What are the reasons for the emergence of the black chip phenomenon of the monocrystalline silicon, which aspects of the production process have an impact on it, preventive measures, and improvement measures?
Preventive measures are in the ultra clean environment, indirect or direct contact with the silicon process, can not have any metal objects, especially stainless steel, is determined not to appear. There's a silicon chip! It is necessary to ensure the cleanliness of the chemical cleaning liquid, and the ratio is correct. Otherwise, it will also appear on the surface of the silicon wafer. Check polishing machine polishing head, calibration pressure. Also, there can not be bad to the silicon wafer, belonging to scrap wafers, shall be returned to the original factory to find the reasons.
Or storage time is too long, vacuum packaging problems, the outside world has the dust into the adsorption on the surface of silicon, this will happen. There is the central part of the polishing process, there is a problem of pressure, resulting in the removal of the center is not enough, the surface roughness is very poor, in the semiconductor level light irradiation, the center of the silicon will appear black.
You say the phenomenon called flower piece, the formation of many factors, the main reason is that contamination, because in the process, the wafer surface after polishing the silicon atom is bond breaking, it is easy to adsorb metal ions and cannot completely by cleaning out.
