Floating gate type split gate flash memory process method

Abstract

The invention discloses a floating gate type split gate flash memory process method. The process method comprises the following steps: S1, defining a floating gate flash memory and an active region of a peripheral logic region; s2, removing the silicon nitride layer, and sequentially forming a silicon oxide layer, a silicon nitride layer, a sacrificial silicon oxide layer and a silicon nitride layer; s3, depositing to form a polycrystalline silicon layer, and performing anisotropic etching to form a first side wall control gate; s4, depositing and etching to form a second side wall dielectric layer; s5, etching to remove the floating gate polycrystalline silicon layer in the opening; s6, thermal oxidation is carried out to form protective etching at the top end of the selection grid polycrystalline silicon layer; s7, performing injection to form a lightly doped drain Halo ion injection layer; and S8, performing source-drain heavily-doped injection to form a source-drain heavily-doped ion injection layer. According to the control gate, first side wall control gate polycrystalline silicon is formed through isotropic deposition and anisotropic etching of a polycrystalline silicon layer; according to the invention, the initial height of the lamination can be reduced; in addition, because the first side wall control gate and the floating gate are made of the same material, part of the control gate polycrystalline silicon layer is etched at the same time during the first etching of the floating gate, and the height of the Cell is further reduced; therefore, the compatibility of the flash memory device and an advanced process is improved; in the subsequent process, metal silicide can be simultaneously formed on the top of the polycrystalline silicon with the selection gate, so that the on resistance of the control gate is reduced, and the integration level of the flash memory is improved.

Description

technical field [0001] The invention relates to the technical field of flash memory, in particular to a process method of floating gate split-gate flash memory. Background technique [0002] Flash memory is a non-volatile memory, and data will not be lost even if the power is turned off. Because flash memory does not rewrite data in units of bytes like RAM (Random Access Memory), it cannot replace RAM. Flash Card is a memory that uses Flash Memory technology to store electronic information. It is generally used as a storage medium in digital cameras, handheld computers, MP3 and other small digital products, so it looks small and compact, like a card, so Call it a flash card. According to different manufacturers and different applications, flash memory cards generally include SmartMedia (SM card), Compact Flash (CF card), MultiMediaCard (MMC card), Secure Digital (SD card), Memory Stick (memory stick), XD-PictureCard Although these flash memory cards (XD card) and micro ha...

AI Technical Summary

Problems solved by technology

The particularity of the 3-fold self-alignment process of 2-bit / cell split-gate floating-gate flash memory makes the height of the flash memory cell much higher than that of CMOS devices, making its compatibility worse

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