Technique method of manufacturing bottom thick gate oxide layer groove Metal Oxide Semiconductor (MOS) through selective epitaxy

Abstract

The invention discloses a technique method of manufacturing a bottom thick gate oxide layer groove metal oxide semiconductor (MOS) through selective epitaxy. The method comprises the following steps: (1) forming a first light doping epitaxial layer; (2) growing silica on the first light doping epitaxial layer; (3) forming photoresist patterning; (4) etching the silica which is not blocked by photoresist out clearly to expose the first light doping epitaxial layer outside the photoresist; (5) selectively growing a second epitaxial layer and laterally growing the second epitaxial layer; (6) etching the epitaxial layer above the silica out clearly to expose the silica and forming a groove with a bottom thick gate oxide layer; and (7) forming a grid in the groove. The method ensures that the forming of the bottom thick gate oxide layer becomes easy, and when the groove MOS is provided with double or three epitaxial layers, the positions of the groove relative to the epitaxial layers van can be accurately controlled, and therefore by respectively optimizing and controlling doping density of each epitaxial layer, breakdown voltage and on-state resistance of devices are optimized.

Description

technical field [0001] The invention relates to a manufacturing method of a semiconductor device, in particular to a process method for making trench MOS with thick gate oxide layer at the bottom by selective epitaxy. Background technique [0002] The bottom thick gate oxide layer (500-10000 angstroms thick) MOS (metal oxide semiconductor) can greatly reduce the capacitance between the gate and drain of the device. Existing processes form trenches by etching, but this method makes formation of a thick bottom gate oxide difficult. Moreover, the existing process generally only has one layer of epitaxy on heavy doping. When two layers of epitaxy are required, the relative position control of the epitaxy and the trench in the prior art process is not accurate enough, so that the optimization of epitaxy doping and device Performance work is more difficult. Contents of the invention [0003] The technical problem to be solved by the present invention is to provide a process me...

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Problems solved by technology

Existing processes form trenches by etching, but this method makes formation of bottom thick gate oxide difficult

Moreover, the existing process generally only has one layer of epitaxy on heavy doping. When two layers of epitaxy are required, the relative position control of the epitaxy and the trench in the prior art process is not accurate enough, so that the optimization of epitaxy doping and device Performance work is more difficult

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