Junction field effect transistor

Abstract

The invention belongs to the semiconductor device field and discloses a junction field effect transistor. According to the junction field effect transistor, a back grid is formed between a trench and a P substrate of the JFET (junction type field effect transistor) and is corresponding to the position of a positive grid, and as a result, when negative voltage is applied to the grids, depletion regions of a positive grid PN junction and a negative grid PN junction do not horizontally extend, but vertically extend with the increase of the negative voltage, so that small pinch-off voltage can be obtained; drain-source voltage is mainly borne by horizontal extension of the depletion regions, and P type lightly-doped regions which are adjacent to a source are formed between the trench and the P substrate of the JFET, so that the distribution of an electric field in the trench of the JFET is more uniform, and N type lightly-doped regions which are located below a drain are formed between the trench and the P substrate of the JFET, and thus, breakdown of a PN junction formed by the trench and the P substrate of the JFET, which occurs at the bottom of a drain end, can be avoided, and as a result, high drain-source breakdown voltage can be obtained. With the junction field effect transistor adopted, contradictions among three parameters, namely, the pinch-off voltage, the drain-source breakdown voltage and current conduction capacity, can be alleviated.

Description

Technical field [0001] The invention relates to the field of semiconductor devices, in particular to a junction field effect tube. Background technique [0002] Junction Field Effect Transistor (JFET) is one of the most common semiconductor devices, including N-channel junction field effect transistors and P-channel junction field effect transistors. In practical applications, commonly used It is an N-channel JFET (JFET in the following refers to an N-channel JFET). [0003] The basic structure of the N-channel JFET is to diffuse two P-type doped regions on both sides of the N-type semiconductor to form two PN junctions. The two P-type doped regions are the gate of the JFET. The N-type semiconductor region between the doped regions is the channel of the JFET, and the two ends of the N-type semiconductor are the source and drain of the JFET respectively. figure 1 Shown is a common JFET structure, such as figure 1 As shown, an N-type lightly doped region 10 is formed in the upper su...

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Problems solved by technology

[0009] The present invention provides a junction field effect transistor, which is used to solve the problem of increasing the doping concentration of the channel in the existing JFET structure and improving the current conduction capability, the pinch-off voltage of the device is also larger, and the drain-source breakdown voltage is lower. The smaller the JFET, the higher the current conduction capability, the drain-source breakdown voltage, and the smaller pinch-off voltage cannot be guaranteed at the same time.

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