Manufacturing method of high-voltage thick gate oxide

Abstract

The invention discloses a manufacturing method of a high-voltage thick gate oxide, and the method comprises the following steps of: depositing cushion silicon oxide on a silicon substrate, and depositing cushion silicon nitride on the cushion silicon oxide; carrying out shallow trench isolation photoetching, etching, silicon oxide filling and chemical mechanical grinding; sequentially depositing mask silicon nitride and mask silicon oxide on a silicon wafer; removing the mask silicon oxide and the mask silicon nitride in ae high-voltage thick gate oxide region through photoetching and etching processes, and reserving the cushion silicon nitride between the two shallow trench isolations in the high-voltage thick gate oxide region; carrying out first thermal oxidation growth to passivate the shallow trench isolation corner of the high-voltage gate oxide region; removing the cushion silicon nitride between the two shallow trench isolations of the high-voltage thick gate oxide region; and carrying out second thermal oxidation growth to generate the high-voltage thick gate oxide. The thick gate oxide and the STI corner gate oxide of the high-voltage device manufactured by the manufacturing method of the high-voltage thick gate oxide are thickened, passivated and smooth, the STI sharp corner problem can be eliminated, the reliability of the high-voltage thick gate oxide and the performance of the high-voltage device are improved, the process is simple, and the cost is low.

Description

technical field [0001] The invention relates to semiconductor manufacturing technology, in particular to a method for manufacturing high-voltage thick gate oxide. Background technique [0002] With the shrinking of the process size, the isolation process of semiconductor devices has changed from LOCOS (LOCAL Oxidation Of Silicon, local silicon oxidation isolation) to STI (Shallow Trench Isolation, shallow trench isolation). The process of filling the trench with a dielectric material is formed. Due to the inherent structural characteristics of STI, when making high-voltage devices and growing thick gate oxides, there will always be problems with thinner gate oxides and sharp corners at the corners of STI, which directly affects the reliability and related issues of thick gate oxides. device performance. [0003] At present, there are some STI thick gate oxide generation solutions to solve the STI corner problem. One is to use a double STI process, such as figure 1 , fig...

AI Technical Summary

Problems solved by technology

Due to the inherent structural characteristics of STI, when making high-voltage devices and growing thick gate oxides, there will always be problems with thinner gate oxides and sharp corners at the corners of STI, which directly affects the reliability and related issues of thick gate oxides. Device performance

[0003] At present, there are some STI thick gate oxide generation solutions to solve the STI corner problem. One is to use a double STI process, such as figure 1 , figure 2 As shown, it is necessary to add a plate to do the high-voltage STI process alone, and the cost is relatively high; the other is to use the oxide layer (oxide) deposition process, such as image 3 As shown, this can only be partially improved, and its reliability is worse than that of thermal oxygen growth

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