摘要:
A trenched DMOS transistor overcomes the problem of a parasitic JFET at the trench bottom (caused by deep body regions extending deeper than the trench) by providing a doped trench bottom implant region at the bottom of the trench and extending into the surrounding drift region. This trench bottom implant region has the same doping type, but is more highly doped, than the surrounding drift region. The trench bottom implant region significantly reduces the parasitic JFET resistance by optimizing the trench bottom implant dose, without creating reliability problems.
摘要:
A trenched field effect transistor suitable especially for low voltage power applications provides low leakage blocking capability due to a gate controlled barrier region between the source region and drain region. Forward conduction occurs through an inversion region between the source region and drain region. Blocking is achieved by a gate controlled depletion barrier. Located between the source and drain regions is a fairly lightly doped body region. The gate electrode, located in a trench, extends through the source and body regions and in some cases into the upper portion of the drain region. The dopant type of the polysilicon gate electrode is the same type as that of the body region. The body region is a relatively thin and lightly doped epitaxial layer grown upon a highly doped low resistivity substrate of opposite conductivity type. In the blocking state the epitaxial body region is depleted due to applied drain-source voltage, hence a punch-through type condition occurs vertically. Lateral gate control increases the effective barrier to the majority carrier flow and reduces leakage current to acceptably low levels.
摘要:
A trenched MOSFET in its on-state conducts current through an accumulation region and through an inverted depletion barrier layer located along the trench sidewalls. Blocking is achieved by gate control depletion of the adjacent region and by the depletion barrier layer (having the appearance of "ears" in a cross sectional view and being of opposite doping type to the adjacent region) which extends laterally from the trench sidewalls into the drift region. This MOSFET has superior on-state specific resistance to that of prior art trenched MOSFETs and also has good performance in terms of on state resistance, while having superior blocking characteristics to those of prior art trenched MOSFETs. The improvement in the blocking characteristic is provided by the depletion barrier layer which is a semiconductor doped region. In the blocking state, the depletion barrier layer is fully or almost fully depleted to prevent parasitic bipolar conduction. The shape and extent of the depletion barrier layer may be varied and more than one depletion barrier layer may be present.
摘要:
A trenched field effect transistor suitable especially for low voltage power applications provides low leakage blocking capability due to a gate controlled barrier region between the source region and drain region. Forward conduction occurs through an inversion region between the source region and drain region. Blocking is achieved by a gate controlled depletion barrier. Located between the source and drain regions is a fairly lightly doped body region. The gate electrode, located in a trench, extends through the source and body regions and in some cases into the upper portion of the drain region. The dopant type of the polysilicon gate electrode is the same type as that of the body region. The body region is a relatively thin and lightly doped epitaxial layer grown upon a highly doped low resistivity substrate of opposite conductivity type. In the blocking state the epitaxial body region is depleted due to applied drain-source voltage, hence a punch-through type condition occurs vertically. Lateral gate control increases the effective barrier to the majority carrier flow and reduces leakage current to acceptably low levels.
摘要:
A trenched field effect transistor suitable especially for low voltage power applications provides low leakage blocking capability due to a gate controlled barrier region between the source region and drain region. Forward conduction occurs through an inversion region between the source region and drain region. Blocking is achieved by a gate controlled depletion barrier. Located between the source and drain regions is a fairly lightly doped body region. The gate electrode, located in a trench, extends through the source and body regions and in some cases into the upper portion of the drain region. The dopant type of the polysilicon gate electrode is the same type as that of the body region. The body region is a relatively thin and lightly doped epitaxial layer grown upon a highly doped low resistivity substrate of opposite conductivity type. In the blocking state the epitaxial body region is depleted due to applied drain-source voltage, hence a punch-through type condition occurs vertically. Lateral gate control increases the effective barrier to the majority carrier flow and reduces leakage current to acceptably low levels.
摘要:
A DMOS field effect transistor having its gate electrode located in a trench includes a lightly doped epitaxial layer overlying the usual epitaxial layer. The trench penetrates only part way through the upper epitaxial layer which is more lightly doped than is the underlying lower epitaxial layer. The lightly doped upper epitaxial layer reduces the electric field at the bottom of the trench, thus protecting the gate oxide from breakdown during high voltage operation. Advantageously the upper portion of the lightly doped upper epitaxial layer has little adverse effect on the transistor's on resistance.
摘要:
An integrated circuit chip has full trench dielectric isolation of each portion of the chip. Initially the chip substrate is of conventional thickness and has semiconductor devices formed in it. After etching trenches in the substrate and filling them with dielectric material, a heat sink cap is attached to the passivation layer on the substrate front side surface. The passivation layer is a CVD diamond film which provides both electrical insulation and thermal conductivity. The substrate backside surface is removed (by grinding and/or CMP) to expose the bottom portion of the trenches. This fully isolates each portion of the die and eliminates mechanical stresses at the trench bottoms. Thereafter drain or collector electrical contacts are provided on the substrate backside surface. In a flip chip version, frontside electrical contacts extend through the frontside passivation layer to the heat sink cap. In a surface mount version, vias are etched through the substrate, with surface mount posts formed on the vias, to contact the frontside electrical contacts and provide all electrical contacts on the substrate backside surface. The wafer is then scribed into die in both versions without need for further packaging.
摘要:
An integrated circuit chip has full trench dielectric isolation of each portion of the chip. Initially the chip substrate is of conventional thickness and has semiconductor devices formed in it. After etching trenches in the substrate and filling them with dielectric material, a heat sink cap is attached to the passivation layer on the substrate front side surface. The substrate backside surface is removed (by grinding or CMP) to expose the bottom portion of the trenches. This fully isolates each portion of the die and eliminates mechanical stresses at the trench bottoms. Thereafter drain or collector electrical contacts are provided on the substrate backside surface. In a flip chip version, frontside electrical contacts extend through the frontside passivation layer to the heat sink cap. In a surface mount version, vias are etched through the substrate, with surface mount posts formed on the vias, to contact the frontside electrical contacts and provide all electrical contacts on the substrate backside surface. The wafer is then scribed into die in both versions without need for further packaging.
摘要:
An integrated circuit chip has full trench dielectric isolation of each portion of the chip. Initially the chip substrate is of conventional thickness and has semiconductor devices formed in it. After etching trenches in the substrate and filling them with dielectric material, a heat sink cap is attached to the passivation layer on the substrate front side surface. The substrate backside surface is removed (by grinding or CMP) to expose the bottom portion of the trenches. This fully isolates each portion of the die and eliminates mechanical stresses at the trench bottoms. Thereafter drain or collector electrical contacts are provided on the substrate backside surface. In a flip chip version, frontside electrical contacts extend through the frontside passivation layer to the heat sink cap. In a surface mount version, vias are etched through the substrate, with surface mount posts formed on the vias, to contact the frontside electrical contacts and provide all electrical contacts on the substrate backside surface. The wafer is then scribed into die in both versions without need for further packaging.
摘要:
A DMOS field effect transistor having its gate electrode located in a trench includes a lightly doped epitaxial layer overlying the usual epitaxial layer. The trench penetrates only part way through the upper epitaxial layer which is more lightly doped than is the underlying lower epitaxial layer. The lightly doped upper epitaxial layer reduces the electric field at the bottom of the trench, thus protecting the gate oxide from breakdown during high voltage operation. Advantageously the upper portion of the lightly doped upper epitaxial layer has little adverse effect on the transistor's on resistance.