A low on-resistance trench mosfet structure and its preparation method

Abstract

The invention discloses a low-on-resistance groove type MOSFET structure and a preparation method thereof. The invention relates to the semiconductor technology. The low-on-resistance trench type MOSFET structure comprises a semiconductor substrate and also comprises a semiconductor epitaxial layer main body, a diaphragm layer and a metal covering layer are sequentially fixed on the semiconductorsubstrate, grooves which are arranged tightly and are of small channel structures are formed in the semiconductor epitaxial layer main body and located on a lower portion of the diaphragm layer in anarray mode, at least one annular groove is formed in each groove in the length direction of the groove, and the grooves and the annular grooves are filled with polycrystalline silicon. The bottoms ofthe grooves and the outer sides of the annular grooves are respectively provided with first ion distribution regions and second ion distribution regions of which the ion concentration is higher than that of the semiconductor epitaxial layer main body. The invention further provides the preparation method of the low-on-resistance trench MOSFET structure, the distribution of current in the whole epitaxial layer is more uniform, and the divergence angle is larger such that the on-resistance of the device is reduced, and the overall breakdown voltage of the device is improved.

Description

technical field [0001] The invention belongs to semiconductor technology, and in particular relates to a low conduction resistance trench MOSFET structure and a preparation method thereof. Background technique [0002] With the rapid development of power semiconductor devices represented by power MOSFET devices, power semiconductor devices are now widely used in computer, traffic, consumer electronics, automotive electronics and other industries. Reasonable management requires effective control of the application of voltage and current, and these controls are inseparable from power devices. [0003] In the ordinary trench MOSFET structure, the current flowing out of the channel region expands to the drain region at a divergence angle of approximately 45° after entering the epitaxial body region. The distribution of the current in the entire epitaxial layer is not uniform, and the divergence angle is limited. The on-resistance of the device is increased, and the potential di...

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