Semiconductor device including an MIS structure

A semiconductor device comprising an MIS structure including:

• a semiconductor layer having a front surface and a rear surface, the semiconductor layer made of SiC;
• a gate insulating film formed on the front surface of the semiconductor layer;
• and
• a gate electrode formed on the gate insulating film,
• a source region of a first conductivity type formed on a front surface side in the semiconductor layer;
• a body region of a second conductivity type formed on the front surface side in the semiconductor layer such that the body region is in contact with the source region;
• a drain region of a first conductivity type formed on the front surface side in the semiconductor layer such that the body region is in contact with the body region,
• wherein the gate insulating film has a layered structure that includes a base SiO2 layer, a high-k layer on the base SiO2 layer and containing Hf, and an upper insulating layer between the high-k layer and the gate electrode,
• the gate electrode has a portion made of a metal material having a work function of equal to or lower than an electron trap level in the high-k layer, the portion being in contact with at least the upper insulating layer and the gate electrode is opposed to the body region via the base SiO2 layer, the high-k layer and the upper insulating layer,
• the upper insulating layer is made of a material having a difference of lower than 4 eV between a lowest energy Ec in the conduction band and a vacuum energy level, and
• the high-k layer includes an HfAlON layer having an Hf composition (Hf/(Hf+Al)) of 30% to 70%.

A semiconductor device comprising an MIS structure including:

• a semiconductor layer having a front surface and a rear surface, the semiconductor layer made of SiC;
• a gate insulating film formed on the front surface of the semiconductor layer;
• and
• a gate electrode formed on the gate insulating film,
• a source region of a first conductivity type formed on a front surface side in the semiconductor layer;
• a body region of a second conductivity type formed on the front surface side in the semiconductor layer such that the body region is in contact with the source region;
• a drain region of a first conductivity type formed on the front surface side in the semiconductor layer such that the body region is in contact with the body region,
• wherein the gate insulating film has a layered structure that includes a base SiO2 layer, a high-k layer on the base SiO2 layer and containing Hf, and an upper insulating layer between the high-k layer and the gate electrode,
• the gate electrode has a portion made of a metal material having a work function of equal to or lower than an electron trap level in the high-k layer, the portion being in contact with at least the upper insulating layer and the gate electrode is opposed to the body region via the base SiO2 layer, the high-k layer and the upper insulating layer,
• the upper insulating layer is made of a material having a difference of lower than 4 eV between a lowest energy Ec in the conduction band and a vacuum energy level, and
• the high-k layer includes an HfAlON layer having an N amount of 10% or less.

A semiconductor device comprising an MIS structure including:

• a semiconductor layer having a front surface and a rear surface, the semiconductor layer made of SiC;
• a gate insulating film formed on the front surface of the semiconductor layer;
• and
• a gate electrode formed on the gate insulating film,
• a source region of a first conductivity type formed on a front surface side in the semiconductor layer;
• a body region of a second conductivity type formed on the front surface side in the semiconductor layer such that the body region is in contact with the source region;
• a drain region of a first conductivity type formed on the front surface side in the semiconductor layer such that the body region is in contact with the body region,
• wherein the gate insulating film has a layered structure that includes a base SiO2 layer, a high-k layer on the base SiO2 layer and containing Hf, and an upper insulating layer between the high-k layer and the gate electrode,
• the gate electrode has a portion made of a metal material having a work function of equal to or lower than an electron trap level in the high-k layer, the portion being in contact with at least the upper insulating layer and the gate electrode is opposed to the body region via the base SiO2 layer, the high-k layer and the upper insulating layer,
• the upper insulating layer is made of a material having a difference of lower than 4 eV between a lowest energy Ec in the conduction band and a vacuum energy level, and
• the high-k layer includes an HfAlON layer which is selected from a group consisting of an amorphous HfAlON layer and a microcrystalline HfAlON layer.