heater. Once a known voltage is applied to the heater, the thermal conductivity of liquid drop that spreads over the heater and the temperature sensors can be determined from the measured temperature responses at different locations of the temperature sensors. This study provides theoretical predictions of temperature responses that are obtained from the diffusion equation of a semi-infinite cylindrical model. The experimental and theoretical analysis results illustrate that the higher thermal conductivity of liquid causes the smaller resistance variation of the temperature sensor, and have larger time constant to steady state.Table of Contents Acknowledgement I Abstract II Nomenclature IV Table of Contents V List of Tables IX List of Tables IX List of Figures X Chapter 1 Introduction 1 1.1 General Remarks 1 1.2 Literature survey 1 1.2.1 Measurement of thermal diffusivity of liquids 1 1.2.2 CMOS-MEMS process 5 1.2.3 Green’s function solution 6 1.3 Motivation and objectives 7 1.4 Overview of this dissertation 8 Chapter 2 Theoretical analysis and ANSYS package simulation 13 2.1 Mathematical model 13 2.1.1 Semi-infinite cylinder with a disk central heater 13 2.1.2 Governing equation and Green’s function solution 14 2.2 ANSYS software simulation 16 2.2.1 ANSYS simulation procedures 17 Chapter 3 Fabrication processes and Post-CMOS process 29 3.1 Principle for measuring the thermal diffusivity of liquids 29 3.2 The design of a CMOS sensor chip 29 3.2.1 Whole chip layout of CMOS 0.5um 2P3M process 30 3.2.2 Subsystems of the CMOS sensor chip 31 3.3 Post-CMOS micromachining processes 33 3.3.1 Isotropic wet etching for removing metal layers 35 3.3.2 Anisotropic Dry Etching for Removing Silicon Dioxide 35 3.3.3 Anisotropic Wet Etching for removing silicon substrate 37 3.3.4 Anisotropic Dry Etching for opening pads 38 3.3.5 Wire bonding 39 Chapter 4 Experimental apparatus and procedures 55 4.1 Experimental Apparatus 55 4.1.1 The experimental apparatus used during the post-CMOS process 55 4.1.2 The measuring apparatus 56 4.2 Specimen liquids preparation 56 4.3 Experimental procedures 57 4.3.1 Procedure of resistance versus temperature calibration 58 4.3.2 Procedures for measuring thermal diffusivity of the liquids 58 Chapter 5 Results and Discussion 70 5.1 Results of Green’s function solution 70 5.2 Results of ANSYS software simulation 71 5.3 Measurement results of CMOS fabricated chip 71 5.3.1 Experimental Results of Different Tested Liquids 71 5.3.2 Experimental Results Comparison of Different Tested Liquids 73 Chapter 6 Conclusions and Future Prospects 92 References 94 List of Tables Table 1.1 The concept of microsystem 9 Table 1.2 The different MEMS companies business models today 10 Table 2.1 Physical properties of the materials. 27 Table 2.2 The dimension of ANSYS model. 28 Table 5.1 The comparison of resistance and temperature variation among four tested liquids at steady state. 89 Table 5.2 The comparison of the thermal diffusivity and time constant among four tested liquids. 90 Table 5.3 The comparison with the temperature rising of experiment, Green’s function solution and ANSYS simulation. (at t =20 sec) 91 List of Figures Figure 1.1 MST market volume existing products. (Wicht, et al., 2002) 11 Figure 1.2 A schematic diagram of transient hot-wire apparatus. 12 Figure 2.1 Schematic view of microdevice for measuring thermal diffusivity of liquid. 20 Figure 2.2 Model for the diffusion equation of a semi-infinite cylinder with a disk heater that is located at the bottom center. The heater has a radius of a. 21 Figure 2.3 The flow chart of ANSYS procedures. 22 Figure 2.4 The Solid 90 element type. 23 Figure 2.5 The Shell 57 element type. 24 Figure 2.6 The ANSYS model of microdevice for measuring the thermal diffusivity of liquids. (a) CMOS chip, (b) tested liquid. 25 Figure 2.7 The mesh result of (a) CMOS chip, and (b) tested liquid. 26 Figure 3.1 A schematic diagram the cross-section view of the novel microdevice for measuring the thermal diffusivity of liquids. 40 Figure 3.2 The cross section sketch of the thin film distribution of the VIS CMOS 0.5μm 2P3M process. 41 Figure 3.3 The whole chip layout drawn using Cadence for CMOS 0.5μm 2P3M process. 42 Figure 3.4 The solid model of the CMOS sensor chip. 43 Figure 3.5 The flow chart of the post-CMOS micromachining process. (a)The diagram of the chip after fabrication by VIS standard CMOS process; (b)The use of isotropic wet etching to remove the metal layers. 44 Figure 3.5 The flow chart of the post-CMOS micromachining process. (c)RIE process to remove thin SiO2 layer upon silicon substrate; (d)The anisotropic wet etching to remove silicon substrate. 45 Figure 3.5 The flow chart of the post-CMOS micromachining process. (e)RIE process to remove passivation and SiO2 layers; (f)The pads of the chip are connected to printed circuit board by wire bonding technique. 46 Figure 3.6 The microscope photograph of the chip fabricated by VIS standard CMOS process without any post-CMOS process. 47 Figure 3.7 The microscope photography of the top view of the CMOS chip after isotropic metal wet etching. 48 Figure 3.8 The microscope photography of the top view of the chip after reaction ion etching. 49 Figure 3.9 Microscope photos of damaged pads and good ones. (a) damaged; (b) good. 50 Figure 3.10 Microscope photo of the top view of the CMOS chip after a TMAH wet etching process. (a) heater and sensors, (b) pads. 51 Figure 3.11 The SEM micrograph of the CMOS chip after TMAH wet etching process. 52 Figure 3.12 Microscope photo of the top view of the pads after RIE process. 53 Figure 3.13 Photo of the wire bonding connecting the pads of the CMOS chip to printed circuit board. 54 Figure 4.1 Thermal evaporator. (DAH YOUNG, DMC-500). (Source: NSC NEMS Center, Taiwan.) 60 Figure 4.2 Spin coater (Karl Suss, RC-8). (Source: NSC NEMS Center, Taiwan.) 61 Figure 4.3 Double side mask aligner (Karl Suss, MA6). (Source: NSC NEMS Center, Taiwan.) 62 Figure 4.4 Reaction ion etching machine (SAMCO, RIE-10N). (Source: NSC NEMS Center, Taiwan.) 63 Figure 4.5 Wire bonder (SUPER POWER, SPB-U668). (Source: NSC NEMS Center, Taiwan.) 64 Figure 4.6 Microscope (Olympus, BX60M). 65 Figure 4.7 Scanning electron microscope (SEM) (Hitachi, S-2400). 66 Figure 4.8 PC Data logger with Digital multimeter (Brymen, BM-817). 67 Figure 4.9 The calibration of resistance and temperature of the polysilicon sensor. 68 Figure 4.10 A sketch of the measuring system. 69 Figure 5.1 The response of temperature rising of water at different distance from center. 75 Figure 5.2 The response of temperature rising of glycerin at different distance from center. 76 Figure 5.3 The response of temperature rising of methanol at different distance from center. 77 Figure 5.4 The response of temperature rising of ethanol at different distance from center. 78 Figure 5.5 The response of temperature rising of toluene at different distance from center. 79 Figure 5.6 The temperature rising versus r* at t = 20 sec. 80 Figure 5.7 The response of temperature rising of liquids at r*=2. 81 Figure 5.8 The response of the temperature rising at r*=2 simulated using ANSYS software. 82 Figure 5.9 The resistance variation of the sensor with time for measuring the thermal diffusivity of toluene. 83 Figure 5.10 The resistance variation of the sensor with time for measuring the thermal diffusivity of ethanol. 84 Figure 5.11 The resistance variation of the sensor with time for measuring the thermal diffusivity of methanol. 85 Figure 5.12 The resistance variation of the sensor with time for measuring the thermal diffusivity of glycerin. 86 Figure 5.13 The results of the response of temperature rising measured using CMOS chip. 87 Figure 5.14 The relation between the thermal diffusivity of liquids and time constant. 883813365 bytesapplication/pdfen-US互補式金氧半導體熱擴散係數互補式金氧半導體後製程格林函數解ANSYSCMOSthermal diffusivitypost-CMOS processGreen’s function solutionthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/61241/1/ntu-94-F87522104-1.pdf