| 摘要 |
PURPOSE: To enable the metallic pollution of lapped wafer or etched wafer for discrete devices to be cut down by HF cleaning the alkaline cleaning wafer. CONSTITUTION: A wafer is produced by slicing an ingot to be lapped after chamfering the wafer. When the lapped wafer is alkaline cleaned up, the residual metal can be notably reduced by increasing the machining allowance. Especially, as for Al, Fe and Zr, the residual metal is rapidly reduced by increasing the machining allowance nearly 3.3μm but the reduction ratio will be decreased later. Accordingly, it is perferable to exceed the machining allowance more than 3.3μm. Furthermore, the surface roughness increases by increasing the machining allowance, but since the surface roughness rapidly increases by exceeding the machining allowance more than 4.0μm, it is recommended to set up the machining allowance not to exceed 4.0μm for HF cleaning thereby enabling the deterioration in this surface roughness to be broken off by HF cleaning step.
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