A modular and generic monolithic integrated MEMS fabrication process

Mónico Linares Aranda,C.R Báez Álvarez,W Calleja Arriaga,A Torres Jacome

doi:10.47566/2017_syv30_1-030030

Mónico Linares Aranda, C.R Báez Álvarez + Show 2 more

Open Access

https://doi.org/10.47566/2017_syv30_1-030030

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Abstract

A modular and generic, monolithic integrated MEMS fabrication process is presented to integrate microelectronics (CMOS) with mechanical microstructures (MEMS). The proposed monolithic integrated fabrication process is designed using an intra-CMOS approach (to fabricate the mechanical microstructures into trenches without the need of planarization techniques) and a CMOS module (to fabricate the electronic devices) with a 3 ?m length as minimum feature. The microstructures module is made up to three polysilicon layers, and aluminum as electrical interconnecting material. From simulation results, using the SILVACO® suite (Athena and Atlas frameworks), no significant degradation on the CMOS performance devices was observed after MEMS manufacturing stage; however, the thermal budget of the modules plays a crucial role, because it set the conditions for obtaining the complete set of devices fabricated near their optimal point. Finally, to evaluate and to support the development of the proposed integrated MEMS process, a modular test chip that includes electrical test structures, mechanical test structures, interconnection reliability test structures and functional micro-actuators, was also designed.

Highlights

The mechanical microstructures (MEMS) (Micro-Electro-Mechanical Systems) acronym is commonly used to describe mechanical structures of micrometric dimensions performing an electronically controlled preset function [1]
The MEMS offered by manufacturers usually consist of sensors and/or actuators that are separately fabricated and bring to interaction with electronic circuitry; such hybrid systems show many functional drawbacks mainly due to external wiring [2]
Each one of these approaches includes a set of fabrication steps to fulfill the desired requirements of an integrated MEMS process

Summary

Introduction

The MEMS (Micro-Electro-Mechanical Systems) acronym is commonly used to describe mechanical structures of micrometric dimensions performing an electronically controlled preset function [1]. According to the nature of the microcomponents, the full potential of MEMS products has been possible only by its proper integration with a specific conditioning electronic circuit In this sense, nowadays MEMS designers are facing different possibilities for integrating a monolithic system (combining sensors/actuators and electronic devices on a single substrate) based on the careful selection of both modules: micro-structures/components and CMOS circuits [2]. Some studies consider that a half of all existing MEMS categories are fabricated using a monolithic integration approach, some examples are print-heads, accelerometers, and recently frequency control [3,4] devices. The monolithic integration approach presented in this work will be developed considering a polysilicon surface micromachining module and a CMOS module, whose integration is designed considering 10 - 20 Ω - cm (~ 5 × 1014 cm-3), p-type, 6-inch diameter, (0 0 1), silicon wafers

Microstructures Module

A Monolithically Integrated MEMS Technology

Conclusions