Abstract: In accordance with the teachings of this invention, a novel electrical interconnect structure is taught, together with the process for forming this structure. In accodance with the teachings of this invention, this structure includes an electrical interconnect layer which is formed on a grooved portion of the surface of a semiconductor device. Thus, the effective cross-sectional area of the electrical interconnect layer is increased because the electrical interconnect material is formed into the grooves. With the thickness of the electrical interconnect layer thus increased as compared with the thickness of prior art electrical interconnect layers, the sheet resistance of the electrical interconnect layer of this invention is reduced over the sheet resistance of prior art electrical interconnect layers. With a lower sheet resistance, a given length of electrical interconnect can be formed of the same resistance as in the prior art with a smaller width.

Abstract: Grooves are formed in a single crystal silicon wafer in a pattern to encircle surface areas. Silicon dioxide is placed in the grooves and on the surface and then removed from certain of the areas. Layers of silicon are epitaxially grown only on these areas and their surfaces are oxidized. Polycrystalline silicon is deposited to a thickness greater than that of the epitaxial layers. Both sides of the wafer are ground and polished to produce flat, planar, opposite surfaces; one surface exposing surface areas of the epitaxial layers, the other surface exposing the silicon dioxide in the grooves. The resulting substrate has two types of silicon sections, each of which is electrically isolated from the other by silicon dioxide partitions. One type of section is of silicon of the original wafer, has a surface area in only one surface, and is suitable for the fabrication of low voltage, low power devices therein.

Abstract: A process for manufacturing a JFET in accordance with our invention includes the steps of forming an N- layer (12) on an N+ substrate (10), and forming an N+ layer (14) on the N- layer. A plurality of trenches (19) are etched to extend through the N+ layer and through a portion of the N- layer. A layer of sidewall oxide (20) is grown along the vertical walls of the trenches. The trenches are then extended so that the sidewall oxide only covers a portion of the vertical walls of the trenches. A layer of P type polysilicon (22) is then deposited in the trenches and impurities are diffused from the P type polysilicon into a surrounding portion of the N- layer to thereby form a plurality of P type regions (23). The size of the depletion region between the P type regions and the N- layer is controlled by applying selected voltages to the P type polysilicon, thereby controlling the current through the resulting JFET.

Abstract: A dual-gate vertical field effect transistor comprises an N+ substrate (102) which serves as a drain, and N-epitaxial layer (104) formed on the N+ substrate, and an N+ layer (106) formed at the surface of the epitaxial layer which serves as a source. A plurality of grooves (108a, 108b) extends through the N+ region and a portion of the N-layer. The grooves are lined with an insulating layer (110a, 110b) and filled with a conductive polysilicon gate (112a, 112b). Underneath each of the grooves is a P+ region (116a, 116b) which serves as a second gate. Thus, the transistor in accordance with the present invention includes a set of polysilicon gates and a set of P+ gates for independently modulating the current permitted to flow between the transistor source and drain.

Abstract: This inventive DMOS transistor provides faster turn-on switching than prior art lateral and vertical DMOS transistors in dV/dt situations and prevents catastrophic failures from high dV/dt's. The preferred embodiment of this improved device combines a Schottky diode with a vertical DMOS transistor, within the semiconductor structure itself, to form a device equivalent to a Schottky diode in parallel with an N channel vertical DMOS transistor. The Schottky diode effectively replaces the body diode of the transistor when forward biasing voltages are applied to the DMOS transistor. Thus, the body diode is never forward biased and there is no recovery time associated with the body diode. This speeds up the turn-on of the DMOS transistor since there are no minority carriers in the P-N junction body diode to recombine. Also, the parasitic bipolar junction transistor (BJT), formed by the source, body region, and drain, cannot turn on, thus preventing second breakdown of the BJT.

Abstract: In order to increase breakdown voltage of a planar junction of a semiconductor device, an oxide layer is provided on a portion of the surface of the semiconductor substrate and covers the junction at that surface, the oxide layer containing a charged ion region extending from the junction over a portion of the substrate, with the polarity of the ions being the same as the polarity of the substrate region over which the oxide layer extends.

Abstract: A j-MOS structure is disclosed which operates at high current densities and provides high current handling capability. A heavily doped N+ substrate, acting as a drain, has grown on it a lightly doped N- epitaxial layer. Within the epitaxial layer are multiple N+ buried regions, each within a corresponding P+ buried region, and bisecting each of the multiple N+ regions are vertical gates extending from the upper surface of the epitaxial layer down into the N+ substrate. These gates are insulated from the epitaxial layer and substrate via a thin gate oxide layer, but are electrically connected to the multiple N+ buried regions. Between each adjacent gate pair, N+ source regions are formed on the upper surface of the epitaxial layer. The gates are connected together via a conductive layer which also electrically shorts the gates to a poly-Si contact making contact with the N+ buried regions.

Abstract: A method of fabricating a semiconductor device capable of handling high voltages includes forming a relatively thick epitaxial layer the top surface of which defines a plurality of generally V-shaped grooves, a pair of the grooves having formed therebetween active device regions, such pair of grooves acting as isolation regions including impurity regions extending on both sides of the groove through the epitaxial layer to a lower layer. A pair of grooves formed inward of the first-mentioned grooves contact active regions of the device into which the V-shaped portions extend, again with each such V-shaped portion having impurity regions extending on both sides thereof. The impurity regions associated with the V-shaped grooves are formed simultaneously with other active regions of the device.

Abstract: An insulated gate transistor (70) modified to increase its latching current density. On one side of gate (22), a high conductivity collector well (76) is provided to divert current which would otherwise flow through collector well (24) in a critical path (50) along source-collector junction (27), tending to forward bias the junction and cause the transistor to latch.

Abstract: Junction field effect transistor, specifically a static induction transistor, and method of fabricating. A low resistivity N-type surface layer is formed at the surface of a high resistivity N-type epitaxial layer which has been grown on a low resistivity N-type substrate of silicon. The surface of the surface layer is coated with silicon dioxide and portions of the silicon dioxide layer are removed to expose alternating gate surface areas and source surface areas. P-type conductivity material is diffused into the silicon from the gate surface areas to produce zones of graded concentration. The difference in concentration of N-type conductivity imparting material in the surface layer and in the remainder of the epitaxial layer causes the resulting P-type gate regions to extend laterally toward each other so as to produce narrow channel regions at a depth beyond the surface layer while limiting the lateral extensions of the P-type gate regions adjacent to the surface.

Abstract: In the fabrication process of a DMOS transistor, a window is formed between polysilicon gate regions. Nitrogen is then implanted in the window. A self-aligning oxide is deposited to cover the exposed side walls of the polysilicon gate regions. P-type impurities are implanted at the exposed surface of the window between the side walls. Using silicon nitride masking, an oxide plug is then grown in the window. N-type impurities are implanted in the window region to form a junction adjacent to the polysilicon gate regions. Metal contacts and a passivation layer are subsequently deposited by masking, and contact windows are formed to complete the transistor structure.

Abstract: Junction field effect transistor, specifically a static induction transistor, and method of fabricating. An epitaxial layer of high resistivity N-type silicon is grown on a substrate of low resistivity silicon. The surface of the epitaxial layer is coated with silicon nitride, portions of the silicon nitride are removed, and the silicon is etched to form parallel grooves with interposed ridges of silicon. A layer of silicon nitride is applied and then removed except from the side walls of the grooves. Exposed silicon at the bottoms of the grooves is converted to silicon dioxide to build up layers of silicon dioxide in the grooves. The remaining silicon nitride is removed. P-type conductivity imparting material is ion implanted into alternate (gate) ridges and diffused to form gate regions which extend laterally beneath the silicon dioxide in the adjacent grooves. N-type conductivity imparting material is ion implanted in the top of the intervening (source) ridges.

Abstract: Junction field effect transistor, specifically a static induction transistor, and method of fabricating. An epitaxial layer of high resistivity N-type silicon is grown on a substrate of low resistivity silicon. The surface of the epitaxial layer is coated with silicon nitride, portions of the silicon nitride are removed, and the silicon is etched to form parallel grooves with interposed ridges of silicon. A layer of silicon nitride is applied and then removed except from the side walls of the grooves. Exposed silicon at the bottoms of the grooves is converted to silicon dioxide to build up layers of silicon dioxide in the grooves. The remaining silicon nitride is removed. P-type conductivity imparting material is ion implanted into alternate (gate) ridges and diffused to form gate regions which extend laterally beneath the silicon dioxide in the adjacent grooves. N-type conductivity imparting material is ion implanted in the top of the intervening (source) ridges.

Abstract: Grooves are formed in a single crystal silicon wafer in a pattern to encircle surface areas. Silicon dioxide is placed in the grooves and on the surface and then removed from certain of the areas. Layers of silicon are epitaxially grown only on these areas and their surfaces are oxidized. Polycrystalline silicon is deposited to a thickness greater than that of the epitaxial layers. Both sides of the wafer are ground and polished to produce flat, planar, opposite surfaces; one surface exposing surface areas of the epitaxial layers, the other surface exposing the silicon dioxide in the grooves. The resulting substrate has two types of silicon sections, each of which is electrically isolated from the other by silicon dioxide partitions. One type of section is of silicon of the original wafer, has a surface area in only one surface, and is suitable for the fabrication of low voltage, low power devices therein.

Abstract: Junction field effect transistor, specifically a static induction transistor and method of fabricating. A low resistivity N-type layer is formed at the surface of a high resistivity N-type epitaxial layer which has been grown on a low resistivity N-type substrate of silicon. The surface of the low resistivity N-type layer is coated with silicon nitride, portions of the silicon nitride are removed and the silicon is etched to form parallel grooves with interposed ridges of silicon. Silicon dioxide is grown in the grooves, removed from the end walls of the grooves, and P-type zones are formed at the end walls of the grooves. The depth of the grooves is increased by etching to remove most of the P-type zone underlying each groove while leaving laterally extending P-type portions. Oxygen is implanted to convert the remainder of the P-type zones underlying the end walls of the grooves to silicon dioxide. Metal layers are deposited in the bottoms of the grooves making contact with the P-type portions.

Abstract: Junction field effect transistor, specifically a static induction transistor, and method of fabricating. A low resistivity N-type surface layer is formed at the surface of a high resistivity N-type epitaxial layer which has been grown on a low resistivity N-type substrate of silicon. The surface of the surface layer is coated with silicon dioxide and portions of the silicon dioxide layer are removed to expose alternating gate surface areas and source surface areas. P-type conductivity material is diffused into the silicon from the gate surface areas to produce zones of graded concentration. The difference in concentration of N-type conductivity imparting material in the surface layer and in the remainder of the epitaxial layer causes the resulting P-type gate regions to extend laterally toward each other so as to produce narrow channel regions at a depth beyond the surface layer while limiting the lateral extensions of the P-type gate regions adjacent to the surface.

Abstract: Junction field effect transistor, specifically a static induction transistor and method of fabricating. A low resistivity N-type layer is formed at the surface of a high resistivity N-type epitaxial layer which has been grown on a low resistivity N-type substrate of silicon. The surface of the low resistivity N-type layer is coated with silicon nitride, portions of the silicon nitride are removed, and the silicon is etched to form parallel grooves with interposed ridges of silicon. Silicon dioxide is grown in the grooves, removed from the end walls of the grooves, and P-type zones are formed at the end walls of the grooves. Metal contacts are applied to the P-type zones at the end walls of the grooves. The grooves are filled with filler material and materials are etched away to produce a flat, planar surface with low resistivity N-type silicon of the ridges exposed in the surface and with filler material in the grooves also exposed at the surface.

Abstract: A gate-source structure and fabrication method for a surface-gate static induction transistor. The method requires only one masking step during fabrication, thereby eliminating or minimizing mask registration problems during fabrication of the devices. The method and the device are characterized by a two-step etching process which forms T-shaped gate windows in layers of poly-crystalline silicon with different doping levels. The source region is formed during an annealing step from the layer with high doping level. During the annealing step, the gate regions are also formed from gate impurities implanted previously in the gate windows. The source structure and the gate structure are separated by a silicon dioxide protective layer.

Abstract: Semiconductor electrode structure with low parasitic capacitance and method for forming low capacitance first and second electrodes in a semiconductor device, such as a static induction transistor, while avoiding the requirement for precision mask alignment and mask to mask registration. During formation of electrode contacts, the first electrodes are protected by silicon nitride and a low resistivity silicon layer is grown over the semiconductor wafer, forming epitaxial regions over the second electrodes of a polycrystalline region over protected portions of the wafer. The silicon layer is selectively etched by a mixture which removes the polycrystalline region but does not appreciably affect the epitaxial regions. Second electrode metallic contacts are made in enlarged regions of the second electrodes where mask alignment is not critical. The reduction in contact window overlap by metallic contacts reduces parasitic capacitance.

Abstract: A gate-source structure and fabrication method for a static induction transistor having improved gain and frequency characteristics and having relatively simple fabrication requirements. The method and the device are embodied by gate regions diffused into the bottom of parallel recessed grooves located in a high resistivity epitaxial semiconductor layer, the surface of the semiconductor layer having a previously diffused source region located between the recessed grooves. The walls of the recessed grooves are covered with silicon dioxide.