Ramp roughness AFM

In atomic force microscope AFM, the probe tracks the sample surface by moving up and down in the Z direction through the feedback system. When the surface is horizontal, the probe only needs to deal with relatively small local ups and downs; but when the test surface is sloped, there are two main problems:

1. Limitations of probe geometry: The needle tip of an AFM probe is not infinitely sharp, it has a specific shape (usually conical or pyramidal with a radius of curvature at the end). When scanning a steep slope, the sides of the probe may contact the slope before the tip of the needle, resulting in measured topography distortion. This is called the "needle tip convolution effect", which makes the measured slope angle smoother than it actually is and the true nanoscale features on the slope cannot be detected.

2. Scanner's Z-direction travel limitation: The space for moving the AFM probe in the Z-direction is limited. If the height difference of the slope exceeds the space stroke in the Z-direction, the probe will not be able to track the entire slope, resulting in a scan failure.

In order to accurately measure slope roughness, it can be achieved by:

• Use probes with high aspect ratios;

• Reduce scanning range and improve resolution;

• In tap mode, use smaller setpoints.

Our company's AFM test can measure the roughness of the sample slope and solve the problem of limited limitations.