多晶硅铸锭诱导吸杂技术

Special Gettering Process for Polysilicon Ingot

由于铸造多晶硅生长工艺特点,硅晶体自发成核以(111)晶向为主,同时Fe杂质的分布在铸锭的头部和尾部高、中间低;硅片少子寿命呈现头部和尾部低、中间高的分布趋势。大量杂质分布使得晶锭底部和顶部的材料难以通过后续吸杂和钝化工艺来改善少子寿命。本文通过特殊的铸锭诱导吸杂技术,诱导产生较强的(220)晶向,有效的减低铸锭,头部和尾部Fe的含量(其中头部和尾部分别降低了16.6%和22.0%),硅片头部和尾部分别提高了41.9%和11.9%。

On account of the growth process of ingot,the（111） orientation is the major crystal orientation for self-nucleation,Iron impurity shows a certain regular distribution for multicrystalline ingot with a higher content in the top and tail.However a lower content in the middle of the mc-Si ingot.Correspondingly the minority carrier lifetime of wafer have the distribution trend with a lower in the top and tail and a higher in the middle of the ingot.The lifetime in the bottom and top of the ingot can hardly be improved by gettering or passivation due to the considerable impurities.Special gettering process was introduced which could produce the（220） crystal orientation and decrease effectively iron content（top decrease 16.6%,tail decrease 22.0%） and improve the minority carrier lifetime in the top（41.9%） and tail（11.9%） of the ingot.