柠檬酸钾对铜、钴和TEOS去除速率及选择性的影响

Effect of potassium citrate on the removal rate and selectivity of copper,cobalt and TEOS

针对钴阻挡层化学机械抛光(CMP)中,Cu、Co、TEOS等多种异质材料去除速率选择性差,采用络合剂柠檬酸钾配制多层铜布线钴阻挡层抛光液,研究了柠檬酸钾含量对Cu、Co、TEOS去除速率及选择性的影响,并在钴阻挡层图形片上进行了平坦化验证。结果表明,柠檬酸钾能够有效地提高Cu、Co、TEOS三者的去除速率,当磨料为5%(质量分数),H 2O_(2)为5 mL/L,TT-LTK为0.5 mL/L,柠檬酸钾为30 mmol/L,pH=10时,铜、钴、TEOS的去除速率分别达到216,530,493/min。此时,Co与Cu和TEOS与Cu的去除速率选择比较高,可达V_(Cu)∶V_(Co)∶V_(TEOS)≈1∶2.45∶2.28,碟形坑和蚀坑的深度得到有效降低,铜钴晶圆表面粗糙度得到明显改善。

Aiming at the problem of poor selectivity in the removal rate of Cu,Co,TEOS various heterogeneous materials in the chemical mechanical polishing(CMP)of cobalt barrier layer,the potassium citrate as the complex agent was used to prepare the slurry for the cobalt barrier layer of multi-layer copper wiring.The effect of potassium citrate on the removal rate and selectivity of Cu,Co and TEOS was studied,and the planarization efficacy of the slurry was verified using patterned wafers with Co barrier layers.The results showed that potassium citrate can increase the removal rate of Cu,Co and TEOS effectively.When the abrasive was 5%,H 2O_(2)was 5 mL/L,TT-LTK was 0.5 mL/L,potassium citrate was 30 mmol/L,and pH=10,the removal rates of copper,cobalt and TEOS were 216,530,493/min respectively.The removal selectivity of Co∶Cu and TEOS∶Cu was comparatively higher and closed to V_(Cu)∶V_(Co)∶V_(TEOS)≈1∶2.45∶2.28,which reduced the depth of dishing and erosion pits and improved the surface morphology of the copper-cobalt wafer.