Study On The Growth Process Of 300 Kg Sapphire Crystal

Due to its excellent physical and chemical properties,sapphire is the material of choice in screens for civilian,military,aerospace,and electronic products.At the same time,it is also a high-quality and inexpensive substrate material for LEDs.At present,the large market demand for LED’s drives the demand for sapphire substrates,especially for 4 and 6-inch substrates.Although the domestic sapphire growth technology has made breakthroughs at this stage,Mono crystal and other major manufacturers have begun to develop and launch 350kg-level sapphire crystals with higher utilization and lower costs.Therefore,combining their own technical foundations,they have begun to develop 300kg-level sapphire crystal growth.The technology is of great significance.The breakthrough of this technology can not only increase the output of large-size substrates,but also greatly improve the utilization rate of crystals,reduce the cost of substrates,and increase the market competitive value of sapphire substrates.In this study,the Kyropoulos sapphire crystal growth technology was adopted,and the 300kg-level sapphire growth thermal field design,process construction,crystal defect analysis and process problem improvement were carried out.The main work and innovations of the thesis are as follows:(1)Selecting the KY method,carrying out the KY method and defect analysis,designing the 300kg sapphire growth heat field and technology,and producing 300kg sapphire single crystal.(2)Use CGSim software to simulate the 300kg thermal field and growth process,and initially solve the problems of irregular fluid and improper solid-liquid interface angles.In addition,the design of a straight heater was applied for a patent and was authorized.(3)Calibration of temperature and corresponding power by introducing infrared temperature measurement,combined with thermal expansion characteristics of sapphire,to conduct crystal annealing experiment:1.Design a two-stage power reduction program to reduce 40h cooling time;2.Carry out charging and cooling in advance to speed up low temperature In-situ cooling,reducing cooling time by 20h.(4)During the experiment,there were process problems such as seed crystal chuck fracture,long crystal cycle,and crystal defects such as color centers,inclusions,and bubbles.Through phenomenon analysis and software simulation,thermal field modification and process optimization were performed,and the output A high-quality 300kg sapphire crystal and produce 4-inch ingot with an effective length of 2533mm.The yield is about 71%.