A shield grid oxide layer of a shield grid-deep groove MOSFET and a formation method thereof

Abstract

The invention discloses a shield grid oxide layer of a shield grid-deep groove MOSFET and a formation method thereof. The method comprises the following steps: 1, grooves are formed in an epitaxial layer through etching; first oxide layers form on the bottom surfaces and the sidewall surfaces of the grooves through adoption thermooxidizing growth technology; 2, nitridation layers form on surfaces of the first oxide layers; 3, deposited polysilicon layers form on the surfaces of the nitridation layers through adoption of polysilicon deposition technology; 4, thermooxidizing is carried out, and the deposited polysilicon layers are all oxidized to form second oxides; and the first oxide layers, the nitridation layers and the second oxide layers together form a shield grid oxide layer. According to the invention, an existing mode of directly depositing oxide layers on nitridation layers through SACVD is replaced by a mode of depositing polysilicon on the nitridation layers and carrying out thermooxidizing on the polysilicon, so that the thickness of each shield grid oxide layer used for isolation between shield grids and the groove sidewalls and between the shield grids and the groove bottom portions is ensured; technology conditions are simplified; the production cost is reduced; and the production power is raised.

Description

Technical field [0001] The present invention relates to the field of semiconductor integrated circuit manufacturing technology, in particular to a shielded gate oxide layer located on the sidewall of the trench in a shielded gate-deep trench MOSFET, and also relates to a shielded gate-deep trench MOSFET located on the sidewall of the trench The formation method of the shielding gate oxide layer. Background technique [0002] Such as figure 1 As shown, it is a schematic structural diagram of an existing trench gate MOSFET with a shield gate (ShieldGate Trench, SGT) structure. Taking an N-type device as an example, the unit structure of the trench gate MOSFET with a shield gate structure includes : [0003] The N-type silicon epitaxial layer 101 is formed on a silicon substrate, the silicon substrate is heavily doped and has a drain formed on the back side, and the silicon epitaxial layer 101 is lightly doped to form a drift region; [0004] The P well 102 is formed on the surface of...

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Problems solved by technology

The final morphology is better, such as Figure 5B As shown, it is commonly used to deposit a 9000 angstrom oxide layer 8 by SACVD at present. This process is expensive and requires special conditions, so the yield is very low.

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