标题: 铜腐蚀抑制剂对铜保护机制在化学机械研磨之研究
tudies of copper inhibitor protecting mechanism against copper corrosion in chemical mechanical polishing
作者: 刘百崇
Lin, Pao-Chung
张翼
Chang, Edward
工学院半导体材料与制程设备学程
关键字: 铜化学研磨;苯并三唑;有机物残留;Cu CMP;BTA;organics residual
公开日期: 2012
摘要: 半导体制程在技术节点进入0.18m后,内连结金属就以铝材改为铜材,而多层金属内连节隔离层也改为低介电材料,化学机械研磨(Chemical-Mechanical Planarization,CMP)因而成为重要的制程之一。本论文研究酸性Cu 研磨液在铜与介电层研磨反应,而其主要以去离子水、氧化剂与抑制剂(Inhibitor)所组成。虽然高浓度的蚀刻抑制剂(Benzotriazole, BTA)可以在铜表面形成钝化层来帮助控制表面研磨,但是也会造成在晶圆表面产生有机物残留而形成缺陷。本研究便以化合物A(长链形酮基化合物)来减少BTA浓度,却仍具有铜钝化层效用,进而减少有机物残留与控制铜研磨率等问题。
本文以不同浓度的BTA与化合物A混合,分别对铜导电层与介电层作研磨,得到铜与介电层的研磨率与研磨选择比。并且利用电化学方式来验证铜在研磨液中的氧化反应机制,最后再对研磨后的晶圆做缺陷测量。综合研磨率、缺陷测量与电化学反应等方式去证化合物A在酸性Cu CMP研磨液作用机制是否达到预期研磨效果与有机物残留减量。
实验结果显示,化合物A确实可以减少BTA使用量,铜金属表面藉由BTA与化合物A形成钝化层保护,减少氧化剂、研磨粒子与异物对铜表面反应与刮伤。介电层表面属疏水性,化合物A直接黏着在介电层表面,形成钝化保护层,来提高研磨选择比,可以调整铜与介电材料的平坦化效果。提高酸性清洁液浓度虽可达到较好的有机物清除效果,但也会造成铜表面的粗糙度变差,化合物A的添加可以减少了有机物数量,也不需提高酸性清洁液浓度清除有机物。
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.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT079975517
http://hdl.handle.net/11536/72004
显示于类别:Thesis