Robot Leg Motion in a Planarized-SOI, 2-Poly Process Hilton Head 2002

Transcription

1 Robot Leg Motion in a Planarized-SOI, 2-Poly Process Hilton Head 2002 Seth Hollar, Dr. Anita Flynn, Sarah Bergbreiter, Professor Kris Pister Berkeley Sensor and Actuator Center, UC Berkeley

2 Acknowledgements Dr. Chris Keller, MEMS Precision Instruments DARPA/ITO SDR NSF Berkeley Sensor and Actuator Center Sponsors UC Berkeley Microfabrication Facility, Robert Hamilton Dr. Azzam Yasseen James Wu, Lawrence Berkeley National Labs Dr. Dimitry Kousminov from Accurel Systems

3 Outline Microrobot History Inchworm Actuation Microrobot Assembly Robot Leg Design Fabrication Process Results Late News Conclusion

4 Previous Microrobot History Courtesy Richard Yeh No Motors No Legs 1988 Microrobot concepts Anita Flynn 1992 Poly-Si pin hinges Kris Pister 1995 Legs in MUMPS Richard Yeh 2001 Electrostatic Inchworm Motors in SOI Richard Yeh No one has shown large force electrostatic actuators combined with robot legs

5 Electrostatic Inchworm Actuators Large Force, Low Power, Large Displacement Actuation Single Mask SOI Process Courtesy Richard Yeh 80µm Displacement, ~100µN Force 4 Control Signals with 30 Volts Input

6 How an Inchworm Motor Works Clutch Clutch Drive Drive 0 V Shuttle Drive Clutch

7 Left Right Clutch Clutch Drive Drive 0 V

8 Left Right Clutch 0 V Clutch Drive 0 V Drive

9 Left Right Clutch Clutch Drive 0 V Drive

10 Left Right Clutch Clutch 0 V Drive Drive 0 V

11 Left Right Clutch Clutch Drive Drive 0 V

12 Left Right Clutch 0 V Clutch Drive 0 V Drive

13 Left Right Clutch Clutch Drive 0 V Drive

14 Left Right Clutch Clutch 0 V Drive Drive 0 V

15 Left Right Clutch Clutch Drive Drive 0 V

16 Left Right Clutch 0 V Clutch Drive 0 V Drive

17 Left Right Clutch Clutch Drive 0 V Drive

18 Left Right Clutch Clutch 0 V Drive Drive 0 V

19 Microrobots Three Processes The Brain - CMOS Digital Circuits Sequencer - generates digital signals to drive motors The Power Solar Cells Step-up converter from 3 volts to 30 volts Solar Cell Arrays The Actuation Hinges, Motors, Legs Planarized SOI / 2 Structural Poly Layers

20 Proposed Integration Method Solar Cell/High Voltage Chip CMOS Chip Inchworm Motors Leg Solar Cells/ High Voltage Assembly CMOS Legs and Motors Wire Bonds Substrate

21 Assembled Robot 4mm Legs of Robot Inchworm Motors Solar Cell High Voltage Chip Low Power Digital Chip

22 Worst Case Design Parameters Mass (mg) Die Area (mm 2 ) Efficiency Power Consumption Motors (+ Legs) % 500nW Step Up Converters % 5µW Solar Cells 2 2 5% Generates 50µW CMOS Controller nW Total % 5.5µW

23 Leg Schematic Hinges Flaps Leg Shuttle Substrate

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35 Hinges Flaps Leg Shuttle Substrate

36 1mm Inchworm Motor Leg

37 SOI wafer Crys. Si ~ ~ Oxide Substrate

38 ASE Etch Crys. Si ~ ~ Oxide Substrate

39 A. Yasseen, J. Cawley, M. Mehregany Thick Glass Film Technology for Polysilicon Surface Micromachining. JMEMS Glass Slurry Glass Slurry Crys. Si ~ ~ Oxide Substrate

40 Organic Burnout Glass Frit Crys. Si ~ ~ Oxide Substrate

41 Celsius Glass Firing Profile 2Torr Softening Point 1ATM Transition Temperature minutes Chris Keller

42 Reflow Glass in Vacuum Reflowed Glass Crys. Si ~ ~ Oxide Substrate

43 CMP to Si-Glass surface Crys. Si ~ ~ Oxide Substrate

44 Structural 2 layer poly-si Poly Si PSG Reflowed Glass Crys. Si ~ ~ Oxide Substrate

45 ASE Backside Etch Poly Si PSG Reflowed Glass Crys. Si Oxide ~ ~ ~ ~ Substrate

46 Timed HF/HCl release Poly Si Crys. Si Oxide ~ ~ ~ ~ Substrate

47 Fabrication Results Shuttle Leg 250 µm Leg Shuttle

48 Hinges Poly-Si Hinges 40 µm Device SOI Substrate Leg

49 Flaps Leg Shuttle Poly-Si Flaps Shuttle 12µm

50 Friction Sliding Tests Flaps Poly Without Substrate With Substrate Substrate Number of Samples SOI Force, µn

51 Surface Bubbles Crys. Si We Want Substrate We Got Bubbles

52 Float Away Structures Poly Si PSG Reflowed Glass Crys. Si Oxide Substrate During Release

53 Presetting Leg out of Plane Shuttle 140 µm

54 Leg Actuation Vertically preset to 360µm. Actuated to 580µm Angular deflection from 34 o to 63 o 200 µm Shuttle travel: 250 µm

55 Autonomous Inchworm Operation from 3 Chip Hybrid CMOS 1.8x0.4 mm 2 One Mask Inchworm Motor Solar Cells 3.0x1.0 mm 2 1.7x2.4 mm 2 Flashlight

56 Conclusion We have demonstrated all 3 key elements of a microrobot: Legs with motors Brains Power bsac.eecs.berkeley.edu/~shollar Integrated motors with hinges using glass reflow technology Microrobots are within reach!!!