Laser-induced flaw formation in nitride semiconductors
View Patent ↗An embodiment is a method and apparatus to induce flaw formation in nitride semiconductors. Regions of a thin film structure are selectively decomposed within a thin film layer at an interface with a substrate to form flaws in a pre-determined pattern within the thin film structure. The flaws locally concentrate stress in the pre-determined pattern during a stress-inducing operation. The stress-inducing operation is performed. The stress-inducing operation causes the thin film layer to fracture at the pre-determined pattern.
1. An apparatus comprising:
a thin film layer of a thin film structure, the thin film layer having flaws formed in a pre-determined pattern, the flaws locally concentrating stress in the pre-determined pattern during a stress-inducing operation to fracture the thin film layer at the pre-determined pattern during the stress-inducing operation, wherein the thin film layer has a thickness and each of the flaws have a depth, wherein the thickness of the thin film layer is greater than the depth of the flaws, and wherein the predetermined pattern is configured to maintain the thickness of the thin film layer when the thin film layer is fractured in the stress-inducting operation; and
a substrate attached to the thin film layer, wherein the substrate is removed in the stress-inducing operation.
2. The apparatus of claim 1 wherein the flaws comprise focused spots with a small spot size, the focused spots being stitched to form a decomposable region in the pre-determined pattern.
3. The apparatus of claim 2 wherein the decomposable region is near diced edges of the thin film structure.
4. The apparatus of claim 2 wherein at least one of the flaws is a trench, a notch, or a void formation.
5. The apparatus of claim 2 wherein the thin film layer is an alloy containing nitride.
6. The apparatus of claim 5 wherein the alloy is one of Gallium Nitride (GaN), Aluminum Gallium Nitride (AlGaN), Indium Gallium Nitride (InGaN), and Aluminum Indium Gallium Nitride (AlInGaN).
7. The apparatus of claim 1 wherein the thin film structure is one of a light emitting diode (LED) structure, a transistor structure, and a laser structure.
8. The apparatus of claim 7 wherein the thin film layer is an epitaxially grown LED, transistor, or laser layer.
9. The apparatus of claim 1 wherein the flaws extend from top surface of the thin film layer toward interface between the thin film layer and the substrate when the stress-inducing process starts from a top surface of the thin film layer towards an interface between the thin film layer and the substrate.
10. The apparatus of claim 1 wherein the flaws extend from interface between the thin film layer and the substrate into the thin film layer when the stress-inducing process starts from the substrate towards the interface.
11. The apparatus of claim 1 wherein the substrate is a sapphire substrate.
12. The apparatus of claim 1 wherein the substrate includes an intermediate layer grown separately from the thin film layer.
13. The apparatus of claim 12 wherein the intermediate layer is an alloy being one of Gallium Nitride (GaN), Aluminum Nitride (AlN), Aluminum Gallium Nitride (AlGaN), Indium Gallium Nitride (InGaN), and Aluminum Iridium Gallium Nitride (AlInGaN).