Study On Particles Before APCVD About 200 Mm Heavily Doped Silicon Wafer

200 mm heavily doped silicon wafers are the main substrate materials for power semiconductors.APCVD(Atmospheric-pressure CVD)deposition film is one of the core processes in the fabrication of 200 mm heavy silicon wafers.As a common contaminant,particles are contaminated on the surface of silicon wafers.It will greatly affect the quality of the deposited film,which will affect the subsequent processing of silicon wafers and the performance of power semiconductor devices.Therefore,it is of great significance to study the particle size of 200 mm APCVD wafers.In this paper,a multi slot cleaning method combined SC-1?SC-2 and HF is used to clean the silicon wafer before APCVD;SiO2 film is deposited on the surface of silicon wafer by APCVD method using SiH4+O2 reactant gas.The surface laser scanning method is used to detect and map the number and distribution of the surface particles of 200 mm wafers;the flight type two ion mass spectrometry technique TOF-SIMS is used to detect the white spots on the surface of the silicon wafer after APCVD deposition.Experiments,involving different types of silicon wafer,change the cleaning method of pure sink,cleaning time of dilute HF chemical tank,and drying time of dry slot in the pre-cleaning process of APCVD;change the storage time in the class 100 environment with FFU before the APCVD completed;count the number of white spots on the surface by different dopants after the APCVD deposition of SiO2 films,in order to develop a more suitable solution to deposited SiO2 film for heavily doped silicon wafers and provide a more clean surface condition before APCVD.The study shows that:1.The surface particles on surface of silicon wafers in the class 100 clean environment,with the longer the storage time,the worse the surface particles are,and the small particles are with larger growth rate and trend;And about the storage of silicon wafers with different dopants,with the prolongation of the storage time,the particles on the surface of the B silicon wafer,whose increase and quantity of particles are the largest compared with other doped silicon wafers,while the growth of particles on As doped silicon wafers and Sb doped silicon wafers has little difference.2.Before APCVD,the drying of silicon wafers and the appropriate increase of the drying time are beneficial to reducing the adsorption of particles on the surface of silicon wafers;In 200s,it is more conducive to the cleanliness of the silicon surface.3.Under the premise that the basic cleaning process is kept constant,the overflow cleaning is more conducive to the removal of the surface particles on the silicon surface than the spray cleaning;Therefore,the spray cleaning tank can be changed into a overflow cleaning tank in actual production;4.The cleaning time of dilute HF can be appropriately increased during the cleaning process before APCVD;The cleaning time in the slot can effectively reduce the particle condition on the surface of the silicon wafer,and the particle number is almost invariable after a certain time.5.The existence of the white spot on the surface of the SiO2 film deposited by APCVD is related to the particles on the surface of the silicon wafer before APCVD;There are more white dots on the surface of the B doped silicon wafers,and it is inferred that the surface particles of the B silicon wafers are relatively poor after cleaning and drying,and the other two kinds of doped silicon wafers have little difference.