STUDY ON NANO-INPROCESS MEASUREMENT OF SILICON WAFER SURFACE DEFECTS

硅片表面缺陷的检测是不断提高器件成品率和可靠性的一个重要方面。目前测量表面颗粒污染的方法分为两大类：(i)在强白光源照射下，用肉眼或显微镜对散射光进行人工颗粒计数；（ii）使用市售的He-Ne或He-Cd激光的自动粒子计数仪器。手工方法不允许精确的颗粒大小；第二种方法不允许检查表面缺陷和颗粒。对于下一代的大规模集成电路来说，这些缺点是很大的问题。因此，本报告描述了一种新的光学测量方法的发展，该方法适用于纳米过程中诸如COP，颗粒等缺陷的测量，并且没有上述缺点。本研究的结果总结如下：首先，我们开发了一种新的光学测量系统，该系统由Ar激光器和高倍率物镜组成，可以通过检测激光散射缺陷图案来定量评估缺陷。可以看出，0.212、0.605和1.16mum的孤立粒子作为激光散射缺陷图能够被清晰地检测出来。通过测量激光散射缺陷图的第一环直径，可以评估颗粒的大小。该方法利用激光散射缺陷图的特性对缺陷进行识别是可行的。其次，为了将该方法应用到过程测量中，我们使用光折变BSO晶体而不是CCD面积传感器来检测激光散射缺陷图。我们提出将光折变BSO晶体应用于硅晶片表面检测过程中检测到的激光散射缺陷图的体全息存储。为了验证所提方法的可行性，进行了基础实验。因此，在BSO晶体中记录激光散射缺陷图案只需10毫秒。利用空间复用技术可以在一个光折变晶体中记录多个全息图，在一个BSO晶体（7mm*7mm*3mm）中可以记录5个全息图。少

The detection of silicon wafer surface defects is a very important aspect in the continued improvement of the yield and reliability of manufactured devices. The current methods for measuring particulate contamination on surfaces are divided into two general types : (i) manual particle counting, by naked eye or with a microscope, of the light scattered under the illumination of an intense white light source ; (ii) automatic particle counting with a commercially available instrument that uses a He-Ne or He-Cd laser. The manual method does not allow for accurate particle sizing ; the second method does not allow examination of surface defects and particles. For LSI in next generation, these disadvantages are big problems. So, this report describes on development of a new optical measuring method applied to the nano-inprocess measurement of imperfections such as COP,particle, and so on without disadvantages mentioned above. The results obtained in this study are summarized as follows ;Firs … More t, we developed a new optical measuring system, consisting of an Ar laser and the objective lens of high magnification, which can quantitatively evaluate the imperfections by detecting the laser scattered defect patterns. It can be seen that an isolated particle of 0.212,0.605, and 1.16mum was able to be detected clearly as the Laser Scattered Defect Patterns. By measuring the first ring diameter of the Laser Scattered Defect Pattern, the particle size can be evaluated. This method has a feasibility to discriminate the imperfections by making the use of the characteristic of the Laser Scattered Defect Pattern.Second, in order to apply this method to the in-process measurement, we detected the Laser Scattered Defect Pattern not with CCD area sensor but with a photorefractive BSO crystal. we proposed to applied a photorefractive BSO crystal to a volume holographic storage of the Laser Scattered Defect Patterns, which were detected during the inspection of the silicon wafer surface. In order to verify the feasibility of our proposed method, the basic experiment was carried out. As a result, it takes only 10 msec to record a Laser Scattered Defect Pattern in a BSO crystal. Multiple holograms can be recorded in one photorefractive crystal using spatial multiplexing techniques and 5 holograms can be recorded in a BSO crystal (7mm*7mm*3mm). Less