Dry etching method for removing silicon nitride film

Abstract

The invention discloses a dry etching method for removing a silicon nitride film and relates to the etching technology in the field of semiconductor manufacture. The dry-method etching method is carried out in a processing procedure chamber, and the electric potential difference of an upper substrate and a lower substrate respectively arranged at both sides of a plasma region in the processing procedure cavity is smaller than 300 volts. Compared with the prior art, the dry etching method for removing the silicon nitride film reduces the electric potential difference of the plasma region to greatly decrease the bombing possibility of plasma bodies on a wafer silicon substrate and optimize the subsequent technologies.

Description

technical field [0001] The invention relates to a dry etching method for manufacturing a semiconductor non-volatile memory device, in particular to a dry etching method for removing a silicon nitride film. Background technique [0002] Flash memory is a non-volatile memory that can store charge even when the system is powered off. The storage unit of the flash memory is a MOS tube, but its structure is slightly different from that of a general MOS tube. The structure of the flash MOS tube is as follows figure 1 As shown, the structure of the flash memory MOS transistor region 1 includes a silicon substrate 10, a gate oxide layer 11, a floating gate 12, an inter-electrode oxide layer 13 and a control gate (not shown) from bottom to top. The floating gate 12 is made of silicon nitride (Si 3 N 4 ) film to store charge. Both the gate oxide layer 11 and the inter-electrode oxide layer 13 are silicon dioxide (SiO 2 )film. [0003] Generally, a variety of semiconductor devic...

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Problems solved by technology

[0004] After adopting the above method, it is found that the gate oxide layer 24 of other semiconductor devices produced is smaller than the expected thickness, and in severe cases, the thickness is 10 Angstroms less than the expected thickness, which seriously affects the electrical performance of the semiconductor device.

The study found that the silicon lattice on the surface of the silicon substrate was damaged by the intense bombardment of the plasma during the above-mentioned dry etching step, so that the gate oxide layer of other devices could not be deposited in the damaged area

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