Patent ID: 6586303
Filing Date: 2003-07-01
Classification: H01L

Abstract:
A method for fabricating buried bit lines of a mask ROM, the method comprising:providing a semiconductor substrate with a photoresist layer coated on the semiconductor substrate; patterning the photoresist layer to form a photoresist pattern with a first line width; performing a first ion implantation process to form a doped region in the semiconductor substrate not covered by the photoresist pattern; trimming the photoresist pattern to shrink the first line width to a second line width by using an ultra-violet (UV) light irradiation process so as to expose a region of the semiconductor substrate next to the doped region; performing a second ion implantation process to form a lightly doped drain (LDD) region in the region of the semiconductor substrate next to the doped region, the doped region and the LDD region being implanted with same type dopants and constituting the buried bit lines of the mask ROM; and stripping the photoresist layer.