燈源加熱之垂直單晶片處理爐內流場觀測研究

Abstract

本篇論文旨在以實驗觀測一燈源加熱之八吋垂直單晶片處理爐內流場。我們以一高導熱之直徑八吋圓形銅板替代晶圓，藉以模擬處理爐內流場變化及熱傳現象。在對單一垂直管 (Single gas jet)進氣分別改變：(1)銅板表面溫度。(2)進氣流量。(3)爐內壓力。我們由爐體一側拍照截取流場形態，以探討因爐內抽低壓及晶圓加熱引起的浮力以及因進氣導致的慣性力和衝擊力對流場所成的影響。在典型的流場中，氣流在銅板表面行進時，受其與銅板間溫差產生的浮力舉起，在氣柱兩側區域會形成兩個對稱的渦漩、而爐壁旁也相應地產生兩個對稱的渦漩。這些渦漩在較低的浮力和慣性力之條件下，氣柱兩側的渦流會較為固定而對稱。而當進氣對銅板的溫差增大或爐內壓力較大時，氣柱兩側的渦漩會因浮力增強的作用而縮小，相對地，爐壁邊的渦漩也就變大。另一方面，若調整使氣流量加大時，增強的慣性力會導致氣柱兩側的渦漩變大，爐壁旁的渦漩也因而變小。整合所得的數據，我們得到雷利數和噴流雷諾數對渦漩尺寸的關係式，也得到將流場形態區分為穩定、週期性和混亂三種區域的關係式。

Recirculating air flow in a model lamp heated, rapid thermal, vertical single wafer processor for an eight-inch wafer is investigated experimentally by flow visualization. A copper plate is used to simulate the wafer for its better uniformity of the surface temperature and air is used to replace the inert gases in the present study. This study concentrates on how the inlet gas flow rate, temperature difference between the wafer and air jet, and chamber pressure affect the recirculating flow in the processing chamber resulting from the air jet impinging on the headed copper plate. The flow photos taken from the chamber side intend to unravel the vortex flow driven by the combining effects of the thermal buoyancy, jet inertia and jet impingement. The results show that typically the flow in the chamber is in the form of two-roll structure characterized by a circular vortex roll around the gas jet along with another circular roll near the side wall of the chamber. The rolls are generated by the deflection of the impinging jet flow along the wafer surface by the upward buoyancy due to the heated wafer. At low buoyancy and inertia the vortex rolls are steady and axisymmetric. At increasing buoyancy associated with the higher temperature difference and chamber pressure, the inner roll becomes slightly smaller and the outer roll becomes correspondingly bigger. Besides, the recirculating flow is stronger at high buoyancy. Moreover, at a higher gas flow rate the inner roll is substantially bigger. Based on the present data, a correlation equation is provided to predict the location where the two rolls contact each other, providing the approximate size of the rolls. Moreover, at high buoyancy and inertia, the flow becomes time dependent and does not evolve to a steady state. A flow regime map is given to delineate the temporal state of the induced flow.