Heavheavy Meatals Contamination On Solargrade Silicon Wafer And Removal Mechanism

Alkaline cleaning is a newly developed applied to the semiconductor industry asa cleaning process, with the function of saponification , emulsifying and with theultrasonic and mechanical movement. The use of surface-active agent can get a goodcleaning effect.This topic using graphite furnace atomic absorption spectrometry (GFAAS)analysis metal content of the silicon surface, verification the effectiveness of thealkaline cleaning process on a clear Cu, Fe and other heavy metal contamination.Alkaline cleaning fluid in the cleaning process may take longer time to maintain acertain pH value, because the surface of silicon wafer cleaning fluid element and theOH-place two-way chemical reaction, the reaction equilibrium, pH value ismaintained from 11.5-12 and will not be decline.Add surface-active agent in the alkaline cleaning solution ,compare with thesolution without surface active agents, metal deposition was significantly reduced.Experiments show that after addition of surfactant cleaning Cu, Fe concentrations arewithin the control limits, process stability, there is no variation points. In which themean Cu content of 6.16×1013atoms/cm2, Fe content of the mean2.853×1013atoms/cm2.Slurry recycle can significantly reduce costs, using Sysmex FPIA-3000 flowparticle image analyzer analyze the SiC particle size and roundness from different recycle time. Recovered PEG had increases in density and metal content and decreaseviscosity incompared with the new PEG and also the suspension is reduced. Withinthe use of the alkaline cleaning process can guarantee that the surface of silicon metalcontent to meet the requirements.