Evaluation of Mechanical Strength and Bondability of BOAC (Bond Pad over Active Circuits) Structures using Nanoindentation

利用奈米壓痕儀量測BOAC (Bond Pad Over Active Circuits)結構的機械強度和接合性

10.6409/JMSE.200612.0187

湯季高(C.K. Tang)；吳炳昌(B.C. Wu)；饒瑞孟(Raymond Jao)；陳國明(K.M. Chen)；呂志鵬(Jihperng Leu)

BOAC ； 奈米壓痕儀 ； 彈性模數 ； 打線接合wire bond ； BOAC ； nanoindentation ； modulus ； wire bonding

材料科學與工程

38卷4期（2006 / 12 / 01）

187 - 194

英文

在這篇研究中，我們成功的建立一套利用奈米壓痕儀量測BOAC銲墊下機械抵抗力的方法。測試的試片包括標準銲墊（其下無主動式電路元件）及兩種不同BOAC設計A、B。此外，我們也提出用以計算BOAC結構機械強度的雙層模式：上層爲鋁，下層則總括鋁銲墊下所有的金屬／絕緣層爲單一複合層。此篇主要在於探討此複合層的機械強度與打線接合時所造成的壓應力之關係。就標準銲墊、BOAC A及BOAC B而言、此複合層之彈性模數分別爲104 GPa、70 GPa、及74.5 GPa。此差異可歸因於BOAC結構中銅導線排列和密度不同性，其中標準銲墊具最高金屬密度及trench/via堆壘。在新的BOAC設計中，吾人推論其複合彈性模數至少應具70 GPa方可通過接合性的測試。

A novel methodology using nano-indentation has been successfully established to distinguish the mechanical resistance of the bond pads among a normal pad with full stack of trench/via dummification and two BOAC layouts with different metal arrangement in the top 2 layers. In addition, a two-layered model is proposed by treating the stack below A1 pad as a composite substrate consists of oxide/FSG-copper in M7 and copper-low-k in M1-6. The modulus of composite substrate for normal pad, BOAC A and BOAC B are 104 GPa, 70 GPa and 74.5 GPa, respectively. The difference can be attributed to metal arrangement and density in the top 2 layer below the A1 pad in different BOAC structures and additional mechanical support from M1-6 region. A modulus of 70 GPa in composite substrate of bond pad structure can be considered as a sufficient condition for new BOAC layouts meeting the bondability tests.