Abstract: The semiconductor device includes: a substrate, an n-type drift region formed on a main surface of the substrate; a p-type well region, an n-type drain region and an n-type source region each formed in the drift region to extend from a second main surface of the drift region opposite to the first main surface of the drift region in contact with the substrate in a direction perpendicular to the second main surface; a gate groove extending from the second main surface in the perpendicular direction and penetrating the source region and the well region in a direction parallel to the first main surface of the substrate; and a gate electrode formed on a surface of the gate groove with a gate insulating film interposed therebetween, wherein the drift region has a higher impurity concentration than the substrate, and the well region extends to the inside of the substrate.

Abstract: A semiconductor device includes a main groove formed in a main surface of a substrate, a semiconductor region formed in contact with a surface of the main groove, an electron supply region formed in contact with a surface of the semiconductor region on opposite sides of at least side surfaces of the main groove to generate a two-dimensional electron gas layer in the semiconductor region, and a first electrode and a second electrode formed in contact with the two-dimensional electron gas layer and apart from each other.

Abstract: A semiconductor device (100) comprises: a semiconductor substrate (1); a drift region (2) of a first conductivity type having a trench in part of an upper portion thereof and arranged on a first main surface of the semiconductor substrate (100); an electric field reducing region (4) of a second conductivity type arranged, in a bottom portion of the trench, only around a corner portion and not in a center portion; an anode electrode (9) embedded in the trench; and a cathode electrode (10) arranged on a second main surface of the semiconductor substrate (100) which is opposite to the first main surface.

Abstract: The semiconductor device includes: a substrate, an n-type drift region formed on a main surface of the substrate; a p-type well region, an n-type drain region and an n-type source region each formed in the drift region to extend from a second main surface of the drift region opposite to the first main surface of the drift region in contact with the substrate in a direction perpendicular to the second main surface; a gate groove extending from the second main surface in the perpendicular direction and penetrating the source region and the well region in a direction parallel to the first main surface of the substrate; and a gate electrode formed on a surface of the gate groove with a gate insulating film interposed therebetween, wherein the drift region has a higher impurity concentration than the substrate, and the well region extends to the inside of the substrate.

Abstract: A semiconductor device (100) comprises: a semiconductor substrate (1); a drift region (2) of a first conductivity type having a trench in part of an upper portion thereof and arranged on a first main surface of the semiconductor substrate (100); an electric field reducing region (4) of a second conductivity type arranged, in a bottom portion of the trench, only around a corner portion and not in a center portion; an anode electrode (9) embedded in the trench; and a cathode electrode (10) arranged on a second main surface of the semiconductor substrate (100) which is opposite to the first main surface.

Abstract: In a method of forming a gate recess, on a surface of an epitaxial wafer including an epitaxial substrate, having a semiconductor layer having the band gap energy varying therein in the depth-wise direction, and a SiN surface protective layer, having a sidewall forming a gate opening and coating the surface of the epitaxial substrate, ultraviolet light having its energy equivalent to the band gap energy of the specific semiconductor layer is irradiated, while the specific semiconductor layer is photoelectrochemically etched from the gate opening with the SiN surface protective layer used as a mask. The gate recess free from plasma ion-induced damage is thus obtained.

Abstract: In a method of forming a gate recess, on a surface of an epitaxial wafer including an epitaxial substrate, having a semiconductor layer having the band gap energy varying therein in the depth-wise direction, and a SiN surface protective layer, having a sidewall forming a gate opening and coating the surface of the epitaxial substrate, ultraviolet light having its energy equivalent to the band gap energy of the specific semiconductor layer is irradiated, while the specific semiconductor layer is photoelectrochemically etched from the gate opening with the SiN surface protective layer used as a mask. The gate recess free from plasma ion-induced damage is thus obtained.

Abstract: There is provided a semiconductor device capable of deactivating 2-dimensional electron gas (2DEG) layers in a buffer layer having a multi-layer film structure. The buffer layer is formed in a high electron mobility transistor (HEMT) formed on a silicon (Si) substrate. The semiconductor device includes the substrate whose uppermost layer is the Si layer, the buffer layer constructed by alternately stacking a plurality of first layers and a plurality of second layers on the Si layer, third layer serving as an electron transit layer formed on the buffer layer, and fourth layer serving as an electron supplying layer formed on the third layer. The first layer is composed of the same material as for the third layer. A p-type impurity is introduced into the first layers so as to deactivate the 2DEG layers formed in the first layer near interfaces between the first and second layers.

Abstract: An opening for forming a gate electrode is provided by a first photoresist pattern formed on an insulating film. Reactive ion etching by inductively coupled plasma is applied to the insulating film through the first photoresist pattern as a mask to thereby expose the surface of a GaN semiconductor layer, evaporating thereon a gate metal such as NiAu, thereby forming the gate electrode by self-aligned process. This prevents an oxidized film from being formed on the surface of the semiconductor layer. After the gate electrode is formed, a second photoresist pattern is formed to form a field plate on the gate electrode and the insulating film through the second photoresist pattern as a mask. Thereby, Ti having a high adhesiveness with an insulating film made of SiN or the like can be used as a field plate metal.

Abstract: A semiconductor device has source and drain electrodes formed on a substrate, a gate insulation film formed on the substrate between the source and drain electrodes, and a gate electrode formed on the gate insulation film. These elements are all covered by a dielectric sub-insulation film. An opening is formed in the sub-insulation film, partially exposing the gate electrode. A field plate extends from the top of the gate electrode down one side of the gate electrode as far as the sub-insulation film covering the gate insulation film, filling the opening. The thickness of the sub-insulation film can be selected to optimize the separation between the field plate and the substrate for the purpose of reducing current collapse by reducing electric field concentration at the edge of the gate electrode.

Abstract: A metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) has a substrate in which an electron supply layer is interposed between an electron channel layer and the surface of the substrate. A pair of main electrodes are formed on the surface of the substrate. A recess is formed in the surface of the substrate between the main electrodes. A gate insulation film is formed on the surface of the substrate, at least between the first and second main electrodes, covering the inside walls and floor of the recess. A gate electrode is formed on the gate insulation film, filling in the recess. The gate insulation film has a crystal density of at least 2.9 g/cm3, which mitigates the reduction in threshold voltage caused by the recess.

Abstract: A semiconductor device has source and drain electrodes formed on a substrate, a gate insulation film formed on the substrate between the source and drain electrodes, and a gate electrode formed on the gate insulation film. These elements are all covered by a dielectric sub-insulation film. An opening is formed in the sub-insulation film, partially exposing the gate electrode. A field plate extends from the top of the gate electrode down one side of the gate electrode as far as the sub-insulation film covering the gate insulation film, filling the opening. The thickness of the sub-insulation film can be selected to optimize the separation between the field plate and the substrate for the purpose of reducing current collapse by reducing electric field concentration at the edge of the gate electrode.

Abstract: A semiconductor device includes a substrate, laminated layers provided on the substrate. The laminated layers include an AlGaN barrier layer as an uppermost layer. A gate electrode is provided in a channel region of the laminated layers. A source electrode and a drain electrode are provided so as to face each other via the channel region interposed therebetween. A silicon nitride film is formed to cover an exposed surface of the laminated layers exposed via the gate electrode, the source electrode and the drain electrode. The silicon nitride film has characteristics that an etching rate thereof is in a range from 1 nm per/min to 2 nm/min for an etchant in which hydrofluoric acid having a concentration of 50 weight percent and ammonium fluoride having a concentration of 40 weight percent are mixed at a mixing ratio of 1:9.

Abstract: An opening for forming a gate electrode is provided by a first photoresist pattern formed on an insulating film. Reactive ion etching by inductively coupled plasma is applied to the insulating film through the first photoresist pattern as a mask to thereby expose the surface of a GaN semiconductor layer, evaporating thereon a gate metal such as NiAu, thereby forming the gate electrode by self-aligned process. This prevents an oxidized film from being formed on the surface of the semiconductor layer. After the gate electrode is formed, a second photoresist pattern is formed to form a field plate on the gate electrode and the insulating film through the second photoresist pattern as a mask. Thereby, Ti having a high adhesiveness with an insulating film made of SiN or the like can be used as a field plate metal.

Abstract: A field effect transistor includes an active layer formed on a semiconductor substrate, source and drain electrodes formed apart from each other on the active layer, a gate electrode formed between the source and drain electrodes, a first interlayer film formed on the active layer, a first field plate (FP) electrode connected to the gate electrode and provided on the first interlayer film between the gate and drain electrodes, a second interlayer film formed on the first interlayer film, and a second FP electrode connected to the source electrode and provided on the second interlayer film between the first FP and drain electrodes. The field effect transistor is provided which exhibits a comparatively high gain factor at high frequencies.

Abstract: A semiconductor body includes, on a substrate, a stack of buffer layer, UID-GaN layer overlying the buffer layer, and UID-AlGaN layer overlying the UID-GaN layer. On the surface of the UID-AlGaN layer, an insulation film is deposited and patterned. An n+-GaN layer is selectively regrown directly on a region of the surface of the semiconductor body other than the insulation film using the patterned insulation film as a mask without etching the surface of the semiconductor body. A portion of the selectively regrown n+-GaN layer corresponding to a region reserved for an ohmic contact electrode is defined and the ohmic contact electrode is formed on the region. An opening exposing a region reserved for a gate electrode is defined and formed within the insulation SiO2 layer, and a gate electrode is formed in the region. An AlGaN/GaN-HEMT or MIS type of AlGaN/GaN-HEMT has lower contact resistance and uniform device characteristics.