CHARGE RESERVOIR IGBT TOP STRUCTURE

摘要

An IGBT device may be formed from a substrate including a bottom semiconductor layer of a first conductivity and an upper semiconductor layer of a second conductivity type located above the bottom semiconductor layer. Trenches for trench gates are formed in the substrate. Each trench extends vertically into the upper semiconductor layer and is provided with a gate insulator on each side of the trench and is filled with polysilicon. A first conductivity type floating body region is formed between two neighboring trenches and over the substrate. A bottom of the floating body region is close in depth to but above a bottom of the polysilicon in the trench. A heavily doped second conductivity type top region is formed over the floating body region. A first conductivity type body region is formed over the top region. The floating body region has a lower doping concentration than the body region.

主权项

1. A method for forming an IGBT device, comprising:
forming one or more trenches for trench gates in a substrate including a bottom semiconductor layer of a first conductivity and an upper semiconductor layer of a second conductivity located above the bottom semiconductor layer, wherein each of the one or more trenches is provided with a gate insulator on each side of the trench and filled with polysilicon and wherein the trench extends vertically into the upper semiconductor layer; forming a floating body region of the first conductivity type between two neighboring trenches and over the substrate, wherein a bottom of the floating body region is close in depth to but above a bottom of the polysilicon in the trench; forming a top region of the second conductivity type over the floating body region, wherein the top region of the second conductivity type is heavily doped; and forming a body region of the first conductivity type over the top region, wherein a doping concentration of the floating body region of the first conductivity type is lower than that of the body region of the first conductivity type.