CMP对低k介质材料的影响及其优化方法研究

发布时间：2018-03-14 11:13

本文选题：低k介质　切入点：化学机械抛光　出处：《河北工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着集成电路产业的不断发展,铜互连特征尺寸不断降低,布线层数不断增加,互连引线延迟(RC延迟)成为不可忽视的制约集成电路发展的一大障碍。因此铜、钽、低k介质等材料被引入到集成电路制造工艺中。伴随新材料的引入,传统刻蚀工艺已经不能满足生产要求,大马士革工艺应运而生。大马士革工艺中,材料平坦化采用化学机械抛光(CMP)的方法。阻挡层的化学机械抛光能够最终决定平坦化效果和集成电路成品率。阻挡层抛光中,低k材料疏松多孔,相对介电常数容易受到CMP工艺影响而升高,影响器件性能和可靠性。因此阻挡层抛光既要实现较高的材料去除速率、保证工艺过程对碟形坑有明显的修正效果,又要保证工艺过程对低k材料的相对介电常数影响较小。低k材料是阻挡层的一部分,本课题首先对阻挡层抛光中的速率选择性进行了深入研究。通过大量单因素实验研究了碱性抛光液的磨料、螯合剂、活性剂、pH对Cu/Ta/SiO2/SiOCH抛光的作用效果,初步研发了一种碱性抛光液,并在12英寸单层图行片上验证了使用碱性抛光液进行阻挡层抛光的可行性。课题进行了低k材料CMP的研究。本文在研究相对介电常数概念的基础上,阐述了通过电容测量相对介电常数的理论基础。通过红外光谱仪观察了CMP前后傅里叶红外光谱图变化情况,发现CMP使材料内的化学物质发生了一定变化。在此基础上,进一步研究了不同磨料浓度和抛光液pH值对相对介电常数的影响情况,发现低磨料或低pH的碱性抛光液对材料介电常数影响更小,另外通过抛光后的退火处理也可以进一步修正材料k值。文章最后采用降低抛光液pH值的方法改进了初步研发的碱性阻挡层抛光液。改进后的碱性阻挡层抛光液可以把碟形坑和蚀坑控制在可接受范围内,并且使图形片电阻值可以控制在1.19kohm至1.46kohm,互连电容为2.24~2.43pF,漏电流极小,满足工业要求,取得了良好的抛光效果。本课题通过一系列研究,使改进后的碱性抛光液对低k介质材料k值的影响可以与主流的酸性抛光液相当,并且在其他性能上取得优良效果。这种抛光液成分简单、便于后续清洗、速率选择好、对设备腐蚀小、环境污染小。
[Abstract]:With the continuous development of the integrated circuit industry, copper interconnect feature size decreases, the wiring layers increasing, interconnection leads delay (RC delay) has become a major obstacle to the development of integrated circuit can not be ignored. Therefore, copper, tantalum, low k dielectric material manufacturing technology was introduced into the integrated circuit. With the introduction of new materials the traditional etching process has been unable to meet the requirements of production process, Damascus Damascus came into being. In the process of flattening materials with chemical mechanical polishing (CMP) method. The chemical mechanical polishing barrier layer can be decided flattening effect and IC yield. Barrier polishing, low k material is porous, relative dielectric constant CMP process vulnerable to the effects of increased, affecting the performance and reliability of devices. Therefore barrier polishing to achieve both high material removal rate, to ensure the process of dish shaped pit There is an obvious compensation effect, but also to ensure the process of low k material relative permittivity is less affected. Low k material is a part of the barrier layer, this paper conducts an in-depth study on the blocking rate of selective layer polishing. Through a single factor experiment of alkaline polishing abrasive, chelating agent. The effect of surfactant, pH Cu/Ta/SiO2/SiOCH polishing, developed an alkaline polishing liquid, and verifies the feasibility of the barrier layer polishing using alkaline slurry in a 12 inch single map sheet. Research of low k material CMP. Based on the research of the relative dielectric constant on the concept describes the theoretical basis of the relative dielectric constant of capacitance measurement. Changes of FTIR spectrums before and after CMP were observed by infrared spectroscopy, the results showed that CMP chemical substances within the material changed. On this basis, further research on the effects of abrasive concentration and slurry pH value effect on the relative dielectric constant, low abrasive or low pH alkaline slurry of the dielectric constant effect is smaller, also by annealing after polishing can be further modified material K value. Finally the basic preliminary improvement research methods to reduce the pH value of slurry of barrier slurry. The improved alkaline barrier slurry can be controlled in an acceptable range of dishing and erosion pits, and the graphics sheet resistance can be controlled in 1.19kohm to 1.46kohm, 2.24~2.43pF interconnect capacitance, small leakage current and meet the requirement of industry, achieve the polishing effect is good. This topic through a series of studies, the effect of alkaline slurry after the improvement of low k dielectric material K value is equal to the acidic polishing liquid and other properties in the mainstream, The polishing liquid has the advantages of simple composition, easy cleaning, good selection of speed, small corrosion to equipment and small environmental pollution.

【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN305.2

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