大面积应用的RF-PECVD技术研究

Large Area Films Growth by RF-Plasma Enhanced Chemical Vapor Deposition

本文探讨采用小电极与大面积基片相对移动的方法来制造大面积薄膜的可行性,提出了采用小电极等离子体源在大面积基片上移动工作的新方法,可用于沉积(或刻蚀)均匀大面积薄膜或根据需求设计的大面积上非均匀膜厚分布的薄膜,从原理上避免大电极带来的不均匀性。介绍了这种方法中由两个电极构成的等离子体增强化学气相沉积(PECVD)系统。分析了当电极移动时,电极与真空室壁相对位置发生变化时对等离子体参数的影响。我们发现当两个射频电极之间的相位差为定值时,等离子体的分布随电极与真空室壁的距离(极地距)变化而变化。当极地距小于80mm时,随极地距的增加,等离子体的悬浮电位和基片的自偏压下降,离子密度变化不明显。当极地距大于80mm时,等离子体的分布呈稳定状态,各参数变化不明显。采用PECVD方法镀制了大面积薄膜厚度呈均匀分布和非均匀分布的两种薄膜,提供了膜厚呈线性渐变和抛物线变化的两种薄膜样片,显示了该方法的灵活性和可行性。

A novel technique has been developed to grow films on large area by modified RF plasma enhanced chemical vapor deposition （PE-CVD） .The highlight of the new technique is moving a rather small plasma source above a big substrate to grow （or etch） large area films with uniform or customized non-uniform thickness distribution. In principle,limitation of the intrinsic non-uniformity film thickness due to large electrode can be removed. The lab-built RF-PECVD setup with rotatory sample holder and two synchronized linear motion RF cathodes was also discussed. We found that as the cathodes move, variations in their nearest distance to the chamber wall significantly affect the characteristics of both the plasma and the substrate. To evaluate the technique, we have grown two types of large area filter films for solar cells on glass disc ： one with linear variations in film thickness in radial direction and the other with parabolic thickness distributions. As expected, the new technique and our lab-made setup work very well.