Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication

Kluba, Marta Maria; Li, Jian; Parkkinen, Katja; Louwerse, Marcus; Snijder, Jaap; Dekker, Ronald

doi:10.3390/mi12040414

Open AccessArticle

Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication

by

Marta Maria Kluba

¹,

Jian Li

^1,*

,

Katja Parkkinen

²,

Marcus Louwerse

³,

Jaap Snijder

³ and

Ronald Dekker

^1,4,*

¹

The Electronic Components, Technology and Materials (ECTM) Group, Delft University of Technology, Mekelweg 5, 2628 CD Delft, The Netherlands

²

Research and Development, Technology, Okmetic Oy, Piitie 2, FI-01510 Vantaa, Finland

³

MEMS & Micro Devices, Philips, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands

⁴

Philips Research, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands

^*

Authors to whom correspondence should be addressed.

Micromachines 2021, 12(4), 414; https://doi.org/10.3390/mi12040414

Submission received: 11 March 2021 / Revised: 2 April 2021 / Accepted: 6 April 2021 / Published: 8 April 2021

(This article belongs to the Special Issue Emerging Micro Manufacturing Technologies and Applications)

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Abstract

Several Silicon on Insulator (SOI) wafer manufacturers are now offering products with customer-defined cavities etched in the handle wafer, which significantly simplifies the fabrication of MEMS devices such as pressure sensors. This paper presents a novel cavity buried oxide (BOX) SOI substrate (cavity-BOX) that contains a patterned BOX layer. The patterned BOX can form a buried microchannels network, or serve as a stop layer and a buried hard-etch mask, to accurately pattern the device layer while etching it from the backside of the wafer using the cleanroom microfabrication compatible tools and methods. The use of the cavity-BOX as a buried hard-etch mask is demonstrated by applying it for the fabrication of a deep brain stimulation (DBS) demonstrator. The demonstrator consists of a large flexible area and precisely defined 80 µm-thick silicon islands wrapped into a 1.4 mm diameter cylinder. With cavity-BOX, the process of thinning and separating the silicon islands was largely simplified and became more robust. This test case illustrates how cavity-BOX wafers can advance the fabrication of various MEMS devices, especially those with complex geometry and added functionality, by enabling more design freedom and easing the optimization of the fabrication process.

Keywords: SOI substrate; cavity-SOI; cavity-BOX; patterned BOX; buried hard-etch mask; flex to rigid (F2R); MEMS; miniaturization; DBS; foldable devices

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MDPI and ACS Style

Kluba, M.M.; Li, J.; Parkkinen, K.; Louwerse, M.; Snijder, J.; Dekker, R. Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication. Micromachines 2021, 12, 414. https://doi.org/10.3390/mi12040414

AMA Style

Kluba MM, Li J, Parkkinen K, Louwerse M, Snijder J, Dekker R. Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication. Micromachines. 2021; 12(4):414. https://doi.org/10.3390/mi12040414

Chicago/Turabian Style

Kluba, Marta Maria, Jian Li, Katja Parkkinen, Marcus Louwerse, Jaap Snijder, and Ronald Dekker. 2021. "Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication" Micromachines 12, no. 4: 414. https://doi.org/10.3390/mi12040414

APA Style

Kluba, M. M., Li, J., Parkkinen, K., Louwerse, M., Snijder, J., & Dekker, R. (2021). Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication. Micromachines, 12(4), 414. https://doi.org/10.3390/mi12040414

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Cavity-BOX SOI: Advanced Silicon Substrate with Pre-Patterned BOX for Monolithic MEMS Fabrication

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