Power semiconductor devices integrated with clamp diodes having separated gate metal pads to avoid breakdown voltage degradation
A structure of power semiconductor device integrated with clamp diodes having separated gate metal pad is disclosed. The separated gate metal pads are wire bonded together on the gate lead frame. This improved structure can prevent the degradation of breakdown voltage due to electric field in termination region blocked by polysilicon.
1. A vertical semiconductor power MOSFET device comprising a plurality of semiconductor power cells with each cell comprising a trenched gate surrounded by a source region with first type conductivity in active area encompassed in a body region with second type conductivity above a drain region disposed on a bottom surface of a low-resistivity substrate with first type conductivity, wherein said trench MOSFET cell further comprising:
an epitaxial layer of said first conductivity type over said substrate, said epitaxial layer having a lower doping concentration than the substrate;
a first insulating layer serving as gate oxide lining the inner surface of openings for trench gates;
a second insulating layer functioning as thick oxide interlayer;
a plurality of trench contacts filled with a barrier layer and tungsten plugs;
a source metal layer connected to the source regions and the body regions via trench source-body contacts;
a gate-source clamp diode connected between a first gate metal and a source metal, composed of multiple back-to-back Zener diodes disposed inside of edge termination area;
a gate-drain clamp diode connected between a second gate metal and a first drain metal, composed of multiple back-to-back polysilicon Zener diodes disposed outside of edge termination area without having said polysilicon Zener diode or said gate metal cross over said edge termination;
said first drain metal connected to the epitaxial layer via trench drain contacts;
a second drain metal layer formed on a bottom surface of the substrate; and
said first and second gate metals connected together at gate lead frame through bonding wires.
2. The MOSFET of claim 1 , wherein said two bond wires used to separately connected said first gate metal and second gate metal to said gate lead frame.
3. The MOSFET of claim 1 , wherein said single bond wire used to connect said first gate metal then said second gate metal to said gate lead frame.
4. The MOSFET of claim 1 , wherein gate metal runner also serving as metal field plate is deposited over body region in termination area.
5. The MOSFET of claim 1 , wherein gate metal runner also serving as metal field plate is deposited over deep guard ring in termination area.
6. The MOSFET of claim 1 , wherein implantation regions of said first doping type in top surface of said epitaxial layer next to body region and underneath trench bottom is implemented for Rds reduction.