公开(公告)号：US20210242086A1

公开(公告)日：2021-08-05

申请号：US17049156

申请日：2019-05-30

Applicant: The Regents of the University of California

Inventor： Srinivas Gandrothula ,  Takeshi Kamikawa

IPC: H01L21/78 ,  H01L21/02 ,  C30B25/04 ,  C30B25/20 ,  C30B29/40 ,  C30B33/02

Abstract: A method of removing semiconducting layers from a substrate, in particular, III-nitride-based semiconductor layers from a III-nitride-based substrate, with an attached film, using a peeling technique. The method comprises forming the semiconductor layers into island-like patterns on the substrate via an epitaxial lateral overgrowth method, with a horizontal trench extending inwards from the sides of the layers. Stress is induced in the layers by raising or lowering the temperature, and applying pressure to the attached film, such that the film firmly fits a shape of the layers. Differences in thermal expansion between the substrate and the film attached to the layers initiates a crack at an interface between the layers and the substrate, so that the layers can be removed from the substrate. Once the layers are removed, the substrate can be recycled, resulting in cost savings for device fabrication.

公开(公告)号：US12205847B2

公开(公告)日：2025-01-21

申请号：US17945717

申请日：2022-09-15

Applicant: The Regents of the University of California

Inventor： Takeshi Kamikawa ,  Srinivas Gandrothula ,  Hongjian Li

IPC: H01L21/78 ,  H01L21/02 ,  H01L33/00 ,  H01S5/02

Abstract: 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.

公开(公告)号：US12146237B2

公开(公告)日：2024-11-19

申请号：US17285827

申请日：2019-10-31

Applicant: The Regents of the University of California

Inventor： Takeshi Kamikawa ,  Srinivas Gandrothula

IPC: H01L21/02 ,  C30B25/04 ,  C30B25/18 ,  C30B29/40 ,  H01L21/78 ,  H01L29/06 ,  H01L29/20 ,  H01L29/40 ,  H01L33/00 ,  H01L33/24 ,  H01L33/32 ,  H01S5/02 ,  H01S5/22 ,  H01S5/343

Abstract: 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.

公开(公告)号：US12046695B2

公开(公告)日：2024-07-23

申请号：US16608071

申请日：2018-05-07

Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Inventor： Takeshi Kamikawa ,  Srinivas Gandrothula ,  Hongjian Li ,  Daniel A. Cohen

IPC: H01L33/00 ,  H01L21/02 ,  H01L25/075 ,  H01S5/02 ,  H01S5/343

CPC classification number: H01L33/0093 ,  H01L25/0753 ,  H01L33/0075 ,  H01S5/0217 ,  H01S5/34333 ,  H01L21/0254 ,  H01L21/02647 ,  H01S2304/12

Abstract: 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.

公开(公告)号：US20230005793A1

公开(公告)日：2023-01-05

申请号：US17945717

申请日：2022-09-15

Applicant: The Regents of the University of California

Inventor： Takeshi Kamikawa ,  Srinivas Gandrothula ,  Hongjian Li

IPC: H01L21/78 ,  H01L33/00 ,  H01L21/02 ,  H01S5/02

Abstract: 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.

公开(公告)号：US20220352410A1

公开(公告)日：2022-11-03

申请号：US17863084

申请日：2022-07-12

Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Inventor： Takeshi Kamikawa ,  Srinivas Gandrothula ,  Hongjian Li ,  Daniel A. Cohen

IPC: H01L33/00 ,  H01S5/02 ,  H01L25/075 ,  H01S5/343

Abstract: 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.

公开(公告)号：US20210381124A1

公开(公告)日：2021-12-09

申请号：US17285827

申请日：2019-10-31

Applicant: The Regents of the University of California

Inventor： Takeshi Kamikawa ,  Srinivas Gandrothula

IPC: C30B25/04 ,  H01L21/02 ,  H01L21/78 ,  C30B25/18 ,  C30B29/40 ,  H01L29/06 ,  H01L29/20

Abstract: 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.

公开(公告)号：US20240194822A1

公开(公告)日：2024-06-13

申请号：US18577358

申请日：2022-07-13

Applicant: The Regents of the University of California

Inventor： Srinivas Gandrothula ,  Shuji Nakamura ,  Steven P. DenBaars

IPC: H01L33/00 ,  H01L25/00

CPC classification number: H01L33/007 ,  H01L25/50 ,  H01L33/0093 ,  H01L33/0095

Abstract: A method for fabricating small size light emitting diodes (LEDs) on high-quality epitaxial crystal layers. III-nitride epitaxial lateral overgrowth (ELO) layers are grown on a substrate using a growth restrict mask. III-nitride device layers are grown on wings of the III-nitride ELO layers, to form island-like III-nitride semiconductor layers. The wings of the III-nitride ELO layers have at least an order of magnitude smaller defect density than the substrate, resulting in superior characteristics for the devices made thereon. Light emitting mesas are etched from the island-like III-nitride semiconductor layers, wherein each of the light emitting mesas corresponds to a device; and a device unit pattern is etched from the island-like III-nitride semiconductor layers, wherein the device unit pattern is comprised of one or more of the light emitting mesas. The device unit pattern including the island-like III-nitride semiconductor layers is then transferred to display panel or a carrier.

公开(公告)号：US20230238477A1

公开(公告)日：2023-07-27

申请号：US18008064

申请日：2021-06-21

Applicant: The Regents of the University of California

Inventor： Srinivas Gandrothula ,  Takeshi Kamikawa

IPC: H01L33/00 ,  H01L33/46 ,  H01L21/683 ,  H01S5/42 ,  H01S5/02 ,  H01S5/0237 ,  H01S5/343 ,  H01S5/183 ,  H01S5/22

CPC classification number: H01L33/0093 ,  H01L33/0075 ,  H01L33/46 ,  H01L21/6838 ,  H01S5/423 ,  H01S5/0201 ,  H01S5/0237 ,  H01S5/34333 ,  H01S5/18361 ,  H01S5/22 ,  H01L25/167

Abstract: A method of fabricating and transferring high quality and manufacturable light-emitting devices, such as micro-sized light-emitting diodes (μLEDs), edge-emitting lasers and vertical-cavity surface-emitting lasers (VCSELs), using epitaxial later over-growth (ELO) and isolation methods. III-nitride semiconductor layers are grown on a host substrate using a growth restrict mask, and the III-nitride semiconductor layers on wings of the ELO are then made into the light-emitting devices. The devices are isolated from the host substrate to a thickness equivalent to the growth restrict mask and then transferred or lifted from of the host substrate. Back-end processing of the devices is then performed, such as attaching distributed Bragg reflector (DBR) mirrors, forming cladding layers, and/or adding heatsinks.

公开(公告)号：US20230127257A1

公开(公告)日：2023-04-27

申请号：US17912976

申请日：2021-04-19

Applicant: The Regents of the University of California

Inventor： Takeshi Kamikawa ,  Masahiro Araki ,  Srinivas Gandrothula

IPC: H01L21/02 ,  H01L33/32

Abstract: An epitaxial lateral overgrowth (ELO) of a III-nitride layer is used to cover a growth restrict mask deposited on a substrate, wherein the III-nitride ELO layer is grown with a low V/III ratio of less than 500 resulting in high-speed lateral growth as compared to low-speed vertical growth. The III-nitride ELO layer contains a large amount of impurities, over 1 × 1018 cm-3, which result in the III-nitride ELO layer comprising a coloring layer. The coloring layer absorbs light from an active region due to the large amount of impurities. When a bar of device layers is removed from the substrate, at least a portion of the coloring layer is removed from the bar. The elimination of the coloring layer reduces absorption losses, which makes the device characteristics improve.