A method of manufacturing embedded flash memory

Abstract

The invention provides a method for manufacturing an embedded flash memory. The semiconductor substrate is divided into a flash memory area and a logic area, and a silicon dioxide layer, a floating gate polysilicon layer and a first silicon nitride layer are sequentially formed on the semiconductor substrate. In the logic area, Form shallow trenches in the and flash memory areas respectively; fill the shallow trenches with insulators to form shallow trench isolation, remove the first silicon nitride layer; form a second nitride layer on the floating gate polysilicon layer and shallow trench isolation silicon layer and planarize the second silicon nitride layer; form a third silicon nitride layer on the second silicon nitride layer; form a groove in the flash memory area; deposit an active polysilicon layer on the third silicon nitride layer , to form the source electrode in the groove; use chemical mechanical polishing to planarize the active polysilicon layer; use wet etching to remove the second silicon nitride layer and the third silicon nitride layer; remove the floating gate polysilicon layer in the logic area , forming a CMOS structure in the logic area and word lines in the flash memory area. The above improves the efficiency of wet etching.

Description

Technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a manufacturing method of embedded flash memory. Background technique [0002] Memory is used to store a large amount of digital information. According to recent surveys, memory chips account for approximately 30% of semiconductor transactions worldwide. Over the years, advances in process technology and market demand have spawned more and more high-density varieties. Types of memory, such as RAM (Random Access Memory), DRAM (Dynamic Random Access Memory) and FRAM (Ferroelectric Memory), among which flash memory is FLASH and has become the mainstream of non-volatile semiconductor storage technology. Among the devices, embedded flash memory is a type of system-on-chip (SOC), which integrates logic circuit modules and flash memory circuit modules in an integrated circuit at the same time, and is widely used in products such as smart cards and microcontrollers. [0003...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a manufacturing method of embedded flash memory to solve the problem that the residual active polysilicon makes the silicon nitride layer difficult to remove

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