高G值微型壓阻式加速度感測器之研製、封測及離心式加速度整合測試平台之架設

Packaging and Integrated Test of High-G Piezoresistive Accelerometer on A Centrifugal Table

張凱翔(Kai-Hsiang Chang)

指導教授 ： 翁宗賢

國立臺灣大學/工學院/應用力學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.10478

摘要

本文以高G值微型壓阻式加速度感測器之訊號為主軸，探討壓阻式感測器換能原理、訊號原理、微感測電路設計、機電耦合壓阻訊號模擬，以及微機電製程、晶片級封裝、元件級封裝及系統級封裝等實際製造過程，並整合於測試加速度感測器穩態特性的高轉速離心機加速度測試平台，詳述系統之規劃、架設與測試結果。
機電耦合壓阻模擬可以在製造前掌握各項設計參數，除了模擬結構應力並驗證設計可承受10,000G加速度外，亦能同時模擬壓阻材料受應力時的阻值變化與輸出電壓。簡言之，可透過ANSYS套裝軟體建構微結構並串接微電路，對其施加衝擊加速度、電壓與等電位條件，完整模擬壓阻式感測器的整個作動情形、應力分佈與電位分佈等，定量化檢視結構的響應與壓阻器輸出電壓。接著將各項驗證後的設計轉為微機械結構的製造，使用微影、薄膜、蝕刻、擴散等半導體製程技術，配合微機電製程中體微機械加工技術及表面微機械加工技術的各項概念繪製所需光罩，實現所設計之可彎曲平板、懸浮壓阻橋結構及由薄膜導線配線構成之壓阻惠斯通電橋；製造完成後，透過晶片級封裝保護元件、元件級封裝設計訊號介面、系統級封裝提供固定夾具，使晶片可相容於離心式加速度整合測試平台執行驗證測試。最後，建構適用於整合測試平台的濾波器模型，並以微控制器電路濾波的方式，濾除雜訊提高線性度與訊噪比(SNR)。
離心式加速度整合測試平台由高速離心機監控系統、無線射頻即時感測傳輸系統及個人電腦端訊號蒐集軟體三大部分構成。高速離心機包含變頻馬達、變頻器、轉速感測器、轉速錶頭與各項輔助元件，可傳輸訊號遠端控制或監視光學平板高速旋轉；無線射頻即時感測傳輸系統則包括訊號感測與無線射頻發射電路、無線射頻接收電路及各項電路元件，由微處理器8051及其韌體統籌各部電路協同運作；個人電腦端訊號蒐集系統則以程式語言建構提供使用者操控之圖形化控制介面，並透過RS-232串列傳輸介面與RS-485 MODBUS-RTU工業控制通訊協定，分別與離心機監控系統及無線射頻即時感測傳輸系統交流資訊，達到遠端圖形化自動控制之目的。
本文所測試的微型加速度感測器為平板型中央有質量塊的構型設計，平板的二端固定，質量塊兩側懸臂樑的長度與深度為600um x 400um，厚度則有120um、100um、80um三種。經實驗測試結果顯示：懸臂樑厚度為120um、100um及80um的敏感度分別為1.30uV/G/V、1.69uV/G/V及1.73uV/G/V，與模擬結果相比誤差分別為4.41%、3.68%及9.4%。但原始類比輸出電壓的訊噪比SNR落在9dB~12dB之間，須配合使用40點移動平均濾波器，方使訊號之線性度與訊噪比合乎設計規範要求。濾波後輸出訊號之線性度分別為98.57%、95.36%及96.64%，均達到線性度設計規範的95%；而濾波後的訊噪比SNR則分別為32.35dB、29.99dB及33.38 dB；濾波後的最大線性誤差分別為1.89%、5.91%、及4.60%。本文的微型加速度感測器的晶片製作與感測性能均屬成功，但加速度感測器並未經合適的元件級訊號封裝，故測試時的雜訊相對偏高；若將感測晶片專業封裝後再測試，其性能將可大幅提升。

關鍵字

加速度感測器 ； 高G值衝擊 ； 衝擊模擬 ； 微機電製程 ； 機電整合 ； 離心式加速度整合測試平台

並列摘要

In this paper, the micro high G of piezoresistive accelerometer signals for the spindle, explore the principles of piezoresistive sensors transducers, signal theory, micro-sensing circuit design, electromechanical coupling piezoresistive signal simulation, as well as MEMS, wafer-level package, component level packaging and system level packaging, the actual manufacturing process, and to test the acceleration sensors integrated in steady state characteristics of high speed centrifuge acceleration test platform, detailed planning system, set up and test results.
Piezoresistive electromechanical coupling simulation can master the design parameters before manufacturing, in addition to the analog structure designed to withstand the stress and validate 10,000 G acceleration , but can also simultaneously simulated by piezoresistive material change in resistance when the output voltage stress . In short , can be constructed by ANSYS software packages microstructure and micro- circuits in series , its impact is applied acceleration voltage and other potential conditions , a complete simulation of the entire piezoresistive sensors for dynamic situations , stress distribution and potential distribution , etc. quantitative structure View piezoresistive response of the output voltage. Then verify the design of the post into the manufacture of micromechanical structures using photolithography , thin film, etching , diffusion semiconductor process technology, with the concept of MEMS bulk micromachining technology and surface micro machining technology draw the mask , designed to achieve the bendable flat , suspended piezoresistive bridge structure and piezoresistive Wheatstone bridge constituted by a thin film conductor wiring ; after fabrication , wafer-level package through the protective element , component -level packaging signal interface design The system -level package provides fixture , so the chip is compatible with centrifugal acceleration integrated test platform to perform validation tests. Finally, the construction of suitable test platform integration filter model , and the way the microcontroller circuit filter to filter out the noise to improve the linearity and signal to noise ratio (SNR).
Centrifugal acceleration test platform consists of integrated high-speed centrifuge control systems, radio frequency transmission systems and real-time sensing signals collected three PC client software constitute the majority. High-speed centrifuge includes inverter motor, inverter, speed sensors, tachometers head and various auxiliary components, signals can be transmitted remotely control or monitor the optical flat high-speed rotation; radio frequency transmission system real-time sensing includes sensing and signal radio frequency transmitter circuit, radio frequency receiver circuit and the circuit elements, collaborative operation by the microprocessor firmware 8051 and co-ordinate ministries circuit; PC terminal signal collection system places a programming language construct provides a graphical user interface manipulation of control and through the RS-232 serial transmission interface and RS-485 MODBUS-RTU industrial control protocol to exchange information with each centrifuge control system and real-time sensing radio frequency transmission system, to achieve the purpose of automatic remote graphical control.
This paper tested miniature accelerometer as a central quality flat-panel configuration block design , two side plates fixed length and depth on both sides of the cantilever mass is 600 um x 400 um, thickness of about 120 um, 100 um, 80 um three. The experimental test results showed that: the thickness of the cantilever 120 um, 100um and a sensitivity of 80um were 1.30 uV/G/V, 1.69 uV/G /V and 1.73 uV/G /V, the simulation results were compared with the error of 4.41% , 3.68 % and 9.4% . But the original analog output voltage signal to noise ratio (SNR) falls between 9dB ~ 12dB, must be compatible with the use of 40 -point moving average filter , side to make the signal linearity and signal to noise ratio in line with the design specifications. Linearity of the output signal of the filter were 98.57% , 95.36% and 96.64% , are up to 95% linearity design specifications ; while the signal to noise filtered respectively 32.35dB, 29.99dB and 33.38 dB ratio SNR; filtered the maximum linearity error of 1.89% , 5.91 % and 4.60% . Chip production and performance of miniature sensing acceleration sensors of this paper are successful, but the acceleration sensor and component-level signals without proper packaging , so the noise test is relatively high; If sensing chip professional package after testing, its performance will be greatly enhanced.

並列關鍵字

acceleration sensors ； high-G shock ； impact simulation ； MEMS fabrication ； mechanical and electrical integration ； integrated test platform centrifugal acceleration

參考文獻

[1] Bean, K.E, "Anisotropic Etching of Silicon," Electron Devices, IEEE Transactions on, Vol. 25, pp. 1185 - 1193, 1978.

[2] Smith Charles S., "Piezoresistance Effect in Germanium and Silicon," Phys. Rev., Vol. 94, pp. 42–49, 1954.

[3] French P.J., Evans A.G.R., "Polycrystalline Silicon Strain Sensors," Sensors and Actuators, Vol. 8, pp. 219-225, 1985.

[4] Geyling F.T., Forst J.J., "Semiconductor Strain Transducers," The Bell System Technical Journal, Vol. 39, pp. 705-731, 1960.

[5] Sparks, D.R, "Application of MEMS Technology in Automotive Sensors and Actuators," International Symposium on Micromechatronics and Human Science, Vol. 86, pp. 9-15, 1998