阻挡层CMP中表面活性剂对抛光效果的影响

研究了阻挡层在化学机械抛光过程中表面活性剂的作用。利用5种活性剂体积分数不同的抛光液对3英寸(1英寸=2.54 cm)Cu/Ta/SiO2光片进行抛光。通过抛光前后质量变化可得各晶圆片的抛光速率,再对12英寸布线晶圆片进行抛光,利用台阶仪测量抛光前后碟形坑大小的变化,最后利用原子力显微镜对抛光后布线晶圆片的表面形貌进行测试。研究表明抛光液中活性剂体积分数不同会引起抛光速率的变化,也会影响碟形坑的修正效果。当抛光液中活性剂体积分数达到2.0%时,修正值达到85.6 nm/min,优于其他活性剂体积分数时的修正值。另外,活性剂体积分数的增加有助于降低抛光后晶圆表面的粗糙度。活性剂体积分数小于3.0%时,粗糙度随着活性剂体积分数的增加而降低。这一发现可以对配制抛光液时活性剂体积分数的确定起到一定的参考作用。     

新型阻挡层抛光液对CMP后清洗效果的影响

当集成电路制造工艺缩小到14 nm及以下,阻挡层抛光清洗后表面缺陷严重影响芯片成品率。针对新型碱性阻挡层抛光液,与线上抛光液对比,通过检测抛光清洗后的晶圆表面缺陷,研究了不同阻挡层抛光液对CMP后清洗效果的影响。研究结果表明：当新型碱性阻挡层抛光液中不含盐酸胍时,抛光清洗后的晶圆表面存在大量划伤,盐酸胍的加入可同时提高TEOS和Cu的去除速率,且显著降低表面划伤数量;使用单一成分清洗液对不同阻挡层抛光液CMP后的晶圆清洗,新型阻挡层抛光液抛光清洗后的晶圆表面无任何污染颗粒,利于CMP后清洗,而线上抛光液的晶圆表面存在大量有机残留物和氧化物颗粒,需复配清洗液清洗;相比较线上阻挡层抛光液+复配清洗液工艺,使用新型碱性阻挡层抛光液+单一成分清洗液工艺产生的Cu/Ta界面腐蚀小,抛光清洗后的晶圆表面无明显的宽线条边缘缝隙和细线条表面塌陷的现象。     

不同表面活性剂对铜互连阻挡层CMP一致性的影响北大核心CSCD

为实现铜互连阻挡层化学机械抛光的高平坦化,研究了阻挡层抛光液中表面活性剂的作用。在抛光液中分别添加非离子型表面活性剂异辛醇聚氧乙烯醚(JFC-E)、本课题组研发的Ⅱ型活性剂以及复合表面活性剂,研究其对阻挡层CMP中铜和正硅酸乙酯(TEOS)去除速率及一致性的影响。实验结果表明,表面活性剂不仅可以改善Cu和TEOS的去除速率一致性和晶圆全局一致性,还可以降低铜表面的粗糙度,通过复配两种不同的表面活性剂,可以提高Cu和TEOS的去除速率,使Cu和TEOS的剩余厚度片内非均匀性(WIWNU)分别降低至1.39%和1.38%,铜表面粗糙度从5.25 nm降至1.51 nm。基于实验结果,研究并提出了表面活性剂影响抛光液润湿性,从而改善片内非均匀性和铜表面质量的机理。     

抛光液添加剂协同作用对铜互连阻挡层CMP后碟形坑及蚀坑的影响

为了有效控制铜互连阻挡层化学机械平坦化(CMP)过程中产生的碟形坑和蚀坑等缺陷,研究了在低磨料下柠檬酸钾(CAK)和FA/OⅡ络合剂协同作用对Cu/TEOS去除速率、碟形坑和蚀坑修正的影响.结果表明:加入质量分数为1％CAK后,TEOS去除速率增加了31.6 nm/min,Cu的去除速率无明显变化,说明CAK在不影响C...     

ULSI铜布线阻挡层Ta CMP及抛光液的研究

ULSI多层铜互连线中,由于Cu与Ta的硬度不同带来抛光速率的差异,使得在CMP过程中各种缺陷如碟形坑缺陷、磨蚀缺陷极易发生。研究分析了H2O2、有机碱对Cu和Ta抛光速率的影响,并进行了不同抛光液配比的试验。实验证明,在温度为30℃、压力0.08 MPa,转速60 r/min、抛光液流量为160 mL/min、抛光液成份为V(H2O2)∶V(有机碱)∶V(活性剂)∶V(螯合剂)=5∶15∶15∶25时,抛光速率一致性较好,能够有效降低碟形坑的出现几率;Cu、Ta的抛光速率均为500 nm/min左右,实现了CMP的全局平坦化。     

多种IC设计中Cu CMP阻挡层浆料选择和去除率的控制

集成电路的前缘技术是在低k介质材料上设计3个盖层的复杂结构,上面的盖层可以用TEOS(tetraethyl orthosilicate)四乙基原硅酸盐和/或氮化硅(SiN),下面的层可以在低k介质之上用氮碳化硅(SiCN),碳化硅(SiC),或CDO(carbon dopped oxide)直接生成。因此,对于适合铜CMP的选择性浆料,除了具备的高去除率之外,须是在去除上面盖层后能够在下面的介质层表面上终止的浆料。Rohm和Haas电子材料已经开发出能够有效地去除TaN,TEPS,SiN,CDO和/或SiCN,或这些材料的任一化合物的一系列浆料,或者是能够在TEOS、SiN、CDO、SiCN和SiC的任何一种或两种薄膜表面终止,这完全取决于这些特殊浆料的配方设计,通过一两种添加剂控制去除率达到要求。系列浆料中的大多数浆料研磨剂的含量较低,在低压力的情况下具有良好的去除率,为了适应多种行业的需求,高低pH值均可使用。大多数浆料是可调的,用一种或两种添加剂来控制薄膜的去除率。描述和讨论了这些浆料的改良原理。     

多层铜布线表面CMP后颗粒去除研究

针对目前清洗技术存在的问题进行了详细分析,研究了微电子材料表面污染物的来源及其危害,并介绍了表面活性剂在颗粒去除方面的作用。研究了化学机械抛光(CMP)后Cu布线片表面的颗粒吸附状态,分析了铜片表面颗粒的吸附机理。采用非离子表面活性剂润湿擦洗方法,使Cu表面的颗粒处于易清洗的物理吸附状态。利用金相显微镜和原子力显微镜(AFM)在清洗前后进行对比分析,实验采用聚乙烯醇(PVA)刷子分别对铜片和铜布线片进行清洗,发现非离子界面活性剂能够有效去除化学机械抛光后表面吸附的杂质,达到了较好的清洗效果。     

ULSI多层铜布线钽阻挡层及其CMP抛光液的优化

分析了铜多层布线中阻挡层的选取问题,根据铜钽在氧化剂存在的情况下,抛光速率对pH值的不同变化趋势,提出优化碱性抛光液配比进而改变pH值,以达到铜钽抛光一致性的方法,并进行了相应的实验研究.     

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.     

ULSl制备中Cu布线的CMP技术及抛光液的研究

对ULSI制备中铜布线技术作了系统的介绍,对CMP相关技术抛光机理、浆料的种类及成分均作了整体的分析和论述,并对目前存在问题及解决的方法和发展方向进行了分析讨论。此外,还对新研制的一种新型、高效、无污染的浆料进行介绍了。     

CMP中铜的碟形缺陷的研究

具体分析了铜的碟形缺陷并非由于抛光垫的弯曲造成,但是与抛光垫的表面形态有关,在此基础上,分析了铜CMP的作用机制,初步定性指出造成铜的碟形缺陷的原因,并对缺陷进行建模。比较了铜的碟形缺陷的电阻实际测量值和理论计算值,发现带碟形缺陷的电阻均大于理论值,并且随着铜的线宽增大,碟形缺陷也呈增大趋势。详细比较了选择性抛光液和非选择性抛光液对碟形缺陷的作用,从理论和测绘图形上证明选择性抛光液是造成碟形缺陷重要因素之一。采用了综合的工艺实验,最后得出抛光垫的种类及选择性抛光液在过抛光的情况下,是造成铜碟形缺陷的主要因素。     

直接敷铜技术中铜箔预氧化层的检测与控制

通过控制氧化的方法对制备敷铜陶瓷基板(DBC基板)的铜层进行预氧化处理。研究了预氧化温度、氧分压对铜箔氧化层物相和厚度的影响,采用拉曼光谱仪测试铜箔氧化膜物相组成,采用紫外-可见分光光度计测试铜箔氧化膜的吸光度,确定了铜箔表面氧化物层吸光度与厚度的关系。结果表明:预氧化温度在400~800℃,氧分压控制在100×10~(–6)~700×10~(–6),铜箔表面生成一层氧化亚铜(Cu_2O)层;在过高的预氧化温度和氧分压条件下,铜箔表面就会生成Cu O物相,而且氧化膜层变厚,表面疏松、局部出现氧化膜脱落,不利于DBC基板的制备。当氧分压为500×10~(–6),预氧化时间为1 h,温度为600℃时,铜箔表面可以获得均匀致密的Cu_2O薄膜,并且氧化膜与基体Cu结合紧密,有效提高DBC基板的结合性能。     

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.     

化学机械抛光工艺中的硅片背压力控制与优化

化学机械抛光（Chemical Mechanical Polishing,CMP）技术是最有效的晶圆全局平坦化技术,抛光头是CMP设备中最核心的部件之一,新一代抛光头的设计主要采用区域压力控制技术。硅片抛光质量不仅取决于抛光液,还取决于对硅片抛光压力的精确控制。在CMP抛光工艺过程中各腔室的压力设定值通常并非一致,而且由于柔性弹性隔膜的存在各腔室之间相互耦合。由于耦合现象的存在使得多区腔室压力控制变得复杂化,针对这一耦合现象本文提出了一种用于多区解耦的控制方法,并基于该方法对多腔室进行了系统辨识以及控制参数整定,最后进行了多腔室同时加压实验,实验结果表明该解耦控制方法的可行性以及正确性。     

Thermomechanical property of diffusion barrier layer and its effect on the stress characteristics of copper submicron interconnect structures

Thermal stresses of thin titanium nitride (TiN) films on Si and Ge substrates have been measured by the bending beam method. The biaxial modulus and coefficient of thermal expansion of TiN thin film were deduced from the thermal stress data and found to be 355 GPa and 7.4 ppm/°C, respectively. Finite element analysis was used to study the effect of TiN diffusion barrier on the stress state of Cu lines in submicron damascene interconnects. The diffusion barrier was found to have a significant effect on the stress state of the Cu lines, especially for those embedded in interlevel dielectrics of low dielectric constant (k) materials. For the Cu/oxide interconnect structure, the metal lines with diffusion barrier were found to have a high near-hydrostatic triaxial stress state as expected. For the Cu/low k interconnect structure, a near-hydrostatic stress state was found to exist in the presence of the diffusion barrier; without the diffusion barrier, the stress state was not near-hydrostatic, instead it was dominated by a shear behavior. The implication of the diffusion barrier effect on the thermomechanical reliability of Cu interconnects is discussed.     

Wafer back pressure control and optimization in the CMP process

Chemical mechanical polishing(CMP) is the most effective wafer global planarization technology.The CMP polishing head is one of the most important components,and zone back pressure control technology is used to design a new generation of polishing head.The quality of polishing not only depends on slurry,but also depends on the precise control of polishing pressures.During the CMP polishing process,the set pressure of each chamber is usually not the same and the presence of a flexible elastic diaphragm causes coupling effects.Because of the coupling effects,the identification of multi-chambers and pressure controls becomes complicated.To solve the coupling problem,this paper presents a new method of multi-chamber decoupled control,and then system identification and control parameter tuning are carried out based on the method.Finally,experiments of multi-chambers inflated at the same time are performed.The experimental results show that the presented decoupling control method is feasible and correct.     

Electrical characterization of the copper CMP process and derivation of metal layout rules

Design rules were developed for the layout of copper Damascene interconnect layers to minimize the within-die resistance variation. The impact of various layout configurations on the metal sheet resistance was characterized using two different test vehicles. An increase in resistance was observed on wide lines and high pattern densities due to dishing and dielectric erosion, respectively. In addition to the above, narrow lines were severely impacted by the presence of wide adjacent features in close proximity. The pattern interaction distance for copper chemical-mechanical planarization (CMP) was calculated by analyzing the resistance variation at the edge of a density or width transition. In this work, the interaction distance was found to be on the order of 25 /spl mu/m (as opposed to a few millimeters for oxide CMP). From these results, a window of about 50 to 60 /spl mu/m was found to be necessary to obtain the effective pattern density for copper CMP. The resistance of the upper metal level was a strong function of the underlying layer density. Hence, multilevel pattern dependencies have to be considered when modeling and predicting the line resistance on a real design. However, unlike oxide polish, pattern density alone is insufficient to predict the final copper thickness. Width-dependent spacing rules are necessary to prevent clustering of features (narrow lines very close to wide buses) and avoid regions of very low density.