本三年期計畫首先將以實驗方式取得Cu(或Ni)墊層固溶在SnAg微銲點的動力學參數(速率常數，活化能等等)。研究的主要條件為:在四種不同Ag添加之SnAg銲料(純Sn，Sn1Ag，Sn2Ag，Sn3Ag，Sn4Ag)，以及不同Cu(或Ni)和SnAg銲料體積的比值(1×10-6、1×10-4、1×10-2以及1)下，探討具不同晶格優選方向之Cu(或Ni)墊層於SnAg銲料固溶行為研究。得到上述Cu(或Ni)固溶SnAg銲料動力學成果之後，可進一步探討，在電遷移下，具不同晶格優選方向之Cu(或Ni)墊層固溶至不同微量Ag添加之SnAg銲料中的動力學行為。配合先前單純熱處理下Cu(或Ni)墊層固溶於SnAg銲料的動力學參數，可以計算出(1)Cu(或Ni)固溶通量(JCu,diss.)和(2)溶解於SnAg銲料中之Cu(或Ni)原子受電遷移作用力而誘發之Cu(或Ni)原子通量(JCu,EM)大小。取得這兩個Cu(或Ni)通量值之後，根據先前本實驗的研究，我們可以有系統的分別建立Cu/SnAg/Cu和Ni/SnAg/Ni覆晶結構的電遷移失效地圖(EM failure map)。此電遷移失效的地圖可以預測在不同操作溫度和電流密度下，產生何種電遷移失效模式(孔洞或金屬墊層消耗)。並且可以幫助最佳的金屬銲墊(晶格優選方向)和銲料(Ag的添加量)的選用，提昇覆晶封裝中微銲料接點的電遷移可靠度。 ;Nowadays, reliability issues are become more important for flip-chip package and 3D IC package due to the size shrinkage of the solder joint. We find that the dissolution of the Cu-pad is the major reason which makes the reliability issues become more important. According to our previous study, we realize that the electro-migration resistance of the solder joint can be improved by doping Ag into lead-free solders. In order to study the cathode Cu-pad dissolution under EM test in detail, we deign an experiment to study the Cu-pad dissolution without electro-migration. However, we find that the Cu-pad dissolution rate is faster in Sn(Ag) solder than in pure Sn solder. Thus, we consider that the details of the Cu-pad dissolution mechanism should be studied more carefully with the pitch size of solder bumps become smaller and smaller. And also the effect of Ag in the Sn(Ag) that affect the dissolution mechanism of Cu. According to the importance of Ni as a good diffusion barrier, we should also consider the dissolution mechanism of Ni into the solder. In this proposed three-years project, we will first study on the mechanism of Cu-pad dissolution into the small pitch size of bump. Also, study the Cu dissolution mechanism with different preferred-oriented Cu-pad. And the effect of different Ag content of lead-free solders on the Cu dissolution mechanism. In addition, we study how does the size shrinkage (different ratio of Cu-pad/solder volume: 1×10-6, 1×10-4, 1×10-2, and 1) affect the mechanism of Cu-pad dissolution. Finally, the EM effect on the Cu (or Ni) dissolved into different Ag-doped solders. The final goal is to build an EM failure map for the micro-flip-chip SnAg solder joints, which can be used to enhance the reliability of flip-chip solder joints.
