雖然有機硫化物已被廣泛用於銅的電鍍製成，促進了銅在半導體芯片中深溝槽和空隙的超填充，它們對銅沉積有重要的影響但它們的角色有時難以了解。本研究採用伏安法，旋轉環盤電極和掃描式穿隧電子顯微鏡（STM）檢測在巰基乙酸（MAA）和巰基丙酸（MPA）預修飾的鉑電極上的銅沉積。儘管這些分子在其結構中僅相差一個-CH2單元，但實驗獲得的結果顯示這兩種化合物以非常不同的方式影響銅沉積。在含有0.1M硫酸銅的0.1M硫酸電解液中進行的循環伏安實驗，MAA修飾後鉑電極比裸露及MPA修飾的鉑電極，對於銅的沉積提升了20和40％，這代表著兩種有趣的發現。首先，硫醇分子雖然和鉑載體具有強的Pt-S鍵結，但這不一定會妨礙銅沉積。其次，分子結構的微小差異可導致在銅沉積上非常不同的結果。STM成像顯示這些添加劑從鉑基底到銅沉積物的轉置速度非常不同，MAA只需幾分鐘，但MPA需要2小時以上。這種顯著的對比源於吸附之MAA、MPA分子具明顯的分子間相互作用的差異。推測因MPA分子間的氫鍵，可以形成一較為剛性的薄膜，造成銅原子沉積的障礙，進而減低鍍銅效率。此外也將採用2-巰基乙磺酸鈉（MESNA）及3-巰基丙磺酸鈉（MPS）來作為預修飾劑，它們的末端官能基為磺酸根，在前述的條件中，兩者都展現比未修飾鉑電極有加速銅沉積的效果。因此，硫醇分子的碳鏈長度及末端官能基結構，都對銅電鍍還原有顯著的影響。;Despite organosulfur compounds have been used extensively in the modern electrodeposition bath of copper, facilitating Cu superfilling in deep trenches and voids present in the electric circuitry in semiconductor chip, their effects on Cu deposition are important and yet elusive issues. This study employing voltammetry, rotating ring disk electrodes, and scanning tunneling microscopy（STM）to examine of Cu deposition on Pt（111）electrode pre-modified with mercaptoacetic（MAA）and mercaptopropanic acids（MPA）. Although these molecules differ by only one –CH2 unit in their structures, obtained results indicate that these two compounds affect Cu deposition very differently. Cyclic voltammetry conducted in 0.1 M sulfuric acid and 0.1 M CuSO4 shows that MAA-modified Pt（111）electrode results in 20 and 40% more Cu deposit than bare and MPA-modified Pt（111）electrodes in potentiodynamic experiments. This finding is surprising in twofold. First, the strong Pt-S bonding strength does not necessarily impede Cu deposition. Second, a slight difference in molecular structure can lead to very different results on Cu deposition. STM imaging reveals that segregation speeds of these modifiers from the Pt substrate onto the Cu deposit are very different. It takes only a few min for MAA, but more than 2 hrs for MPA, to segregate onto the Cu deposit. This contrast stems from the disparity in intermolecular interactions; MPA can form a more rigid molecular film than MAA, despite they both have –COOH as the terminal group. This rigidity can hold back the incorporation of Cu adatoms in the interface of Pt（111）. In addition, sodium 2-mercaptoethanesulfonate（MESNA）and sodium 3-mercaptopropanesulfonate（MPS） are used as the pre-modifiers to explore the effect of terminal functional groups on copper electroplating efficicency.
