| 摘要 |
PURPOSE: A method for testing an etch uniformity is provided to precisely test the etch uniformity when a drop sandwich etching is performed, so that etching efficiency is improved, and a ratio of dopants in a wafer can be precisely calculated. CONSTITUTION: The thickness of an epitaxial layer is measured by a spectrometry of furrier transform infrared ray. Next, a drop sandwich etching is performed to the epitaxial layer. Next, the thickness of the etched epitaxial layer is measured by a spectrometry of fourier transform infrared ray. Also, an analysis for dopants in a wafer is performed by spectrometries of inductively coupled plasma-mass and graphite furnace atomic absorption. Thereby, an etch uniformity can be precisely tested and a ratio of the dopants in the wafer can be precisely calculated.
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