Study On Silicon Wafer Laser Cutting Head And Cutting Performance

Silicon wafer is a kind of commonly used semiconductor material,which is widely used in many fields.Traditional silicon wafer cutting method is high speed diamond wheel contact cutting,but the cutting process is prone to chipping and other defects.Laser cutting can effectively control the defects caused by uneven stress because it used as a non-contact cutting method.Firstly,cutting head was designed according the basic principle of motion principle and optical system of dual galvanometer laser cutting head by using SolidWorks.The thesis focus on optical fiber connection module of cutting head,collimating module and robot connecting module.The cutting range of this cutting head was 200mm×200mm and the cutting precision was ±0.05 mm.According the silicon wafer cutting test,the design of dual galvanometer laser cutting head could meet the requirements of design and production.Silicon wafer laser cutting experiment was conducted by using dual galvanometer laser cutting head and picosecond laser,and grooving test and implicit crystal cutting test were conducted.When in grooving test,the laser output power,pulse frequency and cutting speed were changed.The results showed that the cutting width and cutting depth were increased with the increase of power,deceased with the increase of cutting speed and increased with the increase of frequency.The height of slag and width of spatter were increased with the increase of power,deceased with the increase of cutting speed and increased with the increase of frequency.The power of 30 W,the cutting speed of 100mm/s and the frequency of 40 kHz were the optimum process parameters obtained by the orthogonal test.Scanning Electron Microscope(SEM)and Energy Dispersal Spectrometer(EDS)were used to analyze the grooving test results in the optimum process parameters.The analysis showed that although the high energy density was provided by picosecond laser in cutting process,almost no oxidation was found around the groove,so the physical and chemical properties of groove could keep stable.The test of implicit crystal cutting showed that power of 0.88 W,frequencies of 80 kHz and cutting speed of 300mm/s were the optimum process parameters.Chipping of implicit crystal cutting method was 40?m,decreasing about 42% compered with 70?m of chipping in traditional cutting method,and decreasing about 5% compered with 42?m ofchipping in water guide laser cutting.Water guide laser cutting method was conducted to compare the cutting quality influence in different laser cutting method.The results showed that the optimal process parameters of grooving test were hydraulic pressure of 13 MPa,power of 2W and cutting speed of500mm/min,the optimum process parameters of penetration cutting test were hydraulic pressure of 13 MPa,power of 2W and cutting speed of 200mm/s.When cutting in the optimal process parameters,the slit had no heat affected zone,splash zone didn't appear around of slit,cutting edge was smooth,cutting seam had good verticality.The cutting section was divided into three areas according to its characteristics,they were region 1of the slit near the surface,region 2 of the middle area and region 3 of the slit near the under surface.The roughness of region 1 was 8.037-14.621?m,region 2 was 4.908-6.640?m and region 3 was 6.344-7.108?m.The results showed that there were great difference in roughness of three regions.The roughness of region 2 was the least region and the region 1 was the maximal region.The chipping of water guide laser cutting method was 42?m,decreasing about 40% compered with70?m of chipping in traditional cutting method.