Structure of mask ROM and method for manufacturing the same

Abstract

The invention discloses a screen type read-only memory and and method of manufacture, wherein the arrangement comprises a substrate, a plurality of grid electrodes arranged on the upper portion of part of the substrates, a grid dielectric layer arranged between the substrate and the grid electrode, a plurality of flush type bit lines arranged in the substrate on the two sides of the grid electrodes, an insulating layer arranged between the top of the flush type bit line and the grid electrode, a plurality of word line, each of which is arranged in the same row of grid electrode and insulation layer in the direction perpendicular to the flush type bit line, and encoding layer arranged between the word line and the grid electrode.

Description

technical field [0001] The present invention relates to a memory structure and its manufacturing method, and in particular to a Mask ROM structure and its manufacturing method. Background technique [0002] The structure of a general mask ROM includes several bit lines (Bit Line, BL) and several polysilicon word lines (Word Line, WL) straddling the bit lines. The area below the word line and between two adjacent bit lines is the channel area of ​​the memory cell. For some mask ROMs, the programming method utilizes whether ions are implanted in the channel to store data "0" or "1". The manufacturing process of implanting ions in specific channel regions is also called code implantation manufacturing process. [0003] Usually, the code implantation process of the mask read-only memory first uses a photomask to pattern the photoresist layer formed on the substrate to expose the channel area to be coded. Then, an ion implantation process is performed with the patterned photor...

AI Technical Summary

Problems solved by technology

However, boron ions implanted in the channel region are easy to diffuse into the buried bit lines on both sides

In addition, if the code mask used in the code implantation process has misalignment or critical dimension deviation, the code ions originally planned to be implanted in the channel area will also diffuse into the buried bit line.

The above two situations will cause the ion concentration in the buried bit line to change, so that the current of the buried bit line will be insufficient.

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