A kind of semiconductor device and its forming method

Abstract

The invention provides a semiconductor device and a forming method thereof. The diffusion is performed through a liquid doping source after a groove is formed in a particular doping type of semiconductor substrate, the doping type of the liquid doping source is opposite to the doping type of the semiconductor substrate, the liquid doping source covers the surface of a blocking layer, a doping area is formed in the semiconductor substrate which is located on the periphery of the groove, and the doping type of the doping area is opposite to the doping type of the semiconductor substrate, the conventional epitaxial doping process which is complex and large in technical difficulty is not required, and accordingly the process difficulty is reduced. In addition, the doping area is filled with dielectric materials which are good in filling capability after being formed and accordingly the forming of a filling layer without gap or hole is facilitated, the internal filling of the groove is free of defect, the requirements for the etching process of the groove are reduced, and the high pressure performance and reliability requirements of the device are met.

Description

technical field [0001] The invention belongs to the technical field of semiconductor manufacturing technology, and relates to a semiconductor device and a forming method thereof. Background technique [0002] Super-junction MOSFET (Super-junction MOSFET) is a new type of power device. Due to its special vertical PN column alternating structure, the charges can compensate each other. When the device is in the off state, a lower voltage can be applied. The P-type region and the N-type region can achieve a higher breakdown voltage and lower on-resistance at the same time when a higher doping concentration is used. [0003] In the manufacturing process of superjunction devices, a semiconductor substrate of a specific doping type is usually formed first, and the opposite type of doping is performed on a specific region on the semiconductor substrate of the specific doping type, thereby forming a P-type region, an N-type intersecting superjunction structures. Taking the super-ju...

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Problems solved by technology

Afterwards, the trench 12 is filled with an epitaxial layer using a conventional epitaxial filling process. Due to the deposition principle, during the epitaxial filling process, such as image 3 As shown, the atmosphere at the top of the trench is conducive to deposition so that the top of the trench is sealed first, so an epitaxial accumulation 13 is formed on the top of the trench 12, causing the internal space of the trench 12 to not fill and leaving a gap 13a. The closer the inclination θ1 is to 90 degrees, the worse the ability of epitaxial filling, the easier it is to form large gaps, and even large voids in severe cases

The existence of gaps and cavities makes the arrangement of silicon atoms and dopant atoms discontinuous to form defects, which leads to leakage easily during device operation, especially under high voltage conditions, and affects the performance and reliability of the device

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