The Influence Of Hydrophilic And Hydrophobic Characteristics Of Surface To Topography Measurement

Atomic force microscope(AFM)as a new method,instead of the optical microscope,is to explore microscopic world by humans.The use of AFM is mostly atmospheric,and the water molecules in the atmosphere are adsorbed by the sample and the tip surface to form a water film.When tip a knock to the sample surface,it can form liquid bridge between tip-sample.There are different properties of different samples,include the hydrophilic and hydrophobic characteristics of sample surface.Different samples have different surface properties,including the hydrophobic properties of the sample surface.Due to the different hydrophilic and hydrophobic characteristics,there are different adsorption capacity,which led to the formation of the difficulty of the different bridge.Therefore,the hydrophobic characteristics of the sample surface will make a certain impact to the AFM morphology measurement.In this paper,we research the effects of hydrophilic and hydrophobic characteristics of the surface to topography measurement of AFM.First,for the accuracy of AFM topography measurement,the dynamic characteristics of AFM micro-cantilever must be considered.In this paper,the pendulum model,the mass spring system model and the negative spring model are used to simulate the motion state of the tip of the tapping mode,and the motion formulas of these models are calculated to explain the symmetry of the"frequency drift" phenomenon.Second,this paper uses a variety of methods to produce a variety of hydrophilic and hydrophobic samples,design the experimental route and the implementation of experimental plans.The topography measurement of the hydrophilic and hydrophobic samples was measured at different rows of humidity.The results of the topography measurement survey were analyzed effectively,and the influence of the hydrophilic and hydrophobic characteristics on the topography measurement was explored from the experimental point of view.It was found that the topography measurement of hydrophilic samples had a high sensitivity to humidity,and the relative height of hydrophilic samples showed a tendency to increase first and then decrease.The sensitivity of the hydrophobic sample to the relative humidity is weak,and the relative humidity has no effect on the surface morphology of the hydrophobic sample.Finally,the effect of surface migration on the capillary condensation model in the formation mechanism of liquid bridge is proposed.It is found that the diffusion coefficient of surface migration is 100 times of that of Knudsen diffusion coefficient in capillary condensation model.