TRENCH MOSFET WITH SUPER PINCH-OFF REGIONS
First Claim
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1. A trench MOSFET with super pinch-off regions comprising:
- a semiconductor chip comprising a substrate of a first conductivity doping type and an epitaxial layer of said first conductivity doping type, wherein said epitaxial layer formed onto top surface of said substrate and having lower doping concentration than said substrate;
a plurality of trenched gates extending from top surface of said semiconductor chip, said trenched gates filled with a conductive material insulated by a gate oxide layer from said semiconductor chip;
a source region of said first conductivity doping type located near top surface of a mesa which defined by an area between every two adjacent of said trenched gates;
a body region of a second conductivity doping type located in said mesa below said source region and adjacent to sidewall of said trenched gate;
a contact interlayer formed onto said top surface of said semiconductor chip;
a trenched source-body contact filled with a metal plug penetrating through said contact interlayer, said source region and said body region, and extending into said epitaxial layer in said mesa, wherein depth of said trenched source-body contact is shallower than bottom of said trenched gate;
an anti-punch through region of said second conductivity doping type wrapping around sidewall and bottom of said trenched source-body contact below a portion of said source region, wherein said anti-punch through region having higher doping concentration than said body region, and junction depth of said body region in said epitaxial layer is shallower than that of said anti-punch through region in a portion below bottom of said trenched source-body contact.
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Abstract
A trench MOSFET with short channel length and super pinch-off regions is disclosed, wherein the super pinch-off regions are implemented by forming at least two type pinch-off regions for punch-through prevention: a first type pinch-off region with a wide mesa width generated between lower portion of two adjacent trenched gates and below an anti-punch through region surrounding bottom of a trenched source-body contact filled with metal plug; a second type pinch-off region with a narrow mesa width generated below a body region and between upper portion of one trenched gate and the anti-punch-through region along sidewall of the trenched source-body contact.
24 Citations
34 Claims
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1. A trench MOSFET with super pinch-off regions comprising:
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a semiconductor chip comprising a substrate of a first conductivity doping type and an epitaxial layer of said first conductivity doping type, wherein said epitaxial layer formed onto top surface of said substrate and having lower doping concentration than said substrate; a plurality of trenched gates extending from top surface of said semiconductor chip, said trenched gates filled with a conductive material insulated by a gate oxide layer from said semiconductor chip; a source region of said first conductivity doping type located near top surface of a mesa which defined by an area between every two adjacent of said trenched gates; a body region of a second conductivity doping type located in said mesa below said source region and adjacent to sidewall of said trenched gate; a contact interlayer formed onto said top surface of said semiconductor chip; a trenched source-body contact filled with a metal plug penetrating through said contact interlayer, said source region and said body region, and extending into said epitaxial layer in said mesa, wherein depth of said trenched source-body contact is shallower than bottom of said trenched gate; an anti-punch through region of said second conductivity doping type wrapping around sidewall and bottom of said trenched source-body contact below a portion of said source region, wherein said anti-punch through region having higher doping concentration than said body region, and junction depth of said body region in said epitaxial layer is shallower than that of said anti-punch through region in a portion below bottom of said trenched source-body contact. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for manufacturing a trench MOSFET with super pinch-off regions comprising the steps of:
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opening a plurality of gate trenches in an epitaxial layer of a first conductivity type which supported onto a substrate of said first conductivity type; forming a gate oxide layer covering inner surface of said gate trenches and top surface of said epitaxial layer; depositing doped poly-silicon layer onto said gate oxide layer and etching back to keep said doped poly-silicon within said gate trenches; carrying out ion implantation of a second conductivity doping type dopant for formation of body region; carrying out ion implantation of said first conductivity doping type dopant for formation of source region; depositing a contact interlayer onto entire top surface; applying a contact mask and carrying out dry oxide etching and dry silicon etching successively to open a contact trench between two adjacent of said gate trenches through said contact interlayer, said source region, said body region and into said epitaxial layer to form trenched source-body contact; carrying out anti-punch through ion implantation of said second conductivity doping type dopant through said trenched source-body contact for formation of anti-punch through region surrounding bottom and sidewall of said contact trench below said source region. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification