Photoetching method for improving overlay error difference

The invention discloses a photoetching method for improving overlay error difference. The photoetching method comprises the following steps: step 1, carrying out exposure pretreatment on a photomask to enable the temperature of the photomask to reach saturation temperature; and 2, exposing the wafers by adopting a photomask which reaches the saturation temperature, so that the difference of overlay errors between exposure areas and between wafers is reduced. According to the invention, the defect that the temperature of the photomask is increased along with the increase of the exposure time, so that the difference of the overlay errors between the exposure areas and between the wafers is large can be eliminated, and the difference of the overlay errors between the exposure areas and between the wafers can be reduced. 本发明公开了一种改善套刻误差差异的光刻方法，包括：步骤一、对光罩进行曝光预处理使光罩的温度达到饱和温度。步骤二、采用已经达到饱和温度的光罩对晶圆进行曝光，使曝光区域间以及晶圆间的套刻误差的差异减少。本发明能消除随着曝光时间的增加光罩的温度也会增加从而造成曝光区域间以及晶圆间的套刻误差的差异较大的缺陷，从而能减少曝光区域间以及晶圆间的套刻误差的差异。