Characterization of CMOS-MEMS Resonant Pressure Sensors

Wietstruck

et al. 2018

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In this paper, we share our practical experience gained during the development of CMOS-MEMS (Complementary Metal-Oxide Semiconductor Micro Electro Mechanical Systems) devices in IHP SG25 technology. The experimental prototyping process is illustrated with examples of three CMOS-MEMS chips and starts from rough process exploration and characterization, followed by the definition of the useful MEMS design space to finally reach CMOS-MEMS devices with inertial mass up to 4.3 μg and resonance frequency down to 4.35 kHz. Furthermore, the presented design techniques help to avoid several structural and reliability issues such as layer delamination, device stiction, passivation fracture or device cracking due to stress.

Section: Methodology and An Overview Of The Prototype Chipsmentioning

confidence: 99%

Experiments on MEMS Integration in 0.25 μm CMOS Process

Michalik

Wietstruck

et al. 2018

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“…Based on a structure before studied and tested in [ 10 , 34 ] theoretical graphs of

against pressure sweep at room constant temperature ( Figure 2 a) and against temperature sweep at constant ambient pressure ( Figure 2 b) were made to determinate the regimes of operation, for both pressure and temperature ranges concerning for the prototypes.…”

Section: Design Considerationsmentioning

confidence: 99%

“…The etching depends on the device dimensions and the oxide over the structure. In the case of the 250 nm technology, the depth is about 13

m, and for the 180 nm node, 9.5

m. Given the different stacks and via thicknesses in the prototypes, it was decided to make a correlation between the necessary release time obtained 250 nm and the theoretical facts involved in it [ 10 , 23 , 34 ].…”

Section: Prototype Designmentioning

confidence: 99%

“…This work has a background in this kind of sensors. Some previously developed sensors in the research group are integrated magnetometers [ 9 ], resonant pressure sensors at 250 nm technology [ 10 ], and accelerometers [ 11 , 12 ]. Likewise, a technique has been patented that allows the construction of multilayer membranes, avoiding the technical problems caused by detachment [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

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Resonant MEMS Pressure Sensor in 180 nm CMOS Technology Obtained by BEOL Isotropic Etching

Mata-Hernandez

Banerji

et al. 2020

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This work presents the design and characterization of a resonant CMOS-MEMS pressure sensor manufactured in a standard 180 nm CMOS industry-compatible technology. The device consists of aluminum square plates attached together by means of tungsten vias integrated into the back end of line (BEOL) of the CMOS process. Three prototypes were designed and the structural characteristics were varied, particularly mass and thickness, which are directly related to the resonance frequency, quality factor, and pressure; while the same geometry at the frontal level, as well as the air gap, were maintained to allow structural comparative analysis of the structures. The devices were released through an isotropic wet etching step performed in-house after the CMOS die manufacturing, and characterized in terms of Q-factor vs. pressure, resonant frequency, and drift vs. temperature and biasing voltage.

“…The device was designed using the metal layers available in the Back-End-Of-Line (BEOL) of a standard CMOS (Complementary Metal–Oxide–Semiconductor) process, opening the doors to a future co-integration, side-by-side, in the same die area with the electronics. Moreover, integration with CMOS-MEMS accelerometers and pressure sensors developed by the research group would be possible [ 7 , 8 ]. The design was done taking into account the need of achieving a good sensitivity with lower current and biasing voltage.…”

Section: Introductionmentioning

confidence: 99%

A CMOS-MEMS BEOL 2-axis Lorentz-Force Magnetometer with Device-Level Offset Cancellation

Sanchez-Chiva

Valle

et al. 2020

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Lorentz-force Microelectromechanical Systems (MEMS) magnetometers have been proposed as a replacement for magnetometers currently used in consumer electronics market. Being MEMS devices, they can be manufactured in the same die as accelerometers and gyroscopes, greatly reducing current solutions volume and costs. However, they still present low sensitivities and large offsets that hinder their performance. In this article, a 2-axis out-of-plane, lateral field sensing, CMOS-MEMS magnetometer designed using the Back-End-Of-Line (BEOL) metal and oxide layers of a standard CMOS (Complementary Metal–Oxide–Semiconductor) process is proposed. As a result, its integration in the same die area, side-by-side, not only with other MEMS devices, but with the readout electronics is possible. A shielding structure is proposed that cancels out the offset frequently reported in this kind of sensors. Full-wafer device characterization has been performed, which provides valuable information on device yield and performance. The proposed device has a minimum yield of 85.7% with a good uniformity of the resonance frequency fr¯=56.8 kHz, σfr=5.1 kHz and quality factor Q¯=7.3, σQ=1.6 at ambient pressure. Device sensitivity to magnetic field is 37.6fA·μT−1 at P=1130 Pa when driven with I=1mApp.