多孔性矽的形成研究

Abstract

本論文主要研究多孔性矽的形成及成長特性﹐並籍著對多孔性矽的了解而 研製出濕度的感測器。我們首先研究電流密度及氫氟酸濃度對多孔性矽的 成長速度及多孔性的影響。我們發現電流密度及氫氟酸濃度均對多孔矽的 成長速度產生影響﹔而多孔矽的多孔性的主要影響因素則只是氫氟酸濃度 。在高濃度的氫氟酸下電流密度對多孔性的影響很小﹐只有在低濃度的氫 氟酸下電流密度才會對多孔性產生影響。最後﹐我們利用選擇性成長多孔 矽的製程方法研製出以鋁為金屬電極的交互指狀的濕度感測器。我們將感 測器放在一台多功能及可程式的恆溫恆濕箱內﹐量測它在定電壓下之電流 反應﹐我們量得它的電流反應從濕度15%到90%之間大約有三個階數 (1000倍)的變化。 In this thesis, the growth and the characteristics of porous silicon are studied for the development of humidity sensors. The aim is to gain a better understanding on the physical characteristics and the formation process of porous silicon. An RH sensor has been fabricated with an interdigital aluminum contact on the selectively electrochemical anodization porous silicon area. The increase of current response measured in a multi-function & programmable temperature/humidity chamber is about 3 orders high in magnitude while the humidity changes from 15 to 90 %. The formation rate and the porosity of porous silicon have been investigated. It is found that the HF concentration plays a main role in determining the porosity of silicon, also the formation rate is affected by the current density and the HF concentration.