ULSI多层Cu布线CMP中磨料的研究

超大规模集成电路多层Cu布线平坦化中,抛光磨料是CMP系统的重要组成部分,是决定抛光速率、抛光表面状态和平坦化能力的重要影响因素.分析研究了在CMP中磨料的作用和影响,指出碱性的纳米级SiO2水溶胶是ULSI多层Cu布线CMP的理想磨料.并进一步通过对多层Cu布线CMP硅溶胶磨料的优化研究,指出采用小粒径、低粒径分散度、高质量分数的SiO2水溶胶磨料,可有效地解决平整度差、塌边、碟形坑、表面粗糙度差等问题,获得了良好的抛光效果.     

碱性铜抛光液在CMP工艺中的性能评估

研究了一种碱性铜抛光液,其基本组分是硅溶胶磨料、新型FA/O V型螯合剂、非离子表面活性剂和氧化剂(H2O2)。在压力为2 psi(1 psi=6.895 kPa)、抛头转速与抛盘转速分别为97和103 r/min、流量为300 mL/min的条件下,分析了铜膜去除速率随着螯合剂和氧化剂体积分数增加的作用规律。结果表明,加入体积分数2%的螯合剂和体积分数3%的氧化剂时,抛光液具有较好的自钝化能力和较高的铜膜去除速率。同时,研究了工艺参数在抛光过程中对去除速率和片内非均匀性(WIWNU)的影响,平坦化实验的抛光工艺选择压力1.5 psi、抛头和抛盘转速分别为87和93 r/min、流量300 mL/min。实验结果表明:此种抛光液在上述工艺条件下,抛光结束时剩余高低差为63.7 nm,具有较好的平坦化效果,对抛光液商业化提供了参考价值。     

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。     

磨料特性对InP晶片集群磁流变抛光效果的影响

对InP晶片进行了集群磁流变抛光实验,研究了抛光过程中磨料参数(类型、质量分数和粒径)对InP材料去除速率和表面粗糙度的影响。实验结果表明,InP晶片的去除速率随磨料硬度的增加而变大,表面粗糙度受磨料硬度和密度的综合影响;在选取的金刚石、SiC、Al2O3和SiO2等4种磨料中,使用金刚石磨料的InP去除速率最高,使用SiC磨料的InP抛光后的表面质量最好。随着SiC质量分数的增加,InP去除速率逐渐增加,但表面粗糙度先减小后增大。当使用质量分数4%、粒径3μm的SiC磨料对InP晶片进行抛光时,InP去除速率达到2.38μm/h,表面粗糙度从原始的33 nm降低到0.84 nm。     

催化反应对低磨料浓度化学机械平坦化的影响

通过低磨料浓度下催化反应对铜膜抛光速率的影响,证实了纳米SiO2胶体作为催化反应物可以极大地提高铜膜表面的化学反应速率。通过浸泡在不同磨料浓度抛光液中的铜电极表面腐蚀电位和腐蚀电流数值,进一步证实了催化反应能够加速凹处钝化膜的生成,并确定了在静态腐蚀条件下催化反应速率转换临界点所对应的纳米SiO2溶胶浓度为0.1vol%和1vol%。根据催化反应对铜晶圆各平坦化参数的影响,确定了低磨料CMP的最佳纳米SiO2溶胶浓度为0.3vol%,此时铜晶圆的抛光速率、台阶消除量、平坦化效率、碟形坑高度和腐蚀坑高度分别为535nm/min、299nm、56%、103nm和19nm。     

碱性铜粗抛液中氧化剂对化学机械平坦化的影响

针对不合腐蚀抑制剂苯并三氮唑(BTA)的碱性铜粗抛液,通过对3英寸(1英寸=2.54 cm)铜片上的动态抛光速率和静态腐蚀速率的研究来模拟评估氧化剂对晶圆表面平坦化的影响.在12英寸铜镀膜片和TM1图形片上分别研究氧化剂体积分数对表面平坦化的影响.实验结果表明:动态抛光速率和静态腐蚀速率均随着氧化剂体积分数的增加先逐渐增大,达到最大值,然后下降,趋于平缓.片内非均匀性和剩余高低差均随H2O2体积分数的增加,先呈下降趋势,后缓慢上升.当氧化剂体积分数为3％时,动态去除速率(vRR)为398.988 nm/min,静态腐蚀速率vER为6.834 nm/min,vRR/vER比值最大,片内非均匀性最小为3.82％,台阶高低差最小为104.6 nm/min,此时晶圆片有较好的平坦化效果.     

GLSI钨插塞CMP碱性抛光液组分优化的研究

钨插塞化学机械平坦化(CMP)是极大规模集成电路(GLSI)铜互连多层布线的关键工艺之一。首先研究了钨在碱性条件下化学机械抛光机理;接着采用单因素实验方法分析了抛光液组分中纳米SiO2水溶胶磨料、氧化剂、有机碱(pH调节剂)和表面活性剂对W-CMP速率的影响。最后通过正交优化实验,确定抛光液最优配比为V(纳米SiO2水溶胶)∶V(去离子水)=1∶1,氧化剂体积分数为20 mL/L,pH调节剂体积分数为4 mL/L,表面活性剂体积分数为20 mL/L时,此时抛光液的pH值为10.36,获得的去除速率为85 nm/min,表面粗糙度为0.20 nm。     

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。     

不同磨料质量分数对化学机械平坦化的影响

采用自主研发的碱性铜抛光液,在E460E机台上研究了不同磨料质量分数对铜和钽抛光速率与膜厚一致性的影响;分析了磨料质量分数为2%,2.8%和3.6%时,膜厚一致性对平坦化的影响。抛光结果显示:当磨料质量分数高于2.8%时,抛光液开始对钽进行有效的抛光;随着磨料浓度的增加,抛光液的膜厚一致性提高趋于平缓。磨料质量分数为2.8%和3.6%时,抛光后膜厚一致性变好,碟形坑满足工业生产要求;磨料质量分数为2%时,抛光后膜厚一致性比抛光前恶化,碟形坑相对较大。由此可见,当磨料质量分数为2.8%时,抛光液能有效去除残余铜,并且抛光后膜厚一致性好,有利于实现平坦化,尤其是对提高成品率和优品率有重要的作用。     

氧化剂在TSV铜膜CMP中钝化机理北大核心

为实现TSV硅衬底表面铜去除速率的优化,对影响TSV铜去除速率的最主要因素抛光液组分(如磨料、螯合剂、活性剂和氧化剂)中的氧化剂进行分析。通过对不同体积分数的氧化剂电化学实验进行钝化机理的研究,从而得到最佳的氧化剂体积分数,再进行铜的静态腐蚀实验和抛光实验对铜的去除速率进行验证。实验结果表明,氧化剂体积分数为0.5%时铜具有较高的去除速率,能够满足工业需要。最后,对CMP过程机理和钝化机理进行分析,进一步验证了氧化剂在TSV铜化学机械平坦化中的作用。     

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.     

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.     

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.     

硒化镉晶片的化学机械抛光

硒化镉(CdSe)的表面加工质量对CdSe基器件的性能至关重要.化学机械抛光(CMP)是一种获得高质量晶体加工表面的常用方法.为改善CdSe晶片的表面加工质量,以SiO2水溶胶配制抛光液,研究了抛光液磨料质量分数、抛光液pH值、氧化剂NaClO的质量分数、抛光盘转速和抛光时间等因素对CdSe晶片抛光去除速率和表面质量的影响,优化了CdSe的CMP工艺参数.结果表明,在优化工艺条件下,CdSe的平均去除速率为320 nm/min,晶片的抛光表面无明显划痕和塌边现象.原子力显微镜(AFM)测量结果表明,抛光后的CdSe晶片表面粗糙度为0.542 nm,可以满足器件制备要求.     

Material removal regions in chemical mechanical planarization for submicron integrated circuit fabrication: coupling effects of slurry chemicals, abrasive size distribution,and wafer-pad contact area

A material removal rate (MRR) model as a function of abrasive weight concentration has been proposed for chemical mechanical planarization/polishing (CMP) by extending a material removal model developed earlier in 2001 and 2002. With an increase of the weight concentration of abrasives, three regions of material removal exist: a chemically dominant and rapid increasing region, a mechanically dominant linear region, and a mechanically dominant saturation region. A detailed model is proposed to explain that the transition from the first to the second region is due to a transition from a wafer surface covered with a single soft material to a surface covered with both soft and hard materials. The slope of the linear region is a function of abrasive size distribution, and the saturation removal rate is a function of abrasive size distribution and wafer-pad contact area. The model can help to clarify the roles of chemicals, wafer-pad contact area, and abrasive size distribution in CMP.     

碱性铜抛光液在300mm平坦化系统中CMP工艺优化的研究

CMP process optimization for bulk copper removal based on alkaline copper slurry was performed on a 300 mm Applied Materials Reflexion LK system. Under the DOE condition, we conclude that as the pressure increases, the removal rate increases and non-uniformity is improved. As the slurry flow rate increases, there is no significant improvement in the material removal rate, but it does slightly reduce the WIWNU and thus improve uniformity. The optimal variables are obtained at a reduced pressure of 1.5 psi and a slurry flow rate of 300 ml/min. Platen/carrier rotary speed is set at a constant value of 97/103 rpm. We obtain optimized CMP characteristics including a removal rate over 6452 A/min and non-uniformity below 4% on blanket wafer and the step height is reduced by nearly 8000 A/min in the center of the wafer on eight layers of copper patterned wafer, the surface roughness is reduced to 0.225 nm.     

新型碱性抛光液各组分对铜化学机械平坦化性能的影响

随着集成电路特征尺寸的减小、晶圆尺寸的增大以及布线层的逐渐增多,加工晶圆过程中实现较高的材料去除速率、较小的片内非一致性(WIWNU)及较小的表面粗糙度已经成为铜化学机械抛光工艺的几大难点.采用正交实验法选取5组抛光液进行Cu CMP实验,系统研究了含有双氧水、脂肪醇聚氧乙烯醚(AEO)、FA/O Ⅰ型螯合剂与苯骈三氮唑(BTA)的碱性抛光液化学组分对铜去除速率、WIWNU的影响,并对铜CMP的各种变化规律做出机理分析.结果表明:采用pH值约为8.6,体积分数为3％的H202,质量分数为0.08％的非离子表面活性剂AEO与体积分数为1.5％的螯合剂的碱性抛光液,在12英寸(1英寸=2.54 cm)铜镀膜片抛光后有助于去除速率达到629.1 nm/min,片内非一致性达到4.7％,粗糙度达到1.88 nm.     

300mm铜膜低压CMP速率及一致性

随着铜互连结构中低k介质的应用,要求CMP抛光过程中必须将压力减小到6.89 kPa以下,传统的化学机械抛光已不符合当前的工艺要求,如何兼顾超低压力下抛光速率和速率一致性成为关键问题.对300 mm Blanket铜膜进行了低压化学机械抛光实验,分析研究了碱性抛光液组分及抛光工艺参数对铜膜去除速率及其一致性的影响.通过...