tudies of copper inhibitor protecting mechanism against copper corrosion in chemical mechanical polishing
|關鍵字:||銅化學研磨;苯並三唑;有機物殘留;Cu CMP;BTA;organics residual|
|摘要:||半導體製程在技術節點進入0.18m後，內連結金屬就以鋁材改為銅材，而多層金屬內連節隔離層也改為低介電材料，化學機械研磨(Chemical-Mechanical Planarization，CMP)因而成為重要的製程之一。本論文研究酸性Cu 研磨液在銅與介電層研磨反應，而其主要以去離子水、氧化劑與抑制劑(Inhibitor)所組成。雖然高濃度的蝕刻抑制劑(Benzotriazole, BTA)可以在銅表面形成鈍化層來幫助控制表面研磨，但是也會造成在晶圓表面產生有機物殘留而形成缺陷。本研究便以化合物A(長鏈形酮基化合物)來減少BTA濃度，卻仍具有銅鈍化層效用，進而減少有機物殘留與控制銅研磨率等問題。
When the technology node of semiconductor evolved to below 0.18um, the interconnect metal and dielectric materials were replace by copper (Cu) and low K dielectrics respeetwely. Chemical-mechanical planarization (CMP) hence becomes one of the key processes in manufactory flow of semiconductor. This study focuses on the improvement of Cu CMP defects induced by the acidic CMP slurry. The typical alkaline CMP slurry contains DI water, oxidizer and inhibitor (benzotriazole, BTA). Although high concentration of BTA inhibitor may protect Cu film and suppress Cu reacting rate, it also induces organic residues on the Cu surface. By introducing new additive A, the usage of BTA inhibitor can be effectively decrease without sacrificing the benefits and performance of Cu CMP slurry. In this study, CMP slurry solutions containing various contents of additive A are prepared and they are applied to CMP process to analyze their removal rates and selectivities. Electrochemistry was adopted to investigate the oxidization reaction of Cu in CMP slurry. Finally, all the polished wafers in this study were examined and made a comprehensive review to understand whether additive A is capable of polishing performance improvement. The experimental results, indicated that additive A can reduce the usage of BTA. Cu surface can be passivated by BTA and additive A, reducing surface reaction by oxidants and scratches caused by abrasives. The dielectric surface, which is hydrophobic, could be covered by additive A. The selectivity could be controlled by the passivation of additive A to enhance the planarization performance. Although using high concentration clean agent can provide better clean efficiency for organics, it can also induce worse roughness of Cu surface. The addition of component A reduces the usage of organics, which also indicates that it is unnecessary to use a high concentration clean agent to remove the organics.