AFM：Atomic Force Microscopy
Features
AFM is a method of scanning the surface of a sample by a minute probe. It can measure unevenness three-dimensionally on a nanoscale.
- Wide range of samples such as insulators, metals, semiconductors, oxides, and soft matter such as organic substances.
- Minimizes specimen damage by using the "tapping mode" with weak contact pressure.
Application Examples
- Surface roughness evaluation of bulk substrates, e.g., silicon, compound semiconductors, glass, metals, organic materials.
- Surface roughness evaluation of thin films, e.g., poly-crystalline silicon, oxides, metals, organic materials.
- Shape evaluation of MEMS.
Principle of operation
The sample surface is scanned by a sharp probe that is fabricated by processing a single-crystal silicon wafer. The tip diameter is smaller than 10 nm.
Tapping mode
The probe vibrates vertically at a frequency of about 300 kHz and its amplitude is adjusted so that it decreases when the probe is approaching the sample and increases when moving away from the surface. The surface profile is obtained by scanning the sample surface while controlling the height of the probe to maintain a certain vibration amplitude. Probe position is determined by irradiating the probe by a laser and detecting the reflected light with a photo detector.
Data examples
Platinum-coated Si substrate
Bird's view is recommended when comparing multiple samples.
AFM imaging of a thermoplastic sample in a liquid
Measurements can be made in solutions with varying water temperatures.
In-plane roughness analysis
Roughness analysis of the measured data can be carried out in terms of average surface height (Zc), surface roughness (Ra), root mean square surface roughness (Rq), maximum in-plane height difference (Rmax), and other metrics which are useful when quantitatively comparing the degree of surface irregularity (see Figure 8).
Arbitrary cross-sectional analysis
The height profile of a cross section can be plotted and the distance and height difference between two arbitrary points can be measured. Histogram and particle size analysis is also possible.
Data format of deliverables
仕様
Items for enquiries
- Purpose and scope of the analysis
- Sample information:
● Number of samples, availability of preliminary samples.
● Type of material, dimensions, shape, permissible sample damages (division into smaller pieces, adhesion to sample stage), desired measurement region of interest (ROI), expected surface roughness, etc.
● Handling instructions.
- Details on delivery
● Preferred due date for preliminary analysis report.
● Due date for delivery of final report.
- Additional relevant information
［AFM］原子間力顕微鏡法の分析事例はこちらからご覧ください。