Trenched shield gate power semiconductor devices and methods of manufacture

A semiconductor device comprising:

• a drift region of a first conductivity type;
• a well region extending above the drift region and having a second conductivity type opposite the first conductivity type;
• an active trench extending through the well region and into the drift region, the active trench having its sidewalls and bottom lined with dielectric material, and substantially filled with a first conductive layer and a second conductive layer, the second conductive layer forming a gate electrode and being disposed above the first conductive layer and separated therefrom by inter-electrode dielectric material, the first conductive layer forming a first shield electrode;
• source regions having the first conductivity type formed in the well region adjacent the active trench;
• a charge control trench extending deeper into the drift region than the active trench and substantially filled with material to allow for vertical charge control in the drift region;
• and
• wherein the active trench further comprises a second shield electrode made of conductive material disposed below the first shield electrode, the second shield electrode is smaller than the first shield electrode.

A semiconductor device comprising:

• a drift region of a first conductivity type;
• a well region extending above the drift region and having a second conductivity type opposite the first conductivity type;
• an active trench extending through the well region and into the drift region, the active trench having its sidewalls and bottom lined with dielectric material, and substantially filled with a first conductive layer and a second conductive layer, the second conductive layer forming a gate electrode and being disposed above the first conductive layer and separated therefrom by inter-electrode dielectric material;
• source regions having the first conductivity type formed in the well region adjacent the active trench;
• a charge control trench extending deeper into the drift region than the active trench and substantially filled with material to allow for vertical charge control in the drift region;
• wherein the charge control trench is substantially filled with dielectric material;
• and
• wherein the active trench further comprises a third conductive layer disposed below the first conductive layer, the third conductive layer is smaller than the first conductive layer.

A semiconductor device comprising:

• a drift region of a first conductivity type;
• a well region extending above the drift region and having a second conductivity type opposite the first conductivity type;
• an active trench extending through the well region and into the drift region, the active trench having its sidewalls and bottom lined with dielectric material, and substantially filled with a first conductive layer and a second conductive layer, the second conductive layer forming a gate electrode and being disposed above the first conductive layer and separated therefrom by inter-electrode dielectric material;
• source regions having the first conductivity type formed in the well region adjacent the active trench;
• a charge control trench extending deeper into the drift region than the active trench and substantially filled with material to allow for vertical charge control in the drift region;
• and
• a Schottky structure formed between the charge control trench and a second adjacent charge control trench.

A semiconductor device comprising:

• a drift region of a first conductivity type;
• a well region extending above the drift region and having a second conductivity type opposite the first conductivity type;
• an active trench extending through the well region and into the drift region, the active trench having its sidewalls and bottom lined with dielectric material, and substantially filled with a first conductive layer and a second conductive layer, the second conductive layer forming a gate electrode and being disposed above the first conductive layer and separated therefrom by inter-electrode dielectric material;
• source regions having the first conductivity type formed in the well region adjacent the active trench;
• a charge control trench extending deeper into the drift region than the active trench and substantially filled with material to allow for vertical charge control in the drift region;
• wherein the first conductive layer inside the active trench forms a secondary gate electrode that is configured to be electrically biased to a desired potential;
• and
• wherein the active trench further comprises a third conductive layer disposed below the first conductive layer, the third conductive layer is smaller than the first conductive layer.

A semiconductor device comprising

• a drift region of a first conductivity type;
• a well region extending above the drift region and having a second conductivity type opposite the first conductivity type;
• an active trench extending through the well region and into the drift region, the active trench having its sidewalls and bottom lined with dielectric material, and substantially filled with a first conductive layer and a second conductive layer, the second conductive layer forming a gate electrode and being disposed above the first conductive layer and separated therefrom by inter-electrode dielectric material;
• source regions having the first conductivity type formed in the well region adjacent the active trench;
• a charge control trench extending deeper into the drift region than the active trench and substantially filled with material to allow for vertical charge control in the drift region;
• and
• a Schottky structure formed between the charge control trench and a second adjacent charge control trench;
• wherein the first conductive layer inside the active trench forms a secondary gate electrode that is configured to be electrically biased to a desired potential.