Fundamental Research for Development of CVD Apparatus with Rotating Subatrate

在传统的CVD系统中，原料气体通常沿衬底供应。在这种情况下，边界层厚度沿流动方向变化，因此很难制备出均匀的薄膜。另一方面，人们发现，在旋转的圆盘上，边界层厚度变得恒定。这一事实可以用来开发一种新的系统，在这种系统中，我们可以很容易地控制薄膜的均匀性。为了研制一种新型的旋转衬底CVD装置，我们对圆柱室中旋转圆盘上的流动和换热进行了实验研究。实验结果表明：1.圆盘上发生层流向湍流转变的临界雷诺数约为2？B3 10^5.2。在小进气率的情况下，进气口与圆盘之间存在循环流动。在低转速下，流体与圆盘之间的换热取决于进料率。相反，在高转速下，换热取决于转速。当旋转雷诺数小于2时，局部换热系数趋于恒定。B3 10^5。

In conventional CVD systems material gas is usually supplied along a substrate. In this case the boundary layr thickness changes along flow direction and thus it is difficult to make a uniform thin film. On the other hand it has been found that the boundary layr thickness becomes constant on a rotating disk. This fact can be used for the development of a new system in which we can easily control the uniformity of thin films. In order to develop a new CVD apparatus with a rotating substrate, we investigated experimentally flow and heat transfer on a rotating disk in a cylindrical chamber. From experiments we get the following results :1. The critical Reynolds number at which transition from laminar to turbulent flow occurs on the disk is about 2 ? B3 10^5.2. Circulation flows are observed between inlet and disk in the case of small inflow rate.3. At low rotating speeds the heat transfer between fluid and disk depends on inflow rate. On the contrary, at high rotating speesd the heat transfer depends on its speed.4. The local heat transfer coefficient becomes constant at the rotational Reynolds number less than 2 ? B3 10^5.