Cu CMP工艺对薄膜介电常数的影响机制

Influence Mechanism of Cu CMP Process on Dielectric Film k Value

研究了使用不同研磨液的Cu CMP工艺对超低介电常数(ULK)薄膜介电常数k值的影响。实验结果表明经过Cu CMP工艺,ULK薄膜的介电常数k均有不同程度的增加。XPS成分分析结果表明,ULK薄膜表面C含量的增加是造成介电常数k值升高的主要原因。这主要是由于CMP工艺中,化学品溶液进入多孔的ULK薄膜。而退火工艺可以使得化学品挥发,从而使ULK薄膜表面C含量降低,由此介电常数k基本上得以恢复。初步建立了Cu CMP工艺对介电常数k影响的物理模型。根据模型计算的k结果为2.75,与实测值2.8基本符合。

The effects of Cu CMP process with different slurries on the dielectric constant k value of the ultra low-k film were studied. The results show that after the Cu CMP process ULK film k value increases. And XPS analysis results indicate that the chemical solution entering porous ULK film surface during the CMP causes C content increasing,which is the main root cause of k value increasing. However annealing can evaporate the invaded chemicals,so that C content is decreased in ULK film surface and the k value is restored. One model was setup to evaluate k value shift after Cu CMP process. Calculation results show that k value is 2. 75,in good agreement with the measured vaule of 2. 8.