變壓耦合式電漿製程設備之先進設備控制

Abstract

電漿因其在材料處理上的特殊性質，故在半導體製程中廣泛的被應用。然而雖然電漿有許多應用上的優點，卻也因為複雜的反應機制會造成蝕刻結構的變化與傷害，因此如何達到元件性能的需求，先進製程（設備）控制的引進成為一項重要的課題。而物理化學模型的建立成為描述設備參數與製程參數間重要的關鍵，本項研究將電漿蝕刻製程分為設備模型與製程模型兩段，先架構電漿蝕刻設備模型，並以區域平均模式模型來描述設備輸入參數與電漿製程參數間之關係，再與實驗結果及文獻相互印證。而控制部分則針對電漿成分中之關鍵參數『電子密度』做監控，因為在電漿反應中，主要的能量吸收、反應機制大多由電子來傳遞，故電子的行為可以用來掌控電漿之狀況。控制器設計分為動態模型控制器設計、穩態模型控制器設計兩種。動態模型採用順滑模態的設計方式，設計單一輸入（電漿吸收功率）單一輸出（電子密度）之控制器來控制電漿設備，不受環境擾動及系統參數變動的影響；穩態模型則以反應曲面法的概念設計控制器，模擬數據顯示控制器皆能對外界干擾源做補償，將系統維持在設定的目標值上，以提供製程一穩定的環境。

Plasma is widely used in semiconductor processing because of its special property for material processing. Although there are many advantages for application, some problems of structure variation and damage are caused by complex physical and chemical reaction. Therefore, real-time Advanced Process (Equipment) Control is a major area of research and development in improving the desired device performance. Using physical and chemical model is the key approach to describe relationship between equipment parameters and processing parameters. In this thesis, modeling the plasma etching process consists of equipment model and processing model. The first objective is to focus on equipment model by Spatial Averaged Model to explain relationship between input equipment parameters and output plasma parameters in Transformer Coupled Plasma system and confirm the model from experiment data. The second objective of this thesis is to design a controller in order to control electron density. The most important factor of sustaining the glow discharge in plasma is electron behavior which impacts ionization and power absorption in plasma processing tool. There are two types of controller to achieve controller design goal：dynamic model approach and steady state model approach. The sliding mode controller controls the plasma processing equipment and rejects disturbance and parameter variation using single input (plasma absorption power) single output (electron density) in dynamic model approach. Steady state model approach uses response surface method (RSM) which is based on experiment data or theoretical model. Theoretical model is used in this thesis for controller design. Simulation results show that both types of controller can compensate disturbance effect and parameter change and improve performance of plasma equipment.