Toyoda Gosei Co., Ltd.

Ngk Insulators, Inc.

Other

Osaka University

Kabushiki Kaisha Toyota Chuo Kenkyusho

Seiji Nagai

Masayoshi Koike

Shiro Yamasaki

Shiro Yamazaki

Kazuyoshi Tomita

Yuta Tezen

Takayuki Sato

Norikatsu Koide

Makoto Iwai

Shinya Asami

Junichi Umezaki

Toshio Hiramatsu

Katsuhiro Imai

Miki Moriyama

Yasuhide Yakushi

Fumio Kawamura

Takatomo Sasaki

Yusuke Mori

Shohei Kumegawa

Yasuo Kitaoka

Isamu Akasaki

Hiroshi Amano

Shuhei Higashihara

Akira Kojima

Kenji Ito

Koji Okuno

Masanori Murakami

Koichi Goshonoo

Tetsu Kachi

Jiro Matsuo

Isao Yamada

Koji Hirata

Hiroshi Yamashita

Masahito Kodama

Kenji Matsubara

Tohru Shonai

Akihiro Fuseda

Katsuyuki Tsukui

Hidenori Ishikawa

Yoshihiro Irokawa

The present invention provides a method for producing a Group III nitride semiconductor crystal and a GaN substrate, in which the transfer of dislocation density or the occurrence of cracks can be certainly reduced on a growth substrate, and the Group III nitride semiconductor crystal can be easily separated from a seed crystal. A mask layer is formed on a GaN substrate, to thereby form an exposed portion of the GaN substrate, and an unexposed portion of the GaN substrate. Through a flux method, a GaN layer is formed on the exposed portions of the GaN substrate in a molten mixture containing at least Group III metal and Na. At that time, non-crystal portions containing the components of the molten mixture are formed on the mask layer so as to be covered with the GaN layer grown on the GaN substrate and the mask layer.

Method for producing a group III nitride semiconductor crystal and method for producing a GaN substrate

The present invention provides a method for producing a Group III nitride semiconductor single crystal having excellent crystallinity, and a method for producing a GaN substrate having excellent crystallinity, the method including controlling melting back. Specifically, a mask layer is formed on a GaN substrate serving as a growth substrate. Then, a plurality of trenches which penetrate the mask layer and reach the GaN substrate are formed through photolithography. The obtained seed crystal and raw materials of a single crystal are fed to a crucible and subjected to treatment under pressurized and high temperature conditions. Portions of the GaN substrate exposed to the trenches undergo melting back with a flux. Through dissolution of the GaN substrate, the dimensions of the trenches increase, to provide large trenches. The GaN layer is grown from the surface of the mask layer as a starting point.

Method for producing a group III nitride semiconductor single crystal and method for producing a GaN substrate

The present invention provides a semiconductor crystal removal apparatus which realizes effective removal of a semiconductor crystal from a crucible through rapid melting of a solidified flux, and a method for producing a semiconductor crystal. The semiconductor crystal removal apparatus includes a crucible support for supporting a crucible so that the opening of the crucible is directed downward; a heater for heating the crucible supported on the crucible support; and a semiconductor crystal receiving net for receiving a semiconductor crystal falling from the opening of the crucible. The semiconductor crystal removal apparatus further includes a determination portion for determining removal of the semiconductor crystal on the basis of a change in weight through falling of the semiconductor crystal.

Semiconductor crystal removal apparatus and production method for semiconductor crystal

Provided is a method for producing a Group III nitride-based compound semiconductor having an M-plane main surface. The method employs a sapphire substrate having a main surface which is inclined by 30&#xb0; with respect to R-plane about a line of intersection Lformed by R-plane and A-plane perpendicular thereto. R-plane surfaces of the sapphire substrate are exposed, and a silicon dioxide mask is formed on the main surface of the substrate. AlN buffer layers are formed on the exposed R-plane surfaces. A GaN layer is formed on the AlN buffer layers. At an initial stage of GaN growth, the top surface of the sapphire substrate is entirely covered with the GaN layer through lateral growth. The GaN layer is grown so that the a-axis of the layer is perpendicular to the exposed R-plane surfaces of the sapphire substrate; the c-axis of the layer is parallel to the axis direction Lof the sapphire substrate; and the m-axis of the layer, which is inclined by 30&#xb0; from the a-axis thereof, is perpendicular to the main surface (inclined by 30&#xb0; from the exposed R-plane surfaces) of the sapphire substrate.

Method for producing group III nitride-based compound semiconductor, wafer, and group III nitride-based compound semiconductor device

A mask layer is formed on a Ga polarity surface of the GaN substrate as a growth substrate. Subsequently, a protective film PF is formed on a N polarity surface of the GaN substrate. Then, a plurality of concave portions is formed from the mask layer extending to the GaN substrate, to thereby form a seed crystal. The seed crystal is etched in a Na melt, and a plurality of concave portions having a facet plane exposed. The seed crystal and the raw materials are placed in a crucible, and the pressure and temperature inside the crucible are increased. Thus, a target GaN layer is grown in the upward direction on the surface of the mask layer and the lateral direction over the concave portions.

Method for etching a group III nitride semiconductor, method for producing a group III nitride semiconductor crystal, and method for producing a GaN substrate

An object of the present invention is to realize, by the flux process, the production of a high-quality n-type semiconductor crystal having high concentration of electrons. The method of the invention for producing an n-type Group III nitride-based compound semiconductor by the flux process, the method including preparing a melt by melting at least a Group III element by use of a flux; supplying a nitrogen-containing gas to the melt; and growing an n-type Group III nitride-based compound semiconductor crystal on a seed crystal from the melt. In the method, carbon and germanium are dissolved in the melt, and germanium is incorporated as a donor into the semiconductor crystal, to thereby produce an n-type semiconductor crystal. The mole percentage of germanium to gallium in the melt is 0.05 mol % to 0.5 mol %, and the mole percentage of carbon to sodium is 0.1 mol % to 3.0 mol %.

N-type group III nitride-based compound semiconductor and production method therefor

An object of the present invention is to effectively add Ge in the production of GaN through the Na flux method. In a crucible, a seed crystal substrate is placed such that one end of the substrate remains on the support base, whereby the seed crystal substrate remains tilted with respect to the bottom surface of the crucible, and gallium solid and germanium solid are placed in the space between the seed crystal substrate and the bottom surface of the crucible. Then, sodium solid is placed on the seed crystal substrate. Through employment of this arrangement, when a GaN crystal is grown on the seed crystal substrate through the Na flux method, germanium is dissolved in molten gallium before formation of a sodium-germanium alloy. Thus, the GaN crystal can be effectively doped with Ge.

Method for producing group III nitride semiconductor

In the production of GaN through the flux method, deposition of miscellaneous crystals on the nitrogen-face of a GaN self-standing substrate and waste of raw materials are prevented. Four arrangements of crucibles and a GaN self-standing substrate are exemplified. In FIG.A, a nitrogen-face of a self-standing substrate comes into close contact with a sloped flat inner wall of a crucible. In FIG.B, a nitrogen-face of a self-standing substrate comes into close contact with a horizontally facing flat inner wall of a crucible, and the substrate is fixed by means of a jig. In FIG.C, a jig is provided on a flat bottom of a crucible, and two GaN self-standing substrates are fixed by means of the jig so that the nitrogen-faces of the substrates come into close contact with each other. In FIG.D, a jig is provided on a flat bottom of a crucible, and a GaN self-standing substrate is fixed on the jig so that the nitrogen-face of the substrate is covered with the jig. A flux mixture of molten gallium and sodium is charged into each crucible, and a GaN single crystal is grown on a gallium-face under pressurized nitrogen.

Method for producing group III nitride-based compound semiconductor

Objects of the invention are to further enhance crystallinity and crystallinity uniformity of a semiconductor crystal produced through the flux method, and to effectively enhance the production yield of the semiconductor crystal. The c-axis of a seed crystal including a GaN single-crystal layer is aligned in a horizontal direction (y-axis direction), one a-axis of the seed crystal is aligned in the vertical direction, and one m-axis is aligned in the x-axis direction. Thus, three contact points at which a supporting tool contacts the seed crystal are present on m-plane. The supporting tool has two supporting members, which extend in the vertical direction. One supporting member has an end part, which is inclined at 30&#xb0; with respect to the horizontal plane &#x3b1;. The reasons for supporting a seed crystal at m-plane thereof are that m-plane exhibits a crystal growth rate, which is lower than that of a-plane, and that desired crystal growth on c-plane is not inhibited. Actually, a plurality of seed crystals and supporting tools are periodically placed along the y-axis direction.

Method for producing a semiconductor crystal

An object of the invention is to carry out the flux method with improved work efficiency while maintaining the purity of flux at high level and saving flux material cost. The sodium-purifying apparatus includes a sodium-holding-and-management apparatus for maintaining purified sodium (Na) in a liquid state. Liquid sodium is supplied into a sodium-holding-and-management apparatus through a liquid-sodium supply piping maintained at 100&#xb0; C. to 200&#xb0; C. The sodium-holding-and-management apparatus further has an argon-gas-purifying apparatus for controlling the condition of argon (Ar) gas that fills the internal space thereof. Thus, by opening and closing a faucet at desired timing, purified liquid sodium (Na) supplied from the sodium-purifying apparatus can be introduced into a crucible as appropriate via the liquid-sodium supply piping, the sodium-holding-and-management apparatus, and the piping.

Crystal growing apparatus

The present invention provides a Group III nitride compound semiconductor with suppressed generation of threading dislocations. A GaN layeris subjected to etching, so as to form an island-like structure having a shape of, for example, dot, stripe, or grid, thereby providing a trench/mesa structure, and a maskis formed at the bottom of the trench such that the upper surface of the maskis positioned below the top surface of the GaN layer. A GaN layeris lateral-epitaxially grown with the top surfaceof the mesa and sidewallsof the trench serving as nuclei, to thereby bury the trench, and then epitaxial growth is effected in the vertical direction. In the upper region of the GaN layerformed above the maskthrough lateral epitaxial growth, propagation of threading dislocations contained in the GaN layercan be prevented.

Method for fabricating group III nitride compound semiconductors and group III nitride compound semiconductor devices

In the epitaxial growth process in which each growth region D is zoned by a maskformed in grid pattern, because a consumption region C of the Group III nitride compound semiconductor is formed in the central portion of each band of the maskbetween each adjacent edge portion of the growth region D, Group III or Group V raw material is never unnecessarily supplied to the edge portion of the growth region D. As a result, difference of Group III or Group V rare material supply amount to the edge portion and central portion of the device formation region D is suppressed and the edge portion of the device region may not be convexity.

Method for manufacturing group-III nitride compound semiconductor, and group-III nitride compound semiconductor device

A first Group III nitride compound semiconductor layeris etched, to thereby form an island-like structure such as a dot-like, stripe-shaped, or grid-like structure, so as to provide a trench/mesa such that layer different from the first Group III nitride compound semiconductor layeris exposed at the bottom portion of the trench. Thus, a second Group III nitride compound layercan be epitaxially grown, laterally, with a top surface of the mesa and a sidewall/sidewalls of the trench serving as a nucleus, to thereby bury the trench and also grow the layer in the vertical direction. In this case, propagation of threading dislocations contained in the first Group III nitride compound semiconductor layercan be prevented in the upper portion of the second Group III nitride compound semiconductorthat is formed through lateral epitaxial growth. Etching may be performed until a cavity portion is provided in the substrate. The layer serving as a nucleus of ELO may be doped with indium (In) having an atomic radius greater than that of gallium (Ga) serving as a predominant element. The first semiconductor layer may be a multi-component layer containing a plurality of numbers of repetitions of a unit of a buffer layer and a single-crystal layer.

Production method of III nitride compound semiconductor and III nitride compound semiconductor element

When a substrate layer (desired semiconductor crystal) made of a group III nitride compound is grown on a base substrate comprising a lot of projection parts, a cavity in which a semiconductor crystal is not deposited may be formed between each projection part although it depends on conditions such as the size of each projection part, arranging interval between each projection part and crystal growth. So when the thickness of the substrate layer is sufficiently larger compared with the height of the projection part, inner stress or outer stress become easier to act intensively to the projection part. As a result, such stress especially functions as shearing stress toward the projection part. When the shearing stress becomes larger, the projection part is ruptured. So utilizing the shearing stress enables to separate the base substrate and the substrate layer easily. The larger the cavities are formed, the more stress tends to concentrate to the projection parts, to thereby enable to separate the base substrate and the substrate layer more securely.

Production method for semiconductor crystal and semiconductor luminous element

A reaction prevention layer is formed to prevent Si from reacting with a gallium nitride group semiconductor (semiconductor crystal A) which is deposited after the reaction prevention layer is formed. By forming a reaction prevention layer comprising a material whose melting point or thermal stability is higher than that of a gallium nitride group semiconductor, e.g., AlN, on a sacrifice layer, a reaction part is not formed in the semiconductor substrate deposited on the reaction prevention layer when the gallium nitride group semiconductor is grown by crystal growth for a long time. In short, owing to the effect that the reaction prevention layer prevents silicon (Si) from diffusing, the reaction part is generated only in the sacrifice layer and it is never formed at the upper portion of the reaction prevention layer even by growing the semiconductor crystal A at a high temperature for a long time.

Production method for semiconductor substrate and semiconductor element

Growing community of inventors

Aichi, Japan

Seiji Nagai