Research And Design Of Intelligent Four-probe Tester

As the development of Electronics Science and Technology, the requirement of the semiconductor materials performance parameters is becoming higher and higher. The resistivity of semiconductor materials is one of the main performance parameters. At present, the four-probe tester is an important instrument to measure the resistivity of semiconductor materials. The traditional ones need to look for the measuring point manually, with the disadvantages of long measurement period, low accuracy and efficiency, it can not meet the development of the modern society, and the appliances with high degree of automation are quite expensive on market. Thus, the development of an intelligient and cheap tester is qutie neccessary.The thesis has analyzed the development and status of semiconductor materials testers both at home and abroad. On the basis of traditional ST-103A manual tester, combining with the PC, the control technology of SCM, the video capture technology and so on, the thesis has developed an automatic and intelligent four-probe tester, which can give a automatic measurement of the resistivity of semiconductor materials and has simple operation, with the features of high efficiency and low cost, has a certain value of development and a better market prospect.The main content of this thesis includes the following four parts: the mechanical improvements of probe station, the video capture system, the lower computer controlling block, and the design of upper computer screen. In the first part, based on the ST-103A manual tester, the mechanical connection part between lead screw and stepper motor and also between rolling rail and stepper motor was designed, using the stepper motor to replace the controlling hand wheel to realize the automatic and precise control of tester. The video-capture system is realized through the combination of CCD camera and SDK-2000 video card, with the aim to fulfill the in-time supervision of the sample measurement, and also the rapid and effective observation of sample location and the probe construction. The controlling of lower computer uses the MSP430F449--a kind of low power-consumption SCM, with a multi- I/O port and 12 A/D core as the central controlling circuit. This part includes the drive block of stepper motor, the constant current source block, the four strobe switch block and the Serial Communication block. It realizes the intelligent control of each block by compiling the SCM code. The interface of upper computer is carried out under the Visual C++6.0, and it realizes such functions as the instant display and storage of Microscope Image of test interface, the movement and measurement of the Tester, and the handling of measuring results. The connection between the upper and lower computer is realized through the Serial Communication Protocol. After the adjustment of the hardware and software of the tester, a test of measuring the Si sample was delivered. The result turns out that through the automatic control by the upper computer, the tester can find the measuring point quickly and precisely, and also can measure the resistivity of several points at the same time. The measuring data can be analyzed instantly and directly displayed on the screen of upper computer, which reaches a good communication between operator and computer with precise measurements.