300mm直拉单晶硅生长过程中晶体长度对内应力的影响

Influence of Crystal Length on the Thermal Stress in 300 mm CZ Single Crystal Silicon Growth

晶体内热应力是影响太阳能级单晶硅性能的关键因素之一。本文通过对晶体生长过程中热量的散失方式与晶体内应力之间的关系进行研究。结果表明,在晶体生长初期,晶体内热量主要通过籽晶传热、晶体肩部表面散热和晶体侧表面散失来进行交换。因此,在晶体籽晶下方、肩部下方和晶体侧表面均出现较大应力区域;随晶体生长的进行,热量传输方式转变为以晶体侧表面散热为主,这也导致晶体内最大应力值均集中在该区域。同时,晶体内最大应力值随晶体长度的增加而逐渐降低。

The thermal stress is one of the key factors to affect the quality of solar-grade single crystal silicon. In this paper,the relationship between heat loss behavior and thermal stress in crystal during crystal growth has been analyzed. The results show that the heat exchange in the crystal mainly be conducted by heat conduction by seed,heat loss from shoulder surface and heat loss from crystal peripheral surface in the starting crystal growth. Consequently,the high thermal stress intensity has been located below the seed, shoulder surface and peripheral surface. As crystal growing, the heat transmission way has been changed to heat loss from crystal surface near crystal-liquid interface,resulting to the maximum thermal stress appear in this part. Additionally,the maximum thermal stress decrease with increasing crystal length.