Devices, Methods, and Systems With MOS-Gated Trench-to-Trench Lateral Current Flow
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Abstract
A DMOS transistor is fabricated with its source/body/deep body regions formed on the walls of a first set of trenches, and its drain regions formed on the walls of a different set of trenches. A gate region that is formed in a yet another set of trenches can be biased to allow carriers to flow from the source to the drain. Lateral current low from source/body regions on trench walls increases the active channel perimeter to a value well above the amount that would be present if the device was fabricated on just the surface of the wafer. Masking is avoided while open trenches are present. A transistor with a very low on-resistance per unit area is obtained.
9 Citations
77 Claims
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1-57. -57. (canceled)
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58. A method of operating a MOS-gated downwardly-extended lateral current device, comprising the actions of:
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in a first condition, biasing a downwardly-extended gate electrode to control the carrier concentration in a downwardly-extended channel/shallow-body diffusion which laterally abuts a downwardly-extended source diffusion, and to thereby permit majority carrier transport out of said source diffusion through said channel to a downwardly-extended drain diffusion; in a second condition, assisting depletion of carriers from around said channel, by also depleting from a deep body which extends laterally, from the vicinity of said source diffusion toward said drain diffusion, farther than does said shallow-body diffusion; whereby any breakdown currents which may appear will flow predominantly through said deep-body diffusion rather than said channel. - View Dependent Claims (59, 60, 61)
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62. A system comprising:
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a power source having limited voltage, power, and/or energy; a load element, which is operatively connected to said power source through at least one electronic switch; wherein said switch comprises a three-dimensional active device structure, comprising; a downwardly extended source diffusion having a first conductivity type; a downwardly extended body diffusion having a second conductivity type, and laterally positioned adjacent to said source diffusion; a downwardly extended deep body diffusion having a second conductivity type, and laterally adjoining said body diffusion; a downwardly extended gate electrode, laterally positioned in proximity to at least part of said body diffusion and insulated therefrom; and a downwardly extended drain, positioned so that said body diffusion is laterally interposed between said drain and said source; wherein said source, body, deep body, gate and drain jointly define a respective DMOS-type device structure, at each of multiple different horizontal planes. - View Dependent Claims (63, 64, 65, 66, 67, 68)
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69. A system comprising:
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a power source having limited voltage, power, and/or energy; and a load element, which is operatively connected to said power source through at least one electronic switch; wherein said switch comprises a downwardly extended lateral-conduction device structure, comprising; a merged source/body trench, and source and deep body diffusions of opposite conductivity types adjacent to the walls thereof;
wherein said trench is narrowed at locations where said source diffusions are present;a source contact conductor which extends into said merged trench, and makes contact with said source and deep body diffusions; a gate trench, containing conductive material which is capacitively coupled to said body diffusion; and a downwardly extended drain diffusion, laterally spaced to receive charge carriers from said source diffusion under at least some conditions. - View Dependent Claims (70, 71, 72, 73, 74, 75, 76, 77)
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Specification