A method for inspection of a silicon carbide wafer

Abstract

The invention is a method for inspection of a silicon carbide wafer, the invention reveals the material information of each layer structures of silicon carbide wafer including subsurface-damage zone and no-damage zone in a vertical section, the invention helps to classify silicon carbide wafer for further applications.

Claims

1. A method for testing a silicon carbide wafer, comprising at least: providing a single-crystal silicon carbide wafer to be tested at room temperature; providing a brittleness characteristic analysis standard and performing a test; attaching the single-crystal silicon carbide wafer to be tested to a wedge-shaped metal block by a wax coating method; performing a taper grinding and a polishing; performing a chemical etching with a molten inorganic alkali liquid and a carbonate liquid, wherein the molar number of the carbonate is between 0 and 10 molar percentages (mol.%) compared with the molar number of the inorganic alkali; and removing the single-crystal silicon carbide wafer to be tested and calculating the length L1 of a microcrack on the inclined surface after the chemical etching.

2. The method as described in claim 1, wherein a temperature of the chemical etching is controlled between 380°C and 450°C, and a time of the chemical etching is between 1 minute and 20 minutes.

3. The method as described in claim 1, wherein the inorganic base is selected from the group consisting of lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), barium hydroxide (Ba(OH)2), and calcium hydroxide (Ca(OH)2).

4. The method as described in claim 1, wherein the carbonate is selected from the group consisting of lithium carbonate (Li2CO3), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), magnesium carbonate (MgCO3), and calcium carbonate (CaCO3).

5. The method as described in claim 1, wherein the thickness of the damage layer of the silicon carbide wafer is calculated using L1, the thickness of the damage layer being L1 sin(θ), where θ is the angle between the wedge-shaped metal cone and the horizontal plane.

6. A method for testing a silicon carbide wafer, comprising at least the following steps: performing a heat treatment on a single-crystal silicon carbide wafer to be tested in a high-temperature furnace, wherein the heat treatment includes a temperature between 800°C and 2,200°C and a time between 0.1 hours and 3.0 hours; providing a residual plastic deformation analysis standard under high-temperature ductility conditions and performing a test; attaching the single-crystal silicon carbide wafer to be tested to a wedge-shaped metal block by means of wax coating; performing a taper grinding and a polishing; preparing a molten inorganic alkaline liquid for chemical etching; and removing the single-crystal silicon carbide wafer to be tested and calculating a distance L2 between a differential etching pit on the inclined surface and a wafer polishing interface after the chemical etching.

7. The method as described in claim 6, wherein a temperature of the chemical etching is controlled at 420°C to 530°C, and a time of the chemical etching is between 1 minute and 30 minutes.

8. The method as described in claim 6, wherein the inorganic base is selected from the group consisting of lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), barium hydroxide (Ba(OH)2), and calcium hydroxide (Ca(OH)2).

9. The method as described in claim 6, wherein a plastic deformation layer remaining under the high-temperature ductility condition of the silicon carbide wafer is calculated in terms of L2, the thickness of the plastic deformation layer being L2 sin(θ), where θ is the angle between the wedge-shaped metal cone surface and the horizontal plane.

10. The method as described in claim 6, wherein the thickness of a plastic deformation layer remaining under the high-temperature ductility condition of the single-crystal silicon carbide wafer is calculated using L2, and the thickness of a damage-free layer is obtained by subtracting the thickness of the plastic deformation layer remaining under the high-temperature ductility condition from the thickness of the single-crystal silicon carbide wafer.

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