Method for forming IGBT (insulated gate bipolar transistor) charge storage layer and charge storage type IGBT

Abstract

The invention provides a method for forming an IGBT (insulated gate bipolar transistor) charge storage layer. The method comprises the steps of forming a cut-off ring region; forming a hardmask, photoetching and defining a gate region, etching the gate hardmask, and removing glue and cleaning; performing trench etching for the first time, wherein the etching depth is the target depth of the charge storage layer; accurately injecting ions to the surface layer at the bottom of the trench; performing drive-in for the charge storage layer; performing trench etching for the second time on the trench obtained by the trench etching for the first time, enabling the depth of the etched groove to reach the depth required by the gate; and removing the hardmask. The preparation method disclosed by the invention does not require high-energy injection equipment and reduces the etching times; the prepared charge storage layer is relatively concentrated, high in charge storage density and strong in charge storage effect, and the adjustment and optimization of a device are facilitated; the invention also provides a charge storage type IGBT adopting the charge storage layer prepared by the technological method provided by the invention; and the current density of the charge storage type IGBT in a switch-on state is high, and the performance of the charge storage type IGBT is more excellent.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to a preparation process method of an IGBT charge storage layer. The present invention also relates to a charge storage type IGBT. Background technique [0002] Insulated Gate Bipolar Transistor (Insulated Gate Bipolar Transistor, IGBT) is a composite full-control voltage-driven power semiconductor device composed of a bipolar transistor (BJT) and an insulated gate field effect transistor (MOSFET). A giant transistor (Giant Transistor, GTR) under high voltage and high current is also a power transistor; IGTB has the advantages of high input impedance of MOSFET and low conduction voltage drop of GTR. It is very suitable for the conversion system with a DC voltage of 600V and above, such as AC motors, frequency converters, switching power supplies, lighting circuits, traction drives and other fields. [0003] For IGBT devices, it is very important to inc...

AI Technical Summary

Problems solved by technology

In the existing method for forming a charge storage layer, the charge storage layer 12 will extend the range of the entire P well 4, and the doping of the charge storage layer 12 will affect the doping of the P well 4, and the doping concentration of the P well 4 determines the device The turn-on voltage (Vth), so in order to maintain the normal turn-on voltage, the doping concentration of the charge storage layer 12 will be much lower than the P well 4, so the doping concentration of the charge storage layer 12 is limited by the doping concentration of the P well 4 , while the lower doping concentration of the charge storage layer 12 optimizes the VCE (sat) with E off The effect of the trade-off relationship is weak; the existing method of forming the charge storage layer needs to use the push well for a long time, the Phos diffusion range is wide, and the charge storage effect is relatively weak; at the same time, the diffusion of Phos will affect the Vth, Isc and other parameters. adjustment; moreover, existing charge storage layer formation methods require the use of high-energy implantation equipment in order to drive Phos into deeper locations

It can be seen that the existing method to form the charge storage layer not only has high cost, but also has a large room for improvement in the performance of the device.

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