A Microelectronics-Compatible Process for Surface Micromachining of MEMS and MOEMS

2005 ◽  
Author(s):  
Meetul Goyal ◽  
Robert C. Anderson ◽  
Jordan M. Berg ◽  
Richard O. Gale ◽  
Mark Holtz ◽  
...  
Keyword(s):  
Sacrificial Layer ◽  
Process Conditions ◽  
Glass Wafer ◽  
Mems Devices ◽  
Surface Micromachining ◽  
Industrial Facilities ◽  
Dry Process ◽  
Electrostatically Actuated ◽  
Wafer Substrate ◽  
Etch Time

Many fabrication steps for micro electromechanical and micro optoelectromechanical systems (MEMS and MOEMS) are carried out on specialized or highly customized tools that are not part of a standard microelectronics process flow. This paper presents a surface micromachining process for electrostatically-actuated MEMS devices using standard microelectronics tools, materials, and process conditions. The result should facilitate MEMS development in university laboratories with a microelectronics focus, and encourage the transfer of MEMS production to aging or underutilized industrial facilities. Aluminum structures, with silicon dioxide or silicon nitride dielectric layers, are built upon a silicon or glass wafer substrate. Shipley SC1827 photoresist provides a 2.7 μm thick sacrificial layer. The release etch is the critical fabrication step. This must be a dry process to avoid stiction, should be isotropic to minimize the etch time, and should be capable of large undercut distances to minimize the need for etch holes. Finally, the etch must be sufficiently selective to allow for the necessary release etch time without significantly impacting non-sacrificial structures. An O2/CHF3 plasma etch has been developed to meet these requirements. Using this process we have designed, fabricated and tested structures with moveable mirrors suspended over multiple drive and sense electrodes.

Surface Micromachining of Polyureasilazane Based Ceramic-MEMS Using SU-8 Micromolds

2006 ◽  
Vol 45 ◽  
pp. 1293-1298 ◽  
Author(s):  
Vahid Fakhfouri ◽  
Sébastien Jiguet ◽  
Juergen Brugger
Keyword(s):  
Thermogravimetric Analysis ◽  
Aspect Ratio ◽  
Material Characterization ◽  
Smooth Surface ◽  
Sacrificial Layer ◽  
Green Body ◽  
Mems Devices ◽  
Surface Micromachining ◽  
Free Standing ◽  
Liquid Precursor

We describe a novel surface micromachining process for the fabrication of ceramic-type MEMS devices, such as free-standing cantilevers, that is based on the use of high-aspect ratio micromolds of SU8 and aluminum as sacrificial layer. 250μm-high and 100-1000μm-wide molds were used to confine a liquid precursor of SiC/Si3N4 based ceramics on the sacrificial layer that enables the detachment of the green body before the pyrolysis step at 1000°C. The final ceramic cantilever has dimensions ranging from 100-500μm x 1-2mm x 50μm and a smooth surface. Details of the processing, structural and material characterization such as Dynamic Rheological and Thermogravimetric Analysis under UV will be presented and compared to those found in the literature.

Design of Electrostatic Micro Mirrors for Improved Stability Though Surface Contact

1998 ◽  
Author(s):  
Timothy Moulton ◽  
G. K. Ananthasuresh
Keyword(s):  
Design Method ◽  
Electrostatic Force ◽  
Electrostatic Actuation ◽  
Mems Devices ◽  
Complex Dynamic ◽  
Micro Electro Mechanical Systems ◽  
Electrostatically Actuated ◽  
Surface Contact ◽  
Improved Stability ◽  
Mems Process

Abstract There exists a need to stabilize the electrostatic actuation commonly used in Micro-Electro-Mechanical Systems (MEMS). Most electrostatically actuated MEMS devices act as variable capacitors with varying gap between the charged conductors. Electrostatic force in these devices is a nonlinear attractive force between the conductors resulting in a complex dynamic system. These systems are stable for only a small portion of the initial gap. In this paper a design method is presented for electrostatic micro-mirrors with improved stability. Controllable, stable electrostatic actuation can be achieved through surface contact between the two conductors. Once in contact with the surface, the compliance of the structure is used to stabilize the electrostatic actuation over a long range of motion. Beam based variable angle mirrors were designed and fabricated using the Multi-User MEMS Process at MCNC technology center. The design methods for stable electrostatic actuation were tested on these mirrors. Some characteristics are noted and their implementation into future designs is discussed.

Thin Film Packaging for Vacuum MEMS Encapsulation: A Study on Outgassing Phenomenon

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 002428-002482
Author(s):  
D. Saint-Patrice ◽  
J. L. Pornin ◽  
B. Savornin ◽  
G. Rodriguez ◽  
S. Danthon ◽  
...  
Keyword(s):  
Thin Film ◽  
Ion Beam ◽  
High Vacuum ◽  
Chip Thickness ◽  
Process Conditions ◽  
Mems Devices ◽  
Wafer Level ◽  
Working Pressure ◽  
Baking Process ◽  
Sealing Materials

Most of the time, MEMS devices require hermetic encapsulation for protection against atmosphere, moisture, particles and standard back-end manufacturing technologies. In the last few years, Wafer Level Packaging (WLP) is moving toward developments on Thin Film Packaging (TFP) in order to save footprint, to reduce chip thickness and packaging costs. In the specific case of high-vacuum MEMS encapsulation (gyro, compass), long term pressure stability is required. As the final performances of these kinds of devices are strongly dependent on the working pressure, using TFP for MEMS encapsulation with controlled vacuum becomes more challenging due to very small cavity volumes. It is then necessary to understand the outgassing phenomenon that take place during TFP encapsulation in order to reduce it. In this paper, our latest developments on thin film packaging technology are presented. Outgassing from materials used in TFP and MEMS devices become key parameters to decrease the pressure inside the package and to improve the reliability. In a first part, pressure and Residual Gas Analysis (RGA) of typical TFP and typical MEMS materials are measured under different time / temperature baking processes. Measurements show that material outgassing mainly comes from H2 and maximum pick appears in the beginning of the thermal process. Thanks to these characterizations, an optimized outgassing baking process in term of time and thermal budget is presented. By minimizing the internal outgassing, materials deposited by PVD sputtering can now be implemented as sealing materials for low pressure MEMS devices. In a second part, specific low temperature Al based materials which has been developed on equipment fully compatible with front-end fab is presented. Multi-layer materials like Ti / Al based materials are compared to our single Al based material to decrease the microstructure size and to improve the sealing performances. Scanning Electronic Microscopy (SEM) and Focused Ion Beam (FIB) cross section characterizations confirm that the grain sizes are highly impacted by sputtering process parameters and a compromise has to be done with MEMS outgassing. Finally, the most suitable outgassing baking process for the inside cavity materials and various Al-based sealing materials and stacks are performed for a MEMS compass device on 200 mm wafers. Pressure inside the cavity less than 10 mbar is obtained and the TFP yield is presented on each process conditions. These results are very promising and showed the capabilities of TFP for vacuum MEMS encapsulation applications despite very small volume cavity. Development of such technology is still under way in order to reach high vacuum level in the range of 10-1 to 10-3 mbar.

Fabrication and Test of 3C-SiC Electrostatic Resonators

2007 ◽  
Vol 556-557 ◽  
pp. 949-952
Author(s):  
Marcel Placidi ◽  
Phillippe Godignon ◽  
Jaume Esteve ◽  
Narcis Mestres ◽  
Gabriel Abadal
Keyword(s):  
Sacrificial Layer ◽  
Ambient Condition ◽  
Wet Etching ◽  
Test Results ◽  
Si Substrate ◽  
Capacitive Current ◽  
Step Process ◽  
Electrostatically Actuated ◽  
Icp Etching ◽  
Resonance Frequencies

Silicon Carbide has proven its relevance for various MEMS and sensors devices applications. This paper presents the fabrication and the first test results of 3C-SiC electrostatic resonators actuated by applying a combination of AC and DC voltages. The recipe used for the fabrication has taken the advantage of the starting material, 3C-SiC grown on Si, which allows us to use the Si substrate as sacrificial layer to release the structures. Resonators have been fabricated by a two-step process, combining RIE ICP etching with HF wet etching. Resonators have been successfully electrostatically actuated in air-ambient condition. The resonance frequencies were clearly identified, although capacitive current created by actuation was not detected.

Real time optical correction using electrostatically actuated MEMS devices

1999 ◽  
Vol 46 (2-3) ◽  
pp. 91-101 ◽  
Author(s):  
M. Horenstein ◽  
T. Bifano ◽  
S. Pappas ◽  
J. Perreault ◽  
R. Krishnamoorthy-Mali
Keyword(s):  
Real Time ◽  
Mems Devices ◽  
Electrostatically Actuated ◽  
Optical Correction

scholarly journals Stability, Nonlinearity and Reliability of Electrostatically Actuated MEMS Devices

Sensors ◽  
2007 ◽  
Vol 7 (5) ◽  
pp. 760-796 ◽  
Author(s):  
Wen-Ming Zhang ◽  
Guang Meng ◽  
Di Chen
Keyword(s):  
Mems Devices ◽  
Electrostatically Actuated

Micromachining of mesoporous oxide films for microelectromechanical system structures

2002 ◽  
Vol 17 (8) ◽  
pp. 2121-2129 ◽  
Author(s):  
Jong-Ah Paik ◽  
Shih-Kang Fan ◽  
Chang-Jin Kim ◽  
Ming C. Wu ◽  
Bruce Dunn
Keyword(s):  
Sacrificial Layer ◽  
Oxide Films ◽  
Average Diameter ◽  
High Porosity ◽  
Mems Devices ◽  
Mesoporous Films ◽  
Microelectromechanical System ◽  
Mesoporous Oxide ◽  
Structure Layer ◽  
Mesoporous Oxides

The high porosity and uniform pore size of mesoporous oxide films offer unique opportunities for microelectromechanical system (MEMS) devices that require low density and low thermal conductivity. This paper provides the first report in which mesoporous films were adapted for MEMS applications. Mesoporous SiO2 and Al2O3 films were prepared by spin coating using block copolymers as the structure-directing agents. The resulting films were over 50% porous with uniform pores of 8-nm average diameter and an extremely smooth surface. The photopatterning and etching characteristics of the mesoporous films were investigated and processing protocols were established which enabled the films to serve as the sacrificial layer or the structure layer in MEMS devices. The unique mesoporous morphology leads to novel behavior including extremely high etching rates and the ability to etch underlying layers. Surface micromachining methods were used to fabricate three basic MEMS structures, microbridges, cantilevers, and membranes, from the mesoporous oxides.

scholarly journals Design of a large-range rotary microgripper with freeform geometries using a genetic algorithm

2022 ◽  
Vol 8 (1) ◽  
Author(s):  
Chen Wang ◽  
Yuan Wang ◽  
Weidong Fang ◽  
Xiaoxiao Song ◽  
Aojie Quan ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Human Hair ◽  
Design Methodology ◽  
Large Range ◽  
Design Method ◽  
Actuation Voltage ◽  
Superior Performance ◽  
Mems Devices ◽  
Electrostatically Actuated ◽  
Fabrication Tolerances

AbstractThis paper describes a novel electrostatically actuated microgripper with freeform geometries designed by a genetic algorithm. This new semiautomated design methodology is capable of designing near-optimal MEMS devices that are robust to fabrication tolerances. The use of freeform geometries designed by a genetic algorithm significantly improves the performance of the microgripper. An experiment shows that the designed microgripper has a large displacement (91.5 μm) with a low actuation voltage (47.5 V), which agrees well with the theory. The microgripper has a large actuation displacement and can handle micro-objects with a size from 10 to 100 μm. A grasping experiment on human hair with a diameter of 77 μm was performed to prove the functionality of the gripper. The result confirmed the superior performance of the new design methodology enabling freeform geometries. This design method can also be extended to the design of many other MEMS devices.

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