Low-Wear Silicon Nitride Cantilever
for AC (dynamic) mode AFM
|Low wear Silicon nitride probe||OMCL-HA100WS-1||OMCL-HA100WS-HW|
OLYMPUS OMCL-HA series cantilevers with sharpened wedge tips are a long life time probe designed for thin film study by AC mode AFM measurement in air.
Si3N4 sharpened wedge tip
The silicon tip cantilever is widely used for AC mode AFM measurement. The radius of silicon tip protrudes approx.10nm and make it possible to high resolution AFM measurement. On the other hand, it is pointed out that the fine image first taken can not be obtained after repeating measurement by one cantilever which makes tip wear gradually. It is a special concern for people who are using AFM for product imspection.
OLYMPUS employs silicon nitride (Si3N4), known as low-wear material, as a tip material and minimizes the degradation of AFM data due to tip wear. Because of the thick Si3N4 tip, it reduces tip wear and increases tip life.
OMCL-HA100WS- Series has an oxide sharpened wedge tip on the end of the cantilever as in the pictures above. Sharpened wedge tip has two protrusions. What is called "Twin tip".
The protrusion on the wedge tip in the side of cantilever free end is surely terminated at one point and will act as a substantial probe by attaching the cantilever to the AFM instrument with some tilt angle (for instance 10 degrees).
The two protrusions are located at a distance of 5 micrometers. The protrusion on the right side in the left illustration is 0.8 micrometer away from the sample surface when the cantilever is attached to the instrument with 10 degrees and when the other protrusion touchs on the surface. Therefore the point terminated protrusion with tip radius of 15nm (typ.) can image a variety of thin films with corrugation of 0.2µm or less. Where, the limitation for the sample roughness smaller than 0.2µm is originated from the effective tip height (length): taller than 0.2µm (typ. 0.4µm).
The sharpened wedge tip is made of silicon nitride (Si3N4) with thickness of 0.2µm. Due to the hardness of tip material itself and its thickness, stable and long tip life time measurement can be expected.
The OMCL-HA100WS- series cantilever is not overcoated probe. Compared to the overcoated tip with hard material (SiN, SiC or DLD) which is available in the market now, the thickness of the hard material layer (Si3N4) of the wedge tip is thicker than those of the overcoat layers while the tip is sharp with the radius of 25nm or less. The hard material layer should be enough thick to make the most of the materialistic advantage.
2) High lateral resolution with a point terminated tip:
The small protrusion on the wedge tip acts as a substantial probe to trace a sample surface. The protrusion has a smooth tip surface and small tip radius of 25nm or less (15nm typ.). It is well shaped for revealing a sample surface.
The protrusion is ideally point terminated because the protrusion on the wedge tip is made at the corner of the wedge tip where three redges meet. Three ridges must meet at one point.
And our further sharpening process improves the tip apex and the effective tip height of the protrusion to < 25nm radius and > 200nm height.
So this type of the tip shows good performance on imaging thin film sample surface.
Belows are magnified views of a sharpened wedge tip around the protrusion from up right, side front, and the last is a magnified view from side.
- Tip shape : sharpened wedge (hollow tip)
- Tip height (effective *) : taller than 0.2 micrometers (0.4µm (typ.))
- Tip height (whole tip *) : 12 micrometers
- Tip radius : smaller than 25 nm (15 nm (typ.))
- Tip material : silicon nitride (Si3N4)
Effective tip height is 0.4µm (typ.) although whole tip height is 12µm. Effective tip height means the tip height of the small protrusion on the wedge tip. Whole tip height means the tip height of the wedge tip.
The SEM image in right among the three pictures above shows the effective tip height is 0.2µm and more.
Dimensions of levers
Cantilevers of OMCL-HA100WS- series
One rectangular cantilever protrudes from a glass chip.
Thin gold/chromium film is coated on the back side of the cantilevers for reflecting light from a deflection sensor in the AFM equipment.
Dimensions of chips (substrates)
One rectangular cantilever extends from a glass chip. Each chip is connected at the bottom of the glass chip and makes a chip array (call it "cantilever strip"). The left illustration shows a part of the array of rectangular cantilever chips.
Mechanical properties of levers
Stiffness [N/m] and resonant frequency [Hz] of each cantilevers are Calculated values.
(7.7 - 19)
(130 - 190)
(0.2 - )(10 - 16)
Minimum effective tip height is 0.4µm (typ.) although whole tip height is 12µm. Effective tip height means the tip height of the small protrusion on the wedge tip. Whole tip height means the tip height of the wedge tip.
- Thin film study in AC mode AFM in air
Concerning the tip radius, 25nm or less, OMCL-HA100WS- is not expected as a tip for atomic resolution but for much practical use with longer life time.
- Nanoindentation of relatively soft sample.
- We guarantee more than 90% good cantilevers in this product series. Every good cantilever meets the specifications.
- FAQs on the low wear Silicon nitride probe (here)
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