The Investigation of the Gas Flow Analysis and the Measurement of the Thermal Radiative Properties for Thin Film Deposition in the Stacked Large Silicon Wafers

采用流动可视化和数值模拟相结合的方法研究了垂直低压化学气相沉积（LPCVD）反应器中硅片上反应物气体的流动特性。观测是在一个模型反应堆中，在非常低的压力条件下进行的，由于示踪剂的播种，使得观测非常困难。采用CFD软件FLUENT进行数值模拟。可视化和数值模拟结果表明，气体流动具有较大的粘性，并且受到晶片和支撑矿脉的较大阻力。无论在低压条件下，流动都可以看作是连续系统，并且基于Navier-Stokes方程的CFD程序可以很好地模拟。它表明，大部分的场似乎是层流的。对于均匀流型的建立，双逆流喷嘴优于单喷嘴。流动是自由形式的停滞流动或再循环流动，因此它似乎适合于防止颗粒形成。另一方面，关于不同薄膜的半导体硅片的热辐射特性的数据很少。了解它们对于利用辐射温度计精确测量硅片温度和在现场估算薄膜厚度具有重要意义。在不改变薄膜条件的情况下，利用FT-IR测量了不同薄膜硅片在600℃和900℃下的光谱法向发射率。结果表明，不同薄膜种类和厚度的辐射特性差异很大。利用这一特性，通过测量现场红外光谱，似乎可以估计出加工过程中薄膜的厚度。

This investigation showed the flow characteristics of reactant gas on the silicon wafers in a vertical LPCVD (Low-Pressure Chemical Vapor Deposition) reactor by the flow visualization and the numerical simulation. The observation was made in a model reactor in a very low-pressure condition, which makes observation quite difficult because of tracer seeding. The CFD code FLUENT was used for the numerical simulation. The results of the visualization and the numerical simulation showed that the gas flow was quite viscous and it received large resistance force from the wafers and the supporting lodes. Regardless of the low-pressure condition, the flow can be treated as continuous system and can be simulated well by the CFD code based on Navier-Stokes equation. It shows that the most of the field appeared to be laminar. For the establishment of the uniform flow pattern, twin counter-flow nozzles were better than a single nozzle. The flow was free form stagnant flow or re-circulating flow so that it appears to be suited for the prevention of particle formations.On the other hand, there is seldom data on the thermal radiative properties of semiconductor silicon wafers with various thin films. It is important to know them for the accurate measurement of wafer temperature using radiative thermometer and the estimation of the film thickness at in-situ. We measured the spectral normal emissivity of silicon wafers with various films using FT-IR without changing the condition of a thin film at 600℃ and 900℃. The result showed that radiation characteristics greatly differ by film kind and film thickness. It seems to be able to the estimation of the thin film thickness in the process by measuring the infrared spectrum at in-situ using this property.