A procedure to measure the bulk lifetime (>100 µsec) of silicon wafers by temporarily attaining a very high level of surface passivation when immersing the wafers in hydrofluoric acid (HF) is presented. By this procedure three critical steps are required to attain the bulk lifetime. Firstly, prior to immersing silicon wafers into HF, they are chemically cleaned and subsequently etched in 25% tetramethylammonium hydroxide. Secondly, the chemically treated wafers are then placed into a large plastic container filled with a mixture of HF and hydrochloric acid, and then centered over an inductive coil for photoconductance (PC) measurements. Thirdly, to inhibit surface recombination and measure the bulk lifetime, the wafers are illuminated at 0.2 suns for 1 min using a halogen lamp, the illumination is switched off, and a PC measurement is immediately taken. By this procedure, the characteristics of bulk silicon defects can be accurately determined. Furthermore, it is anticipated that a sensitive RT surface passivation technique will be imperative for examining bulk silicon defects when their concentration is low (<1012 cm-3).
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机译:提出了一种通过在将硅片浸入氢氟酸(HF)中时暂时获得很高水平的表面钝化来测量硅片的总体寿命(> 100微秒)的方法。通过该程序,需要三个关键步骤来达到整体寿命。首先,在将硅晶片浸入HF中之前,先对其进行化学清洗,然后在25%的四甲基氢氧化铵中进行蚀刻。其次,将经过化学处理的晶圆放入装有HF和盐酸混合物的大塑料容器中,然后将其放在感应线圈上以进行光电导(PC)测量。第三,为了抑制表面重组并测量整体寿命,使用卤素灯在0.2太阳下照射晶片1分钟,关闭照明,并立即进行PC测量。通过该程序,可以准确地确定体硅缺陷的特性。此外,可以预期的是,当大块硅缺陷的浓度低(<10 12 sup> cm -3 sup>)时,必须使用灵敏的RT表面钝化技术进行检查。
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