半导体硅熔体的有效(磁)黏度

用钕铁硼(NdFeB)永磁材料构建"魔环"结构的永磁体，向直拉硅生长的熔体所在空间引入磁场，采用回转振荡法测量不同磁场强度下硅熔体的有效黏度(磁黏度).在温度一定时，测得的磁黏度随着磁场强度的增加而增加，二者呈抛物线关系.熔硅温度升高，磁场影响加剧.1490—1610℃温度区间内，磁黏度有异常变化.当引入磁场强度为0068T时，熔硅有效黏度比原黏度增加2—3个数量级，证明引入磁场是硅单晶大直径生长时，抑制熔硅热对流的有效手段. 关键词： 硅熔体 有效(磁)黏度 魔环永磁体 回转振荡法

The effective viscosity of silicon melt in magnetic field

A magnetic field generated by a magic ring was applied to the space containing the silicon melt, and the effective viscosities of silicon melt were measured by the method of rotary vibration. The magic ring was constructed by permanent magnets made of NdFeB permanent-magnet material. The results showed that, at certain temperature, the effective viscosity increased with the increase of magnetic field intensity, and they are parabolically related. The magnet field had stronger effect when the silicon melt temperature increased, which was indicated by a more warped up parabola. In the range of 1490 to 1610℃, the viscosity had an extraordinary fluctuation which indicated a structure change in the silicon-melt. The value of silicon melt viscosity increased by 2—3 orders of magnitude when the magnetic field reached 0.068T. The results indicated that applying a magnetic field to the silicon melt space is an effective way to suppress thermal convection during the growth of large diameter single crystal silicon.