Method for flash technology high-voltage bar oxygen and tunnel-penetration oxidation layer

Abstract

The invention discloses a method for forming a high-voltage gate oxide and a tunneling oxide layer in a flash memory process. Firstly, the floating gate oxide layer after floating gate etching is retained, and its thickness is 50-70; secondly, the floating gate oxide layer is The layer is etched by a wet method, and its thickness is kept at 20-30; after that, a tunnel oxide layer and a high-voltage gate oxide layer are simultaneously formed by using a high-temperature and reduced-pressure chemical vapor deposition process; finally, the thickness of the tunnel oxide layer formed is 160-180, the high-voltage gate oxide layer is formed with a thickness of 180-210. By reducing the thickness of the tunnel oxide layer, the present invention not only enhances the electric field intensity during erasing, but also reduces the number of traps in the oxide layer correspondingly, thereby improving the erasing ability of the memory unit.

Description

technical field [0001] The invention relates to a semiconductor integrated circuit process method, in particular to a method for forming a high-voltage gate oxide and a tunnel oxide layer in a flash memory process. Background technique [0002] As a main non-volatile memory, flash memory is widely used in smart cards, microcontrollers and other fields. Compared with EEPORM, another non-volatile memory, flash memory has obvious advantages in area; but at the same time, the reliability of flash memory, especially the erasable number of times, is worse than EEPROM, so it is used in bank cards, ID cards, etc. Product has not yet been used. [0003] SST flash memory is a type of flash memory invented by Bing Yeh in 1990 (US Patent No. 5029130), and the structure of its storage unit is as follows figure 1 shown. Among them, polycrystalline 1 is a floating gate, and the following is 80~90 Thick floating gate oxide layer. A part of the polycrystalline 2 covers the floating gat...

AI Technical Summary

Problems solved by technology

As the number of erasing and writing increases, the charge traps in the tunnel oxide layer will increase accordingly, so that more and more electrons are trapped in the charge traps during the tunneling process, so that the electric field between the control gate and the floating gate The strength is reduced due to the shielding of the trapped charges, the erasability is continuously reduced, and eventually it fails because it cannot be erased

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