Super-junction trench MOSFET having deep trenches with buried voids
AssigneeForce Mos Technology Co., Ltd.
InventorFu-Yuan Hsieh
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Abstract
A super-junction trench MOSFET is disclosed for high voltage device by applying a first doped column region of first conductivity type between a pair of second doped column regions of second conductivity type adjacent to sidewalls of a pair of deep trenches with buried voids in each unit cell for super-junction. Meanwhile, at least one trenched gate and multiple trenched source-body contacts are formed in each unit cell between the pair of deep trenches.
Claims11
A super junction trench MOSFET comprising a plurality of unit cells with each unit cell in an active area comprising:
- 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;
- a pair of deep trenches filled with dielectric material, starting from a top surface of said epitaxial layer and down extending into said epitaxial layer, each comprising a buried void inside said dielectric material;
- a mesa between said pair of deep trenches;
- a first doped column region of said first conductivity type with column shape within each said mesa;
- a pair of second doped column regions of a second conductivity type with column shape adjacent to sidewalls of said pair of deep trenches within said mesa, in parallel with and surrounding said first doped column region;
- a body region of said second conductivity type in said mesa, covering a top surface of said first and second doped column regions, extending between said pair of deep trenches;
- at least one trenched gate filled with doped poly-silicon layer padded by a gate oxide layer, starting from the top surface of said epitaxial layer and down penetrating through said body region and extending into said first doped column in said mesa;
- multiple trenched source-body contacts with each filled with a contact metal plug extending into said body region in said mesa;
- and
- a source region of said first conductivity type surrounding an upper portion of each said trenched gate, extending between the upper portion of each said trenched gate and sidewalls of adjacent trenched source-body contacts.
A method for manufacturing a unit cell of a super-junction trench MOSFET comprising the steps of:
- forming a pair of deep trenches inside an epitaxial layer of a first conductivity type onto a substrate of said first conductivity type;
- carrying out angle ion implantation of said first conductivity type dopant and diffusion to form a first doped column region with column shape within a mesa area between every two adjacent of said deep trenches;
- carrying out angle ion implantation of a second conductivity type dopant and diffusion to form second doped column regions with column shape adjacent to sidewalls of said deep trenches, in parallel with and surrounding said first doped column region;
- depositing a dielectric material with buried voids in said deep trenches;
- applying a gate trench mask to form at least one gate trench in said mesa by etching into said first doped column region;
- forming a least one trenched gates extending into said first doped column region between said pair of deep trenches;
- and
- forming body regions of said second conductivity type and source regions of said first conductivity type.
Dependencies are inferred from the claim text.