碲镉汞表面处理工艺研究

发布时间：2018-05-01 11:08

本文选题：HgCdTe + RCA　；参考：《中国科学院研究生院(上海技术物理研究所)》2015年硕士论文

【摘要】：碲镉汞(Hg1-x Cdx Te)是由Ⅱ-Ⅵ族的碲化汞(Hg Te)和碲化镉(Cd Te)混合而成的连续固溶体,其禁带宽度可随组分x连续变化,响应波段可覆盖整个红外波段,是最重要的红外半导体材料之一。在导弹制导、环境与资源遥感、夜视、卫星和民用等领域,Hg Cd Te红外探测器发挥着重要的作用。Hg Cd Te表面性质在很大程度上决定了Hg Cd Te红外探测器的光电性能,为了进一步提高Hg Cd Te红外探测器的性能,需要对Hg Cd Te表面处理工艺进行更加深入的研究。Hg Cd Te表面处理的主要工艺是抛光和清洗工艺,这两个工艺与Hg Cd Te表面的粗糙度、平整度、损伤和污染物残留有着直接关系。因此,本文从Hg Cd Te抛光工艺和清洗工艺着手,对化学机械抛光技术(CMP-Chemical Mechanical Polishing)、溴抛光技术(Bromine Polishing)和清洗技术(Cleaning Technology)进行了深入的研究。首先,本文对各种CMP工艺条件处理的Hg Cd Te表面平整度进行了研究。调整CMP过程中载物夹具重量、抛光时间和抛光平台转速三个因素,使用激光干涉仪对调整后的Hg Cd Te表面平整度进行表征,采用正交实验分析法对平整度数据进行分析,从而获得了一个最佳Hg Cd Te平整度的CMP工艺条件。另外,本文对CMP处理后Hg Cd Te晶片中间呈现“凸”形的原因进行了分析,并指出:虽然载物夹具一直在自转,由此导致Hg Cd Te晶片中心位置和边缘位置的瞬时速度不同,但是在载物夹具本身旋转的一个周期T内,Hg Cd Te晶片任何位置在该周期T内的平均速度是相同的。根据CMP抛光速率的机理,抛光速率MRR正比于速度V。从一个周期T综合来看,因为平均速度是相同的,所以速度的不同并不是造成Hg Cd Te晶片中间“凸”形的原因,而Hg Cd Te晶片边缘区域先于中心区域接触到新鲜抛光液,由此导致Hg Cd Te晶片边缘位置的化学反应强于中心位置的化学反应,这点可能是Hg Cd Te晶片中间“凸”形的原因。除了CMP技术被应用在Hg Cd Te减薄和表面优化外,溴抛光技术也是一种常用的Hg Cd Te减薄和表面优化的加工技术。相比CMP技术,溴抛光技术在平整度、厚度控制、抛光速率和工艺区间适应度等方面并没有很大的优势,但是溴抛光技术有一个重要的优点,那就是溴抛光带来的表面损伤很小。要将溴抛光技术应用于Hg Cd Te表面处理工艺中,必须解决溴抛光过程中Hg Cd Te表面极易发黑和出现小麻点的问题。通过调整Br2-CH3OH溶液浓度、抛光垫含水和载物夹具重量三个因素,发现了Hg Cd Te表面发黑或出现小麻点的原因,并建立了一套稳定的溴抛光工艺流程,该溴抛光工艺流程已应用于工程任务Hg Cd Te器件的制作。其次,清洗工艺是去除Hg Cd Te表面有机物、颗粒和离子等沾污的主要工艺,这些沾污对Hg Cd Te器件性能有着巨大影响。本文借鉴了硅片的RCA清洗技术和兆声清洗技术,将其应用于常规碲镉汞清洗工艺的改进,并设计了一种新碲镉汞清洗技术。最后,本文从X-射线光电子能谱、电荷密度和器件性能三个角度对常规碲镉汞清洗技术和新碲镉汞清洗技术的清洗效果进行了表征和对比,获得了四个结论,一是常规碲镉汞清洗技术有可能会引入有机物污染;二是新碲镉汞清洗技术处理的Hg Cd Te表面含有更少的总离子量,并且新清洗Hg Cd Te表面的慢表面态密度要优于常规清洗的Hg Cd Te表面;三是阳极氧化层会引入大量正电荷;四是新碲镉汞清洗技术处理的Hg Cd Te器件性能比常规清洗技术处理的Hg Cd Te器件有一定的提高,但还需更多的数据进行验证。
[Abstract]:Mercury cadmium telluride (Hg1-x Cdx Te) is a continuous solid solution composed of 2 - VI group of mercury telluride (Hg Te) and cadmium telluride (Cd Te). The band gap can be continuously changed with the component X, and the response band can cover the entire infrared band. It is one of the most important infrared semiconductor materials. In missile guidance, environment and resources remote sensing, night vision, satellite and civil collar. Domain, Hg Cd Te infrared detector plays an important role in the.Hg Cd Te surface properties to a great extent determines the photoelectric performance of the Hg Cd Te infrared detector. In order to further improve the performance of Hg Cd Te infrared detector, the main process of surface treatment is to be polished. And cleaning process, these two processes are directly related to the roughness, flatness, damage and residue of the Hg Cd Te surface. Therefore, this paper starts with the Hg Cd Te polishing process and cleaning process, on the chemical mechanical polishing (CMP-Chemical Mechanical Polishing), bromine polishing (Bromine Polishing) and cleaning technology (Cleaning) Ology) carried out a thorough study. First, this paper studies the surface evenness of the Hg Cd Te treated by various CMP process conditions. The weight of the fixture, the polishing time and the speed of the polishing platform in the CMP process are adjusted by three factors, and the laser interferometer is used to characterize the Hg Cd Te surface evenness after the adjustment, and the orthogonal experimental analysis method is adopted. The smoothness data is analyzed and a CMP process condition for the best Hg Cd Te evenness is obtained. In addition, this paper analyzes the cause of the "convex" shape in the middle of the Hg Cd Te wafer after CMP processing, and points out that the instantaneous velocity of the center position and edge position of the Hg Cd Te wafer, although the carrier fixture has been rotated all the time. Different, but the average speed of any position of the Hg Cd Te chip is the same within this period T within a period of T rotation of the carrier fixture itself. According to the mechanism of CMP polishing rate, the polishing rate MRR is proportional to the speed V. from a periodic T, because the average velocity is the same, so the difference of the speed is not the Hg Cd Te. The cause of the "convex" shape in the middle of the wafer, and the Hg Cd Te chip edge area contact with the fresh polishing liquid first in the center area, which leads to the chemical reaction of the edge position of the Hg Cd Te wafer stronger than the central position. This may be the cause of the "convex" shape in the middle of the Hg Cd Te wafer. Besides CMP technology is applied in Hg Cd to reduce and table. Bromine polishing technology is also a common processing technology for Hg Cd Te thinning and surface optimization. Compared to CMP technology, bromine polishing technology has no great advantage in flatness, thickness control, polishing rate and process interval fitness, but bromine polishing technology has an important advantage, that is, the table brought by bromine polishing. In order to apply bromine polishing technology to the Hg Cd Te surface treatment process, it is necessary to solve the problem that the surface of Hg Cd Te is very easy to blacken and appear small pockmarks in the process of bromine polishing. By adjusting the concentration of Br2-CH3OH solution, the water cut of the polishing pad and the weight of the carrier fixture, the reasons for the black or the small pockmarks appear on the Hg Cd Te surface are found. A set of stable bromine polishing process has been established. The bromine polishing process has been applied to the production of Hg Cd Te devices in engineering tasks. Secondly, the cleaning process is the main process to remove the contamination of Hg Cd Te surface organic matter, particles and ions. The contamination has a great influence on the performance of Hg Cd Te devices. This paper draws on the RCA of the silicon wafer. Washing technology and megabyte cleaning technology are applied to the improvement of conventional mercury cadmium telluride cleaning process, and a new mercury cadmium telluride cleaning technology is designed. Finally, the cleaning effect of conventional mercury cadmium telluride cleaning technology and new tellurium mercury cleaning technology is characterized by three angles of X- ray photoelectron spectroscopy, charge density and device performance. Four conclusions are obtained, one is that conventional mercury cadmium telluride cleaning technology may introduce organic contaminants; two the Hg Cd Te surface of the new HgCdTe cleaning technology contains less total ion content, and the slow surface density of the new cleaning Hg Cd Te surface is superior to the conventional cleaning Hg Cd Te surface; three is the anode oxidation layer will introduce a large amount of the surface. Positive charges; four Hg Cd Te devices treated by HgCdTe cleaning technology have a certain improvement in the performance of Hg Cd Te devices treated with conventional cleaning technology, but more data need to be verified.

【学位授予单位】：中国科学院研究生院(上海技术物理研究所)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN305.2

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