AFM Surface Contamination Solution

This July, AFM Workshop is happy to present our NP-AFM for nano-profiling applications. The NP-AFM is a nano-profiler used for analysis of features such as surface roughness and metrology of technical samples. With a price point starting around $35,000, this AFM is ideal for researchers and process development engineers who need routine AFM scanning on a limited budget. For a quick overview of the NP-AFM, check out the NP-AFM Video.

AFM Workshop’s NP-AFM is primarily intended for use in process development and process control of technical samples. This atomic force microscope is capable of scanning samples as wide as 200 mm, including wafers, discs, and other technical samples for nanotechnology research. With a noise floor as low as 0.1 nm, this high-resolution stylus profiler is capable of making several types of measurements on processed wafers including visualization of surface features, surface roughness and step-height measurements. Some example measurements below illustrate the capabilities of the NP-AFM.

The NP-AFM is allows researchers and engineers to perform several types of measurements on large samples used in process control and development. Visualization of surface features helps us understand why a given process is working or not working. Surface roughness measurements at the nanoscale are possible only with AFMs; in the proper vibration isolation environment, it is possible to measure surface textures down to 0.1 nm. Step height measurements between 0.3 nm up to 1 µm can also be done using an NP-AFM.

The following are 3 example of measurements taken on a patterned wafer polished by CMP (chemical mechanical planarization). Fig 1 describes the regions where measurements were taken. Also visible in Fig 1 is the cantilever with reflected laser light used in the AFM force sensor.

AFM Vizualization

Fig 1. Video microscope image of the 3 regions where measurements were made.

 

 

Visualization

By scanning the square identified as region 1 in Fig 1, we see a scattering of pockmarks not visible in the video microscope image (See Fig 2). By zooming in with the AFM, we find the pockmarks have debris at the edges. Data shows us the width of the pockmarks to be about 90 nm and the depth to be about 10 nm.

NP-AFM Zooming

Fig 2. Left: AFM image of region 1; Right: Zoomed in AFM image of region 1.

Surface Texture


Scanning region 2 does not show the same noticeable surface structure as was observed in region 1. A 3D color scale image of the scan in region 2 is shown in Fig 3. Data measured by the AFM shows us the surface roughness (Sa) of region 2 is 1.69 nm, which is 10 times greater than the noise floor of the NP-AFM, creating a high-resolution image.

 

 

Nano-profiling Atomic Force Microscope Scanning image

Fig 3. Left: 3D color scale image of region 2 AFM scan; Right: data from the AFM scan.

Step-Height Measurements

In region 3 are a series of lines about 1 µm wide, which are visible in the video microscope. An AFM image of this region is shown below in Fig 4. Using a histogram of the AFM image, we find the height of each line to be 43 nm.

 

 

Atomic Force Microscope Scan and Histogram of AFM scan

Fig 4. Left: AFM scan of region 3; Right: Histogram of AFM scan.

 

To learn more about what the NP-AFM can do for your research and process development needs, watch this brief introduction video and check out more details at NP-AFM.

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