| 摘要 |
PURPOSE:To equalize the threshold voltage value of a device without generating a crystal defect by coating SiO2 with PSG and thermally treating SiO2 in a decompression atmosphere of an inert gas within a fixed range. CONSTITUTION:A boat 4 on which wafers 3 are arranged is entered in a core pipe 2 under the state in which the inside of an oven is kept at a low temperature, pressure is decompressed within a range of 0.1-760Torr, and N2 5 is introduced. The temperature of the oven is elevated up to a fixed temperature and the wafers are thermally treated, the temperature is dropped up to a temperature in case of the entering of the wafers and pressure is returned up to atmospheric pressure, and the wafers are discharged from the oven. According to the constitution, oxidation due to a drag-in to atmospheric air is avoided, the thermal distribution of the wafers is equalized, and a thermal strain such as the crystal defect is not generated because of a slow temperature-rise and temperature-drop. Consequently, the threshold voltage value of the wafers is equalized in the boat. |
