Extreme ultraviolet lithography patterning method

A method for patterning a semiconductor substrate, the method comprising:

• forming a stack structure over a target layer of the semiconductor substrate, the stack structure comprising:
• a secondary electron generation layer configured to emit secondary electrons when exposed to extreme ultraviolet (EUV) radiation, and
• a photoresist layer disposed over the secondary electron generation layer;
• exposing the photoresist layer to a patterned EUV radiation from above the photoresist layer;
• wherein the patterned EUV radiation passes through portions of the photoresist layer and causes the secondary electron generation layer to emit secondary electrons that expose the photoresist layer from below;
• developing the photoresist layer to form a patterned photoresist;
• and
• transferring the pattern from the patterned photoresist to the target layer.

A method for fabricating a semiconductor device with reduced extreme ultraviolet (EUV) exposure dose, the method comprising:

• forming a mask layer over a semiconductor substrate;
• forming an electron emission layer over the mask layer, the electron emission layer having a thickness between 0.5 nm and 5 nm;
• modifying a surface of the electron emission layer to enhance adhesion with a photoresist material;
• forming a photoresist layer on the modified surface of the electron emission layer;
• exposing the photoresist layer to a pattern of EUV radiation at an exposure dose that is 10% to 50% lower than a standard exposure dose required without the electron emission layer, wherein:
• the EUV radiation passes through portions of the photoresist layer and interacts with the electron emission layer, and
• the electron emission layer emits electrons that contribute to exposure of the photoresist layer from below;
• developing the photoresist layer to form a patterned photoresist layer;
• and
• using the patterned photoresist layer as a mask to etch the electron emission layer and the mask layer.