University of California

Srinivas Gandrothula

Takeshi Kamikawa

Hongjian Li

Daniel A Cohen

Masahiro Araki

A method for flattening a surface on an epitaxial lateral overgrowth (ELO) layer, resulting in obtaining a smooth surface with island-like III-nitride semiconductor layers. The island-like III-nitride semiconductor layers are formed by stopping the growth of the ELO layers before they coalesce to each other. Then, a growth restrict mask is removed before at least some III-nitride device layers are grown. Removing the mask decreases an excess gases supply to side facets of the island-like III-nitride semiconductor layers, which can help to obtain a smooth surface on the island-like III-nitride semiconductor layers. The method also avoids compensation of a p-type layer by decomposed n-type dopant from the mask, such as Silicon and Oxygen atoms.

Method for flattening a surface on an epitaxial lateral growth layer

A method of fabricating a semiconductor device, comprising: forming a growth restrict mask on or above a III-nitride substrate, and growing one or more island-like III-nitride semiconductor layers on the III-nitride substrate using the growth restrict mask. The III-nitride substrate has an in-plane distribution of off-angle orientations with more than 0.1 degree; and the off-angle orientations of an m-plane oriented crystalline surface plane range from about +28 degrees to about −47 degrees towards a c-plane. The island-like III-nitride semiconductor layers have at least one long side and short side, wherein the long side is perpendicular to an a-axis of the island-like III-nitride semiconductor layers. The island-like III-nitride semiconductor layers do not coalesce with neighboring island-like III-nitride semiconductor layers.

Method of fabricating non-polar and semi-polar devices using epitaxial lateral overgrowth

A method of removing a substrate from III-nitride based semiconductor layers with a cleaving technique. A growth restrict mask is formed on or above a substrate, and one or more III-nitride based semiconductor layers are grown on or above the substrate using the growth restrict mask. The III-nitride based semiconductor layers are bonded to a support substrate or film, and the III-nitride based semiconductor layers are removed from the substrate using a cleaving technique on a surface of the substrate. Stress may be applied to the III-nitride based semiconductor layers, due to differences in thermal expansion between the III-nitride substrate and the support substrate or film bonded to the III-nitride based semiconductor layers, before the III-nitride based semiconductor layers are removed from the substrate. Once removed, the substrate can be recycled, resulting in cost savings for device fabrication.

Method of removing a substrate with a cleaving technique

A method for obtaining a smooth surface of an epi-layer with epitaxial lateral overgrowth. The method does not use mis-cut orientations and does not suppress the occurrence of pyramidal hillocks, but instead embeds the pyramidal hillocks in the epi-layer. A growth restrict mask is used to limit the expansion of the pyramidal hillocks in a lateral direction. The surface of the epi-layer becomes extremely smooth due to the disappearance of the pyramidal hillocks.

Method of obtaining a smooth surface with epitaxial lateral overgrowth

A method for dividing a bar of one or more devices. The bar is comprised of island-like III-nitride-based semiconductor layers grown on a substrate using a growth restrict mask; the island-like III-nitride-based semiconductor layers are removed from the substrate using an Epitaxial Lateral Overgrowth (ELO) method; and then the bar is divided into the one or more devices using a cleaving method.

Method for dividing a bar of one or more devices

An epitaxial lateral overgrowth (ELO) layer is grown on an opening area of a substrate, wherein the ELO layer is higher than a surfaceof a trench in the substrate. The trench is apt to form a symmetric shape of the ELO layer, which renders it suitable for flip-chip bonding The shape of the ELO layer has a depressed surface region at a back side of a bar formed by the ELO layer. A cleaving point is located higher than the bottom of the ELO layer, so that a force can be efficiently applied tothe cleaving point for removing the bar.

Method for removal of devices using a trench

A method of removing a substrate, comprising: forming a growth restrict mask with a plurality of striped opening areas directly or indirectly upon a GaN-based substrate; and growing a plurality of semiconductor layers upon the GaN-based substrate using the growth restrict mask, such that the growth extends in a direction parallel to the striped opening areas of the growth restrict mask, and growth is stopped before the semiconductor layers coalesce, thereby resulting in island-like semiconductor layers. A device is processed for each of the island-like semiconductor layers. Etching is performed until at least a part of the growth restrict mask is exposed. The devices are then bonded to a support substrate. The GaN-based substrate is removed from the devices by a wet etching technique that at least partially dissolves the growth restrict mask. The GaN substrate that is removed then can be recycled.

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Santa Barbara, CA, United States of America

Srinivas Gandrothula