Process Integration for active polysilicon resonant microstructures

Putty, Michael W.; Chang, Shinan; Howe, Roger T.; Robinson, Andrew; Wise, K. D.

doi:10.1016/0250-6874(89)87112-4

Cited by 55 publications

(13 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence the dynamic model is less sensitive to thickness errors than the static model. Using a similar technique, elastic modulus measurements have been carried out on annealed polysilicon cantilever beams 43 and on boron-doped, single-crystalline, (HO)-oriented silicon beams. 33 Dynamic modulus measurement using microbridges (doubly supported beams) have been made on polysilicon 41 and on boron-doped (100)-oriented single-crystalline silicon beams.…”

Section: Elasticity Propertiesmentioning

confidence: 99%

Mechanical Characterization of Thin Films by Micromechanical Techniques

Schweitz¹

1992

MRS Bull.

153

View full text Add to dashboard Cite

Evaluating the mechanical properties of thin films on thick substrates is tricky. Some useful techniques for mechanical property measurements on macroscopic film specimens exist, e.g., internal stress measurements by x-ray diffraction or by wafer buckling. Many conventional techniques, however, such as indentation for hardness measurement or scratch testing for evaluation of adhesion or wear resistance, yield results that are difficult or impossible to evaluate in terms of more fundamental film properties. In fact, these techniques are more practical engineering tools than tools for scientific study.One solution is to miniaturize the test probe to dimensions approaching the film thickness. The nanoindentation technique for submicrohardness measurement described elsewhere in this issue by Pharr and Oliver is a recent example of such an approach. Still, for very thin films it is difficult to separate the influence of the substrate properties from the film properties, and the indentation process is inherently too complex to be well suited for determining fundamental materials parameters.The rapidly evolving field of micromechanics offers some new possibilities in thin film characterization. Important film properties such as internal stress, elastic moduli, plastic yield limit, and fracture data can be extracted from experiments with micromachined test structures in the 10–1,000 μm size range.

show abstract

Section: Elasticity Propertiesmentioning

confidence: 99%

Mechanical Characterization of Thin Films by Micromechanical Techniques

Schweitz¹

1992

MRS Bull.

153

View full text Add to dashboard Cite

show abstract

“…(3), certain simplifying assumptions are made, e.g., an ideal clamped boundary condition at the fixed end is assumed. In real devices, however, the microcantilever beam flares at the anchor [6] . On the other hand, as shown in Fig.…”

Section: Rs=85kmentioning

confidence: 98%

<title>Integrated process for smart microstructures</title>

Pan

Melzak

Garverick

et al. 1996

Smart Structures and Materials 1996: Smart Electronics and MEMS

View full text Add to dashboard Cite

An eight-mask integrated process for smart microstructures is presented, based on an enhancement-depletion NMOS circuit process and a two-layer polysilicon surface micromachining process. Design and fabrication issues, such as circuit encapsulation, interconnect, and thermal budget are addressed. Two types of micromechanical structures, microcantilever beams and shear stress sensors, were fabricated with on-chip signal conditioning circuits. Electrical test results on circuitry both integrated and not integrated with micromechanisms are discussed. Electromechanical test data demonstrating the resonant frequency of integrated microcantilever beam structures is presented as well as calibrated flow channel data for micromachined shear stress sensors.

show abstract

“…Furnace annealing is commonly employed to reduce the stress, where the wafers are heated to 1,050 for 1 h in nitrogen ambient. Recently, rapid-thermal annealing has also proven effective in reducing the stress in the polysilicon films [82,84] . A PSO layer is deposited before the stress annealing step so that the polysilicon layer, sandwiched by the PSG layers on the top and bottom, will be annealed symmetrically and the stress gradient will be minimized.…”

Section: Fabrication Technologymentioning

confidence: 99%

“…Conventionally, the film is furnace annealed at 1,050 in a nitrogen ambient for an hour. It has been demonstrated that rapid thermal annealing (RTA) can be used to reduced the stress level in the polysilicon film [82,83] . Experiment has shown that RTA at 1,100 for 60 s will reduce the stress level comparable to that achievable by long furnace annealing.…”

Section: Rapid Thermal Processmentioning

confidence: 99%

A Surface Micromachined Accelerometer with Integrated CMOS Detection Circuitry

Yun¹

2012

Microsystems and Nanotechnology

View full text Add to dashboard Cite

A surface micromachined, capacitive accelerometer described here integrates the mechanical sensing microstructures with CMOS detection circuits. The capacitive sensing structure consists of two polysilicon layers with the sensing and feedback electrodes underneath and the suspended plate as the proof mass. The sensing axis is perpendicular to the substrate. A full capacitive bridge is formed to translate a mechanical displacement signal into an electrical voltage signal. Electrostatic feedback is used to counteract the proof mass displacement due to acceleration. Interdigitated fingers are employed to generate a levitation force using the asymmetrical distribution of electrical fields. A unity gain buffer with low input capacitance is designed to actively drive the ground plane to minimize the parasitic capacitance. A S-D modulation technique is employed as the feedback control loop where the mechanical proof mass is used as the double integrator in the secondorder S-D modulator.Further described is the accelerometer prototype fabrication using a typical double polysilicon surface micromachining process for microstructures and a 3 mm conventional CMOS process for the electronics. The total chip size is 2.5 mm u5 mm. The unity gain buffer has a gain of 0.9 kHz and 500 kHz bandwidth that is limited by the parasitic capacitance from the measurement setup. The gain of the variable gain amplifier (VGA) can vary from unity to 40 and is controlled externally. The accelerometer is first characterized in the open-loop, self-testing mode. The damping coefficient is measured to be 1.2 u10 -3 N/(m/s), which agrees with 1 u10 -3 N/(m/s) from theoretical analysis. The open-loop sensitivity of the accelerometer is 100 mV/g with a 100 mV driving voltage. The stiction of suspended microstructures is observed and various possible solutions are discussed.

show abstract

Process Integration for active polysilicon resonant microstructures

Cited by 55 publications

References 5 publications

Mechanical Characterization of Thin Films by Micromechanical Techniques

Mechanical Characterization of Thin Films by Micromechanical Techniques

<title>Integrated process for smart microstructures</title>

A Surface Micromachined Accelerometer with Integrated CMOS Detection Circuitry

Contact Info

Product

Resources

About