硼掺杂金刚石薄膜的制备和性能研究

通过热丝化学气相沉积法，在硅基上沉积硼掺杂金刚石薄膜，研究硼源流量对硼掺杂金刚石薄膜的导电性能、晶粒尺寸、晶面方向及残余应力等的影响。结果表明:随硼流量增加，金刚石薄膜电阻迅速降低；超过一定流量后，薄膜的缺陷和杂质增多，阻碍了电阻的进一步下降。硼流量在0~25 mL/min内逐渐升高时，金刚石薄膜平均晶粒尺寸从3.5 μm增长到8.3 μm，硼元素促进了（111）晶面的生长；硼流量继续增大到35 mL/min时，对（111）晶面的促进作用减弱，晶粒尺寸减小且晶粒表面缺陷增多而失去完整性。X射线衍射分析表明:随硼流量增加，金刚石薄膜（111）晶面和（110）晶面的衍射峰面积比，呈先增加后减少的趋势，在硼流量为20 mL/min时达到最大值；且硼掺杂金刚石薄膜残余应力为压应力。在硼源流量小于10 mL/min时，应力随流量的增加而减小；当硼流量大于30 mL/min时，应力随流量的增加而增大。 

Preparation and properties of boron doped diamond films

Boron doped diamond films were deposited on the silicon substrate by hot-filament chemical vapour deposition (HFCVD). The effects of boron source flow on the conductivity, grain size, crystal direction and residual stress of boron doped diamond films were investigated. The results show that the resistance of diamond films decreases rapidly with increasing boron flux. After a certain flow rate, the defects and impurities increase and hinder the further decline of resistance. The boron flow increases gradually in 0-25 mL/min, and the average grain size of the diamond film increases from 3.5 to 8.3 μm. The boron element promotes the growth of (111) crystal surface. When the boron flow rate continues to increase to 35 mL/min, the promotion effect on the (111) crystal surface weakens and the grain size decreases. Therefore, the surface defects increase and the integrity is lost. The X-ray diffraction analysis shows that with the increase of boron flow, the diffraction peak area ratios of the diamond film (111) surface and (110) surface increase first and then decrease, and that the maximum value is reached when the boron flow rate is 20 mL/min. The residual stress of boron doped diamond film is compressive stress. When the flow rate of boron source is less than 10 mL/min, the stress decreases with the increase of flow rate, and the stress increases with the increase of flow rate when the flow rate is more than 30 mL/min.