多层互连工艺中铜布线化学机械抛光研究进展

对ULSI中多层铜布线的CMP进行了分析,主要针对铜抛光液的研究现状以及进展进行综述,重点比较了各种不同种类抛光液的抛光效果,以及抛光液对铜和介电层的选择性研究,并提出了目前需要解决的问题,对今后铜抛光研究方向及方法进行了进一步探讨.     

ULSI铜互连线CMP抛光液的研制

介绍了一种碱性抛光液,选用有机碱做介质,SiO2水溶胶做磨料,依据强络合的反应机理,克服了SiO2水溶胶做磨料对铜去除速率低及在溶液中凝胶的难点.实验结果表明:该抛光液适用于Cu化学机械抛光过程第一阶段的抛光,并达到了高抛光速率及铜/钽/介质层间的高选择性的效果.     

ULSI铜互连线CMP抛光液的研制

介绍了一种碱性抛光液,选用有机碱做介质,SiO2水溶胶做磨料,依据强络合的反应机理,克服了SiO2水溶胶做磨料对铜去除速率低及在溶液中凝胶的难点.实验结果表明:该抛光液适用于Cu化学机械抛光过程第一阶段的抛光,并达到了高抛光速率及铜/钽/介质层间的高选择性的效果.     

ULSI制备中铜布线的两步抛光技术

在超大规模集成电路 (U L SI)铜布线工艺中 ,采用阻挡层来提高铜与衬底的粘附性 ,主要是为了防止铜原子向介质或衬底中扩散 .为了达到全局平面化 ,就需要克服阻挡层金属与布线金属铜因化学和物理性质的不同而导致其化学机械抛光 (CMP)速率的不同 .通过研究和一系列试验 ,采用两步抛光 ,初抛中采用高化学作用 ,终抛中采用高机械作用 ,达到较好的全局平面化效果 ,并提出了初抛的 CMP模型 .     

ULSI制备中铜布线的两步抛光技术

在超大规模集成电路(ULSI)铜布线工艺中,采用阻挡层来提高铜与衬底的粘附性,主要是为了防止铜原子向介质或衬底中扩散.为了达到全局平面化,就需要克服阻挡层金属与布线金属铜因化学和物理性质的不同而导致其化学机械抛光(CMP)速率的不同.通过研究和一系列试验,采用两步抛光,初抛中采用高化学作用,终抛中采用高机械作用,达到较好的全局平面化效果,并提出了初抛的CMP模型.     

TSV铜抛光液的研究进展

对硅通孔技术(TSV)在3D堆叠封装领域的优势进行了简单阐述,同时指出化学机械抛光(CMP)技术作为具有高质量和高精度的全局平坦化工艺,是TSV制备过程中最重要的步骤之一。影响化学机械抛光质量以及效率的因素有很多,其中比较关键的是化学机械抛光液的组成成分及其性能。重点从抛光速率、抛光质量(抑制碟形坑、表面粗糙度等)和绿色环保几个方面对抛光液性能的影响进行了讨论,概述了近年来国内外铜抛光液的研究进展。最后,通过对比总结目前铜抛光液的研究成果,对TSV铜抛光液今后的研究重点和发展趋势进行了分析和预测,其应朝着抛光速率和抛光质量的优化、低成本及环境友好的方向发展。     

ULSI制造中铜CMP抛光液的技术分析

对ULSI制造中的层间介质化学机械抛光的发展趋势和要求进行了讨论,分析了铜化学机械抛光的材料去除过程、影响因素和抛光液的重要作用,讨论了酸性和碱性两种铜抛光液的组成和一些组分的功能,对研究铜化学机械抛光的电化学手段进行了阐述和机理分析,指出了铜化学机械抛光今后的研究趋势和重点以及抛光液研究的发展方向.     

用于钴互连CMP抛光液的研究进展

当集成电路技术节点进入10 nm及以下，传统的铜(Cu)互连材料面临着阻容(RC)延迟高、电子散射强等问题，钴(Co)作为制程工艺中的新材料，以其更低的电阻率、更高的硬度和更低的平均电子自由程，成为了替代Cu作为互连材料的优选金属。化学机械抛光(CMP)是去除Co布线层多余材料，实现全局平坦化的唯一技术。而抛光液作为CMP工艺中最重要的耗材之一，其性能的好坏直接决定了晶圆的抛光效果和良品率。回顾了近年来钴互连金属材料的各种新型抛光液的国内外研究进展，讨论了不同化学添加剂对Co材料的去除速率、腐蚀抑制和表面质量的影响。同时总结了钴互连CMP抛光液面临的挑战及发展方向。     

新型碱性阻挡层抛光液对铜布线化学机械平坦化的评估研究

化学机械平坦化(CMP)是铜互连制备过程中唯一的全局平坦化技术。但是由于互连线铜与扩散阻挡层物理及化学性质上的差异,在阻挡层的化学机械平坦化过程中将加剧导致碟形坑的产生。目前,国际上抛光液以酸性为主,但是其存在固有的问题,如酸性气体挥发,腐蚀严重等。本论文研发出一种新型碱性阻挡层抛光液,与商用的阻挡层抛光液做对比,评估了其抛光性能。实验结果表明,新型碱性阻挡层抛光液抛光后表面状态好,粗糙度较低。另外,碟形坑及电阻测试结果表明,新型碱性阻挡层抛光后铜布线的表面形貌好,碟形坑小,能够应用于铜布线阻挡层的CMP中。     

碱性抛光液对铜与钽CMP选择比的影响

在ULSI多层铜布线中,由于钽与铜在物理及化学性质上的差别导致这两者的CMP去除速率不同,从而在抛光结束后出现蝶形坑等缺陷,影响器件性能。通过实验分析碱性抛光液中磨料、螯合剂、氧化剂、pH值、活性剂对铜与钽CMP选择比的影响。根据铜与钽的CMP去除机理,从实验结果分析出对铜、钽去除速率影响较为明显的成分,调节这些成分得到特定配比的抛光液,分别实现了铜与钽的去除速率相等、铜的去除速率大于钽、铜的去除速率小于钽。使用上述铜去除速率小于钽的抛光液对12英寸(1英寸=2.54 cm)图形片进行抛光,通过原子力显微镜观察,证明了这种抛光液能有效地修复多层布线CMP中的蝶形坑等缺陷。     

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。     

Alkaline barrier slurry applied in TSV chemical mechanical planarization

We have proposed a TSV （through-silicon-via） alkaline barrier slurry without any inhibitors for barrier CMP （chemical mechanical planarization） and investigated its CMP performance. The characteristics of removal rate and selectivity of Ti/SiO2/Cu were investigated under the same process conditions. The results obtained from 6.2 mm copper, titanium and silica show that copper has a low removal rate during barrier CMP by using this slurry, and Ti and SiO2 have high removal rate selectivity to Cu. Thus it may be helpful to modify the dishing. The TSV wafer results reveal that the alkaline barrier slurry has an obvious effect on surface topography correction, and can be applied in TSV barrier CME     

不含抑制剂的碱性抛光液对铜布线平坦化的研究

本文提出一种碱性铜布线抛光液,其不含通用的腐蚀抑制剂,并对其化学机械抛光和平坦化 (CMP)性能进行了研究。首先研究了此抛光液对铜的静态腐蚀速率和抛光速率,并与含抑制 剂的铜抛光液做了对比实验。在静态条件下,此不含抑制剂的碱性铜抛光液对铜基本无腐蚀速率,而在动态抛光过程中对铜有较高的速率。而含抑制剂的抛光液对静态腐蚀速率略有降低,但是却大幅度降低了铜的去除速率。另外,对铜布线的化学机械平坦化研究表明,此不含抑制剂的碱性铜抛光液能够有效的去除铜布线表面的高低差,有较高的平坦化能力。此抛光液能够应用于铜CMP的第一步抛光,能够去除大量多余铜时初步实现平坦化。     

ULSI多层互连中的化学机械抛光工艺

介绍了化学机械抛光(CMP)技术在大规模集成电路多层互连工艺[1]中的重要作用,对CMP过程和CMP的影响因素进行简单分析。总结出CMP技术在多层互联平坦化中的优势,介绍目前常用互连材料中SiO2介质及其金属材料钨和铜的化学机械抛光常用分析机理,并简单介绍了各种互联材料常用的抛光液及抛光液的组分,对抛光液作了简单的对比。针对传统CMP过程存在的问题,分析了皮带式和固定磨料的CMP技术。     

阻挡层浆料特性对CMP后清洗效力的影响

铜化学机械平面化不同阻挡层浆料的应用引起了铜CMP后清洗的问题。阻挡层浆料的差异包含但不限于pH、研磨剂粒子材料和尺寸及铜腐蚀的抑制剂。为观察阻挡层浆料对清洗工艺的影响进行了清洗实验。阻挡层浆料不同于pH和所有作为铜抑制剂的BTA材料。抑制性BTA溶液的pH值将确定BTA与铜复合物的特性和随后在清洗工艺中去除这种膜的条件。因此,为了研究pH、化学成份以及阻挡层浆料留在铜表面的BTA与铜的复合物去除的化学程序的影响而改变了清洗工艺。从而发现阻挡层浆料的pH值对各种清洗设备的效力均有影响,而且,某些添加剂和两步化学清洗工艺的使用,改进了可变pH值阻挡层浆料的清洗性能。这种工作的结果表明,在最佳结果中,清洗工艺应该致力于阻挡层浆料方面。     

镁合金抛光机理与CMP工艺研究

将化学机械抛光(CMP)技术引入到镁合金片(MB2)的抛光中,打破过去镁合金以单一化学或机械加工为主的加工手段,用自制的抛光液对镁合金片进行抛光实验。结果发现,抛光液中加入双氧水易产生胶体,不利于抛光的进行,因此提出无氧化剂SiO2碱性抛光。同时分析了镁合金的抛光机理,抛光中压力、转速和抛光液流量参数对抛光过程的影响,利用Olympus显微镜对抛光前后镁合金表面进行观察,通过合理控制工艺参数,能够得到较佳的镁合金抛光表面,远优于单一的机械加工,为镁合金抛光工艺和进一步研究抛光液的配比奠定了基础。     

Application of CMP process monitor to Cu polishing

We have developed a chemical mechanical polishing (CMP) process monitor which uses polishing vibration. The monitor enables us to accurately detect the polishing end point in copper (Cu) polishing even when the process conditions such as initial film thickness, slurry flow and polishing rate are changed and when polishing multilayer film. Furthermore, the monitor is not only applicable to Cu polishing but also to planarizing polishing of an inter-level dielectric layer. The monitor can be also used to control the processes and the equipment because of its capability to detect abnormalities in the polishing conditions     

Effect of 1,2,4-triazole on galvanic corrosion between cobalt and copper in CMP based alkaline slurry

Cobalt has become a new type of barrier material with its unique advantages since the copper-interconnects in the great-large scale integrated circuits (GLSI) into 10 nm and below technical nodes,but cobalt and copper have severe galvanic corrosion during chemical-mechanical flattening.The effect of 1,2,4-triazole on Co/Cu galvanic corrosion in alkaline slurry and the control of rate selectivity of copper and cobalt were investigated in this work.The results of electrochemical experiments and polishing experiments had indicated that a certain concentration of 1,2,4-triazole could form a layer of insoluble and dense passive film on the surface of cobalt and copper,which reduced the corrosion potential difference between cobalt and copper.Meantime,the removal rate of cobalt and copper could be effectively controlled according to demand during the CMP process.When the study optimized slurry was composed of 0.5 wt％ colloidal silica,0.1％vol.hydrogen peroxide,0.05 wt％ FA/O,345 ppm 1,2,4-triazole,cobalt had higher corrosion potential than copper and the galvanic corrosion could be reduced effectively when the corrosion potential difference between them decreased to 1 mV and the galvanic corrosion current density reached 0.02 nA/cm2.Meanwhile,the removal rate of Co was 62.396 nrn/min,the removal rate of Cu was 47.328 nm/min,so that the removal rate ratio of cobalt and copper was 1.32:1,which was a good amendment to the dishing pits.The contact potential corrosion of Co/Cu was very weak,which could be better for meeting the requirements of the barrier CMP.     

Effect of polishing pad with holes in electro-chemical mechanical planarization

Electro-chemical mechanical planarization (ECMP) process dissolves copper ions electrochemically by applying an anodic potential on the copper surface in an aqueous electrolyte, and then removes a copper (Cu) complex layer by the mechanical abrasion of a polishing pad or abrasives in the electrolyte. The ECMP process is a low pressure polishing method for metals such as copper, aluminium (Al) and tungsten (W) on dielectric materials such as silicon dioxide, low-k (LK) and ultra low-k (ULK) dielectrics, comparing to the amount of defects by the traditional Cu chemical mechanical planarization (CMP). The polishing pad used in the ECMP process is a conventional closed cell type pad (IC 1400 K-groove pad) with holes. It supplies the aqueous electrolyte to the copper surface and removes the copper complex layer. The material removal rate (MRR) and MRR profile were simulated and tested according to the changes of the wafer overhang distance (WOD) from the platen and the electric contact area (ECA). In order to derive the design rule of the system, the experimental results are compared with the simulation results. After the ECMP process, it was verified that the within wafer non-uniformity (WIWNU) was lower than 2% using the relatively uniform ECA pad (C-type) under the smallest WOD condition. The experimental results well matched the simulated results.