基底温度控制方式对直流弧光放电PCVD金刚石膜的影响

Effects of Substrate Temperature Control Methods on DC Arc Discharge Plasma Chemical Vapor Deposition Diamond Film

如何精确、高效地实现对基底温度的测控,并获得优化的温度参数,对于CVD金刚石制备技术至关重要。本文采用自主研制的具有新型基底温度自动控制系统的直流弧光放电PCVD设备,分别进行了基底温度开环、闭环及开闭环复合控制下的金刚石薄膜制备研究,并采用SEM,激光Raman光谱仪对所制备薄膜的形貌品质进行了分析。研究结果表明:基底温控方式的不同会明显影响CVD金刚石膜的晶体、生长特征及品质,尤其造成了薄膜生长中二次形核密度以及非金刚石成分的显著变化;在保证系统稳定运行的前提下,当其它沉积参数恒定时,受控下的基底温度控制精度及控制品质的实时变化是影响CVD金刚石膜生长性能的主要因素,其中控制精度介于±5℃～±15℃间变化,而控制品质受控制方式的影响较大;相对于控制精度而言,控制品质的变化对常规金刚石薄膜生长性能的影响更为明显。对于此系统,只有采用开-闭环复合控制,且开环流量维持在其单独工作流量的20%时,才能保证基底温度控制精度、控制品质及所制备的CVD金刚石薄膜的质量最佳。

In order to obtain optimized substrate temperature parameters,how to accurately,efficiently measure and control the substrate temperature in CVD diamond films deposition,is critical for CVD diamond deposition technology.The diamond films have been deposited by the home-made DC arc discharge plasma CVD device with a novel substrate temperature control system under opened-loop,closed-loop,opened and closed-loop compound method,respectively.The morphology and quality of diamond films was characterized by scanning electron microscopy and laser Raman spectroscopy.The results indicated that using different substrate temperature control methods has evident effect on the crystal,growth features and quality of the CVD diamond films,in particular,causes a significant change in the secondary nucleation density and non-diamond components in the films.In the premise of ensuring the stability of the control system,as other deposition parameters constant,the substrate temperature control accuracy and control quality real-time altering under different control methods is the main factor affecting the CVD diamond film growth and quality,which the control quality is greatly affected by the control method,and lead to the control precision change from ± 5 ℃ to ±15 ℃.Compared with the substrate temperature control accuracy,the effect of the control quality on the morphology and quality of DC arc discharge PCVD diamond films is even more significant.For this system,only using opened and closed-loop compound control method and maintaining open-loop flow in its work alone 20%,can be obtain the best control accuracy,control quality and high quality of diamond films in the whole DC arc discharge PCVD process.