研究了十甲基环五硅氧烷(D5)的电子回旋共振等离子体沉积的SiCOH薄膜中Si-OH基团对介电性能和漏电流的影响.结果表明Si-OH含量的增大会导致介电常数k的增大、漏电流的降低和介电色散的增强.由于Si-OH结构的强极化补偿了薄膜密度减小带来的介电常数降低,导致总的介电常数k增大.高Si-OH含量下漏电流的降低是由于封端的Si-OH基团降低了薄膜中Si-O网络的连通概率p而导致网络电导下降的缘故.介电色散的增强与Si-OH封端结构的快极化过程有关.改变放电参数以提高电子能量,从而提高源的电离程度,使更多的Si-OH基团断裂并通过缩合反应形成Si-O-Si网络,可以进一步降低薄膜的介电常数.
This paper investigates the effect of Si-OH groups on dielectric property and leakage current of the SiCOH low dielectric constant films deposited by decamethylcyclopentasioxane (DS) electron cyclotron resonance plasma. The results show that the increasing of Si-OH content in the films can lead to the increasing of dielectric constant k, decreasing of leakage current and rise in dielectric dispersion. The increasing of k value is the result of compensation of the decreasing of k value originated from cage by the strong polarization of Si-OH groups. The decreasing of leakage current at high Si-OH content is due to the low connecting probability p of networks because the networks break at the terminal Si-OH groups. In the case of high ionization degree of D5 plasma, more Si-OH groups break and form Si-O-Si linkages by chemical condensation occurring between proximal Si-OH groups. As a result, the k value of SiCOH films can be further reduced.