Super-junction trench MOSFETs with closed cell layout having shielded gate
A super-junction trench MOSFET with closed cell layout having shielded gate is disclosed, wherein closed gate trenches surrounding a deep trench in each unit cell and the shielded gate disposed in the deep trench. Trenched source-body contacts are at least formed between the closed gate trenches and the deep trench. The deep trench has square, rectangular, circle or hexagon shape.
1. A super-junction trench MOSFET comprising a plurality of unit cells with each unit cell in an active area comprising:
at least one gate trench surrounding a deep trench as a closed cell shape wherein a shielded gate is formed within said deep trench;
trenched source-body contacts disposed at least between said gate trench and said deep trench;
a substrate of a first conductivity type;
an epitaxial layer of said first conductivity type grown on said substrate, said epitaxial layer having a lower doping concentration than said substrate;
said deep trench having deeper trench depth than said gate trench;
said shielded gate formed within said deep trench and surrounded by a dielectric material;
a first doped column region of a second conductivity type with a second column shape between two adjacent of said deep trench;
a pair of second doped column regions of said first conductivity type with a column shape adjacent to sidewalls of said deep trench formed in parallel with and surrounding said first doped column region to form a charge balance area in connection with said first doped column region;
a body region of said second conductivity type, covering a top surface of said first and second doped column regions, extending between said deep trenches;
said gate trench filled with a doped poly-silicon layer padded by a gate oxide layer, starting from the top surface of said epitaxial layer and penetrating down through said body region and extending into said pair of second doped column regions;
said trenched source-body contacts with each filled with a contact metal plug extending into said body region;
a source region of said first conductivity type surrounded an upper portion of each said gate trench, extending between the upper portion of each said gate trench and sidewalls of adjacent trenched source-body contacts; and
a source metal connected with said shielded gate and said source region.
2. The super-junction trench MOSFET of claim 1 wherein said gate oxide has a thickness thinner than said dielectric material filled into said deep trench.
3. The super-junction trench MOSFET of claim 1 wherein said deep trench has a square shape.
4. The super-junction trench MOSFET of claim 1 wherein said deep trench has a circle shape.
5. The super-junction trench MOSFET of claim 1 wherein said deep trench has a hexagon shape.
6. The super-junction trench MOSFET of claim 1 wherein said deep trench has a rectangular shape.
7. The super-junction trench MOSFET of claim 1 further comprising a body contact region of said second conductivity type surrounded at least bottom of each of said trenched source-body contacts, wherein said body contact region has a higher doping concentration than said body region.
8. The super-junction trench MOSFET of claim 1 , wherein said contact metal plug is a tungsten plug padded by a barrier metal layer of Ti/TiN or Co/TiN or Ta/TiN.