基板表面粗糙度对电阻薄膜微观形貌及电学性能的影响

Effect of Substrate Surface Roughness on the Morphology and Electrical Properties of Resistance Films

摘要:

不同表面粗糙度的基板显著影响其溅射膜层的微观形貌、电阻以及残余应力，同时其本身的制备成本也相差甚远。选择表面粗糙度适合的基板，能够在保证产品性能良好、可靠性高的同时，兼顾生产成本的有效调控。基于实际生产考量，通过磁控溅射工艺制备两种Ti、TaN功能薄膜，系统性评估了表面粗糙度大范围梯度（R_a=20—1000 nm）变化的氧化铝基板对溅射膜层的影响，包括镀膜前后表面粗糙度、室温电阻率以及电阻温度系数（TCR）。结果表明：当基板表面粗糙度R_a<350 nm，镀膜后R_a无显著变化；当R_a>350 nm，随着基板R_a增加其镀膜后R_a显著降低；不同于R_a，镀膜后功能薄膜层R_z明显低于基板值；Ti、TaN薄膜电阻率，随基板R_a的增加而增大；TaN功能薄膜TCR随基板R_a值的增加先增大后减小，负偏明显并保持在-500×10^-6—-550×10^-6 ℃^-1 区间。

Abstract:

Substrates with different surface roughness significantly affect the microscopic morphology， resistance and residual stress of the sputtered films， and their preparation costs are also quite different. Choosing a substrate with suitable surface roughness can ensure good product performance and high reliability， meanwhile allow the effective control of production costs. In this paper， based on practical production considerations， two functional films of Ti and TaN were prepared by magnetron sputtering processes. The influence of alumina substrates with a wide gradient of surface roughness （R_a=20—1000 nm） on the sputtered films was systematically evaluated， including surface roughness before and after coating， room temperature resistivity， and temperature coefficient of resistance （TCR）. Experiments showed that： when the surface roughness of the substrate R_a<350 nm， R_a has no significant change after coating； when R_a>350 nm， R_a decreased significantly after coating with the increase of substrate R_a； different from R_a， the functional thin film layer after coating R_z was significantly lower than the substrate value； the resistivity of Ti and TaN films increased with the increase of substrate R_a； the TCR of TaN functional films increased first and then decreased with the increase of substrate R_a value， and the negative bias was obvious and remained in the range of -500×10^-6—-550×10^-6 °C^-1.