| 摘要 |
Embodiments of the present invention are directed to a method of reducing boron outgassing at trench power IC's oxidation process for the sacrificial oxide layer whereby the threshold voltage of the power ICs can be improved and the yield of the product can be enhanced. Nitrogen is introduced into the furnace in the entire oxidation process, including the main oxidation steps. In the preparing step of ramp up, the ramp up step and the stable step, prior to the main oxidation, nitrogen is introduced in a sufficient flow rate to make the environment near the saturated vapor pressure to reduce boron outgassing at the trench.
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