磷酸和酒石酸在GSI阻挡层CMP抛光液中的应用

在阻挡层的化学机械平坦化(CMP)过程中,Cu与阻挡层去除速率的一致性是保证平坦化的关键问题之一。低k介质材料的引入要求阻挡层在低压力下用弱碱性抛光液进行CMP,这给抛光液对不同材料的选择性提出了新的挑战。研究了低压2 psi,(1 psi=6.89 kPa)CMP条件下,磷酸和酒石酸作为阻挡层抛光液pH调节剂对Cu和Ta的络合作用。实验结果表明,酒石酸对Cu和Ta有一定的络合作用,能够提高它们的去除速率;磷酸能提高Ta的去除速率,而对Cu的去除有抑制作用。最终在加入磷酸浓度为2×10-2mol/L,酒石酸浓度为1×10-2mol/L,H2O2体积分数为0.3%,pH=8.5时,Cu/Ta/SiO2介质的去除速率选择比达到了1∶1∶1,去除速率约为58 nm/min;同时,磷酸和酒石酸的加入能够有效改善Cu的表面状态。

Phosphoric Acid and Tartaric Acid Applied in GSI Barrier Layer CMP Slurry

In the process of chemical mechanical planarization(CMP)of the barrier layer,guarantying the uniformity of removal rates of Cu and barrier layer is one of the key problems concerning planarization.The introduction of low-k dielectric materials required barrier layer CMP with weakly alkaline slurry at low down pressure and this raised a new challenge for slurry on the different materials selectivity.The complication of phosphoric acid and tartaric acid were studied which were as barrier layer slurry pH adjusting agents on copper and tantalum at low down pressure 2 psi(1 psi=6.89 kPa),CMP.The results of the experiment show that tartaric acid has certain complication on Cu and Ta,the phosphoric acid can accelerate the removal rate of Ta,but the phosphoric has inhibitory action to the removal of Cu.Eventually when adding phosphoric acid of 2×10-2 mol/L,tartaric acid of 1×10-2 mol / L,H2O2 0.3%,pH=8.5,the removal rate selection ratio of Cu/Ta/SiO2 reaches 1∶1∶1 and the removal rate is about 58 nm/min.At the same time,the addition of phosphoric acid and tartaric acid can improve the surface state of Cu.