硅外延工艺与基座的相关性研究

Research of Relativity Between Si Epitaxial Process and Susceptor

硅外延使用包封SiC的石墨基座,基座的尺寸及基座上承载槽的形貌和硅外延片的滑移位错直接相关。为使高温下Si片内产生的应力不超过滑移位错产生的临界应力,必须使Si片处于均匀的温区。实际使用表明,基座边缘热辐射及热量被气流带走使基座两个边缘温度急剧下降,必须对边缘温区进行补偿及装片时避开基座边缘一定距离;高温时Si片通过基座获得热量并发生形变,基座上承载槽的形貌设计必须兼顾厚度匀匀性及Si片高温时形变的方向。研究表明,金属沾污尤其是重金属催化作用及过腐蚀是影响基座寿命的关键因素。

The coated SiC graphite susceptor was used in Si epitaxial process,the slip dislocation was closely related to the dimension and pocket shape of susceptor.In order to control stress under high temperature not to exceed the critical stress of slip dislocations generated,the wafer was put in even temperature zone.The results show that the edges temperature is relative cold and must be compensated,the wafer was loaded from a certain distance of the susceptor edge.The wafer was heated through the susceptor,this caused the wafer to bow.The design of pocket shape of susceptor should consider both thickness uniformity and bow direction.Metal contamination,especially heavy metal catalysis,and over-etching are the predominant causes of susceptor failure.