Double access path mask rom cell structure
AssigneeHoltek Semiconductor Inc.
InventorJinn-Nan Kao
Life of this patent
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Abstract
The present invention discloses a double access path mask read-only memory cell array structure, characterized in that the stored data is accessed simultaneously through two access paths disposed on both sides of a memoery cell array structure. The reliability is improved since the value 0 or 1 stored in the data can be accessed through two paths and the operation speed is enhanced since the resistance in the conductive path from the sense amplifier to the ground is effectively reduced when accessing 0.
Claims6
A double access path mask ROM array structure, comprising a plurality of pairs of banks, wherein said each pair of banks comprises:
- a plurality of n+-buried regions formed on a substrate to function as part of a first access path and part of a second access path;
- an insulating layer of substantially constant thickness formed on said substrate;
- a plurality of contact holes penetrating said insulating layer, wherein two of said contact holes construct a conductive path to the ground and another two of said contact holes construct a conductive path to an external sense amplifier;
- a plurality of block select transistors;
- a plurality of select cell transistors;
- a plurality of conductive bit lines, connecting the sources of said different block select transistors to said respective contact holes;
- a plurality of word lines;
- a cell array composed of said plurality of word lines to store data;
- and,
- a first metal line and a second metal line, forming part of a double access path.
Dependencies are inferred from the claim text.