# US 10,319,754 B2 · Method of fabricating crystalline island on substrate

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- Number: US 10,319,754 B2
- Document ID: US10319754B2
- Status: Granted
- Kind: B2
- Application number: 15/429,367
- Filed: 2017-02-10
- Published: 2017-06-01
- Granted: 2019-06-11
- Earliest claimed: 2014-06-04
- Assignees: Diftek Lasers, Inc.
- Applicants: Diftek Lasers, Inc.
- Inventors: Douglas R. Dykaar
- Web page: https://patentgrep.com/patent/US10319754B2

## CPC

- H10D 86/0227: {using structural arrangements to control crystal growth, e.g. placement of grain filters}
- C30B 11/002: {Crucibles or containers for supporting the melt}
- C30B 11/003: {Heating or cooling of the melt or the crystallised material}
- C30B 29/06: Silicon
- H10D 86/0212: {comprising manufacture, treatment or coating of substrates}
- H10D 86/411: {characterised by materials, geometry or structure of the substrates}
- H10D 86/60: wherein the TFTs are in active matrices
- H10P 14/2925: {Surface structures}
- H10P 14/3411: {Silicon, silicon germanium or germanium}
- H10P 14/3451: {Structure}
- H10P 14/3802: {Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth}
- H10P 14/6308: {of Group IV semiconductors}
- H10P 90/1912: {using selective deposition, e.g. epitaxial lateral overgrowth [ELO] or selective deposition of single crystal silicon}
- H10W 10/181: {Semiconductor-on-insulator [SOI] isolation regions, e.g. buried oxide regions of SOI wafers}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

Certain electronic applications, such as OLED display back panels, require small islands of high-quality semiconductor material distributed over a large area. This area can exceed the areas of crystalline semiconductor wafers that can be fabricated using the traditional boule-based techniques. This specification provides a method of fabricating a crystalline island of an island material, the method comprising depositing particles of the island material abutting a substrate, heating the substrate and the particles of the island material to melt and fuse the particles to form a molten globule, and cooling the substrate and the molten globule to crystallize the molten globule, thereby securing the crystalline island of the island material to the substrate. The method can also be used to fabricate arrays of crystalline islands, distributed over a large area, potentially exceeding the areas of crystalline semiconductor wafers that can be fabricated using boule-based techniques.

## Claims

### Claim 1

A method of fabricating a crystalline island of an island material, the method comprising:
depositing the island material on a substrate;
heating the substrate and the island material, the heating melting the island material to form a molten corpus, the heating also forming a molten disk comprising oxygen and the island material, the molten disk disposed between the molten corpus and the substrate; and
cooling the substrate, the molten corpus, and the molten disk to crystallize the molten corpus to form a crystallized corpus, at least a portion of the crystallized corpus forming the crystalline island of the island material.

### Claim 2 (depends on 1)

The method of claim 1, further comprising planarizing at least a portion of the crystalline island to expose a cross-section of the crystalline island.

### Claim 3 (depends on 1)

The method of claim 1, further comprising, after the cooling:
over-coating the crystalline island and the substrate with an over-coating layer to form a stack; and
planarizing the stack to expose a cross-section of the crystalline island.

### Claim 4 (depends on 1)

The method of claim 1, further comprising, before the depositing:
forming an oxide layer on the substrate; and
wherein:
the depositing comprises depositing the island material on the oxide layer; and
the molten disk comprises the oxide layer in a molten state.

### Claim 5 (depends on 4)

The method of claim 4, wherein the forming the oxide layer comprises depositing on the substrate the oxide layer comprising an oxide of the island material.

### Claim 6 (depends on 5)

The method of claim 5, wherein the depositing comprises depositing the oxide layer according to a predetermined pattern.

### Claim 7 (depends on 4)

The method of claim 4, wherein the forming the oxide layer comprises:
depositing the island material on the substrate according to a predetermined pattern; and
oxidizing the island material.

### Claim 8 (depends on 4)

The method of claim 4, wherein the heating comprises heating the substrate, the island material, and the oxide layer in a non-oxidizing atmosphere.

### Claim 9 (depends on 1)

The method of claim 1, further comprising one or more of, before the depositing:
polishing the substrate according to a predetermined pattern; and
roughening the substrate according to the predetermined pattern.

### Claim 10 (depends on 1)

The method of claim 1, wherein the substrate comprises alumina.

### Claim 11 (depends on 10)

The method of claim 10, wherein the molten disk further comprises aluminum originating from the substrate.

### Claim 12 (depends on 1)

The method of claim 1, wherein the island material comprises silicon and the heating comprises heating the substrate and the island material to at least about 1500° C.

### Claim 13 (depends on 1)

The method of claim 1, wherein:
cooling the molten corpus forms a first solid portion distal from the substrate and a second solid portion proximal the substrate, the first solid portion separating spontaneously from the second solid portion during the cooling, the second solid portion forming the crystalline island.

### Claim 14 (depends on 1)

The method of claim 1, wherein the depositing comprises:
positioning a template on a surface of the substrate, the template comprising a channel having a first end abutting the surface and a second end opposite the first end, the surface capping the first end; and
filling at least a portion of the channel with the island material.

### Claim 15 (depends on 14)

The method of claim 14, further comprising:
after the cooling, removing the template from the substrate.

### Claim 16 (depends on 15)

The method of claim 15, wherein after the removing, a first portion of the crystallized corpus remains on the substrate to form the crystalline island and a second portion of the crystallized corpus remains in the channel.

### Claim 17 (depends on 14)

The method of claim 14, wherein the channel comprises:
a first region proximate the first end, in the first region the channel having a first cross-sectional area; and
a second region distal from the first end, in the second region the channel having a second cross-sectional area, the first cross-sectional area different from the second cross-sectional area.

### Claim 18 (depends on 17)

The method of claim 17, wherein an inner surface of the channel defines a vertex separating the first region from the second region.

### Claim 19 (depends on 14)

The method of claim 14, wherein:
the template further comprises one or more further channels, each further channel having a corresponding first end abutting the surface and a corresponding second end opposite the corresponding first end, the surface capping the corresponding first end; and
the depositing further comprises filling at least a portion of the one or more further channels with the island material.

### Claim 20 (depends on 14)

The method of claim 14, wherein the second end is in communication with a reservoir configured to store the island material for at least partially filling the channel with the island material.

### Claim 21 (depends on 20)

The method of claim 20, wherein the reservoir is integrally formed with the template.

### Claim 22 (depends on 20)

The method of claim 20, wherein the reservoir comprises a crystallization initiator, the crystallization initiator comprising one or more of a depression into and an extension from a reservoir surface, the crystallization initiator configured to come into contact with the molten corpus and initiate crystallization during the cooling.