A gate-controlled thyristor with composite gate dielectric

Abstract

The invention provides a gate-controlled thyristor with a composite gate dielectric, in which a metallized anode, a first conductivity type semiconductor substrate, a second conductivity type semiconductor epitaxial layer, and a metallized cathode are sequentially stacked from bottom to top; the first conductivity type is also included Semiconductor well region, second conductivity type semiconductor well region, heavily doped first conductivity type semiconductor region, gate structure; the gate structure consists of a first dielectric material layer, a second dielectric material layer and an upper surface of the two dielectric material layers The gate electrode composition; the thickness of the first dielectric material layer is equal to the thickness of the second dielectric material layer, and the dielectric constant of the first dielectric material layer is lower than the second dielectric material layer; the present invention reduces the threshold voltage of the off channel , while not affecting the threshold voltage when turned on, improving the reliability of the gate-controlled thyristor device.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a gate-controlled thyristor with a composite gate dielectric. Background technique [0002] With the continuous development of human society, energy consumption continues to increase, while increasing energy output, there are also higher and higher requirements for energy utilization. The realization of these requirements depends on the development of power electronic devices. As a new type of semiconductor power switching device, MOS gate-controlled thyristor has attracted more and more people's attention. [0003] figure 1 Shown is a schematic structural diagram of a traditional N-type gate-controlled thyristor. Gate-controlled thyristor (MOS Controlled Thyristor, MCT) is a composite power device that combines the characteristics of MOSFET and thyristor. It also has high input impedance of MOSFET, fast switching speed, convenient gate control and high blocking ...

AI Technical Summary

Problems solved by technology

However, since the traditional gate-controlled thyristor manufacturing process is based on the triple diffusion process of DMOS technology, the P well and N well on the cathode side are formed by implantation and diffusion, so the doping concentration of the N well is usually greater than that of the P well. , the adjustable range is very small, so adjusting the doping concentration of the N well cannot effectively reduce the threshold voltage of the OFF-FET

Thinning the gate dielectric—silicon dioxide to reduce the threshold voltage of OFF-FET will reduce the threshold voltage of ON-FET at the same time, causing problems such as false turn-on, and a thinner gate oxide layer will also cause reliability problems

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