Manufacturing method of double diffusion field effect transistor

Abstract

The invention discloses a manufacturing method of a double diffusion field effect transistor, comprising the following steps: a drift region of the transistor can form a gradient slope with certain dosage concentration in a channel direction (namely in transverse direction) and a direction vertical to the channel direction (namely in longitudinal direction) by increasing one selective ions injection process for forming a second drift region, so that the junctions of the whole transistor in the transverse direction and longitudinal direction have approximately equal breakdown voltages and the transistor will not be broken down with small voltages; furthermore, the saturation currents of the transistor can be increased by increasing the dosage concentration at the drift region with certain breakdown voltages.

Description

technical field [0001] The invention relates to semiconductor process technology, in particular to a method for manufacturing a double-diffusion field effect transistor. Background technique [0002] For the existing semiconductor process technology, double diffused field effect transistor (Double Diffuse Drain MOS, DDDMOS for short) is a mainstream high-voltage device structure, which is widely used in driver chips and power devices. [0003] Such as figure 1 As shown, in the prior art, the double-diffused transistor is generally manufactured according to the following method: [0004] Firstly, performing ion implantation on the silicon substrate to form a well region, and then performing selective ion implantation in the well region to form a drift region; [0005] Then, growing a gate silicon oxide layer on the well region; [0006] The third step is to deposit a gate polysilicon layer on the gate silicon oxide layer; [0007] The fourth step is to use known photolith...

AI Technical Summary

Problems solved by technology

[0009] Due to the limitation of the above-mentioned method of manufacturing double-diffused transistors, it is difficult to obtain an optimal result between the saturation current and the breakdown voltage of the double-diffused field effect transistor (that is, to ensure a certain breakdown voltage, so that the saturation current reaches the maximum)

This is mainly because the doping distribution of the drift region does not have a certain concentration gradient change in the channel direction (that is, the lateral direction) of the transistor manufactured by the above-mentioned common process, specifically as figure 2 As shown, when the doping concentration of the drift region is increased in order to increase the saturation current, the breakdown voltage of the lateral abrupt junction in the drift region of the device will drop rapidly due to the increase of the doping concentration of the drift region, so that the breakdown of the entire device voltage drops rapidly

Images