薄膜热扩散系数的在线测试研究

On-Line Evaluation of Thin Film Thermal Diffusivity

提出了一种在线提取多晶硅薄膜热扩散系数的简单测量方法,测试结构可随表面器件工艺加工制作,无需附加工艺。通过分析两个长度不同、宽度与厚度相同梁的瞬态冷却特性,获取其冷却时的温度衰减时间常数,便可以提取出表面加工多晶硅薄膜的热扩散系数。给出了瞬态冷却热电分析模型,综合考虑了梁冷却过程中各种散热因素即对流、辐射以及向衬底传热的影响。实验测得的该表面加工多晶硅薄膜热扩散系数是0.165 cm2s-1(方块电阻R□是116.25Ω)。理论分析和实验表明,该方法也能够实现其他工艺制作的导体薄膜热扩散系数的在线提取。

A novel technique has been developed to on-line evaluate the thermal diffusivity of the surface micro-machined polycrystaUine silicon thin films,using two polycrystalline silicon micro-beams with the same width and thicknesses but different lengths.The thermal diffusivity can be derived by analyzing time dependence of the thermal resistance of the two beams cooled in air at room temperature. A transient electrothermal model was proposed with proper considerations given to all possible factors affecting the coding, including heat exchange by convection, radiation and heat diffusion into the substrate or through the air gap. Only 4-probe and a digital oscilloscope are needed. The thermal diffusivity of the polycrystalline Si film, with a sheet resistance R□ of 116.25Ω, is measured to be 0.165 cm^2s^-1.