An object is to provide a semiconductor device that can prevent organic contamination of an electrode including a plurality of laminated metal layers. A semiconductor device includes: a semiconductor substrate; and an electrode including a plurality of layers laminated on a principal surface of the semiconductor substrate. The electrode includes: a first metal layer in contact with the principal surface of the semiconductor substrate, the first metal layer containing Al; an oxide layer formed on a surface of the first metal layer, the oxide layer containing a metal and oxygen; and a second metal layer formed on a surface of the oxide layer. Concentrations of the oxygen in the oxide layer are higher than or equal to 8.0×10.sup.21/cm.sup.3 and lower than or equal to 4.0×10.sup.22/cm.sup.3.

A transistor includes a semiconductor layer and a channel region. The transistor further includes a first doped contact region in the semiconductor layer and adjacent the channel region. The transistor further includes a first ohmic contact including an interface region comprising a first interface length between the first ohmic contact and the first doped contact region larger than a length of the interface region.

A semiconductor device is made by: forming an ohmic electrode including Al on a semiconductor substrate; forming a SiN film covering the ohmic electrode; forming a first photoresist on the SiN film, the first photoresist having an opening pattern overlapping the ohmic electrode; performing ultraviolet curing of the first photoresist; forming an opening in the SiN film exposed through the opening pattern and causing a surface of the ohmic electrode to be exposed inside the opening; forming a barrier metal layer on the first photoresist and on the ohmic electrode exposed through the opening; forming a second photoresist in the opening pattern; performing a heat treatment on the second photoresist and covering the barrier metal layer overlapping the opening with the second photoresist; and etching the barrier metal layer using the second photoresist.

Provided is a semiconductor epitaxial wafer, including a substrate, a first epitaxial structure, a first ohmic contact layer and a second epitaxial stack structure. It is characterized in that the ohmic contact layer includes a compound with low nitrogen content, and the ohmic contact layer does not induce significant stress during the crystal growth process. Accordingly, the second epitaxial stack structure formed on the ohmic contact layer can have good epitaxial quality, thereby providing a high-quality semiconductor epitaxial wafer for fabricating a GaAs integrated circuit or a InP integrated circuit. At the same time, the ohmic contact properties of ohmic contact layers are not affected, and the reactants generated during each dry etching process are reduced.

An ohmic contact for a multiple channel FET comprises a plurality of slit-shaped recesses in a wafer on which a multiple channel FET resides, with each recess having a depth at least equal to the depth of the lowermost channel layer. Ohmic metals in and on the sidewalls of each recess provide ohmic contact to each of the multiple channel layers. An ohmic metal-filled linear connecting recess contiguous with the outside edge of each recess may be provided, as well as an ohmic metal contact layer on the top surface of the wafer over and in contact with the ohmic metals in each of the recesses. The present ohmic contact typically serves as a source and/or drain contact for the multiple channel FET. Also described is the use of a regrown material to make ohmic contact with multiple channels, with the regrown material preferably having a corrugated structure.

A Group III-V semiconductor structure having a semiconductor device. The semiconductor device has a source and drain recess regions extending through a barrier layer and into a channel layer. A regrown, doped Group III-V ohmic contact layer is disposed on and in direct contact with the source and drain recess regions. A gate electrode is disposed in a gap in the regrown, doped Group III-V ohmic contact layer and on the barrier layer A dielectric structure is disposed over the ohmic contact layer and over the barrier layer and extending continuously from a region over the source recess region to one side of the stem portion and then extending continuously from an opposite side of the stem portion to a region over the drain recess region, a portion of the dielectric structure being in contact with the stem portion and the barrier layer.

A semiconductor structures and methods for manufacturing the same are provided. The semiconductor structure includes a substrate; a first nitride semiconductor layer disposed on the substrate; a second nitride semiconductor layer disposed on the first nitride semiconductor layer and having a bandgap greater than that of the first nitride semiconductor layer, the second nitride semiconductor layer forming a first recess and a second recess; and an electrode disposed on the second nitride semiconductor layer and comprising an element; wherein the electrode is disposed in the first recess and the second recess.

A circuit element is formed on a substrate made of a compound semiconductor. A bonding pad is disposed on the circuit element so as to at least partially overlap the circuit element. The bonding pad includes a first metal film and a second metal film formed on the first metal film. A metal material of the second metal film has a higher Young's modulus than a metal material of the first metal film.

A semiconductor device includes a III-V compound semiconductor layer and a source/drain structure. The source/drain structure is disposed on the III-V compound semiconductor layer. The source/drain structure includes a metal layer and metal silicide patterns. The metal layer is disposed on the metal silicide patterns, and a portion of the metal layer is disposed between the metal silicide patterns adjacent to each other.

Disclosed are a transistor and a method for forming the transistor. The method includes concurrently forming gate and source/drain openings through an uppermost layer (i.e., a dielectric layer) in a stack of layers. The method can further include: depositing and patterning gate conductor material so that a first gate section is in the gate opening and a second gate section is above the gate opening and so that the source/drain openings are exposed; extending the depth of the source/drain openings; and depositing and patterning source/drain conductor material so that a first source/drain section is in each source/drain opening and a second source/drain section is above each source/drain opening. Alternatively, the method can include: forming a plug in the gate opening and sidewall spacers in the source/drain openings; extending the depth of source/drain openings; depositing and patterning the source/drain conductor material; and subsequently depositing and patterning the gate conductor material.