微量铜-铁对硅片表面污染的初步分析

通过比较微量铜铁单独存在和共存时对p-型硅片表面的污染,采用电化学直流极化和交流阻抗技术以及SEM、EDX和AES等现代表面分析技术,对未污染和受污染的硅片表面进行了初步的研究.结果表明,当氢氟酸溶液中同时含有ppb-水平(10-9)的铜铁杂质时,不但铜会沉积在硅片表面上发生铜污染,而且还导致硅片表面的碳污染,并从电化学极化电阻、元素深度分布和空间电荷效应等方面对硅片表面铜与碳污染进行了初步的分析和讨论.     

半导体硅片的P-n结和铜沉积行为的电化学研究

分别采用电化学直流极化和交流阻抗技术,通过控制光照和溶液化学组分,研究了半导体硅片/氢氟酸体系的电化学特性和半导体性能.对p(100)和n(100)两种硅片的研究结果均表明,有光照条件下硅/氢氟酸界面上的电化学反应很容易发生且起着主导作用,而黑暗条件下硅片则处于消耗期,电化学反应难于发生,因而其半导体性能起着重要的作用.当溶液中有微量铜存在时,硅/溶液界面上的电化学反应将被加速.通过单独研究两种硅片的电化学行为,讨论了半导体硅片在氢氟酸溶液中形成的p-n接点行为,并通过考察溶液中的铜离子浓度、光照条件和沉积时间对铜在硅片上的沉积行为的影响,探讨了铜沉积机理.研究结果表明,电化学交流阻抗法对研究稀释氢氟酸溶液中PPb浓度水平的微量铜杂质对硅片表面的污染极为有效,有望用于半导体硅片表面铜污染的检测.     

半导体硅片的p-n结和铜沉积行为的电化学研究

分别采用电化学直流极化和交流阻抗技术,通过控制光照和溶液化学组分,研究了半导体硅片/氢氟酸体系的电化学特性和半导体性能.对p(100)和n(100)两种硅片的研究结果均表明,有光照条件下硅/氢氟酸界面上的电化学反应很容易发生且起着主导作用,而黑暗条件下硅片则处于消耗期,电化学反应难于发生,因而其半导体性能起着重要的作用.当溶液中有微量铜存在时,硅/溶液界面上的电化学反应将被加速.通过单独研究两种硅片的电化学行为,讨论了半导体硅片在氢氟酸溶液中形成的p-n接点行为,并通过考察溶液中的铜离子浓度、光照条件和沉积时间对铜在硅片上的沉积行为的     

硅片背面铜污染的清洗

H2SO4/H2O2/H2O、HNO3/HF和HF/H2O2/H2O为半导体芯片生产过程中三种去除硅片背面铜污染的化学清洗液。在单片湿法清洗机上采用这三种化学液对直径300 mm具有类似于实际生产中铜污染的硅片进行了清洗,结果发现H2SO4/H2O2/H2O在清洗过程中不对硅片表面的Si3N4膜产生损伤,但铜污染的去除效率较低;HNO3/HF和HF/H2O2/H2O对Si3N4膜产生微量刻蚀,从而去除扩散至硅片内部铜污染,从而显示出较佳的去除效果。通过比较HF/H2O2/H2O中HF体积分数与Si3N4膜刻蚀深度和清洗后铜原子浓度,HF的体积分数为1.5%时,可以使硅片表面铜原子浓度降至1010cm-2以下,并且Si3N4膜厚的损失小于1 nm。     

半导体硅片金属微观污染机理研究进展

综述了近10年来国内外在半导体硅片金属微观污染研究领域的进展.研究了单金属特别是铜的沉积、形成机理和动力学以及采用的研究方法和分析测试手段,包括对电化学参数和物理参数等研究.指出了随着科学技术的不断发展,金属污染金属检测手段也得到了丰富,为金属微观污染的研究提供了有力的工具.     

清洗后硅片表面的电子结构

介绍了一种含表面活性剂和螯合剂的新型半导体清洗剂和清洗工艺。利用红外吸收谱、X射线光电子谱和原子力显微镜等 ,把它和标准 RCA清洗工艺的清洗效果做了比较。测试结果表明 ,经清洗过的硅片表面主要是由硅、氧和碳三种元素组成 ,它们分别以 Si-O键、C-O键和 Si-C键的形式存在。两种清洗技术都在硅片表面产生氧化硅层 ,在硅片表面都存在有机碳污染 ,但新型半导体清洗工艺产生的有机碳污染少于标准 RCA清洗。在对硅片表面的粗糙化影响方面 ,新型半导体清洗技术清洗明显优于标准 RCA清洗技术     

抛光液中缓蚀剂对铜硅片的影响

以硝酸铁为氧化剂选用不同缓蚀剂对铜化学机械抛光用抛光液的缓蚀效果进行了研究.通过测试不同缓蚀剂作用下铜的电化学极化曲线,来获得的腐蚀电流值和计算不同缓蚀剂的缓蚀效率.采用表面粗糙度为1.42nm的铜硅片进行静腐蚀和抛光实验,利用ZYGO粗糙度仪测试了硅片表面的粗糙度变化,并采用原子力显微镜分析腐蚀表面形貌.研究结果表明,在以硝酸铁为氧化剂的酸性环境中,苯丙氮三唑(BTA)作为铜抛光液的缓蚀剂具有良好的缓蚀效果.根据电化学参数计算出1.5wt%硝酸铁溶液中添加0.1wt%BTA的缓蚀率达99.1%;无论在静腐蚀还是在抛光过程中,在抛光液中添加BTA均可避免硅片严重腐蚀,使表面光滑.     

抛光液中缓蚀剂对铜硅片的影响

以硝酸铁为氧化剂选用不同缓蚀剂对铜化学机械抛光用抛光液的缓蚀效果进行了研究.通过测试不同缓蚀剂作用下铜的电化学极化曲线,来获得的腐蚀电流值和计算不同缓蚀剂的缓蚀效率.采用表面粗糙度为1.42nm的铜硅片进行静腐蚀和抛光实验,利用ZYGO粗糙度仪测试了硅片表面的粗糙度变化,并采用原子力显微镜分析腐蚀表面形貌.研究结果表明,在以硝酸铁为氧化剂的酸性环境中,苯丙氮三唑(BTA)作为铜抛光液的缓蚀剂具有良好的缓蚀效果.根据电化学参数计算出1.5wt%硝酸铁溶液中添加0.1wt%BTA的缓蚀率达99.1%;无论在静腐蚀还是在抛光过程中,在抛光液中添加BTA均可避免硅片严重腐蚀,使表面光滑.     

CVS技术在监控电镀铜槽液中的运用

介绍CVS技术在监控电镀铜槽液中有机添加剂的运用。文章首先将对电镀铜中的有机添加剂和CVS技术的电化学原理进行解说,然后对CVS分析仪对有机添加剂浓度进行测量的原理和CVS中有机添加剂程序的创建进行介绍,最后简要介绍CVS在有机添加剂来料查验、镀液污染值、碳处理情况等监控方面的运用,希望此文章能够对CVS化验分析人员对此仪器有更深一步的了解。     

分子污染和硅片隔离技术

大直径硅片千兆技术的发展对洁净生产环境提出控制分子级污染的要求。主要从“硅片隔离技术”和消除分子级污染的技术措施两方面着手。     

Overview of Cu contamination during integration in a dual damascene architecture for sub-quarter micron technology

A detailed study of copper contaminating steps performed during integration of multilevel Cu metallisation in dual damascene architecture has been performed. Contamination at the wafer back and the bevel edge should make it difficult to use the same equipment for conventional technology and new copper based technology. Several barrier materials have been claimed as efficient against copper diffusion. However, during process integration, contamination issues will be faced before deposition of the barrier layers. Heavy contamination can occur either during Cu chemical mechanical polishing (CMP) or during dielectric etching and via opening on top of contacted copper lines. These residues, concentrated at the dielectric surface, could result in current leakage and shorts between interconnection lines. Several cleaning solutions to remove metal contamination are reviewed and their efficiencies are compared.     

HF溶液中铜离子在硅片表面沉积的研究

研究了溶液中的铜离子在硅片表面的沉积情况,尝试采用几种螯合剂来减少铜在硅片表面的沉积.GFAAS的测试结果表明,HF稀溶液中加入少量螯合剂,均可以使硅片表面的金属Cu的沉积量显著减少,但不同的螯合剂效果不同,而且与溶液中螯合剂与铜形成的络合物稳定性质并不完全一致.加入螯合剂后,铜离子与螯合剂不仅在溶液中反应,而且在硅片表面形成竞争吸附,对铜离子在硅片表面的沉积量影响较大.     

Quantifying the impact of homogeneous metal contamination usingtest structure metrology and device modeling

Deposition of metallic impurities from HF process solutions has been investigated experimentally and explained theoretically in a qualitative manner. The depositions are shown to be electrochemical in nature in that an oxidation reduction reaction results in metal ions in solution depositing on the wafer as elements with an oxidation state of 0. The theory is only qualitative in that it can only predict which metals will deposit, not how much. Experimentally, simple transmission equations can be determined which relate metallic contamination levels on Si wafer surfaces (atoms/cm²) to metal concentration in the solution (ppb). Simple test structures have been fabricated with known amounts of iron and copper contamination in the pregate oxide clean of a 1.25 μm CMOS process. Device measurements indicate device degradation in the case of copper, confirming deposition studies that copper deposits from HF solutions. Iron contaminated wafers show no contamination related device effects, in support of theoretical predictions and deposition studies indicating iron does not deposit from HF solutions. The importance and potential usefulness of test structures as homogeneous contamination monitors is illustrated through device modeling of the contamination effects observed in the test structures that can then be used to estimate the effects of such contamination on ULSI circuit performance     

Si抛光片存储中表面起"雾"的研究

存储中Si片起"雾"是Si片存储面临的最大挑战,"雾"缺陷是可见或可印刷的晶体结构,从污染生长而来,已是困扰半导体业界长达10年以上的大问题.半导体制造商们至今还未能提出良好的解决方案.所以研究Si片的"雾"缺陷,并克服"雾"缺陷显得尤为迫切.从实际生产出发,根据实验数据分析和理论推导,建立了一个起"雾"原因基本模型,对引起"雾"缺陷影响因素进行了独立细致的分析,并在这个模型的基础上提出了相对应的有效的解决方案.     

Chemical studies of CVD Cu deposited on Ta and TaN barriers under various process conditions

Contamination in the matrix of CVD copper films and at the interface between CVD copper films and barrier layers has been characterized using XPS, SIMS, XRD and RGA. Contamination in the CVD copper matrix has been found to increase with increasing precursor flow rate and with decreasing wafer temperature. Interfacial contamination has been investigated in an attempt to quantitatively define acceptable levels of contamination and ultimately reduce the effect of these contaminants on the integrated film stack. Sputtered copper flash layers for CVD copper deposition are also shown as highly effective for reducing the levels and effects of incorporated contamination.     

An Electrochemical Cleaning Technique for Removal of Surface Contamination before Texturization of Silicon Solar Cells

In order to decrease the consumption of reagents and silicon during removal of surface contamination before silicon texturing in solar cell manufacturing industry, a new low-cost surface treatment approach of electrochemical cleaning technique(ECT) is reported. In this technique, a powerful oxidizing electrolyte was obtained from the electrochemical reaction on Boron-doped Diamond(BDD) electrodes, and applied during removal of surface contaminations on silicon wafer surfaces. The slightly polished monocryst...     

Chemical analysis of metallic contamination on a wafer after wetcleaning

The chemical analysis of trace metallic contamination on a wafer can be achieved by using total reflection X-ray fluorescence (TRXRF) with HF condensation and with poly silicon encapsulation secondary ion mass spectroscopy (PC-STMS). HF condensation can concentrate almost all atoms, such as Fe, Cr, and Ni, within 10 mm of the center of a wafer, which leads to lower detection limits. Poly silicon encapsulation eliminates the surface problems that tend to occur with normal SIMS, which results in good reproducibility. A combination of both methods is suitable for analyzing lower-level contaminations up to 10⁸ atoms/cm² level for many elements such as transient metals and lightly elemental metals. The application of the analyses to wet cleaning reveals the contamination removal and adhesion effects for various solutions and cleaning procedures, as well as variation between experimental cleaning batches     

螯合剂对酸性抛光液中铜离子沉积的影响

研究了几种螯合剂减少金属铜在晶片表面沉积的作用.将晶片放入含有或不含螯合剂的酸性抛光液中浸泡10min,用GFAAS测定表面沉积铜的浓度.结果表明,PAA、HEDP和AMPS的加入都能明显减少金属铜在硅片表面的沉积量,去除率分别为83%、79%和44%.进一步的研究发现,PAA过量时,即使螯合剂或者铜离子的浓度成倍增加,金属铜沉积量减少率变化不大.因此,加入过量PAA螯合剂不仅能够减少金属铜的沉积量,而且可以减弱沉积量的波动,增强工艺的稳定性.