Toyoda Gosei Co., Ltd.

Shohei Kumegawa

Miki Moriyama

Seiji Nagai

Shiro Yamazaki

Yasuhide Yakushi

The seed substrate comprises a base substrate and a base layer comprising a Group III nitride semiconductor formed on the base substrate, which has a high dislocation density region and a low dislocation density region. The planar pattern of the high dislocation density region is a honeycomb pattern. A hollow exists between the base substrate and the low dislocation density region. The object layer is grown through a flux method using the seed substrate. The high dislocation density region is melted back at an initial stage of crystal growth, and thereafter, the object layer is grown on the top surface of the low dislocation density region. A cavity remains between the high dislocation density region and the object layer. The presence of the cavity and the hollow makes easy to peel the object layer from the seed substrate.

Method for producing Group III nitride semiconductor, seed substrate and Group III nitride semiconductor crystal

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

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

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Kiyosu, Japan

Shohei Kumegawa