Method for fabricating a mask ROM
AssigneeUnited Microelectronics Corp.
InventorYi-Ting Wu
Life of this patent
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Abstract
A patterned photoresist layer is coated onto a semiconductor substrate. Then a doped region is formed in the semiconductor substrate not covered by the patterned photoresist layer. In addition, a semiconductor process is performed to trim the patterned photoresist layer, and a lightly doped drain (LDD) region is formed in the region of the semiconductor substrate next to the doped region. The doped region and the LDD region constitute the buried bit lines of the mask ROM. Finally, the photoresist layer is stripped.
Claims16
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.
A method for fabricating buried bit lines on a semiconductor substrate, the method comprising:
- forming a patterned photoresist layer on the semiconductor substrate;
- performing a first ion implantation process to form a source/drain (S/D) region in the semiconductor substrate not covered by the patterned photoresist layer;
- performing a thermal curing process to reduce a width of part of the patterned photoresist layer so as to expose a region of the semiconductor substrate next to the S/D region;
- performing a second ion implantation process after the thermal curing process to form lightly doped drain (LDD) region in the region of the semiconductor substrate next to the S/D region, the S/D region and the LDD region being implanted with same type dopants;
- and
- stripping the photoresist layer.
Dependencies are inferred from the claim text.