Isolated High Voltage Field Effect Transistor

Abstract

The invention discloses an isolated high-voltage-resistance field effect transistor with a current sampling function. The field effect transistor comprises a sampling tube and at least one sampled tube of the same structures, wherein the sampling tube is separately formed at a source region at the periphery of a multi-finger array structure of the sampled tube; a drain region and a polycrystalline silicon field gate are shared by the sampling tube and the sampled tube; a high-voltage-resistance buffer region is arranged at a position close to the polycrystalline silicon gate between the sampling tube source region and the sampled tube source region, consists of a silicon substrate P type substrate and crosses the polycrystalline silicon gate to isolate the source regions of the sampling tube and the sampled tube, a substrate P type well and a P type doped region; the polycrystalline silicon gate crosses the source regions of the sampling tube and the sampled tube, the substrate P type well and an N type drift region of the source region. According to the transistor, the integrated area can be reduced on the premise that high voltage resistance of the sampling tube and the sampled tube is kept, the effective area of the sampled tube is increased, and the sampling ratio of the device can be increased.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to an isolated high withstand voltage field effect transistor. Background technique [0002] At present, the commonly used isolation type high withstand voltage FET sampling tube structure is as follows: figure 1 As shown, the layout implementation is divided into two types: discrete type and integrated type. The discrete sampling tube is to place an independent small tube next to the sampled tube as the sampling tube. The drain area, drift area, source area, and channel area of ​​the sampling tube are the same in size and process as the sampled tube, that is, the section A-A is in The sampling tube is the same as the sampled tube, so that the current characteristics of the two tubes tested under the same voltage conditions are the same, so that the linear relationship between the sampling current and the sampled current can be guaranteed to achieve the purpose of samplin...

AI Technical Summary

Problems solved by technology

[0003] 1. Additional area is required to place a circular sampling tube, and the drain end of the sampling tube and the sampled tube need to be connected together through packaging, and the sampling tube packaging requires solder joints, which further increases the area of ​​the sampling tube;

[0004] 2. The smallest effective channel of the sampling tube is the circumference of the circle, so the current of the sampling tube cannot be made smaller, and the corresponding sampling ratio (current of the sampling tube / current of the sampled tube, under the same test conditions) cannot be increased;

[0006] 1. The position of a sampled tube is wasted to place the sampled tube. The higher the height of the sampled tube array is designed, the greater the loss of the current capacity of the sampled tube;

[0007] 2. The egg-shaped height of the sampling tube cannot be made very small, the smaller it is, the lower the pressure resistance, such as Image 6 shown

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