A novel method for in-situ monitoring the thickness of a wafer during wet etching
Date Issued
2004
Date
2004
Author(s)
Lee, Chi-Yuan
DOI
zh-TW
Abstract
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
Subjects
即時監控
晶片厚度控制
板波感測器
濕蝕刻
wet etching
controlling the thickness of a wafer
in-situ monitoring
plate wave sensor
Type
thesis