本研究以電流為驅動力，探討電子遷移效應對錫鬚晶的影響，藉以了解當線路轉彎或線寬大小改變時，其電流密度有一梯度分布之情況下，錫鬚的生長行為。 實驗的基材為P-type矽晶圓，先用濺鍍法置上一層1 um的銅薄膜，再利用微影蝕刻的方式定義出所需的線路圖形。接著再以化學鍍錫的方法將銅置換成錫，錫層的厚度為1 um。試片上有三種線寬的凹槽形狀線路，由小到大分別為50 um、100 um及200 um，電流密度比分別為4：2：1，其餘線路之線寬皆為200 um。操作條件共有兩種電流值及三種溫度。 實驗結果顯示，電流密度高的試片錫鬚生長數量較多於電流密度低的試片。並且在電流密度大的線路會最快生長錫鬚，而較小電流密度的線路則需較長的時間，才有機會看到錫鬚的生長。在相同電流密度下，溫度為50 ℃的試片較容易生長錫鬚，而30 ℃的試片錫鬚生長較慢，但在70 ℃之下，沒有看到錫鬚的生長。且錫鬚的生長皆發生於電流密度改變處，即轉彎角或線寬大小改變處。電流密度的大小及其分佈將會影響錫鬚的生長情形。 In this study, we used electric currents to provide the driving force and investigated the effect of electromigration on the tin whisker growth. By the result, we found that the distribution of current density will influence the behavior of whisker growth. The substrate used in this experiment was a p-type silicon wafer. Sputter was used to deposit a 1 um copper film on the substrate. Then the lithography process was applied to define copper circuits. Afterward, the immersion tin was used to exchange the copper for tin. The thickness of the tin film was 1 um. Three different widths of tin lines, 50 um, 100 um, and 200 um, were designed on our sample. The current density ratio of high to low was 4：2：1. Two different testing currents and three different temperatures were employed in this study. Tin whisker growth at high current density was more than the one at lower current density. The numbers of tin whiskers at 50 °C were more than that at 30 °C under stressing. Additionally, the tin whisker was not observed at 70 °C during current stress. Furthermore, whiskers were frequently observed on the locations where the current density changed, such as the corners or the junctions of different width lines. The distribution of the current density will decide the region of tin whisker occurred.
