The Research And Preparation On Fz Single Crystal Silicon With Large Diameter

With the development of semiconductor technology, large diameter single crystal silicon has been inevitable trend. However, the growth of floating zone silicon with larger diameter(for short FZ-silicon), especially 6 inches and more large, is extremely difficult. At the same time, foreign technology has been strictly blockaded to our country. In order to break the status quo, domestic technology development for growing 8 inches FZ-silicon become imperative. Based on this situation, we established the research goal and made detailed experiment design. With the advanced FZ furnace and high purity polycrystalline silicon, we grew 8 inches FZ-silicon successfully, whose various technical indicators have perfectly achieved the goal after Neutron Transmutation Doping and heat treatment.This paper focuses on the growth technology of FZ-silicon with large diameter and heat treatment technology. Intrinsic difficulty for large diameter FZ-silicon single crystal growth involves thermal stress, which results in the crack of the single crystal dislocation or cracks, silicon thorn appeared during melting polycrystalline bar material, and the improvement of the original single crystal radial resistivity distribution. By the design of heating coil and shield, as well as the crystal growth rate, crystal rotate speed, coil position, working frequency, and so on, the symmetry of thermal field was improved. The radial and axial temperature gradient was reduced, and then single crystal thermal stress decreased, and finally the technical problem of single crystal cracks was solved successfully. By the research on melting technology, we improved the melting behavior and avoided appearance of silicon thorn, simultaneously effectively improved FZ-silicon radial resistivity variation(for short RRV). The optimum heat treatment has been obtained, by the study of heat treatment process after the NTD and with comprehensive consideration of heat treatment temperature, time and cooling rate and other important parameters. And we successfully eliminate damage from NTD process, restore the target level of single silicon, and ensure minority carrier lifetime.Through this study, we determine the growth technology for 8in FZ-silicon growth and heat treatment technology after NTD, and successfully get 8in FZ-silicon whose various performance indicators meet the target. Specific performance parameters as follows: N-type <100>+20′,Diameter 202-203 mm, resistivity 538/536 ?·cm, the head and tail RRV are 4.2% and 3.7% respectively, oxygen concentration <1×1016 at/cm3, carbon concentration <1×1016 at/cm3, minority carrier lifetime 861 ?s.