The Application Of Image Identify In The Micro-Area Four-Probe Testing System

With the high speed development of computer , the integrated circuit as the basis of computer have been developed from VLSI to ULSI . So in one hand it requires the wafer's diameter to be more large in order to enhance the productivity, and on the other hand it puts forward more strict requirement about the crystal perfection and electricity character .Especially the electronic character and the equality of micro-area in the crystal wafer has become the key factor to determine whether the device can be made on it or not .So the resistivity measurement of micro-area become one most important procedure in the chip machining .To ensure the produce quality of chip and the perfect performance of final production ,the four-probe testing technology need to be deeply studied .This paper mainly accomplished the following research: summarize the classify and application fields of four-probe testing technology ;take the square four-probe testing technology study by using the advantage of Rymaszewski method in auto-eliminating the portrait wandering influence to induct Ry method to square-probe testing method ;deeply study the influence of probe wandering to progressed Ry method testing result ;complete the design of testing panel and testing circuit ,realize the auto-testing of mono crystal wafer ;discuss the image enhancement and threshold selection problem in image identify ,and finally accomplish the identify of probe pinpoint.The main new view points of the research:1. It is the first time for applying image manipulation and analysis technique to the sheet resistance measurement, and achieving the auto-location function of the probe. This is the first time in this field.2. Putting forward Rymaszewski method to square four point probe measurement.3. Studying various pretreatment for the probe image and applying the pixel threshold selection technique to distinguish the probe from wafer and adjust the measurement position automatically.4. Accomplishing the development of square four point probe instrument with the function of image manipulation for testing sheet resistance automatically .