Method of thermally treating semiconductor wafers in furnace and wafer hanger useful therein

DETAILED DESCRIPTION The present invention is directed to a method of thermally treating semiconductor wafers by heating the wafers in furnace having a heating space.
According to the present invention, the method comprises the steps of: (a) hanging the wafers from a wafer hanger; (b) putting the wafer hanger holding the wafers into the heating space of the furnace; and (c) supplying a heating power to the furnace, to thereby heat the wafers hung by the wafer hanger.
The wafer hanger may have a hanging portion from Which the wafers are hung and a supporting portion supporting the hanging portion.
Preferably, the step (b) includes the step of: (b-1) placing the wafer hanger holding the wafers in the heating space such that respective center points of the wafers are substantially held at a center level of the heating space.
Since the wafers are hung by the wafer hanger, plastic deformation due to the gravity of the wafers is not caused in the wafers.
Consequently, a positional adjustment of a mask or the like in the processes following the heat treatment can be conducted at a high accuracy.
Furthermore, residual impurities or dusts hardly adhere to the wafers, because the wafers are at the center level of the heating space.
The wafers can uniformly receive the heat radiation from respective areas of heating means such as a heating tube.
Therefore, uniform heat treatment of the wafers is attained.
The present invention is also directed to wafer hanger useful for hanging semiconductor wafers therefrom in a furnace in order to thermally treat the wafers.
According to the present invention, the wafer hanger comprises: (a) a rod member capable of being inserted into respective engage holes formed in edge portions of the wafers; and (b) a supporting member for supporting the rod member in a horizontal direction at both end portions of the rod member, wherein the rod member is separatable from the supporting member, and the rod member and the supporting member are made of a material resistant to a temperature for a heat treatment of the wafers in the furnace