Accurate XY Scan by Crosstalk Elimination
XE scan system
- independent, loop XY and Z flexure scanners for sample and probe tip
XY flexure scanner
- Flat and orthogonal XY scan with low residual bow
Figure 9. Zero background curvature by Park Systems XE-system (a) and typical background curvature of a conventional AFM system with a tube scanner (b). (c) shows the cross section of these background curvatures.
Figure 9. shows unprocessed AFM images of a bare silicon wafer taken with the XE-system (a), and with a conventional AFM (b). Since the silicon wafer is atomically flat, most of the curvatures in the image are scanner-induced artifacts. Figure 9. (c) shows the cross section of the images in Figure 9. (a) and (b). Since the tube scanner has intrinsic background curvatures, the maximum out-of-plane motion is as much as 80 nm when the X-axis moves 15 μm. The XE scan system has less than 1nm of out-of-plane motion for the same scan range. Another advantage of the XE scan system is its Z-servo response.
Figure 10. Figure 11.
Figure 10. is an image of a porous polymer sphere (Styrene Divinyl Benzene), whose diameter is about 5 µm, taken with the XE-system in Non-Contact mode. Since the Z-servo response of the XE-system is very accurate, the probe can precisely follow the steep curvature of the polymer sphere as well as small porous surface structures without crashing or sticking to the surface. Figure 11. shows another example that demonstrates the high performance of the z-servo response with a flat background.
Best Life, by True Non-Contact™ Mode
- Quick tip wear = Blurred low-resolution scan
- Destructive tip-sample interaction = Sample damage and modification
- Highly parameter-dependent
Longer Tip Life and Less Sample DamageThe sharp end of an AFM tip is so brittle that once it touches a sample, it becomes instantly blunt and limits the resolution of an AFM and reduces the quality of the image. For softer samples, the tip will damage the sample and also result in inaccuracies of sample height measurements. Consequently, preserving tip integrity enables consistent high resolution and accurate data. True Non-Contact Mode of theXE-AFM superbly preserves the tip, resulting in much longer tip life and less sample damageThe figure, displayed in 1:1 aspect ratio, shows the unprocessed raw data image of a shallow trench isolation sample imaged by the XE-AFM, whose depth is also confirmed by scanning electron microscope (SEM). The same tip used in the imaging of the sample shows no tip wear even after taking 20 images.
Park XE7 features
The XY scanner consists of symmetrical 2-dimensional flexure and high-force piezoelectric stacks provides high orthogonal movement with minimal out-of-plane motion as well as high responsiveness essential for precise sample scanning in the nanometer scale. The compact and rigid structure was designed for low noise, high speed servo response.
Driven by a high-force piezoelectric stack and guided by a flexure structure, its rigidity allows it to move at higher speeds in the vertical direction than the scanners used in conventional AFMs. The maximum Z scan range can be extended from 12 µm to 25 µm with the optional long range Z scanner (optional).
The AFM head is easily inserted or removed by sliding it along a dovetail rail. The low coherency of the Super Luminescence Diode (SLD) enables accurate imaging of highly reflective surfaces and precise measurements for pico-Newton Force-distance spectroscopy. The SLD wavelength eliminates interference issues for users interested in combining the AFM with experiments in the visible spectrum.
The unique head design can handle up to 100 mm sample size and allows for easy side access to the sample and tip.
The measurement location of the sample is easily and precisely controlled by the manual XY stage. The travel range of the XY sample stage is 13 mm x 13 mm.
The nanoscale signals from the AFM are controlled and processed by the high performance Park XE electronics. With its low noise design and high speed processing unit, Park XE electronics successfully realize True Non-Contact™ mode ideal for nanoscale imaging as well as precise voltage and current measurement.
• High performance processing unit of 600 MHz and 4800 MIPS speed
• Low noise design for precise voltage and current measurement
• Versatile system to utilize various SPM techniques
• External Signal Access Module to access AFM input/output signals
• Maximum 16 data images
• Maximum data size: 4096 × 4096 pixels
• ADC/DAC in 16 bit, 500 kHz speed
• Electric noise isolation from PC by TCP/IP connection