Single step fabrication of Silicon resistors on SOI substrate used as Thermistors

Serena Rollo,Wouter Olthuis,Dipti Rani,César Pascual García

doi:10.1038/s41598-019-38753-x

Serena Rollo, Wouter Olthuis + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-38753-x

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Abstract

Temperature sensing is one of the important features of Micro Electro Mechanical Systems and a monolithic integration provides advantages for both fabrication simplicity and performance. The use of Silicon On Insulator substrates allows simple fabrication of integrated wires that can be used as thermistors. We fabricated rectangular and triangular silicon wires with different dimensions in a single step fabrication process based on the wet etching of a <110> Silicon On Insulator substrate. We determined the experimental resistivity of the two kinds of devices and tested their performance as thermistors in a temperature range between 24 and 100 °C. The accuracy and normalized sensitivities of our devices were 0.4 °C and 0.3–0.5%/°C, respectively. The potential of the proposed method resides in the possibility of having devices with different shapes in a single straightforward process.

Highlights

Online and real-time measurements of temperature are fundamental for many applications in different domains ranging from bio-sensing, environment, electronics, etc.[1,2]
In this paper we present a single step fabrication process of silicon resistors with different shapes on a Silicon on Insulator (SOI) chip, following the study of the etching rates of tetramethylammonium hydroxide (TMAH) solutions on different crystallographic directions on the silicon device layer, to produce both triangular and rectangular devices
The anisotropic etching of Si is well understood[22,23,24,25] but a recipe to obtain different shapes in a single step process requires the calibration of the simultaneous etching rates depending on the plane orientation

Summary

Introduction

Online and real-time measurements of temperature are fundamental for many applications in different domains ranging from bio-sensing, environment, electronics, etc.[1,2]. The most often used options include thermocouples[3,4] and resistive thermometers (thermistors)[5,6], the later ones offering robust and cost-effective manufacturing with a considerably good stability and accuracy (reaching

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