氧化銦錫的蝕刻及離子蝕刻對氧化銦錫/矽異質接面電性的影響

Abstract

以射頻磁控濺鍍法製備氧化銦錫於未加熱的基板上, 探討在不同氧分壓的 濺鍍條件下氧化銦錫的蝕刻特性及矽基材的表面處理對氧化銦錫/矽異質 接面電性的影響。 在氧百分比為1%的濺鍍條件下可得電阻率為3E-4Ω-cm 及在可見光區穿透率大於80%的氧化銦錫膜。氧化銦錫的蝕刻特性和蝕刻 液濃度、溫度、膜厚及在濺度中氧含量的多寡有關。在蝕刻氧化銦錫的過 程中有針孔產生, 且針孔區域逐漸擴大以致膜完全被蝕刻掉。當矽基板經 過離子蝕刻後,氧化銦錫/矽異質接面的電性對P-型矽而言, 將由電阻特性 變成整流接面; 對 N-型矽而言, 將由整流接面變成電阻特性。此現象歸 因於經離子蝕刻的矽表面上有淨正電荷的累積。 Indium tin oxide (ITO) films were deposited onto unheated substrates with r.f. magentron sputtering. The etching characteristics of ITO fimls deposited in various oxygen partial pressures in the sputtering ambient and the effect of the silicon surface treatment on the dark current-voltage characteristics of the ITO/Si heterojunction were investigated. The ITO films deposited at the ratio of oxygen partial pressure to the chamber pressure about 1% in the sputtering ambient have a resistivity of 3E-4Ω-cm and an average visible transmission above 80%. The etching characteristics of ITO films depend on etchant concentration, temperature, film thickness and oxygen partial pressure during sputtering. Pinholes are found during etching of ITO film, and the ITO film will be etched off fully by linking the pinholes. When the silicon substrates are sputter-cleaned by argon ion prior to the deposition of ITO film, the current- voltage characteristics of ITO/Si heterojunction change from ohmic contact to rectifying junction for p-type Si and from rectifying junction to ohmic contact for n-type Si. This result is attributed to the net positive charge accumulation on the damaged silicon surface.