GB/T 42902-2023Test method for surface defects on silicon carbide epitaxial wafers—Laser scattering method (English PDF)

3.1 Falling particulate matter defect down fal defect

Before epitaxial growth or during the growth process, black amorphous carbon or SiC microparticles on the wall of the reaction growth chamber fall onto the substrate or epitaxial growth chamber.

On the surface of the layer, after epitaxial growth, some or all of them are deeply sunk into the epitaxial layer, forming point defects.

3.2 Triangular defect triangle defect

Surface defects on silicon carbide epitaxial wafers appear to be triangular in shape.

Note 1. The triangular defect is composed of the deformed 4H-SiC crystal boundary and the triangular area containing the 3C crystal interlayer. It is the step flow during the epitaxial growth process.

Caused by interference due to the presence of foreign particles, crystal defects or scratches on the substrate surface.

Note 2. The photoluminescence channel presents a triangular shape, while the surface channel presents one, two or three sides, and the third side is almost in line with the main reference side.

90°. Sometimes there is an obvious small triangular dent on the triangular head, which contains a 3C-SiC crystal layer. At this time, it is a shallow triangular defect.

3.3 Carrot defect

Carrot-shaped surface defects on silicon carbide epitaxial wafers.

Note: Sometimes carrots have sharp edges and corners. These defects are arranged in parallel. As the thickness of the epitaxial layer increases, the carrot defects extend along the [1120] direction and are in line with the thickness of the epitaxial layer.

The direction of the main reference edge [1120] is parallel. The carrot defect length (L) tends to be the same and satisfies L=d/sintheta, where d is the thickness of the 4H-SiC epitaxial layer, theta is the deflection angle of the substrate surface (theta=4°).

3.4 Trapezoiddefecttrapezoiddefect

Surface defects on silicon carbide epitaxial wafers appear to be trapezoidal in appearance.

Note: The distance L between the upstream short embankment line and the downstream long giant step line increases as the thickness of the epitaxial layer increases, satisfying L=d/sintheta, where d is 4H- The thickness of the SiC epitaxial layer, theta is the deflection angle of the substrate surface (theta = 4°).