基于微结构参数建模的多孔硅绝热层热导率研究

多孔硅由于具有较低的热导率,因而可以将其作为半导体器件中的绝热层.与其他从边界散射等复杂微观热传导机制出发建模研究多孔硅的热导率不同,将多孔硅热导率影响机制更表观地归结到孔洞的存在和分布等结构因素上,把整个多孔硅视为由硅连续材料介质和孔洞连续介质通过串联和并联组合成的复合微结构,给予其低热导率一个更为易于理解和简化的解释.进一步把孔隙率对等效热导率的影响分解为两个不同的部分,即纵向部分和横向部分,半定量地给出不同的孔洞结构和分布下孔隙率与等效热导率的关系.与实验数据进行对比后验证了模型的有效性.继而从结构的角度说明了多孔硅热导率较低的原因.

Study on thermal conductivity of porous silicon thermal isolation layer based on micro-structure mathematical model

Porous silicon can be used as a thermal isolation layer because of its low thermal conductivity. Different from other models based on the mechanism that the thermal conductivity of porous silicon is attributed to complex microcosmic thermal conductivity through such as boundary scattering, the model used in this paper is based on the mechanism that the low conductivity of the porous silicon material is due to its structure factors, such as the existence and distribution of pores and porous silicon is viewed as a compound microstructure piece, which is constructed by both silicon continuous material and pore continuous material medium, connecting in parallel and series patterns. Therefore, the authors give a more understandable and simpler reason why the conductivity of such a material is at such a low level. It is pointed out that the influence of porosity on equivalent thermal conductivity can be divided into two parts: vertical and horizontal, thereby giving semi-quantitative relationships between the porosity and equivalent thermal conductivity for different pore structures and distributions. A comparison between the calculated results and experimental results shows the validity of this model, thus supporting the reason why the thermal conductivity of porous silicon material is relatively low.