|Budget Amount *help
¥6,700,000 (Direct Cost : ¥6,700,000)
Fiscal Year 1996 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1995 : ¥5,800,000 (Direct Cost : ¥5,800,000)
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 ;
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).