Semiconductor structure and forming method thereof

Abstract

The invention provides a semiconductor structure and a forming method thereof. The forming method comprises the following steps that a substrate is provided, wherein the substrate comprises a cell memory region and a content addressable memory region; a gate structure is formed on the substrate, wherein the gate structure comprises a tunneling oxide layer and a floating gate layer located on the tunneling oxide layer; a first source-drain doping region is formed in the substrate on the two sides of the gate structure of the cell memory region; and a second source-drain doping region is formedin the substrate on the two sides of the gate structure of the content addressable memory region, wherein the doping concentration of the second source-drain doping region is smaller than that of thefirst source-drain doping region. By reducing the doping concentration of the second source-drain doping region, the initial threshold voltage of the content addressable memory is increased, so that the number of electrons is increased when the floating gate layer is in an intrinsic state, and therefore, and the trap-assisted tunneling effect can be improved, thereby improving the data retention capacity of the content addressable memory; and in addition, the doping concentration of the first source-drain doping region is not affected, so that the performance of the cell memory region is not affected.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a semiconductor structure and a forming method thereof. Background technique [0002] At present, flash memory (Flash), also known as flash memory, has become the mainstream of non-volatile memory. According to different structures, flash memory can be divided into two types: Nor Flash and NAND Flash. The main feature of flash memory is that it can keep stored information for a long time without power on, and has the advantages of high integration, fast access speed, easy erasing and rewriting, etc., so it has been widely used in many fields such as microcomputer and automatic control a wide range of applications. [0003] Among them, NAND Flash includes not only cell (Cell) memory, but also content addressable memory (Content Addressable Memory, CAM). Content-addressable memory is a special type of memory that can search the entire memory in a single operation, so i...

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