ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Diode Sensor Lab Dr. Lynn Fuller Webpage: http://people.rit.edu/lffeee 82 Lomb Memorial Drive Rochester, NY 14623-5604 Tel (585) 475-2035 Fax (585) 475-5041 Email: Lynn.Fuller@rit.edu Department webpage: http://www.microe.rit.edu 4-16-2013 Diode_Lab.ppt Page 1
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
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) 30-40 µm Si diaphragm Page 3
MEMS SENSORS CHIP LAYOUT Thermocouple Poly Heater Diode Temperature Sensor Photo Diode Page 4
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
SHOWS DEVICES ARE ON A DIAPHRAGM Vacuum applied to back of chip Diaphragm bends down Page 6
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
Poly Heater, Buried pn Diode, N+ Poly to Aluminum Thermocouple P+ Diode Lab DIODE I-V CHARACTERISTICS N+ Page 8
PACKAGED DIODE TEST CHIP Page 9
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 = 0.64-0.48 = 0.16 Delta T = 0.16 / 2.2mV = 72.7 C Page 10
SPICE FOR DIODE TEMPERATURE SENSOR Page 11
TEST SETUP Take data for room T up to 100 C Page 12
TEMPERATURE TEST DATA I T2 T1 V T1<T2 Diode Voltage (Volts) Diode Voltage vs Temperature 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 20 40 60 80 100 120 Temperature ( C) Dial Vdiode Temp 0 0.6539 20 0.5 1 1.5 2 0.601 54.5 2.5 3 0.5747 71 3.5 0.556 83 4 0.543 90 4.5 0.5246 100 5 0.51 108.5 Temperature ( C0 120 100 80 60 40 20 Temperature vs Dial Setting 0 0 1 2 3 4 5 6 Dial Setting Page 13
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
TEMPERATURE TEST RESULTS OF WATER 800 Temperature Sensor Voltage Output vs. Temperature Output Signal (mv) 700 600 500 400 680 500 y = -18.895x + 1125 R 2 = 0.9906 400 300 20.0 25.0 30.0 35.0 40.0 45.0 Te mperature (C) Measurement of Amplified and Shifted Diode Voltage in Different Temperature Water Baths The output changes by -19 mv/ C Page 15
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. 2004 Page 16
THERMOCOUPLE TEMPERATURE SENSOR Volt Meter Heater TC Output Diode Volts Volts Volts 0 ~0 0.7 1. 2. 3. 4. 5 ~15mV 0.55 Page 17
PHOTO DIODE RESPONSE TO LIGHT Page 18
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
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 NJU703-3.3 R3 10K R4 100K + 3.3V NJU703-3.3 Vout 0 to 1V Gnd Gnd Page 20
PHOTO DIODE I TO V LOG AMPLIFIER 3.3V R1 20K IR LED I n p + 3.3V NJU703 1N4448-3.3 Vout 0 to 1V Linear amplifier uses 100K ohm in place of the 1N4448 Vout vs. Diode Current Gnd Gnd 3.5 3.0 Linear Amplifier Log Amplifier Output Voltage (V) 2.5 2.0 1.5 1.0 Photodiode 0.5 0.0 0.01 0.1 1 10 100 1000 10000 Diod e C urrent (ua) Page 21
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
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
LED IV CHARACTERISTICS Light Emitting Diode -LED I D Light -10.0 Flat n - V a + p LED 2.0 V D Page 24
TURBIDITY Infrared LED Photocell Packaged Sensor Chip and LED Sensor Chip Page 25
IR LED Digital Cameras can see the light from an infrared LED that the human eye can not see Page 26
TURBIDITY SIGNAL CONDITIONING CIRCUIT Gain and Level Shifting Photo- Current to Voltage Page 27
TURBIDITY TEST RESULTS Plot of output voltage for different standard turbidity samples Turbidity Standards Page 28
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 0.0 300 400 500 600 700 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
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
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 3.34 6.71 58um 117um 550 nm 5.24 10.6 92um 187um 750 nm 7.17 14.5 126um 259um Page 31
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
FIRST TEST CHIP Photo diodes Marion Jess 1996 Shielded area Pads to 128 diodes Page 33
RESULTS OF FIRST TEST CHIP Some Light More Light Photodiode Current vs Voltage Measurements from 128 diodes illuminated through different color filters Page 34
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 0000000B) Clock Reset Page 35
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
SECOND TEST CHIP Multiplexer T Type FF Binary Counter Photodiodes Page 37
REFERENCES 1. Micromachined Transducers, Gregory T.A. Kovacs, McGraw- Hill, 1998. 2. Microsystem Design, Stephen D. Senturia, Kluwer Academic Press, 2001. 3. IEEE Journal of Microelectromechanical Systems. Page 38
HOMEWORK DIODE SENSOR LAB 1. Calculate the sensitivity (mv/ C) from the data on page 13. 2. 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 20. 4. Write an expression for the output voltage of the circuit on page 21 and 22. Page 39