エッチング液中の溶解金属によるケイ素ダイオード表面の汚染

抄録

The metal contamination of silicon surface during the acid etching process of silicon diodes equipped with electrodes has been studied by ion microanalyzer(IMA). Silicon diode devices consist of silicon pellets soldered by aluminium, tungsten electrodes and copper lead wires. Both aluminium and copper become dissolved in HF-HNO₃, etchant. The analysis by IMA indicated that copper only deposited on the silicon surface and selectively on the n⁺ layer at the junction. Potentials in the HF-HNO₃ etchant were measured on constituent materials in devices. Copper had a higher potential than silicon and the n⁺ layer indicated the lowest potential in the silicon surface of diode. It is concluded that copper in the etchants deposits selectively on the n⁺ layer having the lowest potential in the silicon surface.