Structure and manufacturing method of mask read-only memory

Abstract

The invention discloses a manufacturing method of a mask read-only memory. The method comprises the steps of 1) forming shallow isolation trenches and performing P trap injection, 2) forming N-type buried sources and drains, 3) forming polysilicon gates, first isolation side walls and second isolation side walls, 4) performing source and drain injection on an NMOS (N-channel Metal Oxide Semiconductor) and performing N-type doping on an area of an information unit "1", 5) performing source and drain injection on a PMOS (P-channel Metal Oxide Semiconductor) and performing P-type doping on an area of an information unit "0", and 6) forming metal silicide on the polysilicon gates to complete manufacturing of the mask read-only memory. According to the method, the information unit "1" adopts the N-type polysilicon gate and the information unit "0" adopts the P-type polysilicon gate by changing a code write-in method and a device structure of the mask read-only memory; and a difference between threshold voltage of the N-type polysilicon gate and the P-type polysilicon gate is about 1.12eV and is stable, so that write-in of information "0" is realized, and the device uniformity is ensured.

Description

technical field [0001] The invention relates to the field of integrated circuit manufacturing, in particular to the structure and manufacturing method of a mask type read-only memory. Background technique [0002] Read-Only Memory (Read-Only Memory) is a memory that can only read data. The data of this memory is written at the time of production. In the manufacturing process, the data is burned into the circuit with a special mask (mask), so it is sometimes called "mask ROM" (mask ROM). In fact, it is very similar to the principle of a CD disc, in which the data state is written in the photolithography process of the semiconductor. [0003] The data of this mask-type read-only memory cannot be changed after writing, so the data cannot be lost, and its manufacturing cost is very low. Therefore, in devices that do not require data update, Mask ROM is very widely used use. [0004] In order to achieve as high a device density as possible in a traditional mask-type read-only...

AI Technical Summary

Problems solved by technology

Since this implantation must pass through the polysilicon gate, the implantation energy required is relatively large, and the impurity loss during the implantation process is relatively large.

Therefore, devices with high threshold voltages have poor uniformity, resulting in a smaller space between information "0" and "1"

In addition, the writing of the code also requires an additional photomask and a separate photolithography and ion implantation process, so the process cost is relatively high

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