PULLING UP OF SILICON SINGLE CRYSTAL

摘要

PROBLEM TO BE SOLVED: To prevent breakage of a crystal and minimally suppress increase of cost in a squeezing step for obtaining dislocation-free state in pulling up a silicon single crystal having crystal axis <110> by Czochralki process. SOLUTION: In a squeezing step, a crystal diameter is squeezed to <2.0mm while applying magnetic field having >=1,500 gauss to a hot zone in a squeezing step. Vibration and change of temperature of the melt surface become small by application of magnetic field and breakage of crystal in solid-liquid interface which occurred from the past is prevented. In a shoulder-making step followed by the squeezing step, the strength of the applied magnetic field is gradually decreased and the strength of magnetic field is decreased to 0 until step is moved from the shoulder-making step to a drum-making step. Dislocation-free single crystal having crystal axis <110> is obtained by the method and increase of cost is minimally suppressed, because magnetic field is not applied in a step after the drum-making step.