氩离子溅射锡氧化物及焊料合金的光电子能谱探究

利用X射线光电子能谱(XPS)及深度剖析技术,定量研究了SnO和SnO₂在不同氩离子束能下化学损伤。0.5、1、2 keV的离子束能溅射后,SnO₂无明显化学损伤;而SnO则出现不同程度的还原,分别产生了7.0%、15.3%、20.6%的Sn单质。实验还表明,同离子束能不同电流下,Sn²⁺还原程度相差无几。因而利用XPS及深度剖析技术对Sn焊料进行表面分析时,须选用尽可能低的束能以减少化学损伤。定性讨论了Sn价带,4d和3d电子层的图谱特征,并确定了用Sn 3d5图谱进行Sn价态的定量分析。利用获得的Sn⁰、Sn²⁺、Sn⁴⁺图谱参数,以模拟波峰焊的锡铜焊料为例,定量分析了Sn价态随深度的变化,结果表明,氧化层最表面主要为SnO₂并逐步过渡到SnO。

X-ray photoelectron spectroscopy investigation of argon ion sputtered tin oxides and solder alloy

The chemical damages of stannic oxide (SnO₂) and stannous (SnO) oxide under various argon ion bombardment beam energies were quantitatively investigated by X-ray photoelectron spectroscopy (XPS) combined with the depth profile technique.After sputtered using the ion beam energies of 0.5, 1 and 2 keV, no obvious chemical damages on SnO₂ were observed. However,SnO was reduced in varying degrees,and 7.0%,15.3%,and 20.6% of elemental Sn were generated, respectively. The results also indicated that the reduction degree of Sn²⁺ was almost same at fixed ion beam energy but different current. Therefore, it would be better to use the lowest available beam energy to limit the chemical damage when profiling the tin oxide surface by XPS and depth profile technique. The spectra of Sn valence band, 4d and 3d core levels were also qualitatively discussed. The selection of Sn 3d5 spectrum for qualitative analysis of Sn valence was determined. The obtained spectral parameters of Sn⁰, Sn²⁺ and Sn⁴⁺ were used to quantitatively analyze the variation of Sn valence with the depth using the simulated wave-soldering tin-copper solder as an example. The results showed that the outmost surface was primarily dominated by SnO₂, and then altered to SnO gradually.