300mm Silicon Wafer Specifications | Silicon Specialists LLC

 

Bow

During the processing of semiconductor wafers, the flatness of the wafer plays a key role. The geometrical properties of the surface of the wafer determine the amount of bow and warp that is produced. In a free unclamped wafer, the median surface has the same curvature throughout. In a clamped wafer, the median surface may vary. This is because the axis of the wafer can be affected by thermal processing. Moreover, the front surface of the wafer is adversely affected by photolithographic processes.

The three point reference plane of the center surface is determined by measuring the middle surface of the wafer. Then, the distance of the center point from the three point reference plane is calculated. If the distance is greater than the three point reference plane, the bow is positive. If the distance is below the three point reference plane, the bow is negative.