表面加工多晶硅薄膜热扩散系数的在线提取

On-line Extracting the Thermal Diffusivity of Surface-micromachined Polysilicon Thin Films

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。通过分析两个长度相同、宽度与厚度相同梁的瞬态冷却特性,获得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 cm2-s 1(方块电阻是116.25Ω/sq)。该方法能够实现多晶硅薄膜热扩散系数的在线测试。

Thermal diffusivity of surface micromachined polysilicon thin films is measured using two polysilicon microbeams, with same width and thickness but variant length. The thermal diffusivity can be extracted from the time dependence of the two thermal resistances cooling in free air. The effects of all heat exchange by convection, radiation and the heat transfer through the air gap and into the substrate are considered in the electrothermal model, and all measurements can be carried out in free air, and only the four-probe arrangement and digital oscilloscope are needed in the experiments. The surface-micromachined polysilicon thin films, p^＋-doped with a sheet resistance 116.25 Ω/sq. ,the thermal diffusivity obtained using this technique is 0. 165 cm^2s^-1 ,and only the lengths of the two beams and two time contants are need in the model of the thermal diffusivity.