新型阻挡层材料钌的研究进展北大核心

随着集成电路特征尺寸不断缩小到14 nm及以下,钌凭借其低的电阻率、对铜高的依附性而被考虑替代传统阻挡层材料Ta/TaN。但是,钌作为阻挡层材料依然存在很多问题,如低去除速率、容易引起铜的界面腐蚀、铜钌去除的不均匀性。针对以上问题,主要从三个方面介绍了近几年的研究进展。首先,介绍了氧化剂及络合剂对钌去除速率的影响;然后,总结了针对铜钌界面腐蚀问题的研究进展;最后,阐述了国内外解决铜钌去除速率选择性问题的研究进展。此外,提出未来新型阻挡层钌的抛光液的研究应综合解决上述问题,而非单一解决,才能真正应用于生产领域。     

非离子表面活性剂在钽基阻挡层CMP中的作用

碱性条件下,非离子型表面活性剂在阻挡层化学机械平坦化中起着重要的作用。分别对阻挡层材料Cu、Ta以及SiO₂介质进行抛光,然后测量铜表面粗糙度。对含有不同浓度活性剂的抛光液进行接触角和Zeta电位的测试,并对活性剂的作用机理进行分析。活性剂体积分数达到3%时,铜表面粗糙度可达0.679 nm,抛光液在铜膜表面的接触角低至10.25°,Zeta电位达到-50.2 mV。实验结果表明,活性剂在减小粗糙度的同时可提高抛光液的湿润性和稳定性,便于抛光后清洗和长时间放置。     

Synergetic effect of chelating agent and nonionic surfactant for benzotriazoleremoval on post Cu-CMP cleaning

The cleaning of copper interconnects after chemical mechanical planarization (CMP) process is a critical step in integrated circuits (ICs) fabrication. Benzotriazole (BTA), which is used as corrosion inhibitor in the copper CMP slurry, is the primary source for the formation of organic contaminants. The presence of BTA can degrade the electrical properties and reliability of ICs which needs to be removed by using an effective cleaning solution. In this paper, an alkaline cleaning solution was proposed. The alkaline cleaning solution studied in this work consists of a chelating agent and a nonionic surfactant. The removal of BTA was characterized by contact angle measurements and potentiodynamic polarization studies. The cleaning properties of the proposed cleaning solution on a 300 mm copper patterned wafer were also quantified, total defect counts after cleaning was studied, scanning electron microscopy (SEM) review was used to identify types of BTA to confirm the ability of cleaning solution for BTA removal. All the results reveal that the chelating agent can effectively remove the BTA residual, nonionic surfactant can further improve the performance.     

低压下碱性铜抛光液对300mm多层铜布线平坦化的研究

随着微电子技术进一步发展,低k介质的引入使得铜的化学机械平坦化(CMP)须在低压下进行。提出了一种新型碱性铜抛光液,其不含常用的腐蚀抑制剂,并研究了其在低压下抛光及平坦化性能。静态条件下,铜的腐蚀速率较低仅为2nm/min。在低压10.34kPa时,铜的平均去除速率可达633.3nm/min,片内非均匀性(WIWNU)为2.44%。平坦化效率较高,8层铜布线平坦化结果表明,60s即可消去约794.6nm的高低差,且抛光后表面粗糙度低(0.178nm),表面状态好,结果表明此抛光液可用于多层铜布线的平坦化。     

65nm多层铜布线的碱性化学机械平坦化工艺

主要研究了65 nm碱性铜布线的平坦化工艺。对不同尺寸铜线条进行抛光,讨论了抛光压力、抛光液流量和转速对平坦化的影响。结果表明,压力是影响平坦化的主要因素;分别改变压力、流量或转速时,窄线条的平坦化效果优于宽线条;平坦化效果随着压力的减小逐渐变好,即压力为1.0 psi(1 psi=6.895 kPa)时,平坦化效果最好;抛光液流量在300 mL/min时,化学反应和机械作用都达到饱和,平坦化效果最佳;平坦化效果随着转速的提高逐渐变好,转速在100 r/min时,保证了质量传递效率,所有铜线条都达到了最好的平坦化。     

化学机械抛光制程中铜抛光液平坦化能力的评估

The evaluation methods of planarization capability of copper slurry are investigated.Planarization capability and material removal rate are the most essential properties of slurry.The goal of chemical mechanical polishing(CMP) is to achieve a flat and smooth surface.Planarization capability is the elimination capability of the step height on the copper pattern wafer surface,and reflects the passivation capability of the slurry to a certain extent.Through analyzing the planarization mechanism of the CMP process and experimental results,the planarization capability of the slurry can be evaluated by the following five aspects:pressure sensitivity,temperature sensitivity,static etch rate,planarization efficiency and saturation properties.     

碱性抛光液中H_2O_2对铜布线CMP的影响

化学机械平坦化(CMP)过程中,抛光液的化学作用对平坦化效果起着不可替代的作用。介绍了碱性抛光液中氧化剂(H2O2)对铜布线CMP的作用:H2O2对铜的强氧化性可以将铜氧化为离子状态,然后在螯合剂的螯合作用下快速去除铜膜;H2O2对铜的钝化作用可以保护凹处铜膜不被快速去除,从而有效降低高低差。此外,还研究了碱性抛光液中不同H2O2浓度对铜的静态腐蚀速率、动态去除速率及铜布线平坦化结果的影响。研究表明:抛光液对铜的静态腐蚀速率随H2O2浓度的增大逐渐降低然后趋于饱和;铜的动态去除速率随H2O2浓度的增大而逐渐降低;抛光液的平坦化能力随H2O2浓度的增大逐渐增强再趋于稳定。     

PS-b-PDMS/环氧树脂制备疏水性环氧涂层的性能

用共混法将聚苯乙烯-b-聚二甲基硅氧烷(PS-b-PDMS)嵌段共聚物与环氧树脂E-44复合制备了一种疏水性环氧涂层。研究了PS-b-PDMS的用量对涂层力学性能、表面性能及耐化学腐蚀性的影响。结果表明,随着共聚物用量的增加,涂层的冲击强度及柔韧性明显提高,表面能显著降低,接触角明显增大,当PS-b-PDMS用量为E-44的7%(质量分数)时,冲击强度和柔韧性分别为50kg.cm和0.5mm,表面能为13.8mN/m,对水接触角增大至115.9°,具有优异的疏水性及耐化学腐蚀性。     

无氧化剂条件下铜钴CMP去除速率的控制北大核心

利用不含氧化剂的碱性抛光液对铜和钴进行化学机械抛光,深入分析了抛光液组分包括硅溶胶磨料、FA/O螯合剂以及非离子表面活性剂对两种金属去除速率的影响规律及作用机理。实验结果表明,铜和钴的去除速率随着磨料质量分数的增加而升高,并且在磨料质量分数低于5%时钴的去除速率为20~30 nm/min,而铜的去除速率几乎为零;加入FA/O螯合剂可增强其与金属离子的络合,从而加快铜和钴的去除速率;非离子表面活性剂可以有效降低铜和钴的表面粗糙度。在抛光液各组分的协同作用下,可以达到两种材料的低表面粗糙度和高去除速率选择性。