Local anodization of silicon as a step for electrical isolation process

• Published in: IOP conference series. Materials Science and Engineering Vol. 13; no. 1; pp. 012026 - 5
• Main Authors: Gharbi, A, Souifi, A, Remaki, B
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2010
• Subjects: Anodic; Anodizing; Charge exchange; Current voltage characteristics; Doping; Formations; Hydrofluoric acid; Origins; Porous silicon; Selectivity; Silicon; Silicon wafers; Thermionic emission; Volt-ampere characteristics
• ISSN: 1757-899X; 1757-8981; 1757-899X
• DOI: 10.1088/1757-899X/13/1/012026

The selective formation property of porous silicon PS is presented which is a basis step for the local electrical isolation process. In fact, when a silicon wafer of different doping concentration regions is anodized at a fixed potential, the dissolution current will be more important in the higher doping level regions where PS formation can only take place. The analysis of anodic current-voltage I-V characteristics of p-type silicon in the conditions corresponding to porous silicon formation shows a potential shift in the I-V characteristics with the silicon doping concentration which can explain the selectivity of PS formation towards the doping level of silicon. In addition, it is noticed that the mechanism at the origin of PS formation on p-type silicon in concentrated hydrofluoric acid solution is determined by the charge exchange at the silicon surface over a Schottky barrier which is formed at the interface through a thermionic emission process.