Usage of Porous Al2O3 Layers for RH Sensing

TL;DR

This paper presents a CMOS-compatible capacitive relative humidity sensor utilizing porous Al2O3 layers, demonstrating how fabrication parameters influence pore structure and sensor sensitivity.

Contribution

It introduces a novel porous Al2O3-based RH sensor with detailed analysis of how manufacturing parameters affect its porous structure and performance.

Findings

Porous Al2O3 layers enhance sensor sensitivity.

Technological parameters significantly influence pore size and distribution.

The developed sensor is cost-effective and compatible with CMOS processes.

Abstract

At the Department of Electron Devices a cheap, more or less CMOS process compatible capacitive type RH sensor has been developed. Capacitive sensors are based on dielectric property changes of thin films upon water vapour uptake which depends on the surrounding media's relative humidity content. Because of the immense surface-to-volume ratio and the abundant void fraction, very high sensitivities can be obtained with porous ceramics. One of the ceramics to be used is porous Al2O3, obtained by electrochemical oxidation of aluminium under anodic bias. The average pore sizes are between 6...9 nm. In our paper we intend to demonstrate images representing the influence of the technological parameters on the porous structure and the device sensitivity.