Preparation method of LDNMOS tube

Abstract

The invention provides a preparation method of an LDNMOS tube. According to the method provided by the invention, first of all, a first groove is arranged based on the position of a drain electrode area at a doping layer of a substrate, afterwards, a first drift region is formed around the first groove, and a second drift region is formed based on the position of a source electrode area; then, the first groove is filled up with an insulation material, and the surface of a formed structure is planarized; and finally, a grid electrode area is formed on the structure formed when the groove is filled up. Preferably, a second groove can also be arranged on the basis of the position of the source electrode area at the doping layer of the structure, and a second drift region is formed by surrounding the second groove, such that the LDNMOS tube formed by use of the preparation method provided by the invention can effectively decrease body region currents of the LDNMOS tube and reduces the hot carrier injection effect.

Description

technical field [0001] The invention relates to the field of semiconductors, in particular to a method for preparing an LDNMOS tube. Background technique [0002] A laterally diffused MOS transistor (LDMOS transistor) is a power device with a double-diffusion structure, which is widely used because it is easier to be compatible with a CMOS process. LDMOS tubes with various structures are disclosed in Chinese patent documents with application numbers: 200810043765.8, 200810043767.7, 201010147337.7, 201010274487.4, 201010576679.0, 201110005812.1, and 201110434492.1. For LDMOS transistors, the thickness of the epitaxial layer, the doping concentration, and the length of the drift region are the most important characteristic parameters. Although the breakdown voltage can be increased by increasing the length of the drift region, this will increase the chip area and on-resistance. The withstand voltage and on-resistance of high-voltage LDMOS devices depend on the compromise bet...

AI Technical Summary

Problems solved by technology

Although the performance of this kind of LDNMOS transistor with trenches is superior, the relationship between the substrate current and the gate voltage (ie figure 2 ), it can be seen that there are two peaks in the substrate current, while the MOS tube usually only has one peak value. Therefore, it is necessary to improve the existing method of preparing LDNMOS tubes to further improve the performance of LDNMOS tubes

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