主要是随着衬底尺寸的增长，外延层的厚度、电阻率均匀性无法满足要求。
With large size wafer, the uniformity of thickness & Resistivity was out of control line.
而采用传统的“弹跳方程”进行厚度控制，虽然其无滞后，快速性好，但绝对精度差，也不能满足要求。
The traditional " elastic-plastic deformation equation has a good response without any delay, but it can not meet the requirement due to its poor absolute accuracy ."
接着，测试了厚度及透水性都满足要求的试样的轧光前、后的拉伸断裂性能。
The property testing of the samples before and after finishing shows that calendaring finishing can lower the thickness and water permeability rate of the samples significantly.
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