What Does A Wafer Notch Look Like

Nov 21, 2024Leave a message

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What is a wafer notch?

A notch is a small groove cut directly below a silicon wafer, usually in a V or U shape. Notch has two functions. One is to mark the crystal orientation of the silicon wafer, such as <100>, <110>, <111>, etc. The other function is to enable the silicon wafer to be correctly positioned and aligned in semiconductor manufacturing equipment. Generally, notches are found in 8-inch and 12-inch wafers.

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What does Notch look like?

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The size of the notch must strictly comply with SEMI standards, as shown in the figure above:

1. Vw represents the total width of the notch, and its size is related to the diameter and thickness of the silicon wafer.

2. Vh is the depth of the notch, which indicates the vertical distance from the edge of the silicon wafer to the bottom of the groove. It generally ranges from 1.0 to 1.25 mm. Vh is crucial to ensure the alignment accuracy of the notch.

3. AngV, that is, Notch Angle. AngV is the angle of the notch, which is the angle between the edges of the groove on both sides. It is generally between 89° and 95°. This angle plays a decisive role in the geometry and positioning of the notch.

4. R1 and R2 represent the radii of the corners on both sides of the notch. These two radii determine the smoothness of the groove corners, affect the stress concentration of the notch, and affect the mechanical properties of the silicon wafer.

5. Vr is the radius of curvature at the bottom of the notch, indicating the size of the arc at the bottom of the groove. Vr can change the curve shape and smoothness of the notch. A larger Vr can make the bottom of the notch flatter, which helps reduce stress concentration.

6. Notch Orientation: The direction of the groove is parallel to the specific crystal orientation of the wafer, and a deviation of ±2 degrees is allowed.