GaSb基PECVD法制备SiO_2薄膜的应力研究

Study of SiO_2 Thin Films Stress Deposited on GaSb Substrate by PECVD

为了实现在GaSb衬底上获得低应力的SiO_2薄膜,研究了等离子体增强化学气相沉积法(PECVD)在晶格失配较大的GaSb衬底上沉积SiO_2薄膜的应力情况。通过改变薄膜沉积时的工艺条件,如反应温度、射频功率、反应压强、气体流量比,并基于曲率法模型,对镀膜前后的曲率半径进行了实验测量,利用Stoney公式计算相关应力值并绘制应力变化曲线。详细讨论了PECVD工艺条件的改变对SiO_2薄膜应力所产生的影响。同时通过在Si衬底上沉积SiO_2薄膜,对比分析了导致薄膜应力产生的因素及变化过程。实验结果表明,在沉积温度为300℃、射频功率为20 W、腔体压强为90 Pa、气体流量比SiH_4/N_2O为125/70 cm^3·min^(-1)的工艺参数下,PECVD法在GaSb衬底上沉积的SiO_2薄膜应力相对较小。

In order to deposit a low stress SiO 2 dielectric film on a GaSb substrate, the stress of SiO 2 film deposited on GaSb substrate with larger lattice mismatch by plasma enhanced chemical vapor deposition（PECVD） was investigated. The SiO 2 film was experimentally tested based on the curvature model by changing the process parameters of PECVD, such as deposition temperature, RF power, cavity pressure and gas flow ratio. And the stress was calculated by Stoney formula. The effects of these parameters on the stress of SiO 2 film were analyzed in detail. At the same time, the causes and the mechanism of the stress generation as change of the process conditions compared with the stress of SiO 2 film deposited on Si substrate were discussed. Experimental results indicate that the stress of SiO 2 film deposited on GaSb substrate by PECVD is relatively small under the process parameters of deposition temperature of 300 ℃, RF power of 20 W, cavity pressure of 90 Pa, gas flow ratio of SiH 4/N 2O of 125/70 cm 3·min -1 .