A trench mosfet with a terminal withstand voltage structure and its manufacturing method

Abstract

The invention brings forward a groove MOSFET with a terminal voltage-withstanding structure and a manufacturing method of the groove MOSFET. Grooves are formed in a cellular area and a terminal area of the groove MOSFET respectively. The grooves of the terminal area are at least two enclosed annular grooves which surround the cellular area. At least one annular groove, which is close to the cellular area, is an isolation ring which is connected with a zero potential. At least one annular groove, which is close to a scribing channel, is a cutoff ring which is connected with the scribing channel. According to the groove MOSFET with the terminal voltage-withstanding structure, the isolation ring is connected with the zero potential so that electric leakage can be effectively inhibited; and the cutoff ring is connected with the scribing channel so that carriers are not accumulated along the cutoff ring, and thus isolation effect and voltage-withstanding effect of the terminal voltage-withstanding structure are enhanced. According to the manufacturing method, voltage-withstanding and electric leakage problems of the groove MOSFET prepared by the three-layer photo-etching technology are solved, transverse electric leakage of the groove MOSFET is reduced, voltage withstanding of devices is enhanced, technology process is simplified and manufacturing cost is lowered without increasing technology complexity.

Description

technical field [0001] The invention belongs to the field of basic electrical components and relates to the preparation of semiconductor devices, in particular to a terminal withstand voltage structure of a trench MOSFET and a manufacturing method thereof. Background technique [0002] Trench MOSFET is a new generation of power semiconductor device that integrates microelectronics technology and power electronics technology. It is widely used in DC- DC converters, voltage regulators, power management modules, automotive electronics and electromechanical control and other fields. [0003] Trench MOSFET was proposed as early as the early 1980s. In the development of trench MOSFET, research on reducing product development costs revolves around obtaining higher cell density, lower on-resistance, more reliable structure and simpler The technological process and other aspects are expanded. [0004] In terms of improving cell density and reducing product cost, with the developmen...

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Problems solved by technology

However, the problem of increasing the cell density is that the cell size of the current low-voltage trench MOSFET has been reduced to 1um, and the space for further decline is getting smaller and smaller, and the reduction in size will lead to an increase in local field strength, which will inevitably bring Device Reliability Life Reduction

However, if Figure 5 As shown, this process step cannot limit the P-well area and N+ area, and it is impossible to continue to form a P-type annular pressure-resistant ring on the periphery of the chip to improve the withstand voltage and reduce leakage. It is necessary to propose a new terminal design to solve the breakdown The problem of voltage drop and leakage increase

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