Manufacturing method of flash memory

Abstract

The invention discloses a method for manufacturing a flash memory. The steps include: completing the fabrication of the gate structure and the source region of the flash memory unit; adopting growth and overall etching processes to form the first side walls on both sides of the polysilicon row; growing the second side wall The fourth nitride layer completely fills the space between the first side of the two polysilicon rows; photolithography protects the fourth nitride layer on top of the source region, followed by etching of the fourth nitride layer on the second side of the polysilicon row Forming the second sidewall; performing the first source-drain injection to form the drain region of the flash memory unit; depositing the fifth silicon oxide layer, using the photomask of the active area to define the photolithography and etching the fifth silicon oxide layer; Use the photomask of the source region for photolithographic definition and remove the fourth nitride layer on the top of the source region; at the same time, form metal silicide on the surface of the source region and drain region on both sides of the polysilicon row; form an interlayer film; form a contact hole , the front metal layer, patterning the front metal layer. The invention can reduce the contact resistance of the source area and improve the programming efficiency.

Description

Technical field [0001] The present invention relates to a method of manufacturing a semiconductor integrated circuit, particularly a method of manufacturing a flash memory. Background technique [0002] With the development of semiconductor technology, non-volatile flash market share is getting higher and higher. The current flooding flash memory device admires a source, which is relatively small, and the source end size is relatively small. The source terminal reduces the source resistance by a relatively heavy ion implantation, and the drain end is formed by forming nickel in addition to normal ion implantation. Silicon to reduce the drain resistance, but since the source size is small in the current process, nickel is unable to form nickel silicon, so that the source is large; for non-volatile split flash devices, the programming principle is thermal electronics Inject (HCI) programming, if you can reduce the source resistance, it is very important to improve the programming e...

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Problems solved by technology

[0020] It can be seen from the above that in the prior art, no metal silicide 217 is formed on the surface of the source region 209, which will cause a large contact resistance in the source region and affect the programming efficiency of the flash memory.

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