Formation method of thermal oxygen dielectric layer between polysilicon of trench type double-layer gate MOS
A thermal oxygen dielectric, polysilicon technology, used in electrical components, semiconductor/solid-state device manufacturing, circuits, etc., can solve the problems of difficulty in controlling the thickness of the dielectric layer, weakening the gate-source breakdown voltage, etc., to simplify the process control difficulty and avoid gate. source breakdown voltage, the effect of improving stability
Active Publication Date: 2016-06-08
SHANGHAI HUAHONG GRACE SEMICON MFG CORP
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Problems solved by technology
This method can solve the problem that the thickness of the dielectric layer between the two polysilicon layers is difficult to control, and improve the stability of the performance of the MOS device; at the same time, it can avoid weakening the gate-source breakdown voltage due to the strong electric field generated at the two ends of the polysilicon tip
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[0056]The method for forming the thermal oxygen dielectric layer between the polysilicon in the trench type double-layer gate MOS of the present invention, its steps are as follows:
[0057] 1) On the silicon substrate 1, grow the first nitride film 3, that is, the silicon nitride layer, by low-pressure chemical vapor deposition or plasma-enhanced chemical vapor deposition, and the thickness of the first nitride film 3 is 500-3000 angstroms (Such as Figure 5 shown);
[0058] The first nitride film 3 in this step can be used as a protective layer on the top of the trench in subsequent processes;
[0059] 2) performing trench etching on the silicon substrate 1;
[0060] 3) On the sidewall and bottom of the trench, grow a dielectric layer 4 (i.e., silicon oxide) with a thickness of 500-3000 angstroms by means of thermal oxygen or low-pressure chemical vapor deposition;
[0061] 4) On the dielectric layer 4, a first layer of polysilicon 5 is grown by low-pressure chemical vapo...
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The invention discloses a thermal oxidation dielectric layer forming method in groove type double-layer grid MOS polysilicon; the method comprises the steps of: 1, growing a first nitride film; 2, etching a groove; 3, growing a dielectric layer; 4, growing a first polysilicon layer; 5, first step inverse etching the first polysilicon layer; 6, photoetching and second step inverse etching the first polysilicon layer, and removing a groove side wall dielectric layer above the first polysilicon layer; 7, depositing a second nitride film, etching the second nitride film to expose the first polysilicon layer; 8, growing a thermal oxidation dielectric layer; 9, removing the nitride film; 10, growing a gird oxide layer; 11, depositing and inverse etching a second polysilicon layer; 12, forming a base electrode and a source electrode; 13, forming a contact hole, metal and a passivation layer. The method can solve the problem that the dielectric layer thickness between two polysilicon layers is different to control, thereby improving the stability of MOS device performance; simultaneously, the condition in which the strong electric field generated on two sides of the polysilicon tips can weaken the grid source and breakdown the voltage is prevented.
Description
technical field [0001] The invention relates to a method for forming a thermal oxygen dielectric layer in the field of semiconductors, in particular to a method for forming a thermal oxygen dielectric layer between polysilicon in a trench-type double-layer gate MOS. Background technique [0002] Among power devices, trench double-layer gate power MOS devices have the characteristics of high breakdown voltage, low on-resistance, high conversion efficiency and fast switching speed. Usually, the polysilicon electrode of the first layer is used as a shielding electrode and is short-circuited with the source or drawn out separately, and the polysilicon electrode of the second layer is used as a gate. The thickness of the oxide layer between the two polysilicon electrodes needs to be strictly controlled, otherwise leakage or lower breakdown voltage will occur. [0003] At present, the preparation method of the oxide layer between two layers of polysilicon electrodes in the existi...
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IPC IPC(8): H01L21/283
CPCH01L29/42364
Inventor 李陆萍张博
Owner SHANGHAI HUAHONG GRACE SEMICON MFG CORP