Structure of inclosure curtain type read-only storage and its manufacturing method

Abstract

A mask-mode read-only memory structure and its manufacturing method, the structure includes a substrate; a buried bit line disposed in the substrate; a patterned stack layer disposed on a part of the substrate surface, Wherein the stack layer is composed of a first dielectric layer, a termination layer and a second dielectric layer; a gate oxide layer is disposed on a part of the surface of the substrate; and a word line spans the buried Above the bit line, a number of coded memory cells are formed, wherein among these coded memory cells, the one with the stacked layer is a logic state "0", and the one with the gate oxide layer is a logic state "1".

Description

Technical field [0001] The present invention relates to a structure of a memory and a manufacturing method thereof, and in particular to a structure of a mask ROM and a manufacturing method thereof. Background technique [0002] The structure of a general mask read-only memory includes several bit lines (Bit Line, BL) and several polysilicon word lines (Word Line, WL) across 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 is to store data "0" or "1" by implanting ions into the channel. And this process of implanting ions into a specific channel area is also called a code implantation process. [0003] Generally, the encoding injection process of the mask ROM is to first use a photomask to pattern the photoresist layer formed on the substrate to expose the channel region to be encoded. Then, an ion implantation process is performed using the patterned photoresist lay...

AI Technical Summary

Problems solved by technology

However, this method must design a photomask with a special pattern

Therefore, in addition to the time-consuming production of the photomask, it also increases the difficulty and cost of manufacturing the photomask.

In addition, after the photomask is manufactured, it is extremely difficult to improve (Debug) the defects of the photomask pattern.

[0005] In addition, in the known method, 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 region will also diffuse to the buried position. in line

In this way, the ion concentration in the buried bit line will change, and the current of the buried bit line will be insufficient.

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