氮化钛阻挡层化学机械抛光液的研究

为了解决Cu互连线污染和形成高阻铜硅化物以及Cu与SiO2粘附性差等问题,提出增加扩散阻挡层的解决方案。主要关于氮化钛阻挡层化学机械抛光的研究。分析了氮化钛的抛光机理,研究了氧化剂浓度及抛光液的pH对抛光速率的影响,最后配制了适合氮化钛阻挡层的碱性抛光液。     

石英晶片化学机械抛光工艺优化

为同时优化化学机械抛光(CMP)后石英晶片平面度和表面粗糙度,进行化学机械抛光协调控制实验。分析了抛光时间、抛光转速和抛光压力对石英晶片平面度和表面粗糙度的影响,确定了最佳工艺参数。研究结果表明：石英晶片平面度和表面粗糙度都随抛光时间延长而优化,在150 min时,平面度和表面粗糙度都能达到稳定。抛光时间为150 min、抛光盘转速为50 r/min、抛光压力为53.5 N时,能使晶片同时得到较好的平面度和表面粗糙度,此时平面度为2.03μm,表面粗糙度为0.68 nm。     

抛光垫使用期对300 mm Si片Haze值影响研究

抛光垫是化学机械抛光(CMP)过程中重要的消耗材料之一.由于抛光垫与Si片直接接触,所以抛光垫的物理特性会直接影响到所加工Si片品质的优劣.通过研究不同使用时间的抛光垫结构以及所抛光Si片表面haze值,发现抛光Si片表面haze值在抛光垫使用前期逐渐减小,中期稳定缓慢升高,后期快速升高.从理论上系统地对结果进行了分析,充分证实了在CMP过程中,保持抛光垫特性的稳定对Si片表面质量具有非常重要的意义.     

铜化学机械抛光工艺中碟形缺陷的优化

铜化学机械抛光是近些年发展最快的一种工艺,铜碟形是铜化学机械抛光工艺中的主要问题之一。严重的碟形缺陷会造成产品良率的缺失,使得利润下降。碟形是由于在抛光过程中铜线与介质层不同的抛光速率所导致。文章详细地介绍了铜化学机械抛光的基本步骤和不同作用,然后指出了在抛光过程中碟形产生的基本原理,最后对抛光过程中最重要的抛光液及其成份对碟形的影响进行了分析。通过试验各种成分的剂量组成不同配方的抛光液,最终给出了减少碟形的具体改进方案。     

铜抛光液对片内非均匀性影响的研究

对于低介电常数材料和铜互连结构在低压化学机械抛光中,研发新的抛光液和调整工艺参数是非常必要的。抛光液的研发是减少抛光表面划伤和解决磨料剩余的关键。抛光液组成由片内非均匀性和铜抛光去除速率特性来优化。氧化剂浓度1Vol%;磨料浓度0.8Vol%;螯合剂浓度2Vol%。工作压力1kPa。抛光后表面缺陷减小并且表面干净无污染。去除速率289nm/min,片内非均匀性0.065。化学机械抛光后用原子力测量粗糙度为0.22 nm。     

碱性抛光液在CMP过程中对低k介质的影响

以p型111硅片为衬底,经过旋涂固化制备低介电常数(低k)材料聚酰亚胺。经过化学机械抛光(CMP)过程,考察实验前后低k材料介电性能的变化。实验中分别使用阻挡层抛光液、Cu抛光液以及新型抛光液对低k材料进行抛光后,利用电参数仪对低k材料进行电性能测试。结果显示,低k材料介电常数经pH值为7.09新型抛光液抛光后,k值由2.8变为2.895,漏电流在3.35 pA以下,去除速率为59 nm/min。经新型抛光液抛光后的低k材料,在电学性能等方面均优于阻挡层抛光液和Cu抛光液,抛光后的低k材料的性能能够满足应用要求。     

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.     

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 .     

化学机械研磨垫

OPTIVISIONTM 4540化学机械研磨垫的设计目标是在使用寿命内实现低缺陷率和低拥有成本。它使用了独特的聚合物化学组成和细孔结构，以达到使铜阻挡层研磨的缺陷率降至最低，并提供更高的介电层去除率；拥有双孔结构以精确控制研磨，并且在研磨垫使用寿命中提供一致的研磨垫表面。尤其在铜阻挡层研磨方面，与POLITEXTM研磨垫产品相比，它在颤动和微划痕缺陷率方面取得了一个数量级的进步，从而实现了更高的生产良率。     

高稀释倍数碱性铜精抛液在Cu CMP中的应用

采用自制的不含常用的腐蚀抑制剂(BTA)碱性铜精抛液对铜和钽进行了化学机械抛光。研究了高稀释倍数(50倍)的精抛液对铜膜的静态腐蚀速率和抛光速率以及钽抛光速率的影响,并对65 nm技术节点的300 mm单层铜布线片进行了平坦化研究。结果表明,铜膜的静态腐蚀速率为1.5 nm/min,动态抛光速率为206.9 nm/min,阻挡层Ta/TaN抛光速率仅为0.4 nm/min,Cu/Ta选择比高。此精抛液能够有效去除残余铜,进一步过抛完全去除残余铜时,对阻挡层的去除速率趋于0,而沟槽里的铜布线去除量低,碟形坑和蚀坑大小满足实际平坦化要求。此精抛液可满足65 nm技术节点平坦化的要求。     

软抛光垫条件下非晶态Ge2Sb2Te5的化学机械抛光

Chemical mechanical planarization（CMP） of amorphous Ge₂Sb₂Te₅（a-GST） is investigated using two typical soft pads（politex REG and AT） in acidic slurry.After CMP,it is found that the removal rate（RR） of a-GST increases with an increase of runs number for both pads.However,it achieves the higher RR and better surface quality of a-GST for an AT pad.The in-situ sheet resistance（R_s） measure shows the higher R_s of a-GST polishing can be gained after CMP using both pads and the high R_s is beneficial to lower the reset current for the PCM cells. In order to find the root cause of the different RR of a-GST polishing with different pads,the surface morphology and characteristics of both new and used pads are analyzed,it shows that the AT pad has smaller porosity size and more pore counts than that of the REG pad,and thus the AT pad can transport more fresh slurry to the reaction interface between the pad and a-GST,which results in the high RR of a-GST due to enhanced chemical reaction.     

Chemical mechanical polishing with fixed abrasives using different subpads to optimize wafer uniformity

Chemical mechanical polishing (CMP) processes are widely used in the semiconductor industry and are conventionally carried out using abrasive slurry and a polishing pad. In an alternative procedure, called ‘slurry free CMP’, the abrasive particles are embedded in the pad material (‘fixed abrasives’). A microreplicated resin layer of pyramids filled with the abrasives is placed on top of a rigid polycarbonate layer and a resilient foam sublayer. Instead of slurry, only DI-water or a basic solution is applied. Drying in of the slurry and glazing of the pad is not possible and pad conditioning is not required. Experiments were carried out for slurry free CMP to optimize the with-in-wafer non-uniformity (WIW-NU), removal rate and planarization of oxide ILD. Results of this optimization are compared with our best slurry process.

It is shown that the fixed abrasives process is superior to the slurry process with regard to planarization: the rate of planarization is almost three times faster for the slurry free process. This enables further process optimization, such as the use of a thinner pre-CMP oxide layer.

Besides higher planarization rates, better with-in-die non-uniformity (WID-NU) can be obtained by adjusting the subpad construction of these ‘slurry free’ pads. The flexibility of the pad construction makes it possible to optimize the WID-NU and WIW-NU. Stiffer pads give lower WID-NU, but for the stiffest pad the WIW-NU will slightly increase. However, compared to the slurry process both WID-NU and WIW-NU are better.     

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。     

基于化学机械动力学的碱性铜抛光液平坦化机理研究

The planarization mechanism of alkaline copper slurry is studied in the chemical mechanical polishing (CMP) process from the perspective of chemical mechanical kinetics.Different from the international dominant acidic copper slurry,the copper slurry used in this research adopted the way of alkaline technology based on complexation. According to the passivation property of copper in alkaline conditions,the protection of copper film at the concave position on a copper pattern wafer surface can be achieved without the corrosion inhibitors such as benzotriazole(BTA),by which the problems caused by BTA can be avoided.Through the experiments and theories research,the chemical mechanical kinetics theory of copper removal in alkaline CMP conditions was proposed. Based on the chemical mechanical kinetics theory,the planarization mechanism of alkaline copper slurry was established. In alkaline CMP conditions,the complexation reaction between chelating agent and copper ions needs to break through the reaction barrier.The kinetic energy at the concave position should be lower than the complexation reaction barrier,which is the key to achieve planarization.     

Study on the Mechanical Properties of CMP Pads

The mechanical properties of chemical–mechanical planarization (CMP) pads are very important to their performance. In this paper, pads are described in terms of their bulk properties and the properties of their asperity layer for applications in copper CMP. In particular, the elastic properties of these layers are studied.      

柠檬酸在钴基铜互连CMP及后清洗的研究进展

钴(Co)具有较低的电阻率、良好的热稳定性、与铜(Cu)粘附性好等优点,可以替代钽(Ta)成为14 nm以下技术节点集成电路(IC) Cu互连结构的新型阻挡层材料。化学机械抛光(CMP)是唯一可以实现Cu互连局部和全局平坦化的方法,也是决定Co基Cu互连IC可靠性的关键技术。柠檬酸含有羟基,在电离后对金属离子有较强的络合作用,成为Co基Cu互连CMP及后清洗中的主要络合剂。文章评述了柠檬酸在Cu互连CMP及后清洗中的应用和研究进展,包括柠檬酸对Cu/Co去除速率选择比、Co的表面形貌以及Co CMP后清洗中Co表面残留去除等方面的影响,并展望了络合剂及Cu互连阻挡层CMP的发展趋势。     

低磨料浓度的碱性铜抛光液平坦化性能的研究

A novel alkaline copper slurry that possesses a relatively high planarization performance is investigated under a low abrasive concentration.Based on the action mechanism of CMP,the feasibility of using one type of slurry in copper bulk elimination process and residual copper elimination process,with different process parameters,was analyzed.In addition,we investigated the regular change of abrasive concentration effect on copper and tantalum removal rate and within wafer non-uniformity(WIWNU) in CMP process.When the abrasive concentration is 3 wt%,in bulk elimination process,the copper removal rate achieves 6125 °/min,while WIWNU is 3.5%,simultaneously.In residual copper elimination process,the copper removal rate is approximately 2700°/min,while WIWNU is 2.8%.Nevertheless,the tantalum removal rate is 0 °/min,which indicates that barrier layer isn’t eliminated in residual copper elimination process.The planarization experimental results show that an excellent planarization performance is obtained with a relatively high copper removal rate in bulk elimination process.Meanwhile,after residual copper elimination process,the dishing value increased inconspicuously,in a controllable range,and the wafer surface roughness is only 0.326 nm(sq < 1 nm) after polishing.By comparison,the planarization performance and surface quality of alkaline slurry show almost no major differences with two kinds of commercial acid slurries after polishing.All experimental results are conducive to research and improvement of alkaline slurry in the future.     

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     

Visualized characterization of slurry film between wafer and padduring chemical mechanical planarization

Chemical mechanical planarization (CMP) has emerged recently as an indispensable processing technique for planarization in submicrometer multilevel very large scale integration (VLSI). The demand from industry for fast material removal and a high degree of uniformity has been a serious challenge for the advancement of this key technology. Among various process aspects, the slurry flow between wafer and pad plays an important role in the pursuit of these goals. This study provides a visualized characterization of the amount and distribution of the fluid film between the wafer and pad. The fluid film is analyzed by the digital picture obtained through the transparent carrier and dyed fluid. The effects of process parameters are extensively investigated, including platen and carrier speed, pad design, rinsing location, and flow rate of slurry and wafer size. Suggestions for process recipes aiming at fast and uniform CMP are drawn based on the current results     

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。