Low-Resistance Silicon-Germanium Contact Technology for Modular Integration of MEMS with Electronics

Eyoum, Marie-Ange; King, Tsu‐Jae

doi:10.1149/1.1644143

Cited by 11 publications

(3 citation statements)

References 9 publications

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“…The Howe/King groups at Berkeley developed LPCVD boron-doped Si 1-x Ge x films with thicknesses between 1 to 5 μm. The Si to Ge composition and process temperature is optimized to obtain a tradeoff between low resistance contacts, low residual stress, and low stress gradient (8). Ge-rich films are readily oxidized and etched, making a pure Ge film an ideal sacrificial material.…”

Section: Cmos Mems Approachesmentioning

confidence: 99%

(Invited) CMOS MEMS Integration

Fedder¹

2011

ECS Trans.

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The "More than Moore" trend in the microelectronics industry is driving a renewed interest in mixed-physics CMOS MEMS integration. Integration becomes a necessity for multi-component microsystems, where interconnect issues are significant. Integration also drives down parasitic capacitances and provides opportunities for ultra-low-power microsystems. Several monolithic approaches exist that create MEMS from the layers in the back-end-of-line CMOS stack or by adding materials on top of the CMOS stack. These processes have been used to create a variety of microsystems including inertial sensors, RF tunable capacitors and probe manipulators. Process extensions include addition of sensitizing polymers by inkjet for gravimetric gas chemical sensors, etch of intermediate metal layers followed by polymers fill for capacitive chemical sensors, and plasma polymer deposition on micro-meshes to form diaphragms. The chip-stacking approach to integration is still in its infancy but benefits from the rapid maturation of technologies for chip thinning and for through-silicon vias.

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Section: Cmos Mems Approachesmentioning

confidence: 99%

(Invited) CMOS MEMS Integration

Fedder¹

2011

ECS Trans.

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“…The process to form lowresistance electrical contact between doped poly-SiGe and metal (i.e. aluminum) has been developed and was reported in [6]. The mirror assembly process, which would take place after the fabrication of the actuator but before the sacrificiallayer release, is out of the focus of this paper and hence not described here, either.…”

Section: Fabrication Processmentioning

confidence: 99%

Poly-SiGe MEMS actuators for adaptive optics

Lin

King

Muller

2006

MEMS/MOEMS Components and Their Applications III

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Many adaptive optics (AO) applications require mirror arrays with hundreds to thousands of segments, necessitating a CMOS-compatible MEMS process to integrate the mirrors with their driving electronics. This paper proposes a MEMS actuator that is fabricated using low-temperature polycrystalline silicon-germanium (poly-SiGe) surface-micromaching technology (total thermal budget is 6 hours at or below 425°C). The MEMS actuator consists of three flexures and a hexagonal platform, on which a micromirror is to be assembled. The flexures are made of single-layer poly-SiGe with stress gradient across thickness of the film, making them bend out-of-plane after sacrificial-layer release to create a large nominal gap. The platform, on the other hand, has an additional stress-balancing SiGe layer deposited on top, making the dual-layer stack stay flat after release. Using this process, we have successfully fabricated the MEMS actuator which is lifted 14.6 µm out-of-plane by 290-µm-long flexures. The 2-µm-thick hexagonal mirror-platform exhibits a strain gradient of -5.5×10 -5 µm -1 (equivalent to 18 mm radius-of-curvature), which would be further reduced once the micromirror is assembled.

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“…less than 10 −6 cm 2 [7]. Eyoum et al [8] proposed a Ni-silicide process to achieve low contact resistances. In this paper, a model is presented in which the different parts that contribute to the measured Kelvin resistance are encapsulated.…”

Section: Introductionmentioning

confidence: 99%

Improvement of the poly-SiGe electrode contact technology for MEMS

Claes¹,

Severi²,

Célis³

et al. 2010

J. Micromech. Microeng.

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Polycrystalline silicon-germanium (poly-SiGe) has already been shown to be an excellent structural material for microelectromechanical systems. It also enables a monolithic integration with CMOS due to its deposition temperature 450 • C. An important factor in the success of this monolithic integration is the electrical resistance between MEMS and CMOS. In this paper the contact resistance between a poly-SiGe MEMS electrode and an Al-top CMOS electrode was investigated using a stacked Greek cross structure. It was significantly reduced by the use of a combined soft sputter etch and a Ti-TiN interlayer. All parameters influencing the contact resistance were identified and taken into account to determine the specific contact resistivity using a simplified model. A very low specific contact resistivity of 3.15 × 10 −7 cm 2 was achieved on combining an Ar soft sputter etch (20 nm) and a Ti-TiN (5-20 nm) interlayer. The resistivity achieved is better than previously reported values using a complex Ni-silicide process.

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Low-Resistance Silicon-Germanium Contact Technology for Modular Integration of MEMS with Electronics

Cited by 11 publications

References 9 publications

(Invited) CMOS MEMS Integration

(Invited) CMOS MEMS Integration

Poly-SiGe MEMS actuators for adaptive optics

Improvement of the poly-SiGe electrode contact technology for MEMS

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