Optimization control method and system for initial etching rate of oxide film

Abstract

The invention provides an optimization control method and system for the initial etching rate of an oxide film, which are used for improving the etching rate stability of the oxide film in a hot phosphoric acid wet etching silicon nitride process. The method comprises the steps of setting the initial etching rate of the oxide film; obtaining the number of silicon wafers actually entering an etching groove for production in the current batch, the thickness of a silicon nitride film on the surface of the silicon wafer and the etching area ratio of the silicon nitride film, and calculating the total etching amount of the silicon nitride film; setting the unit input amount of hot phosphoric acid when the silicon nitride film with unit thickness is etched, and calculating the total input amount of the hot phosphoric acid according to the total etching amount and the unit input amount of the silicon nitride film; and after the etching process of the current batch is finished, adding the total input amount of the hot phosphoric acid into the etching groove. The total amount of the hot phosphoric acid is added into the etching groove to dilute the solution in the etching groove, so that the concentration of silicon ions is reduced, the initial etching rate of each batch of oxide films is ensured to be consistent, and the etching stability of the oxide films is ensured.

Description

technical field [0001] The invention relates to the technical field of wet etching, in particular to an optimization control method and system for improving the initial etching rate of an oxide film in a hot phosphoric acid wet etching process of silicon nitride. Background technique [0002] Due to the high selectivity nature of wet etching, wet etching is sometimes used to remove surface layer materials including masking layers. Silicon nitride is widely used as a masking layer material in the manufacture of STI (Shallow Trench Isolation), LOCOS (Local Oxygen Isolation of Silicon) and self-aligned contact structures in the silicon wafer manufacturing process. In the groove wet etching process, hot phosphoric acid solution is often used to completely etch the silicon nitride film on the surface of the wafer (silicon wafer). Such as figure 1 , figure 1 It is a schematic diagram of etching a silicon nitride film using a hot phosphoric acid solution in the prior art. Since ...

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Problems solved by technology

[0005] Although the current input method of new acid has largely solved the problem of stabilizing the initial etch rate of a part of the oxide film, this method of fixed input does not take into account the actual thickness of the silicon nitride film required to produce the wafer. After the hot phosphoric acid solution is put into the oxide film, the etching rate still fluctuates greatly, which affects the actual etching amount of the final oxide film

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