Diode Sensor Lab. Dr. Lynn Fuller

Transcription

1 ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Diode Sensor Lab Dr. Lynn Fuller Webpage: 82 Lomb Memorial Drive Rochester, NY Tel (585) Fax (585) Department webpage: Diode_Lab.ppt Page 1

2 OUTLINE RIT MEMS Bulk Process MEMS Sensor Chip Layout Heater I-V Characteristics Diode Sensor I-V Characteristics Response to Heater Response to Light LED I-V Characteristics Diode Optical Communication Link Page 2

3 RIT MEMS BULK PROCESS 1 P+ Diffused Layer (90 Ohm/sq) 1 N+ Layer (50 Ohm/sq) 1 N-Poly layer (40 Ohm/sq) 1 metal layer (Al 1µm thick) µm Si diaphragm Page 3

4 MEMS SENSORS CHIP LAYOUT Thermocouple Poly Heater Diode Temperature Sensor Photo Diode Page 4

5 CLOSE UP OF MEMS SENSORS CHIP Poly Heater, Buried pn Diode, N+ Poly to Aluminum Thermocouple Heater L/W = 225µm/200µm Photo Diode Area = 1mm X 1.5mm Page 5

6 SHOWS DEVICES ARE ON A DIAPHRAGM Vacuum applied to back of chip Diaphragm bends down Page 6

7 HEATER RESISTOR I-V CHARACTERISTICS Poly Heater, Buried pn Diode, N+ Poly to Aluminum Thermocouple P+ N+ R = Rhos L/W find Rhos R= 1/1.34E-2 = 74.7 ohms Page 7

8 Poly Heater, Buried pn Diode, N+ Poly to Aluminum Thermocouple P+ Diode Lab DIODE I-V CHARACTERISTICS N+ Page 8

9 PACKAGED DIODE TEST CHIP Page 9

10 DIODE TEMPERATURE SENSOR RESPONSE Poly Heater, Buried pn Diode, N+ Poly to Aluminum Thermocouple P+ N+ Apply 5 volts (gives ~ 65mA) P=IV =0.3 watts Delta Vd = = 0.16 Delta T = 0.16 / 2.2mV = 72.7 C Page 10

11 SPICE FOR DIODE TEMPERATURE SENSOR Page 11

12 TEST SETUP Take data for room T up to 100 C Page 12

13 TEMPERATURE TEST DATA I T2 T1 V T1<T2 Diode Voltage (Volts) Diode Voltage vs Temperature Temperature ( C) Dial Vdiode Temp Temperature ( C Temperature vs Dial Setting Dial Setting Page 13

14 SIGNAL CONDITIONING CIRCUIT Diode Voltage Buffer Gain and Inversion Level Shifting and Buffer Signal Conditioning Circuit Improves the sensitivity to changes in temperature Page 14

15 TEMPERATURE TEST RESULTS OF WATER 800 Temperature Sensor Voltage Output vs. Temperature Output Signal (mv) y = x R 2 = Te mperature (C) Measurement of Amplified and Shifted Diode Voltage in Different Temperature Water Baths The output changes by -19 mv/ C Page 15

16 SEEBECK EFFECT When two dissimilar conductors are connected together a voltage may be generated if the junction is at a temperature different from the temperature at the other end of the conductors (cold junction) This is the principal behind the thermocouple and is called the Seebeck effect. V = α 1 (T cold -T hot ) + α 2 (T hot -T cold )=(α 1 -α 2 )(T hot -T cold ) Hot Where α 1 and α 2 are the Seebeck coefficients for materials 1 and 2 Material 1 Material 2 Cold V Nadim Maluf, Kirt Williams, An Introduction to Microelectromechanical Systems Engineering, 2 nd Ed Page 16

17 THERMOCOUPLE TEMPERATURE SENSOR Volt Meter Heater TC Output Diode Volts Volts Volts 0 ~ ~15mV 0.55 Page 17

18 PHOTO DIODE RESPONSE TO LIGHT Page 18

19 PHOTO DIODE RESPONSE TO LIGHT No light Full light P=IV = (7.09e-5)( 0.4) =28.4µwatts P/unit area = 28.4e-6/1500e-6/1000e-6 = 18.9watt/m 2 ~ Max Power Out No Light and Max Light Using 8X Objective Lens Page 19

20 UV LED AND PHOTO DIODE SENSOR Material Characterization by UV Light Absorption 3.3V R1 20K UV LED I p n R2 20K + 3.3V NJU R3 10K R4 100K + 3.3V NJU Vout 0 to 1V Gnd Gnd Page 20

21 PHOTO DIODE I TO V LOG AMPLIFIER 3.3V R1 20K IR LED I n p + 3.3V NJU703 1N Vout 0 to 1V Linear amplifier uses 100K ohm in place of the 1N4448 Vout vs. Diode Current Gnd Gnd Linear Amplifier Log Amplifier Output Voltage (V) Photodiode Diod e C urrent (ua) Page 21

22 PHOTO DIODE I TO V INTEGRATING AMPLIFIER Reset C - + Internal 100 pf Ri Rf - + Analog Vout Integrator and amplifier allow for measurement at low light levels Page 22

23 TURBIDITY Turbidity = loss of transparancy due to the presence of suspended solids, water < 1-5 NTU (Nephelometric Turbidity Units), measured by a nephelometer or turbidimeter, which measures the intensity of light scattered at 90 degrees as a beam of light passes through a water sample. R LED I p n + Vout = IR PCB Sensor Chip With Photodiode Page 23

24 LED IV CHARACTERISTICS Light Emitting Diode -LED I D Light Flat n - V a + p LED 2.0 V D Page 24

25 TURBIDITY Infrared LED Photocell Packaged Sensor Chip and LED Sensor Chip Page 25

26 IR LED Digital Cameras can see the light from an infrared LED that the human eye can not see Page 26

27 TURBIDITY SIGNAL CONDITIONING CIRCUIT Gain and Level Shifting Photo- Current to Voltage Page 27

28 TURBIDITY TEST RESULTS Plot of output voltage for different standard turbidity samples Turbidity Standards Page 28

29 MICRO SPECTRO RADIOMETER Diffraction Grating Electronics Light Plasma Etch Endpoint Detect Nanospec Like Film Thicknes Light Source Characterization 1.0 Output i-line, 365 nm clock 0.5 h g-line, 436 nm f e Diodes Wavelength (nm) Acknowledgments: Photodiode Number Marion Jess, Visiting Scholar from Germany Wessel Valster, Student of Hogeschool Enschede,The Netherlands Zoran Uskokovic, RIT, graduate student in MicroE Page 29

30 DIFFRACTION GRATING S a a ξ Light is diffracted into a series of intensity spots called diffraction orders d 1 3rd 2nd 1st 1st 2nd 3rd r1 Page 30

31 CALCULATIONS Grating of 2 um lines and 2 um space gives S=4 um k is the diffraction order λ is wavelength The angle ξ sin ξ = k λ / n S and tan ξ = r/d for d = 1000um, and n = 1.5 for glass ξ1 ξ2 r1 r2 350 nm um 117um 550 nm um 187um 750 nm um 259um Page 31

32 MICRO-SPECTRO-RADIOMETER Diffraction Grating 1mm Glass Analog Switches Multiplexer Shift Registers I/O Pads 128 Ion Implanted p+ diode Photo Detectors n-type silicon Page 32

33 FIRST TEST CHIP Photo diodes Marion Jess 1996 Shielded area Pads to 128 diodes Page 33

34 RESULTS OF FIRST TEST CHIP Some Light More Light Photodiode Current vs Voltage Measurements from 128 diodes illuminated through different color filters Page 34

35 MICRO-SPECTRO-PHOTOMETER ON CHIP ELECTRONICS FOR ELECTRONIC READOUT 128 PHOTODIODES D1 D2 D3 D4 D5 D6 D7 D8 SWITCHES A A B B C C Analog out A.G 7 BIT COUNTER Sync Sync pulse (at B) Clock Reset Page 35

36 POLY GATE PMOS + DEPLETION MODE IMPLANT MULTIPLEXER 7 B it Counter A B C A B C Reset C - Internal 100 pf Rf Vout Ri D7 D0 Page 36

37 SECOND TEST CHIP Multiplexer T Type FF Binary Counter Photodiodes Page 37

38 REFERENCES 1. Micromachined Transducers, Gregory T.A. Kovacs, McGraw- Hill, Microsystem Design, Stephen D. Senturia, Kluwer Academic Press, IEEE Journal of Microelectromechanical Systems. Page 38

39 HOMEWORK DIODE SENSOR LAB 1. Calculate the sensitivity (mv/ C) from the data on page Calculate reasonable values to fill in the table on page 17. state your assumptions and show equations you used. 3. Calculate the gain (V/µA) of the signal conditioning circuit on page Write an expression for the output voltage of the circuit on page 21 and 22. Page 39