| 摘要 |
PURPOSE:To enable to reduce the dispersion of the corner eroding amount by a method wherein a semiconductor wafer is made to get in touch to an etching reaction phase only. CONSTITUTION:KOH water solution and water solution of isopropyl alcohol (IPA), each having a prescribed concentration, are added in an etching tank 7, are sufficiently stirred with a magnetic stirrer, etc., and are stored in the thermostatic bath having been kept at a prescribed temperature. At this time, an etching reaction phase 8 and a floating IPA phase 9 are produced in the etchant. When the etchant itself has reached a prescribed temperature, the floating IPA phase 9 only is removed one time. This removed flating IPA phase 9 is stored in the thermostatic bath having been controlled at a prescribed temperature as well. Then, a silicon wafer 1 set in a wafer holder is put in the reaction phase 8, and immediately after that, the removed floating IPA phase 9 having been kept at a prescribed temperature is returned in the etching tank 7 to prevent it for the IPA in the etching reaction phase 8 to evaporate and keep the concentration of the IPA in the etching reaction phase 8 constant. |
