A wafer-level encapsulated CMOS MEMS thermoresistive calorimetric flow sensor with integrated packaging design

Xu, Wei; Gao, Bo; Ahmed, Moaaz; Duan, Mingzheng; Wang, Bo; Mohamad, Saqib; Bermak, Amine; Lee, Yi-Kuen

doi:10.1109/memsys.2017.7863577

Cited by 24 publications

(7 citation statements)

References 10 publications

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“…Since sccm is a volume flow rate unit, taking into account the cross-sectional area of the gas channel (13 mm × 10 mm), the sensitivity of the flow sensor can be written as 123.006 mV (m/s) −1 in terms of gas velocity unit (m/s). The sensitivity of the flow sensor is higher relative to some typical thermal flow sensors [29][30][31][32]. The reason may be that we use heavily doped N-type polysilicon and P-type polysilicon as thermocouples, they have a large Seebeck coefficient, which results in a high output response and sensitivity of the flow sensor.…”

Section: Basic Output Characteristics Of the Flow Sensormentioning

confidence: 99%

“…The reason may be that we use heavily doped N-type polysilicon and P-type polysilicon as thermocouples, they have a large Seebeck coefficient, which results in a high output response and sensitivity of the flow sensor. In addition, the response time and accuracy of the flow sensor are also measured [29]. Figure 7(c) shows the voltage response of the flowmeter as the gas flow rate changes from 1200 sccm to 100 sccm, from which we see that the response time of the flow sensor is approximately 250 ms. the response time is relatively large.…”

Section: Basic Output Characteristics Of the Flow Sensormentioning

confidence: 99%

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MEMS thermal gas flow sensor with self-test function

et al. 2019

J. Micromech. Microeng.

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In this paper, the design, fabrication and characterization of a MEMS thermal gas flow sensor with self-test function are presented. The flow sensor is composed of a platinum heater and thermopiles, where the heater is served as a heat source and the thermopiles are used for voltage output. In order to improve the performance of the flow sensor, the heavily doped N/P-polysilicon is utilized to form the thermocouple and XeF 2 front-side isotropic etching is adopted to realize thermal isolation of the device. At the same time, the effects of the chip position in the gas channel and heater voltage on device performance are also studied from both experiment and simulation. Moreover, a self-test method and corresponding test system based on the thermal flow sensor are proposed, which use an equivalent heater voltage to simulate the gas flow rate for monitoring the dynamic response of the flow sensor to the gas. This method is simple and effective compared with traditional methods for detecting the performance flow sensors. In addition, the basic output performance of the flow sensor using nitrogen as the test gas is characterized. The experimental results show that the flow sensor owns a relatively high sensitivity of 123.006 mV (m/s) −1 (no amplification), a low response time of about 250 ms and good accuracy of ±1.97%.

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Section: Basic Output Characteristics Of the Flow Sensormentioning

confidence: 99%

Section: Basic Output Characteristics Of the Flow Sensormentioning

confidence: 99%

MEMS thermal gas flow sensor with self-test function

et al. 2019

J. Micromech. Microeng.

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“…Because the thermistors of the two sensors have the same resistance value, the step response and noise of the two sensors keep the same value. According to the definition of the response time of the flow system [16], with a constant input nitrogen gas flow of 1.8 SLM, an electric impulse heating power of 4.0 mW was applied to the heater directly to estimate the dynamical response of the type B flow sensor. As shown in Figure 10, the sensor exhibits a response time of 1.5 ms.…”

Section: Device Characterizationmentioning

confidence: 99%

“…Area mm 2 Thin Film Structure/Fabrication Style Sensitivity* mV/(m/s)/mW [9] 36 SiO2 Double-sided process 0.039 [11]/ [14] 2.25 SiO2 Single-sided process 0.154 [16] 3.4 Si/SiO2 Silicon-On-Insulator (SOI)-wafer/single-sided process 0.112…”

Section: Refmentioning

confidence: 99%

A Front-Side Microfabricated Thermoresistive Gas Flow Sensor for High-Performance, Low-Cost and High-Yield Volume Production

Xue

Wang

2020

Micromachines

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In this paper, we present a novel thermoresistive gas flow sensor with a high-yield and low-cost volume production by using front-side microfabricated technology. To best improve the thermal resistance, a micro-air-trench between the heater and the thermistors was opened to minimize the heat loss from the heater to the silicon substrate. Two types of gas flow sensors were designed with the optimal thermal-insulation configuration and fabricated by a single-wafer-based single-side process in (111) wafers, where the type A sensor has two thermistors while the type B sensor has four. Chip dimensions of both sensors are as small as 0.7 mm × 0.7 mm and the sensors achieve a short response time of 1.5 ms. Furthermore, without using any amplification, the normalized sensitivity of type A and type B sensors is 1.9 mV/(SLM)/mW and 3.9 mV/(SLM)/mW for nitrogen gas flow and the minimum detectable flow rate is estimated at about 0.53 and 0.26 standard cubic centimeter per minute (sccm), respectively.Micromachines 2020, 11, 205 2 of 10 insulation membrane is formed by potassium hydroxide (KOH) anisotropic etching from the wafer backside. The anisotropic etching-induced inclined sidewalls cause the chip size to be quite large and the back-sided KOH etching is time-consuming, which yield a higher batch-fabrication cost [10]. Thus, developing a new strategy to minimize the chip size for realizing batch-fabrication with a lower cost is an important issue. Recently, a commercial 0.35 µm 2P4M microelectromechanical systems (MEMS) process was used in [11] to fabricate a sensor from the front-side of a (100) wafer. The approach decreased the chip-size and fabrication cost. However, the insulation membrane was released through XeF 2 isotropic etching, Thus, a depth-limited insulation cavity was formed, which would increase the heat loss, lower the thermal resistance and cause a relatively lower sensitivity of the sensor. Here, this paper expands on preliminary research presented in [12] and explores a tiny-sized ultrasensitive thermoresistive gas flow sensor that is single-side processed in an ordinary single-polished (111) silicon wafer. By changing the number of thermoresistive sensors, we developed two types of differential thermoresistive gas flow sensors, a half-bridge type and a full-bridge type.

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“…They found that the sensor has a more considerable sensitivity in the velocity range up to 1 m/s. Wei et al [5] analyzed a wafer-level encapsulated Thermo-Resistive Micro Calorimetric Flow (TMCF) sensor. Gas nitrogen was selected for the fluid.…”

Section: Introductionmentioning

confidence: 99%

Metrology and Measurement Systems

Babaelahi,

Sadri

2021

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Sensitive MEMS-based thermal flow sensors are the best choice for monitoring the patient's respiration prompt diagnosis of breath disturbances. In this paper, open space micro-calorimetric flow sensors are investigated as precise monitoring tools. The differential energy balance equation, including convection and conduction terms, is derived for thermal analysis of the considered sensor. The temperature-dependent thermal conductivity of the thin silicon-oxide membrane layer is considered in the energy balance equation. The derived thermal non-linear differential equation is solved using a well-known analytical method, and a finite-element numerical solution is used for the confirmation. Results show that the presented analytical model offers a precise tool for evaluating these sensors. The effects of flow and thin membrane film parameters on thermo-resistive micro-calorimetric flow sensors' performance and sensitivity are evaluated. The optimization has been performed at different flow velocities using a genetic algorithm method to determine the optimum configuration of the considered flow sensor. The geometrical parameters are selected as a decision variable in the optimization procedure. In the final step, using optimization results and curve-fitting, the expressions for the optimum decision variables have been derived. The sensor's optimum configuration is achieved analytically based on flow velocity with the analytical terms for optimum decision variables.

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A wafer-level encapsulated CMOS MEMS thermoresistive calorimetric flow sensor with integrated packaging design

Cited by 24 publications

References 10 publications

MEMS thermal gas flow sensor with self-test function

MEMS thermal gas flow sensor with self-test function

A Front-Side Microfabricated Thermoresistive Gas Flow Sensor for High-Performance, Low-Cost and High-Yield Volume Production

Metrology and Measurement Systems

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