Research On InP Single Crystal Equipment And Process Thermal Field Technology

Indium Phosphide?InP?is a key semiconductor material for the production of photonic devices,which has been widely used in civil and military fields.In recent years,with the rapid development of the demand for InP materials,InP crystal growth technology and equipment are also constantly improved.Large-scale and domestic production has become the main trend of InP equipment.At the same time,there are some problems in the localization of crystal furnace,especially thermal field?thermal system?.The thermal field structure and materials cannot achieve the best effect in the thermal stability and energy consumption,which will affect the performance of the crystal furnace,thus affecting the quality of single crystal products.In order to solve the problems,the Cz-50 type of InP single crystal device based on the phosphorus vapor injection in situ synthesis technology and liquid encapsulated Czochralski single crystal InP technologyand the thermal field have been developed.The results were as follows:?1?Based on the principle of Phosphorus vapor injection in-situ synthesis and liquid encapsulated Czochralski?LCE?crystal growing method,the CZ-50 Indium Phosphide?InP?single crystal furnace was designed.The main structure of CZ-50single crystal furnace was introduced,especially the structure of the in-situ synthesis device,where the Polycrystalline InP material was in-situ synthesized with phosphorus vapor injection method.Furthermore,considering the particularities of InP materials synthesis and single crystal growth,some innovative structure of the CZ-50 InP single crystal furnace were designed.A set of lifting thermocouple was designed and installed in the furnace cover that measuring the melt temperature directly in the crucible during the process of polycrystalline synthesis and single crystal growth.Using two sets of observation window shading device and the method of heating the observation windows with auxiliary electrodes and special heater,the long existing problem that the observation window pollution of the InP crystal furnace caused by phosphorus volatilization was solved.?2?In order to solve the problems of instability,poor symmetry and high energy consumption of the traditional graphite thermal field,the carbon/carbon?C/C?thermal field were optimized.Through the simulation and experiments,it is found that the heating power in the crystal growth process is obviously reduced,and the temperature gradient of solid-liquid interface is improved,and the symmetry of the thermal field is obviously increased by using C/C composite.?3?For the best performance of the C/C thermal field and Cz-50 type single crystal furnace,a series of crystal growth and synthesis experiment with the C/C thermal field and the Cz-50 type single crystal furnace were carred out.The experimental conditions of InP single crystal furnace were explored also.The study were as follows:the temperature control in the phosphorus injection synthesis stage,the melt temperature control of synthesis,heating power control,and the global phosphorus and phosphorus bubble insertion depth control etc.,The 8Kg In P polycrystalline and 4 inch InP single crystals were successfully prepared,and the crystal size and quality have reached the international advanced level.?4?The normal temperature Hall,the X ray rocking curve,etch dislocation density?EPD?and numerical simulation of thermal stress was used to analyze the crystal quality of single crystal grown by the Cz-50 single crystal furnace.Test results show that the carrier concentration of the undoped crystal is 1-10×10¹⁵ cm^-3,the carrier concentration of the doped S crystal is 1-10×10¹⁸ cm^-3,the resistivity of doped Fe crystal is>1×10⁷?.cm,the mobility of the non-doped crystal is greater than 4000 cm²/V.s,the mobility of the doped S crystal is greater than 1000 cm²/V.s,and the mobility of the doped Fe crystal is greater than 1000 cm²/V.s,the etch dislocation density?EPD?of the undoped and Fe doped crystals is less than 1×10⁵cm^-2,and the etch dislocation density?EPD?of the doped S crystal is between 500¹×10⁴cm^-2.The above parameters fully meet the use of optoelectronic devices and microelectronic devices.In addition,by numerical simulation,the change of crystal diameter was been found to have serious influence on thermal stress in the crystal.The defects of the crystal grown in the indium rich,near chemical ratio and phosphorus rich melt analyzed deeply.