濕蝕刻晶片厚度即時監控之新穎方法

A novel method for in-situ monitoring the thickness of a wafer during wet etching

李其源(Chi-Yuan Lee)

指導教授 ： 張培仁 ； 陳炳煇

國立臺灣大學/工學院/機械工程學研究所/博士(2004年)

https://doi.org/10.6342/NTU.2004.01399

摘要

本文提出利用在不同基材上製作出板波感測器用來即時監控濕蝕刻中石英晶片及矽晶片厚度之新穎方法。聲波元件常需要精確地控制晶片厚度，故濕蝕刻中能夠精確地控制晶片厚度是很重要的，因為控制地精不精準，會嚴重地影響其後製程進行、頻率控制及元件性能之好壞。在理論部分，考慮板波在壓電平板及多層結構中有液體負載之波傳行為。從理論模擬出相位速度跟晶片厚度之關係，並跟實驗結果作比較。其它如在不同基材上板波感測器之設計、製程、實驗架設及結果與討論，亦在本文做詳盡之探討。

在石英基材之板波感測器上，考慮板波在石英壓電平板中有液體負載之波傳行為。從理論模擬出相位速度跟石英晶片厚度之關係，並跟實驗結果作比較。理論模擬部分係利用八階矩陣之公式用來計算板波在壓電平板中有液體負載之波傳行為，此研究方法為將運動方程式及組成律結合為一階矩陣微分方程式，藉此將變數對應至下一層，使用此種方法最大之優點為不會因為結構層數之增加而使矩陣的維度增加造成計算上耗時。實驗結果顯示與理論模擬比較，兩者之監控厚度誤差在2

關鍵字

即時監控 ； 晶片厚度控制 ； 板波感測器 ； 濕蝕刻

並列摘要

This work presents a novel method based on the plate wave sensor for in-situ monitoring of the thickness of a wafer during wet etching. Some acoustic wave devices require that the thickness of a wafer be known precisely. Precisely controlling the thickness of a wafer during wet etching is important, because it strongly influences post-processing, frequency control and device performance. In the theoretical simulation, a formulation based on the eight-dimensional matrix method was used for calculating the dispersion relations for a general piezoelectric layered medium. Additionally this study described the principles of the method, including the detailed process flows, measurement set-up and the simulation and experimental results. The experimental and theoretical values correlate well with each other.

In the plate wave sensor based on a quartz substrate, the eight-dimensional matrix formalism was employed for propagating surface waves in piezoelectric plate loaded with viscous liquid. This formulation derives the dispersion equation of surface waves in such a structure from continuity conditions at the solid-liquid interface. The size of the matrix in the computation is independent of the number of layers. The formulation based on the surface impedance tensor method was used to calculate the dispersion curve of the viscous liquid loaded an AT-cut quartz substrate. The simulation results, which are phase velocity with respect to the thickness of a quartz substrate. The theoretical and measured values differ by an error of less than 2

並列關鍵字

wet etching ； controlling the thickness of a wafer ； in-situ monitoring ； plate wave sensor

參考文獻

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