金屬有機化學氣相沈積製程的即時監測研究

Abstract

矽基氮化鎵發光二極體(LED)的磊晶製程在真空密閉腔體內進行，常見的製程方法為金屬有機化學氣相沈積(MOCVD)與分子束磊晶(MBE)。溫度變化、沈積材料及薄膜厚度等，都會使影響磊晶品質。本研究發展線上光學量測技術，即時測量磊晶製程的參數。晶圓反射率是磊晶膜的光折射率及厚度的函數，也是高溫輻射溫度計的修正因子，由反射率歷時曲線可觀察晶圓表面的粗糙度及磊晶膜成長率。矽基氮化鎵製程的晶圓曲率大，磊晶膜容易產生缺陷或薄膜脫落。本文以理論推導預測製程參數對於晶圓彎曲及殘留應力的可能影響，透過有效監測可即時回饋製程系統做補償，提昇矽基氮化鎵的磊晶技術。

Metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) are widely used in manufacture of GaN-on-silicon light emitting diodes (LED). Both epitaxial processes have to operate in sealed vacuum chambers. The quality and efficiency of LED lighting depend on wafer temperature, epitaxial compositions, thin film thickness, etc. This study develops on-line optical techniques to real-time measure manufacture situations during epitaxy. Reflectance from the epitaxial thin film is a function of its refractive index and the film thickness. The emissivity of a material equals subtraction of the reflectance from 1, and is used as a correction factor for the pyrometer. A history of reflectance during epitaxy shows surface roughness of wafer and growth rate of epitaxial film. Large curvature of the substrate in the GaN-on-silicon process usually results in dislocations and peeling off in epitaxial films. The wafer bow and residual stress based on the measured results was formulated to explore the influences caused by manufacture parameters. The in-situ measurement during MOCVD process will promote GaN-on-silicon technology through an efficient monitoring and following-up feedback and compensation for process control.