© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 1 Rochester Institute of Technology Microelectronic Engineering ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Rev MEM_BULK_2007_08.ppt Bulk Micromachined Laboratory Project  Dr. Lynn Fuller,  Ivan Puchades  Webpage:  Rochester Institute of Technology  82 Lomb Memorial Drive  Rochester, NY  Tel (585)  Fax (585)   Department webpage:

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 2 Rochester Institute of Technology Microelectronic Engineering OUTLINE Lab Project Expectations Lab requirements Design considerations Maskmaking Testing Approach Test Results

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 3 Rochester Institute of Technology Microelectronic Engineering LAB PROJECT EXPECTATIONS  Objective: design, fabricate and test a MEMS device utilizing the provided process flow.  Lab project is 50% of grade  Meet all required project timelines33%  Weekly attendance and participation33%  Quality of work33%  Project timelines  Design calculations and 1 st Draft layout design 2 rd week  Final layout design in dropbox 3 rd week  Report theory section and test plan5 th week  Final presentation11 th week  Final report11 th week

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 4 Rochester Institute of Technology Microelectronic Engineering LAB REQUIREMENS AND TOOLS  Design:  Mentor graphics IC Layout in CE VLSI lab  Account to be provided by TA during second week  Review mems_cad bulk_20072.pdf posted on  Fabrication  Complete safety training and pass safety exam by 3 rd week   Complete your lab notebook, sign each page, date each page, diary format, comments and observations, etc.  Fabrication schedule will be reviewed and ed to students on Fridays.  TA with available hours during the week. One 3-hour block (AM or PM) is required per week plus the 1 hour review session on Friday at 1:00pm

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 5 Rochester Institute of Technology Microelectronic Engineering RIT MEMS BULK PROCESS 1 P+ Diffused Layer (90 Ohm/sq) 1 Poly layer (40 Ohm/sq) 1 metal layer (Al 1µm thick) µm Si diaphragm Top hole

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 6 Rochester Institute of Technology Microelectronic Engineering DESIGN GUIDELINES Microelectromechanical Systems The basic unit of distance in a scalable set of design rules is called Lambda, For the current MEMS process  is ten microns (10 µm) The process has eight mask layers, they are: P++ Diffusion (Green)(layer 1) Poly Resistor (Red)(layer 2) Contact (Gray)(layer 3) Metal (Blue)(layer 4) Diaphragm (Purple) (layer 5) /tools/ritpub/process/mems_bulk_072

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 7 Rochester Institute of Technology Microelectronic Engineering DESIGN CONSIDERATIONS  Building blocks of a microfluidic system (lab on a chip) [24] Pinget, M. et al, “Multicentre trial of a programmable implantable insulin pump in type 1 diabetes”, Int. J. of Anaesthesian, vol. 6, pp , 1994.

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 8 Rochester Institute of Technology Microelectronic Engineering POSSIBLE DEVICES Thermally actuated bimetallic micro-pump Thermally actuated bimetallic micro-pump with resistors for sensing and feedback Pressure Sensor, diffused resistors or poly resistors Thermocouples (Thermopile) on diaphragm with built-in heater Optical Pyrometer Heater on diaphragm either poly or diffused resistor heater Heater plus temperature sensor (diffused heater, poly resistor sensor) Heater plus interdigitated chemical sensor Humidity sensor Gas flow sensor single resistor anemometer Gas flow sensor with heater and two resistors Transistors and logic

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 9 Rochester Institute of Technology Microelectronic Engineering POSSIBLE DEVICES Pressure sensor Flow sensor Thermocouples Micro-pump

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 10 Rochester Institute of Technology Microelectronic Engineering DESIGN AREA  Design for a 2mm wide by 25 or 100µm tall channel.  Probe pads and connections must be as large as possible and away from channel, pads on one side is good, bigger is better.  Design space is 4mmx4mm. 4mm

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 11 Rochester Institute of Technology Microelectronic Engineering PREVIOUS CLASS DESIGN

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 12 Rochester Institute of Technology Microelectronic Engineering MASK ORDER FORM Individual Student Designs are sent to a dropbox to be combined with other designs. Click: File/Cell/Save/as: /dropbox/MEMS_07_08/your_name_design Example: /dropbox/MEMS_07_08/lynn_fuller_mirror

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 13 Rochester Institute of Technology Microelectronic Engineering PREVIOUS LAB SECTION 1X ARRAY

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 14 Rochester Institute of Technology Microelectronic Engineering PREVIOUS MASKS

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 15 Rochester Institute of Technology Microelectronic Engineering ETCHED BULK MEMS PROCESS FLOW

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 16 Rochester Institute of Technology Microelectronic Engineering PRESSURE SENSOR EXAMPLE Front Back

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 17 Rochester Institute of Technology Microelectronic Engineering FINITE ELEMENT ANALYSIS Points of Maximum Stress

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 18 Rochester Institute of Technology Microelectronic Engineering CALCULATION OF EXPECTED OUTPUT VOLTAGE R1 R3 R2 R4 Gnd +5 Volts Vo2 Vo1 The equation for stress at the center edge of a square diaphragm (S.K. Clark and K.Wise, 1979) Stress = 0.3 P(L/H) 2 where P is pressure, L is length of diaphragm edge, H is diaphragm thickness For a 3000µm opening on the back of the wafer the diaphragm edge length L is 3000 – 2 (500/Tan 54°) = 2273 µm Layout

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 19 Rochester Institute of Technology Microelectronic Engineering CALCULATION OF EXPECTED OUTPUT VOLTAGE (Cont.) Stress = 0.3 P (L/H) 2 If we apply vacuum to the back of the wafer that is equivalent to and applied pressure of 14.7 psi or 103 KN/m 2 P = 103 N/m 2 L= 2273 µm H= 25 µm Stress = 2.49E8 N/m 2 Hooke’s Law: Stress = E Strain where E is Young’s Modulus  = E  Young’s Modulus ofr silicon is 1.9E11 N/m 2 Thus the strain = 1.31E-3 or.131%

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 20 Rochester Institute of Technology Microelectronic Engineering CALCULATION OF EXPECTED OUTPUT VOLTAGE (Cont.) The sheet resistance (Rhos) from 4 point probe is 61 ohms/sq The resistance is R = Rhos L/W For a resistor R3 of L=350 µm and W=50 µm we find: R3 = 61 (350/50) = ohms R3 and R2 decrease as W increases due to the strain assume L is does not change, W’ becomes 50+50x0.131% W’ = µm R3’ = Rhos L/W’ = 61 (350/ ) = ohms R1 and R4 increase as L increases due to the strain assume W does not change, L’ becomes x0.131% R1’ = Rhos L’/W = 61 ( /50) = ohms

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 21 Rochester Institute of Technology Microelectronic Engineering CALCULATION OF EXPECTED OUTPUT VOLTAGE (Cont.) Gnd 5 Volts R1=427 R3=427 R2=427 R4=427 Vo2=2.5v Vo1=2.5v Gnd 5 Volts R1=427.6 R3=426.4 R2=426.4 R4=427.6 Vo2=2.5035v Vo1=2.4965v No stress Vo2-Vo1 = 0 With stress Vo2-Vo1 = 0.007v =7 mV

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 22 Rochester Institute of Technology Microelectronic Engineering OUTPUT VOLTAGE VERSUS PRESSURE Pressure (psi) Vout (mV)

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 23 Rochester Institute of Technology Microelectronic Engineering REFERENCES 1.Process Development for 3 D Silicon Microstructures, with Application to Mechanical Sensor Devices, Eric Peeters, Katholieke Universiteit Leuven, March 1994.] 2.United States Patent 5,357,803 3.S.K. Clark and K.D. Wise, “Pressure Sensitivity in Anisotropically Etched Thin-Diaphragm Pressure Sensors”, IEEE Transactions on Electron Devices, Vol. ED-26, pp , 1979.

© March 10, 2008, Dr. Lynn Fuller, Professor Bulk Micromachined MEMS Laboratory Page 24 Rochester Institute of Technology Microelectronic Engineering FINAL LAB REPORT AND NOTEBOOK 1.Complete your lab notebook, sign each page, date each page, diary format, comments and observations, etc. 2.Write a ~4 page technical paper on this laboratory project. Use the standard IEEE conference proceedings format. See attached format and example paper. Both Due 1 st day of Finals Week