High Power Si Sidewall Heaters for Fluidic Applications Fabricated by Trench-Assisted Surface Channel Technology

Veltkamp, Henk-Willem; Zhao, Yiyuan; Boer, Meint J. de; Sanders, Remco G.P.; Wiegerink, Remco J.; Lötters, Joost Conrad

doi:10.1109/memsys.2019.8870667

Cited by 3 publications

(15 citation statements)

References 8 publications

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“…The microchannels can be completely released from the bulk silicon. Furthermore, using refilled trenches it was shown that silicon sidewall microheaters can be integrated in a microreactor with the Trench-Assisted Surface Channel Technology (TASCT) [26]. In this paper, we report an extension to the standard SCT process to integrate silicon sidewall electrodes between adjacent free-hanging microchannels in a silicon wafer.…”

Section: Surface Channel Technologymentioning

confidence: 99%

“…All electrical functionalities are realized by thin film metal electrodes on top of the microchannels. For example, resistive strain gauges [23], temperature sensors [24], thin film microheaters [25], and capacitive readouts [26,27] have been implemented using this approach. In these cases, sensing and actuation is only possible from the topside.…”

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

“…s (b) SCT process in an SOI wafer [27]. s (c) TASCT proces in an SOI wafer [26]. Having electrodes only on top of the microchannels limits the device design freedom and several attempts were made to embed electrodes in the sidewalls of the channels [26,27].…”

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

“…s (c) TASCT proces in an SOI wafer [26]. Having electrodes only on top of the microchannels limits the device design freedom and several attempts were made to embed electrodes in the sidewalls of the channels [26,27]. For example, in-line relative permittivity sensors were realized with the SCT process in an SOI wafer (Figure 1b) by isolating two silicon electrodes at the sidewalls of the microchannels [27].…”

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

“…It was previously reported that silicon microheaters can be embedded in the channel sidewalls by the TASCT process (Figure 1c) and temperatures up to 400 • C were reached by Joule heating, limited by the absence of flexure structures to allow for thermal expansion [26]. In order to integrate silicon sidewall electrodes, the currently existing methods either use SOI wafers [18,27] and/or refilled trenches [26], which add more complexity to the fabrication process.…”

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

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Heavily-Doped Bulk Silicon Sidewall Electrodes Embedded between Free-Hanging Microfluidic Channels by Modified Surface Channel Technology

et al. 2020

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Surface Channel Technology is known as the fabrication platform to make free-hanging microchannels for various microfluidic sensors and actuators. In this technology, thin film metal electrodes, such as platinum or gold, are often used for electrical sensing and actuation purposes. As a result that they are located at the top surface of the microfluidic channels, only topside sensing and actuation is possible. Moreover, in microreactor applications, high temperature degradation of thin film metal layers limits their performance as robust microheaters. In this paper, we report on an innovative idea to make microfluidic devices with integrated silicon sidewall electrodes, and we demonstrate their use as microheaters. This is achieved by modifying the original Surface Channel Technology with optimized mask designs. The modified technology allows to embed heavily-doped bulk silicon electrodes in between the sidewalls of two adjacent free-hanging microfluidic channels. The bulk silicon electrodes have the same electrical properties as the extrinsic silicon substrate. Their cross-sectional geometry and overall dimensions can be designed by optimizing the mask design, hence the resulting resistance of each silicon electrode can be customized. Furthermore, each silicon electrode can be electrically insulated from the silicon substrate. They can be designed with large cross-sectional areas and allow for high power dissipation when used as microheater. A demonstrator device is presented which reached 119.4 ∘ C at a power of 206.9 m W , limited by thermal conduction through the surrounding air. Other potential applications are sensors using the silicon sidewall electrodes as resistive or capacitive readout.

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Section: Surface Channel Technologymentioning

confidence: 99%

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

Section: Demands For Sidewall Microelectrodesmentioning

confidence: 99%

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Heavily-Doped Bulk Silicon Sidewall Electrodes Embedded between Free-Hanging Microfluidic Channels by Modified Surface Channel Technology

et al. 2020

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Sacrificial grid release technology: a versatile release concept for MEMS structures

Zhao

Janssens

Veltkamp

et al. 2021

J. Micromech. Microeng.

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Micro-electro-mechanical-systems (MEMS) structures with different in-plane dimensions often need to be released simultaneously from the bulk of the wafer and a single dry etching or wet etching technique cannot fulfill all release requirements. In this paper we present a universally applicable solution to release MEMS structures with different surface areas in a controlled and uniform way, which combines isotropic etching of a sacrificial silicon support structure by xenon difluoride with a predefined etch surface made by deep reactive ion etching. Two applications of this Sacrificial Grid Release Technology are presented, in which MEMS devices are released in silicon-on-insulator wafers. The demonstrated applications involve the release of microstructures with in-plane dimensions ranging from tens of micrometers to a few millimeters. The sacrificial silicon structure provides mechanical support which allows freedom in process flow design for fragile MEMS structures. The release technique can also be used to separate the chips from the wafer.

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Method for Keyhole-Free High-Aspect-Ratio Trench Refill by LPCVD

et al. 2022

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In micro-machined micro-electromechanical systems (MEMS), refilled high-aspect-ratio trench structures are used for different applications. However, these trenches often show keyholes, which have an impact on the performance of the devices. In this paper, explanations are given on keyhole formation, and a method is presented for etching positively-tapered high-aspect ratio trenches with an optimised trench entrance to prevent keyhole formation. The trench etch is performed by a two-step Bosch-based process, in which the cycle time, platen power, and process pressure during the etch step of the Bosch cycle are studied to adjust the dimensions of the scallops and their location in the trench sidewall, which control the taper of the trench sidewall. It is demonstrated that the amount of chemical flux, being adjusted by the cycle time of the etch step in the Bosch cycle, relates the scallop height to the sidewall profile angle. The required positive tapering of 88° to 89° for a keyhole-free structure after a trench refill by low-pressure chemical vapour deposition is achieved by lowering the time of the etch step.

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High Power Si Sidewall Heaters for Fluidic Applications Fabricated by Trench-Assisted Surface Channel Technology

Cited by 3 publications

References 8 publications

Heavily-Doped Bulk Silicon Sidewall Electrodes Embedded between Free-Hanging Microfluidic Channels by Modified Surface Channel Technology

Heavily-Doped Bulk Silicon Sidewall Electrodes Embedded between Free-Hanging Microfluidic Channels by Modified Surface Channel Technology

Sacrificial grid release technology: a versatile release concept for MEMS structures

Method for Keyhole-Free High-Aspect-Ratio Trench Refill by LPCVD

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