Investigation of MultiLayer Actuation Carlos R Jimenez California

Motivations for out of plane actuation. n Currently fabricated X-Y axis gyroscope driven by

Out of Plane Actuation has a wide range of applications MEMS micro mirrors For

How are lateral combs actuated? n Regular lateral combs for inplane actuation driven by

Motivations on using offset combs for out-of-plain actuation vs. parallel plates. n Si. O

Target objectives for the research. n n Model various lateral comb architectures in Finite

Modeling Results contd. . Force in the Z direction Vs Height of Ground Comb.

Modeling Results contd. . n Force in the Z Direction Vs. Potential across Offset

Modeling Contd. . Out of Plane Force Vs. Comb Displacement. -1. 4 e-12 N/um

Fabrication parameters force Maximization n Sensitivity Analysis from the standard model. Standard@35 um Tests:

Designing test structures Making and evaluating masks. n n First approach: Opaque combs were

Manufacturing devices Lithography and etch for two mask process. n Protect the high combs

Manufacturing Results Evaluating the etching process n Despite the significant height decrease, the final

Pre-Characterization Isolating the Moving Structure n Between the combs we deposited Sylgard 182, an

How likely are offset combs to lift a structure? Standard in-plane vs. out-of plane

Full MEMS experience. 1. Idea 6. Characterization 5. Fabrication 2. Concept. 3. Modeling 4.

Acknowledgments Thanks to: n Faculty Mentor: Prof. Andrei Shkel n Graduate Student Mentors: Max

Slides: 19

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Investigation of Multi-Layer Actuation Carlos R. Jimenez. California State Polytechnic University, Pomona. Electrical Engineering, Fall 2006 Faculty Mentor: Professor Andrei Shkel. Graduate Student Mentors: Max Perez, Adam R. Schofield. Department of Mechanical Aerospace Engineering. 08 -30 -2005

Motivations for out of plane actuation. n Currently fabricated X-Y axis gyroscope driven by in-plane actuation. n Desired X-Y-Z axis gyroscopes driven by in-plane and out-ofplane actuation. sense direction Z Driving direction Y X Additional Sense capabilities © C. Jimenez 2005, IM-SURE

Out of Plane Actuation has a wide range of applications MEMS micro mirrors For optical switching. X-Y-Z Gyroscopes for the aerospace and automotive industry. © C. Jimenez 2005, IM-SURE

How are lateral combs actuated? n Regular lateral combs for inplane actuation driven by an AC voltage signal. +V o - Vo n Experimental concept for out-ofplane actuation driven by an AC voltage signal. +V o - Vo t t © C. Jimenez 2005, IM-SURE

Motivations on using offset combs for out-of-plain actuation vs. parallel plates. n Si. O 2 Limitations when fabricating structures in Silicon. On-Insulator for out-of-plane actuations. V Si Electrode Unfortunately current fabricating techniques do not allow placing an electrode under a microstructure. © C. Jimenez 2005, IM-SURE

Target objectives for the research. n n Model various lateral comb architectures in Finite Element Analysis Software along with MATLAB. Design fabrication techniques to achieve lateral combs with different heights. Fabricate test structures to observe the deepness differences in the combs. Attempt to characterize structures. © C. Jimenez 2005, IM-SURE

Modeling Results contd. . Force in the Z direction Vs Height of Ground Comb. Constant 70 um Changing Height 0 -70 um © C. Jimenez 2005, IM-SURE

Modeling Results contd. . n Force in the Z Direction Vs. Potential across Offset Combs Variable Potential From 0 to 100 V Ground © C. Jimenez 2005, IM-SURE

Modeling Contd. . Out of Plane Force Vs. Comb Displacement. -1. 4 e-12 N/um levitated Force becomes Negative after A 25 um rise. Displacement. © C. Jimenez 2005, IM-SURE

Fabrication parameters force Maximization n Sensitivity Analysis from the standard model. Standard@35 um Tests: 15, 35, & 55 um Standard Gap@10 um Tests: 5, 10 & 15 um Standard Gap @10 um. Tests: 5, 10 & 15 um © C. Jimenez 2005, IM-SURE

Designing test structures Making and evaluating masks. n n First approach: Opaque combs were thought to partially protect combs from UV light when exposed. Second approach: Create Structures with a two mask deposition. This mask was not successful for its Unexpected roughness Successful mask with 250 um. resolution © C. Jimenez 2005, IM-SURE Smooth mask used to fabricate the structure

Manufacturing devices Lithography and etch for two mask process. n Protect the high combs with a first mask and develop the wafer. Hard Bake the wafer. Apply a thin layer of Photo-resist. Protect all combs a second Apply a thick layerwith of Photo-Resist. mask and develop again Deep etch for 90 minutes n Deep etch for 45 more minutes. n nn Si © C. Jimenez 2005, IM-SURE

Manufacturing Results Evaluating the etching process n Despite the significant height decrease, the final etch was not evenly across the exposed combs. n A Dektek 3 surface profiler was used to estimate the roughness on the small comb surfaces. Very rough © C. Jimenez 2005, IM-SURE

Pre-Characterization Isolating the Moving Structure n Between the combs we deposited Sylgard 182, an elastomer with flexible and isolating properties. n Three days after, the elastomer cured, giving the possibility for electrical isolation. n The Characterization of the test device was started but not fully completed. © C. Jimenez 2005, IM-SURE

Full MEMS experience. 1. Idea 6. Characterization 5. Fabrication 2. Concept. 3. Modeling 4. Design Layout © C. Jimenez 2005, IM-SURE

Acknowledgments Thanks to: n Faculty Mentor: Prof. Andrei Shkel n Graduate Student Mentors: Max Perez, Adam Schofield. n Lab: Jesper Eklund, Max Perez, Adam R. Schofield, Alexander Trusov, Chandra S. Tupelly. n IM SURE: Said Shokair. n Calit 2: Goran Matijasevic. Funded by: *National Science Foundation (NSF). *Undergraduate Research Opportunity Program (UROP). © C. Jimenez 2005, IM-SURE