Frequently Asked Questions

Q: What are chip, cantilever, and tip?

A: Basically a chip is a relatively large piece of silicon to which one or several cantilevers are attached (Fig. 1). Cantilevers (or just levers) are thin beams of silicon or silicon nitride. They usually have rectangular or triangular shape and well-defined mechanical properties. Finally, a tip is a very sharp protrusion at the end of a cantilever, although cantilevers themselves are often referred to as 'tips' as in 'contact tips', for example.

Fig.1 Chip, cantilever, and tip

Q: Are your products compatible with …?

A: Our products are compatible with the microscopes of all major SPM manufacturers, including Digital Instruments, ThermoMicroscopes, JEOL, Burleigh, and others. Note that to use cantilevers in ThermoMicroscopes SPM you need to mount them first.

The dimensions of the chip are 1.6 mm x 3.4 mm x 0.4 mm (Fig. 2).

Q: Do you sell pre-mounted cantilevers?

A: No.

Q: What is the difference between silicon and silicon nitride cantilevers and tips?

A: Silicon and silicon nitride (Si₃N₄) are the two materials most often used in fabrication of cantilever assemblies. Each has its advantages and disadvantages. Silicon nitride tips usually have larger radii (on the order of tens of nanometers) and lower aspect ratios, which may degrade lateral resolution and ability to image steep features. Silicon tips can be manufactured to have radii of curvature of less than 10 nanometers and aspect ratios as high as 1:5. The price for this is that silicon tips wear down more quickly and break more easily. Another problem associated with silicon nitride cantilevers is that they tend to have residual stress that may result in the twist of a cantilever if its thickness is greater than 1 micron. For this reason, non-contact and tapping mode cantilevers are usually made of silicon.

Q: Do you make silicon nitride cantilevers?

A: No, we only make monolithic silicon-etched cantilevers.

Q: What is the crystallographic orientation of your rectangular cantilevers?

A: The tips point in the <100> direction, the edges of cantilevers are along the <110> direction.

Q: What is the doping type and concentration in your cantilevers?

A: We use phosphorous-doped silicon (n-type), the concentration of phosphorous is from 10¹⁷ cm^-3 to 5*10¹⁷ cm^-3.

Q: What is the purpose of reflective coating?

A: Reflective coating is deposited on the backside of cantilevers to increase the reflected laser signal and prevent interference of light reflected from the two surfaces of the cantilever. The most popular reflective coatings are gold and aluminum. Reflective coating is not used when cantilever already has another type of overall coating (conductive or magnetic).

Important! Use uncoated cantilevers whenever experimental conditions may lead to the corrosion of the reflective coating. If you need any series without the reflective coating, you should specify this in your order.

Q: What is the meaning of the different cantilever types: A, B, C …?

A: Some of our chips have more than one cantilever. In this case, instead of calling them "left short cantilever" or "middle long cantilever" we use one-letter names. The letters by themselves do not have any meaning, refer to the description of a specific series for specifications.

Fig.2 Silicon chip with cantilevers.

Q: Should I break off the tips I don't use?

A: It is not necessary. Although you cannot control the force applied by the lever you are not using, in most cases nothing will happen to it and you will be able to use it later (e.g. by realigning the laser).

Q: I need cantilevers without tips. Can you make them?

A: Yes. Cantilevers of all our standard models can be manufactured without tips (minimum order - 15 chips). We can also custom make cantilevers for you (minimum order - 200 chips). As a matter of fact, we receive quite a few orders for tipless levers. So there are often some in stock and ready for delivery. You may want to check this out with our sales department.

Q: I am going to image _______ in _______ mode. What cantilevers should I use?

A: Unfortunately this important question does not have a simple answer. A lot will depend on the properties of your sample and imaging conditions and there is often a trade-off of some sort. Here are a couple of general remarks.

In contact mode soft levers should be used to minimize damage to the sample and the tip. However, very soft levers are noisy.

In tapping mode stiff levers are used so that the tip does not stick to the sample surface. Cantilevers with very high resonance frequencies (and force constants) allow faster scanning but can damage very soft samples. Rectangular cantilevers are preferable because they typically have better Q-factors than triangular ones.

Q: Do you have tips suitable for tapping mode in liquid?

A: Yes. Try the NSC36 probes. These cantilevers are the shortest and suffer the least dumping forces in liquid media. Corresponding resonance peaks (10-35 kHz in water) are clearly seen in a cantilever tune.

Q: I have a question the FAQ didn't answer, where can I send it?

A: To support@mikromasch.com.

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