熱處理對鍍錫銅線路抗遷移性之影響

Effect of Heat Treatment on the Migration of Sn-coated Copper Circuits

本研究在探討熱處理對鍍錫銅線路的電解質遷移之影響。銅線路表面電鍍1、2及3µm 錫後，分別在蒸餾水及0.01M (NH4)2SO4水溶液中，施以5V偏壓，進行遷移研究。結果顯示：銅線路表面經鍍1µm厚之錫，雖在蒸餾水及0.01M (NH4)2SO4水溶液中不能抵抗遷移現象。但將鍍1µm錫之銅導線在250℃持溫300秒後，立即具良好抗遷移性，顯然鍍錫銅導線因熱處理而增強其抗遷移性。為了解鍍錫銅線路之電解質遷移原因，在0.01M (NH4)2SO4水溶液中進行電化學陽極極化分析。配合ESCA表面分析，得知：經熱處理後之錫鍍層在銅線路表面因陽極鈍化而生成SnO2保護膜，可以抑制底層銅的溶解及氧化。

Effect of heat treatment on the migration of Sn-coated copper circuits has been studied. Sn-coated in thickness of 1 2 and 3 µm copper circuits, before and after heat treatment have been immersed in distilled water and 0.01M (NH4)2SO4 solution at a bias of 5V to access their resistance to copper electrolytic migration. It was found that the resistance to migration is not sufficient for the Sn-coated copper circuits. In contrast, the migration is completely inhibited in the case heat-treated (at 250℃ for 300s) Sn-coated copper circuits, even through the thickness of the Sn-coat is only at 1 µm. Electrochemical methods such as potentiodynamic and potentiostatic polarization were conducted to delineate the mechanism of migration inhibition. ESCA analysis indicates that the reaction product SnO2 produced on the surface of anodic is responsible for anodic passivation, thus inhibiting the migration in the heat-treated Sn-coated copper circuits.