KLA probe type stair step meterBased on the 'probe contact scanning+sensor feedback' technology, the probe contacts and scans the sample surface, combined with high-precision sensors to provide real-time feedback on displacement changes, to achieve two-dimensional/three-dimensional measurement of step height, surface morphology, and stress at the nanometer to micrometer level. The following is a detailed analysis of its working principle:

Core working principle:

Probe contact and scanning

Probe design: Using diamond material probe, the tip radius can be as fine as 0.7 μ m or smaller, ensuring high lateral resolution. The probe contacts the sample surface with extremely light force (0.03~50mg) to avoid damaging soft or brittle materials (such as photoresist and silicon wafers).

Scanning method: By moving the sample stage or probe at a constant speed in the X-Y plane, the probe moves along the surface and generates Z-axis displacement due to surface micro undulations (such as steps and roughness).

Sensor feedback and displacement measurement

LVDC sensor technology: The KLA P series step meters (such as P-7, P-17) use low-voltage differential capacitance (LVDC) sensors. The movement of the probe drives the thin metal blade to move between two capacitor plates, causing a change in capacitance, which is converted into an electrical signal and real-time feedback displacement.

Advantages: LVDC design has small mass and linear blade movement, minimizing hysteresis and friction, achieving vertical resolution of 0.01 Å (0.001nm) and high-precision measurement across the entire vertical range.

Force control: The LVDT (Linear Variable Differential Transformer) sensor is used to detect the deformation of the spring, accurately control the probe pressure, ensure constant force scanning, and improve measurement consistency.

Data Processing and 3D Rendering

Height dot matrix acquisition: The Z-axis data of multiple scanning lines are concatenated to form a dense "height dot matrix", covering the entire surface area of the sample (such as P-17 supporting a 200mm scanning platform, no need for stitching).

3D Shape Reconstruction: The software renders height data into color 3D images or contour maps, visually displaying surface features such as step edges, scratches, and protrusions, and supporting the extraction of cross-sectional/line data.