Transient-voltage-suppression (TVS) diode device and method of fabricating the same

A transient-voltage-suppression (TVS) diode device, comprising:

• a substrate having a first conductivity type;
• a second conductivity type first epitaxial layer and a second conductivity type second epitaxial layer disposed over the substrate, wherein a top surface and a bottom surface of the second conductivity type second epitaxial layer respectively adjacent to the second conductivity type first epitaxial layer and the substrate, wherein the second conductivity type first epitaxial layer and the second conductivity type second epitaxial layer have a second conductivity type that is different from the first conductivity type;
• and
• a Zener diode formed in the second conductivity type first epitaxial layer and the second conductivity type second epitaxial layer;
• wherein the Zener diode comprises:
• a first conductivity type doped well region disposed in the second conductivity type second epitaxial layer, wherein the first conductivity type doped well region has the first conductivity type;
• a second conductivity type doped well region disposed in the second conductivity type first epitaxial layer, wherein the second conductivity type doped well region has the second conductivity type;
• and
• a first conductivity type buried layer disposed in the second conductivity type second epitaxial layer, wherein the first conductivity type buried layer has the first conductivity type.

A method for fabricating a transient-voltage-suppression (TVS) diode device, comprising:

• providing a substrate having a first conductivity type, the substrate comprises a plurality of defined regions for a plurality of trench isolation features, wherein the plurality of defined regions divide the substrate into a first active region, a second active region, a third active region, a fourth active region and a fifth active region;
• performing a first epitaxial growth process to epitaxially grow a second conductivity type epitaxial layer, wherein the second conductivity type epitaxial layer has a second conductivity type that is different from the first conductivity type;
• performing a first doping process to form a first conductivity type doped well region in the second conductivity type epitaxial layer within the first active region, wherein the first conductivity type doped well region has the first conductivity type;
• performing a second doping process to form a first conductivity type buried layer on the first conductivity type doped well region within the first active region, wherein the first conductivity type buried layer has the first conductivity type;
• performing a second epitaxial growth process to epitaxially grow another second conductivity type epitaxial layer on the second conductivity type epitaxial layer, wherein the other second conductivity type epitaxial layer has the second conductivity type;
• performing a third doping process to form a second conductivity type doped well region in the other second conductivity type epitaxial layer within the first active region, wherein the second conductivity type doped well region has the second conductivity type;
• and
• forming a plurality of trench isolation features in the plurality of defined regions for a plurality of trench isolation features, wherein the plurality of trench isolation features is formed extending into the substrate from a top surface of the other second conductivity type epitaxial layer and passing through a bottom surface of the second conductivity type epitaxial layer.