Experiments on MEMS Integration in 0.25 μm CMOS Process

Michalik, P.; Fernandez, Daniel; Wietstruck, Matthias; Kaynak, Mehmet; Madrenas, Jordi

doi:10.3390/s18072111

Cited by 16 publications

(13 citation statements)

References 22 publications

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“…Results show that the theoretical motional resistance prediction matches the experimental data with an error below 20% in the worst case; such a reliable calculation is also a direct consequence of the amplifier gain being accurately characterized. In any case, the remaining error could be attributed to the metal layers’ degradation caused by the etching step that is intended to remove only the sacrificial oxide but in practice has an impact on the metal layers as well [ 35 ]. Such a metal degradation can reduce the overall resonator-driving coupling capacitance, resulting in experimental motional resistances larger than expected.…”

Section: Electrical Characterizationmentioning

confidence: 99%

A Tunable-Gain Transimpedance Amplifier for CMOS-MEMS Resonators Characterization

et al. 2021

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CMOS-MEMS resonators have become a promising solution thanks to their miniaturization and on-chip integration capabilities. However, using a CMOS technology to fabricate microelectromechanical system (MEMS) devices limits the electromechanical performance otherwise achieved by specific technologies, requiring a challenging readout circuitry. This paper presents a transimpedance amplifier (TIA) fabricated using a commercial 0.35-µm CMOS technology specifically oriented to drive and sense monolithically integrated CMOS-MEMS resonators up to 50 MHz with a tunable transimpedance gain ranging from 112 dB to 121 dB. The output voltage noise is as low as 225 nV/Hz1/2—input-referred current noise of 192 fA/Hz1/2—at 10 MHz, and the power consumption is kept below 1-mW. In addition, the TIA amplifier exhibits an open-loop gain independent of the parasitic input capacitance—mostly associated with the MEMS layout—representing an advantage in MEMS testing compared to other alternatives such as Pierce oscillator schemes. The work presented includes the characterization of three types of MEMS resonators that have been fabricated and experimentally characterized both in open-loop and self-sustained configurations using the integrated TIA amplifier. The experimental characterization includes an accurate extraction of the electromechanical parameters for the three fabricated structures that enables an accurate MEMS-CMOS circuitry co-design.

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Section: Electrical Characterizationmentioning

confidence: 99%

A Tunable-Gain Transimpedance Amplifier for CMOS-MEMS Resonators Characterization

et al. 2021

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“…One of the key concerns when designing MEMS sensors using the BEOL metal layers is the curvature of the device structures due to BEOL thin metals residual stress and different temperature coefficients of stacked layers [ 19 , 25 , 26 , 27 , 30 , 31 ]. The device proposed in this article is not an exception as described in Section 5.2 , even though the final device curvature was minimized by using various metal and oxide layers stacked together using long vias, a technique used in numerous CMOS-MEMS devices in the literature [ 25 , 26 , 27 ]. Unfortunately, due to foundry design rules not allowing the crossing of long vias, it was not possible to put acid penetration blocking vias in the plate periphery, as they would have collided with spring vias.…”

Section: Discussionmentioning

confidence: 99%

“…The plate rotor consists of a stack of M3–M5 metals kept together with long vias, which provide both mechanical attachment and electrical connection between the different metal layers. Moreover, the use of various metal and oxide layers stack reduces the plate curvature after oxide release [ 19 , 25 , 26 , 27 ]. In order to allow the release agent to penetrate the MEMS structure and release the oxide between the rotor and the stator, the MEMS plate has

m openings uniformly distributed across the plate.…”

Section: Proposed Devicementioning

confidence: 99%

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

Sanchez-Chiva

Valle

Fernandez

et al. 2020

Sensors

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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.

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“…Content may change prior to final publication. --CMOS micromachining or BEOL CMOS-MEMS: MEMSIC [19], Bosch [20], Abadal et al [21], Baolab Microsystems [22] and UPC [3,[23][24][25][26][27][28] are good examples. It uses the Back-End-Of-Line (BEOL) layers of the finished CMOS process to create the MEMS.…”

Section: Introductionmentioning

confidence: 99%

Manufacturing Issues of BEOL CMOS-MEMS Devices

Valle

Fernandez

Gibrat³

et al. 2021

IEEE Access

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In this paper we present a comprehensive report on the issues found during the manufacturing of high-yield CMOS-MEMS sensors based on vapor-phase hydrogen fluoride (vapor-HF ) oxide etching.During the study we have identified the main issues affecting CMOS-MEMS high-yield manufacturing regarding the silicon oxide as a sacrificial material, the passivation as a release mask, the BEOL as structural material for MEMS design and the aluminum-sputtering as a sealing layer for the MEMS cavity. This study has been carried out by systematically analyzing over 100 full wafers in 10 different runs on four different foundries using 0.5 µm, 0.18 µm and 0.15 µm CMOS processes, containing both test structures and fullsensor designs.

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Experiments on MEMS Integration in 0.25 μm CMOS Process

Cited by 16 publications

References 22 publications

A Tunable-Gain Transimpedance Amplifier for CMOS-MEMS Resonators Characterization

A Tunable-Gain Transimpedance Amplifier for CMOS-MEMS Resonators Characterization

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

Manufacturing Issues of BEOL CMOS-MEMS Devices

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