Abstract
Experiments were conducted in order to obtain the relation between surface tension of molten and oxygen partial pressure. Clarifyiyng the relation holds a key for understanding the Marangoni convection of molten silicon in a Czochralski (CZ) system.Measurements of surface tension and density of molten silicon were performed by the sessile drop method using BN substrate under argon atmosphere at 1693 K. Oxygen partial pressure Po_2 of argon gas was controlled below the equilibrium Po_2, that was, Po_2,_<sat>, of S1O_2 by the aid of argon gas purifier and tightly sealed furnace made of double alumina tubes. Po_2 was determined with oxygen sensor of solid electrolytes, ZrO_2・CaO. Surface tension of molten silicon was 813 mN/m at 1693 K under a condition of Po_2=2.58×l0^<-22> MPa. The surface tension remarkably decreases with increasing Po_2 up to Po_2,_<sat> of SiO_2 at 1693 K. However, above Po_2,_<sat>, the surface tension keeps almost constant with incrcasing Po_2.
