Ngk Insulators, Inc.

Dowa Electronics Materials Co., Ltd.

Shigeaki Sumiya

Mitsuhiro Tanaka

Makoto Miyoshi

Tomohiko Shibata

Mikiya Ichimura

Keiichiro Asai

Yoshitaka Kuraoka

Tomohiko Sugiyama

Sota Maehara

Kei Kosaka

Minoru Imaeda

Asai Keiichiro

Mitsuhiro 703 Arthills-Kirigaoka Minamikan Tanaka

Provided is a semiconductor device in which a reverse leakage current is suppressed and the mobility of a two-dimensional electron gas is high. A semiconductor device includes: an epitaxial substrate in which a group of group-III nitride layers are laminated on a base substrate such that a (0001) crystal plane is substantially in parallel with a substrate surface; and a Schottky electrode. The epitaxial substrate includes: a channel layer made of a first group-III nitride having a composition of InAlGaN (x1+y1+z1=1, z1&#x3e;0); a barrier layer made of a second group-III nitride having a composition of InAlN (x2+y2=1, x2&#x3e;0, y2&#x3e;0); an intermediate layer made of GaN adjacent to the barrier layer; and a cap layer made of AlN and adjacent to the intermediate layer. A Schottky electrode is bonded to the cap layer.

Semiconductor device, HEMT device, and method of manufacturing semiconductor device

Provided is a crack-free epitaxial substrate with reduced warping, in which a silicon substrate is used as a base substrate. The epitaxial substrate includes a (111) single crystal Si substrate, a superlattice layer group in which a plurality of superlattice layers are laminated, and a crystal layer. The superlattice layer is formed of a first unit layer and a second unit layer made of group-III nitrides having different compositions being alternately and repeatedly laminated. The crystal layer is made of a group-III nitride and formed above the base substrate so as to be positioned at an upper side of the superlattice layer group relative to the base substrate. The superlattice layer group has a compressive strain contained therein. In the superlattice layer group, the more distant the superlattice layer is from the base substrate, the greater the compressive strain becomes.

Epitaxial substrate comprising a superlattice group and method for manufacturing the epitaxial substrate

Provided is a crack-free epitaxial substrate having a small amount of warping, in which a silicon substrate is used as a base substrate. The epitaxial substrate includes: a (111) single crystal Si substrate and a buffer layer formed of a plurality of lamination units being continuously laminated. The lamination unit includes: a composition modulation layer formed of a first and a second unit layer having different compositions being alternately and repeatedly laminated such that a compressive strain exists therein; a termination layer formed on an uppermost portion of the composition modulation layer, the termination layer acting to maintain the compressive strain existing in the composition modulation layer; and a strain reinforcing layer formed on the termination layer, the strain reinforcing layer acting to enhance the compressive strain existing in the composition modulation layer.

Epitaxial substrate and method for manufacturing epitaxial substrate

Provided is a crack-free epitaxial substrate having excellent breakdown voltage properties in which a silicon substrate is used as a base. The epitaxial substrate includes a (111) single crystal Si substrate and a buffer layer including a plurality of first lamination units. Each of those units includes a composition modulation layer formed of a first composition layer made of AlN and a second composition layer made of AlGaN being alternately laminated, and a first intermediate layer made of AlGaN (0&#x2266;y&#x3c;1). The relationship of x(1)&#x2267;x(2)&#x2267; . . . &#x2267;x(n&#x2212;1)&#x2267;x(n) and x(1)&#x3e;x(n) is satisfied, where n represents the number of laminations of each of the first and second composition layers, and x(i) represents the value of x in i-th one of the second composition layers as counted from the base substrate side. The second composition layer is coherent to the first composition layer, and the first intermediate layer is coherent to the composition modulation layer.

Provided is an epitaxial substrate capable of manufacturing a HEMT device that has excellent two-dimensional electron gas characteristics and is capable of performing normally-off operation. A channel layer is formed of a first group III nitride represented by InAlGaN (x1+y1+z1=1) so as to have a composition in a range determined by x1=0 and 0&#x2266;y1&#x2266;0.3. A barrier layer is formed of a second group III nitride represented by InAlGaN (x2+y2+z2=1) so as to have a composition, in a ternary phase diagram with InN, AlN and GaN being vertices, in a range surrounded by four straight lines determined in accordance with the composition (AlN molar fraction) of the first group III nitride and to have a thickness of 5 nm or less.

Group III nitride epitaxial substrate for semiconductor device, semiconductor device, and process for producing group III nitride epitaxial substrate for semiconductor device

Provided is an epitaxial substrate having excellent two-dimensional electron gas characteristics and reduced internal stress due to strains. A channel layer is formed of a first group III nitride represented by InAlGaN (x1+y1+z1=1) so as to have a composition in a range determined by x1=0 and 0&#x2266;y1&#x2266;0.3. A barrier layer is formed of a second group III nitride represented by InAlGaN (x2+y2+z2=1) so as to have a composition, in a ternary phase diagram with InN, AlN and GaN being vertices, in a range surrounded by five straight lines determined in accordance with the composition (AlN molar fraction) of the first group III nitride.

An epitaxial substrate, in which a group of group-III nitride layers is formed on a single-crystal silicon substrate so that a crystal plane is approximately parallel to a substrate surface, comprises: a first group-III nitride layer formed of AlN on the base substrate; a second group-III nitride layer formed of InAlGaN (xx+yy+zz=1, 0&#x2266;xx&#x2266;1, 0&#x3c;yy&#x2266;1 and 0&#x3c;zz&#x2266;1) on the first group-III nitride layer; and at least one third group-III nitride layer epitaxially-formed on the second group-III nitride layer, wherein: the first group-III nitride layer is a layer containing multiple defects including at least one type of a columnar crystal, a granular crystal, a columnar domain and a granular domain; and an interface between the first group-III nitride layer and the second group-III nitride layer is a three-dimensional asperity surface.

Epitaxial substrate for semiconductor device, method for manufacturing epitaxial substrate for semiconductor device, and semiconductor device

Provided is a crack-free epitaxial substrate having excellent breakdown voltage properties in which a silicon substrate is used as a base substrate thereof. The epitaxial substrate includes: a (111) single crystal Si substrate and a buffer layer including a plurality of composition modulation layers each formed of a first composition layer made of AlN and a second composition layer made of AlGaN (0&#x2266;x&#x3c;1) being alternately laminated. The relationship of x(1)&#x2267;x(2)&#x2267; . . . &#x2267;x(n&#x2212;1)&#x2267;x(n) and x(1)&#x3e;x(n) is satisfied, where n represents the number of laminations of each of the first and the second composition layer, and x(i) represents the value of x in i-th one of the second composition layers as counted from the base substrate side. Each of the second composition layers is formed so as to be in a coherent state relative to the first composition layer.

Provided is an epitaxial substrate for semiconductor device that is capable of achieving a semiconductor device having high reliability in reverse characteristics of schottky junction. An epitaxial substrate for semiconductor device obtained by forming, on a base substrate, a group of group III nitride layers by lamination such that a (0001) crystal plane of each layer is approximately parallel to a substrate surface includes: a channel layer formed of a first group III nitride having a composition of InAlGaN (x1+y1+z1=1, z1&#x3e;0); and a barrier layer formed of a second group III nitride having a composition of InAlN (x2+y2=1, x2&#x3e;0, y2&#x3e;0), wherein the second group III nitride is a short-range-ordered mixed crystal having a short-range order parameter &#x3b1; satisfying a range where 0&#x2266;&#x3b1;&#x2266;1.

Epitaxial substrate for semiconductor device, schottky junction structure, and leakage current suppression method for schottky junction structure

Provided is a crack-free epitaxial substrate having a small amount of warping, in which a silicon substrate is used as a base substrate. The epitaxial substrate includes a (111) single crystal Si substrate, a buffer layer, and a crystal layer. The buffer layer is formed of a first lamination unit and a second lamination unit being alternately laminated. The first lamination unit includes a composition modulation layer and a first intermediate layer. The composition modulation layer is formed of a first unit layer and a second unit layer having different compositions being alternately and repeatedly laminated so that a compressive strain exists therein. The first intermediate layer enhances the compressive strain existing in the composition modulation layer. The second lamination unit is a second intermediate layer that is substantially strain-free.

Epitaxial substrate with intermediate layers for reinforcing compressive strain in laminated composition layers and manufacturing method thereof

Provided is an epitaxial substrate using a silicon substrate as a base substrate. An epitaxial substrate, in which a group of group-III nitride layers are formed on a (111) single crystal Si substrate such that a (0001) crystal plane of the group of group-III nitride layers is substantially in parallel with a surface of the substrate, includes: a first group-III nitride layer made of AlN with many defects configured of at least one kind from a columnar or granular crystal or domain; a second group-III nitride layer whose interface with the first group-III nitride layer is shaped into a three-dimensional concave-convex surface; and a third group-III nitride layer epitaxially formed on the second group-III nitride layer as a graded composition layer in which the proportion of existence of Al is smaller in a portion closer to a fourth group-III nitride.

Epitaxial substrate for semiconductor element, semiconductor element, and method for producing epitaxial substrate for semiconductor element

Provided is an epitaxial substrate capable of achieving a semiconductor device that has excellent schottky contact characteristics as well as satisfactory device characteristics. On a base substrate, a channel layer formed of a first group III nitride that contains at least Al and Ga and has a composition of InAlGaN (x1+y1+z1=1) is formed. On the channel layer, a barrier layer formed of a second group III nitride that contains at least In and Al and has a composition of InAlGaN (x2+y2+z2=1) is formed such that an In composition ratio of a near-surface portion is smaller than an In composition ratio of a portion other than the near-surface portion.

Epitaxial substrate for semiconductor device, semiconductor device, and method of manufacturing epitaxial substrate for semiconductor device

An underlying filmof a group III nitride is formed on a substrateby vapor phase deposition. The substrateand the underlying filmare subjected to heat treatment in the present of hydrogen to remove the underlying filmso that the surface of the substrateis roughened. A seed crystal filmof a group III nitride single crystal is formed on a surface of a substrateA by vapor phase deposition. A group III nitride single crystalis grown on the seed crystal filmby flux method.

Method for manufacturing group III nitride single crystals

Provided is an epitaxial substrate capable of achieving a semiconductor device that has excellent ohmic contact characteristics as well as satisfactory device characteristics. On a base substrate, a channel layer formed of a first group III nitride that contains at least Al and Ga and has a composition of InAlGaN (x1+y1+z1=1) is formed. On the channel layer, a barrier layer formed of a second group III nitride that contains at least In and Al and has a composition of InAlGaN (x2+y2+z2=1) is formed such that an In composition ratio of a near-surface portion is larger than an In composition ratio of a portion other than the near-surface portion.

A buffer layer formed of InAlGaN formed on a base, with an upper part of the buffer layer containing columnar polycrystalline including a grain boundary existing in a direction substantially perpendicular to a surface of the base. The number of grain boundaries in the lower part of the buffer layer is greater than that in the upper part, and a full width at half maximum of an X-ray rocking curve of the upper part is 300-3000 seconds, RMS of the surface of the buffer layer is 0.2 nm-6 nm, and the ratio of the grain boundary width of the crystal grain of the upper part in a direction parallel to the base surface to the formation thickness of the buffer layer is 0.5-1.5.

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Handa, Japan

Shigeaki Sumiya