射频功率和沉积压强对富硅-SiN_x薄膜微结构的影响

Effect of radio-frequency power and deposition pressure on the microstructure of Si-rich SiN_x films

基于等离子体增强化学气相沉积(PECVD)技术,以硅烷和高纯氮气作为反应气体源,分别设置射频功率为50,80,110,140,170 W和沉积压强为200,250,300,350,400 Pa两组参数沉积富硅-SiNx薄膜.结果表明,薄膜的致密性和沉积速率与射频功率和沉积压强都有关系,射频功率的增加导致光学带隙值变大,而光学带隙值与沉积压强成非线性关系,其二者的光学带隙值均在硅与Si_3N_4薄膜的光学带隙值之间.射频功率的增加,导致反应室中N—N键断裂更加完全,与硅原子结合形成大量的Si—N键,而薄膜中的Si原子含量降低,导致薄膜中含氮量增加,且样品薄膜中Si_3N_4晶粒尺寸增加,表明该条件下沉积得到的是富硅-SiN_x薄膜.

The Si-rich SiN x films were deposited using radio frequency (RF) power of 50, 80, 110, 140 and 170 W under the deposition pressure of 200, 250, 300, 350 , 400 Pa,respectively, based on the plasma enhanced chemical vapor deposition (PECVD) system, in which high purity silane and nitrogen were used as reaction gases. The results show that the compactness and deposition rate of the films are related to the RF power and deposition pressure. It is important that the increase of the RF power leads to the increase of the optical band gap value, while the optical band gap value has a non-linear relationship with the deposition pressure. The optical band gap values of both films are between the optical band gap values of silicon and Si 3N 4 films. With the increase of the RF power, the N-N bond breaks completely in the reaction chamber, and a large number of Si-N bonds are formed by bonding with Si atoms, while the decrease of the content of Si atoms results in the increase of nitrogen content and Si 3N 4 grain size in the films, indicating that the Si-rich SiN x films were deposited under this condition.