Lillis Brian, Jungk Cornelia, Iacopino Daniela, Whelton Andrew, Hurley Eileen, Sheehan Michelle M, Splinter Alexandra, Quinn Aidan, Redmond Gareth, Lane William A, Mathewson Alan, Berney Helen
NMRC, Lee Maltings, Prospect Row, Cork, Ireland.
Biosens Bioelectron. 2005 Aug 15;21(2):282-92. doi: 10.1016/j.bios.2004.09.031. Epub 2004 Nov 26.
An investigation of the fabrication of microporous silicon (MPS) layers as a material for the development of an electrolyte insulator semiconductor (EIS) capacitance sensor has been performed. The goal was to create a high surface area substrate for the immobilisation of biorecognition elements. Structural analysis of MPS layers as a function of key etch parameters, namely implant type (p or n), implant dose, hydrofluoric acid (HF) etch concentration and current density has been performed using scanning electron microscopy (SEM). It was possible to image porous layers with average pore diameter as low as 4 nm. n-type silicon samples had larger pore networks than p-type samples and reducing the silicon resistivity led to a reduction in the pores per microm2. It was found that increasing the HF etch concentration reduced the average pore diameter and increased the pores per microm2. Increasing the current density at which the etch was performed has the same effect. Understanding the effect of these parameters allows the MPS layer to be tuned to match specifications for optimum biocapacity. Different MPS layers were electrically characterised using capacitance-voltage and capacitance-frequency sweeps, in order to determine the effect of porosity on increases in surface area. The measured capacitance increased with increasing pores per microm2. p-type silicon with a boron implant in the back of the wafer, which had been etched in 25% HF in ethanol at a current density of 75 mA/cm2 yielded the highest capacitance signal per unit area. The effect of porosity and pore size on the biocapacity of the samples was also determined. For avidin immobilisation, with pores sizes above 5 nm, as the porosity increased the biocapacity increased. MPS fabricated in p-type silicon with a front and back implant etched in 25% HF at a current density of 25 mA/cm2 was used for the capacitance detection of synthetic oligonucleotides.
已开展一项关于制备微孔硅（MPS）层作为电解质绝缘体半导体（EIS）电容传感器开发材料的研究。目标是创建一个用于固定生物识别元件的高表面积基板。使用扫描电子显微镜（SEM）对MPS层作为关键蚀刻参数（即注入类型（p型或n型）、注入剂量、氢氟酸（HF）蚀刻浓度和电流密度）的函数进行了结构分析。可以对平均孔径低至4nm的多孔层进行成像。n型硅样品的孔网络比p型样品的大，降低硅电阻率会导致每平方微米的孔数减少。发现增加HF蚀刻浓度会减小平均孔径并增加每平方微米的孔数。增加蚀刻时的电流密度也有相同效果。了解这些参数的影响可以调整MPS层以匹配最佳生物容量的规格。使用电容 - 电压和电容 - 频率扫描对不同的MPS层进行电学表征，以确定孔隙率对表面积增加的影响。测得的电容随着每平方微米孔数的增加而增加。在晶圆背面进行硼注入的p型硅，在75mA/cm²的电流密度下于25%的乙醇HF溶液中蚀刻，每单位面积产生最高的电容信号。还确定了孔隙率和孔径对样品生物容量的影响。对于抗生物素蛋白固定，当孔径大于5nm时，随着孔隙率增加生物容量增加。在前后都有注入的p型硅中制备的MPS，在25mA/cm²的电流密度下于25%的HF溶液中蚀刻，用于合成寡核苷酸的电容检测。
