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     

三种胍盐对低磨料浓度碱性阻挡层抛光液性能的影响

The influence of three kinds of guanidinium salt on the removal rate selectivity of different materials was studied during the barrier chemical mechanical polishing(CMP) process at first.The three kinds of guanidine saltguanidine hydrochloride,guanidine nitrate and guanidine carbonate.Then we compared the effect of the three kinds of guanidine salt on the dishing,erosion and surface roughness value.In the end,the reaction mechanism was studied through electrochemical analysis.All the results indicate that there is a better performance of the slurry with guanidine hydrochloride than the slurries with the other two kinds of guanidine salt.It effectively improved the removal rate selectivity and the surface roughness under the premise of low abrasive concentration and low polishing pressure,which is good for the optimization of the alkaline slurry for the barrier CMP process.     

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.     

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.     

铜互连制程中酸碱性抛光液的平坦化效果评估

We observed and analyzed the acid and HEBUT alkaline of Cu chemical mechanical polishing(CMP)slurry to evaluate their effects. Material analysis has shown that the planarity surfaces and the removal rate of alkaline slurry are better than the acid slurry during metal CMP processes. The global surface roughness and the small-scale surface roughness by 1010 m2 of copper film polished by the SVTC slurry are 1.127 nm and2.49 nm. However, it is found that the surface roughnesses of copper films polished by the HEBUT slurry are 0.728 nm and 0.215 nm. All other things being equal, the remaining step heights of copper films polished by the SVTC slurry and HEBUT slurry are respectively 150 nm and 50 nm. At the end of the polishing process, the dishing heights of the HEBUT slurry and the SVTC slurry are approximately both 30 nm, the erosion heights of the HEBUT slurry and the SVTC slurry are approximately both 20 nm. The surface states of the copper film after CMP are tested,and the AFM results of two samples are obviously seen. The surface polished by SVTC slurry shows many spikes.This indicates that the HEBUT alkaline slurry is promising for inter-level dielectric(ILD) applications in ultra large-scale integrated circuits(ULSI) technology.     

碱性阻挡层CMP后铜布线粗糙度的影响机理分析

The surface roughness seriously affects the performance of devices after barrier CMP. Due to the high surface roughness of copper line, the local resistance of a device will be high when working, then the copper line will overheat prompting the generation of electro-migration and the circuit will lose efficacy. Reducing the surface roughness of the copper line in barrier CMP is still an important research topic. The main factors influencing the surface roughness of copper line in alkaline barrier slurry are analyzed in the paper. Aimed at influencing the law on the surface roughness of copper line, using a new type of alkaline barrier slurry with a different p H of the chelating agent and changing the content of non-ionic surfactant, we then analyze the influencing law both on the surface roughness of copper line, and the influence mechanism. The experimental results show that with a chelating agent with a low p H value in the barrier slurry, the surface roughness of the copper line is 1.03 nm and it is the lowest in all of the barrier slurries, and with the increase of non-ionic surfactant concentration, the surface roughness of copper line is reduced to 0.43 nm, meeting the demand of further development of integrated circuits.     

新型碱性精抛液对300mm铜膜全局平坦化的影响

The copper removal rate and uniformity of two types copper slurries were investigated, which was performed on the 300 mm chemical mechanical planarization （CMP） platform. The experiment results illustrate that the removal rate of the two slurries is nearly the same. Slurry A is mainly composed ofa FA/OI1 type chelating agent and the uniformity reaches to 88.32%. While the uniformity of slurry B is 96.68%, which is mainly composed of a FA/OV type chelating agent. This phenomenon demonstrates that under the same process conditions, the uniformity of different slurries is vastly different. The CMP performance was evaluated in terms of the dishing and erosion values. In this paper, the relationship between the uniformity and the planarization was deeply analyzed, which is mainly based on the endpoint detection mechanism. The experiment results reveal that the slurry with good uniformity has low dishing and erosion. The slurry with bad uniformity, by contract, increases Cu dishing significantly and causes copper loss in the recessed region. Therefore, the following conclusions are drawn： slurry B can improve the wafer leveling efficiently and minimize the resistance and current density along the line, which is helpful to improve the device yield and product reliability. This investigation provides a guide to improve the uniformity and achieve the global and local planarization. It is very significant to meet the requirements for 22 nm technology nodes and control the dishing and erosion efficiently.     

不同压力下螯合剂浓度在碱性Cu CMP中的影响

We propose the action mechanism of Cu chemical mechanical planarization(CMP) in an alkaline solution.Meanwhile,the effect of abrasive mass fraction on the copper removal rate and within wafer non-uniformity(WIWNU) have been researched.In addition,we have also investigated the synergistic effect between the applied pressure and the FA/O chelating agent on the copper removal rate and WIWNU in the CMP process.Based on the experimental results,we chose several concentrations of the FA/O chelating agent,which added in the slurry can obtain a relatively high removal rate and a low WIWNU after polishing,to investigate the planarization performance of the copper slurry under different applied pressure conditions.The results demonstrate that the copper removal rate can reach 6125 °/min when the abrasive concentration is 3 wt.%.From the planarization experimental results,we can see that the residual step height is 562 ° after excessive copper of the wafer surface is eliminated.It denotes that a good polishing result is acquired when the FA/O chelating agent concentration and applied pressure are fixed at 3 vol% and 1 psi,respectively.All the results set forth here are very valuable for the research and development of alkaline slurry.     

A new weakly alkaline slurry for copper planarization at a reduced down pressure

This study reports a new weakly alkaline slurry for copper chemical mechanical planarization （CMP）, it can achieve a high planarization efficiency at a reduced down pressure of 1.0 psi. The slurry is studied through the polish rate, planarization, copper surface roughness and stability. The copper polishing experiment result shows that the polish rate can reach 10032 A/rain. From the multi-layers copper CMP test, a good result is obtained, that is a big step height （10870 A） that can be eliminated in just 35 s, and the copper root mean square surface roughness （sq） is very low （〈 1 rim）. Apart from this, compared with the alkaline slurry researched before, it has a good progress on stability of copper polishing rate, stable for 12 h at least. All the results presented here are relevant for further developments in the area of copper CMP.     

The stability of a novel weakly alkaline slurry of copper interconnection CMP for GLSI

Chemical mechanical polishing (CMP) is one of the important machining procedures of multilayered copper interconnection for GLSI,meanwhile polishing slurry is a critical factor for realizing the high polishing performance such as high planarization efficiency,low surface roughness.The effect of slurry components such as abrasive (colloidal silica),complexing agent (glycine),inhibitor (BTA) and oxidizing agent (H2O2) on the stability of the novel weakly alkaline slurry of copper interconnection CMP for GLSI was investigated in this paper.First,the synergistic and competitive relationship of them in a peroxide-based weakly alkaline slurry during the copper CMP process was studied and the stability mechanism was put forward.Then 1 wt％ colloidal silica,2.5 wt％ glycine,200 ppm BTA,20 mL/L H2O2 had been selected as the appropriate concentration to prepare copper slurry,and using such slurry the copper blanket wafer was polished.From the variations of copper removal rate,root-mean square roughness (Sq) value with the setting time,it indicates that the working-life of the novel weakly alkaline slurry can reach more than 7 days,which satisfies the requirement of microelectronics further development.     

一种含有盐酸胍的新型TSV抛光液

本文中,对一种新型的含有盐酸胍的TSV抛光液在CMP(化学机械平坦化)中的性能进行了研究,该TSV抛光液是一种碱性抛光液,并且不含任何抑制剂。在抛光过程中,盐酸胍作为一种有效的表面复合单元,相对于铜和介质的去除速率,钛的去除速率是可以通过调节选择性来控制的。在TSV生产过程中对于表面蝶形坑的修正及得到好的表面平整度是有利的。本文主要研究了抛光液成分的作用机理以及盐酸胍在TSV抛光液中的巧妙应用。     

配置一种不加BTA和氧化剂的弱碱性阻挡层抛光液的机理分析

在阻挡层化学机械抛光中,实现可控的铜,钽,介质去除速率选择比是一项挑战。双氧水作为氧化剂加上BTA作为抑制剂的作用被认为是一种有效的方法。但是,由于双氧水易于分解使得含有双氧水的抛光液使用寿命短。另外,BTA对抛光后清洗带来挑战：在片子表面残留有毒的有机物和颗粒。最近,我们一直致力于研究一种不加氧化剂和BTA的阻挡层抛光液。在这些工作的基础上,本文的目的是通过实验研究抛光液中不同的组分（包括硅溶胶,FA/O螯合剂,溶液PH,硝酸）胍）对铜,钽,介质去除速率的影响来讨论配置这种新型的不加BTA和氧化剂的阻挡层抛光液的机理。相关可能的抛光机也会在本论文中提出。     

碱性铜精抛液中表面活性剂ADS对平坦化效果的影响

研究了阴离子表面活性剂十二烷基硫酸铵(ADS)在弱碱性铜抛光液中对晶圆平坦化效果的影响.对不同质量分数的阴离子表面活性剂ADS下的抛光液表面张力、铜去除速率、抛光后铜膜的碟形坑高度、晶圆片内非均匀性和表面粗糙度进行了测试.实验结果表明,当阴离子表面活性剂ADS的质量分数为0.2％时,抛光液的表面张力降低,铜的去除速率为202.5 nm·min-1,去除速率片内非均匀性减小到4.15％,抛光后铜膜的碟形坑高度从132 nm降低到68.9 nm,表面粗糙度减小到1.06 nm.与未添加表面活性剂相比,晶圆表面的平坦化效果得到改善.     

新型碱性抛光液对300mm TaN镀膜片CMP效果评估

TaN由于其良好的性能广泛用于布线铜与介质之间的阻挡层和黏附层.在对直径为300 mm的TaN镀膜片进行化学机械抛光(CMP)后,对比并分析了两种碱性抛光液对TaN去除速率、片内非均匀性、去除速率选择性和表面粗糙度的影响.结果表明,经过自主研发且不合氧化剂的碱性阻挡层抛光液抛光后,TaN的去除速率为40.1 nm/min,片内非均匀性为3.04％,介质、TaN与Cu的去除速率之比为1.69∶1.26∶1,中心、中间以及边缘的表面粗糙度分别为0.371,0.358和0.366 nm.与商用抛光液抛光结果相比,虽然采用自主研发的抛光液抛光的去除速率低,但片内非均匀性以及选择性均满足商用要求,且抛光后TaN表面粗糙度小,易清洗,无颗粒沾污.综合实验结果表明,自主研发的高性能碱性抛光液对TaN镀膜片具有良好的抛光效果,适合工业生产.     

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。     

Effects of pattern characteristics on copper CMP

Copper chemical mechanical polishing(CMP)is influenced by geometric characteristics such as line width and pattern density,as well as by the more obvious parameters such as slurry chemistry,pad type,polishing pressure and rotational speed.Variadons in the copper thickness across each die and across the wafer Can impact the circuit performance and reduce the yield.In this paper,we propose a modeling method to simulate the polishing behavior as a function of layout pattern factors.Under the same process conditions,the pattern density,the line width and the line spacing have a strong influence on copper dishing,dielectric erosion and topography.The test results showed:the wider the copper line or the spacing,the higher the copper dishing;the higher the density,the higher the dielectric erosion;the dishing and erosion increase slowly as a function of increasing density and go into saturation when the density is more than 0.7.