**3. Force curve**

In lithographic experiments, it is often critical to know the tip pressure on the desired sample. To estimate the pressure corresponding to a specified level of the probe impact, the force created by the probe has to be determined. It can be calculated from force spectroscopy data.

The normal force between tip and sample is estimated from cantilever deflection (nA) curve plotted against Z-displacement of the cantilever and converting this curve to Force-Distance curve (Vanlandingham, 1997; Yeung et al., 2004; Carallini et al., 2003; Santinacci et al., 2005; Sadegh Hassani et al., 2008a; Argento & French, 1996). To take the force curve, to avoid punching surface, it is essential that the sample has a rigid surface such as silicon or polycrystalline substrate. By performing spectroscopy in a point, force curve is obtained.

The conversion factor for converting nA to nm was obtained from the slope of the linear portion of the deflection–distance curve. There was also one conversion needed for the X– axis values. The change in piezo height, which has been used for the distance between the tip and the sample, was corrected for the deflection of the cantilever by subtracting the cantilever deflection from the piezo height.

On the other hand, there are two measurements required to convert photo detector signal into a quantitative value of force. The first stage is to calibrate the distance that the cantilever actually deflects for a certain measured changes in photo detector voltage. This value depends on type of cantilever and the optical path of the AFM detection laser. When every cantilever is mounted in the instrument, this value will be slightly different. Once the deflection of cantilever is known as a distance Z, the spring constant k, is needed to convert

Resolution will be major challenge in lithographic fabrication and the limiting factor for resolution is the tip quality. Sharp silicon tips deliver brilliant and reproducible results. To even further achieve the fine lithographic structure, electron beam deposited tips (EBD tips)

Wearing of probe led to low-quality results and reduced the repeatability of produced scratches. Indeed, by using the same tip at another experiment, the sample surface could experience two completely different values of pressure, because the amount of produced pressure depends on the shape of tip (Hu et al., 1998). To decrease wearing of probe, a soft resist polymer film (usually PMMA film) is coated on the surface. On the other hand, the roughness of surface is very important to take high quality scratches. Observations show that surface roughness is strongly influenced by its thickness as while; the surface roughness increases with the increase of the thickness. So, to perform the lithography process, the

Studies show that in the case of AFM, the possibility of directly machining a surface has been explored in two ways, i.e. by either using a static approach in which the microscope is operated in conventional contact mode (Magno & Bennett, 1997; Sumomogi et al., 1995) or using a dynamic approach in which the microscope is operated in the tapping mode (Heyde et al., 2001; Davis et al., 2003). Usually the lithography developed using both static and dynamic approaches are employed to pattern a resist layer, subsequently the patterned layer is used as an etch mark. Both techniques are giving lithography resolution of the order of

An advantage of the vibration in the tapping mode is that very small lateral forces stress the

In lithographic experiments, it is often critical to know the tip pressure on the desired sample. To estimate the pressure corresponding to a specified level of the probe impact, the force created by the probe has to be determined. It can be calculated from force spectroscopy

The normal force between tip and sample is estimated from cantilever deflection (nA) curve plotted against Z-displacement of the cantilever and converting this curve to Force-Distance curve (Vanlandingham, 1997; Yeung et al., 2004; Carallini et al., 2003; Santinacci et al., 2005; Sadegh Hassani et al., 2008a; Argento & French, 1996). To take the force curve, to avoid punching surface, it is essential that the sample has a rigid surface such as silicon or polycrystalline substrate. By performing spectroscopy in a point, force curve is obtained. The conversion factor for converting nA to nm was obtained from the slope of the linear portion of the deflection–distance curve. There was also one conversion needed for the X– axis values. The change in piezo height, which has been used for the distance between the tip and the sample, was corrected for the deflection of the cantilever by subtracting the

On the other hand, there are two measurements required to convert photo detector signal into a quantitative value of force. The first stage is to calibrate the distance that the cantilever actually deflects for a certain measured changes in photo detector voltage. This value depends on type of cantilever and the optical path of the AFM detection laser. When every cantilever is mounted in the instrument, this value will be slightly different. Once the deflection of cantilever is known as a distance Z, the spring constant k, is needed to convert

can be additionally sharpened in oxygen plasma (Wendel et al., 1995).

smoothest surface has to be chosen (Yasin et al., 2005; Fonseca et al., 2004).

tens of nanometer (Wendel et al., 1994; Quate, 1997).

cantilever deflection from the piezo height.

**3. Force curve** 

data.

tips, resulting in very slow tip degradation (Wendel et al., 1996).

this value into a force F, using Hook's law (F = kZ) (Heimberg & Zandbergen, 2004; Ebrahimpoor Ziaie et al., 2005; Carpick & Salmern, 1997; Sadegh Hassani & Ebrahimpoor Ziaie, 2006).
