Profilometer is an instrument for measuring the surface profile which can be used to determine some surface features such as roughness, curvature and so on. Thus, in terms of application, this device can be compared with scanning probe microscopes such as AFM. One important difference is that in AFM, topography is usually drawn in three dimensions, while in profilometer the surface characteristics are investigated in one dimension and the final results are plotted in two dimensions. Although drawing surface profile in one dimension provides less information than surface topographies, but in fact, for some applications in the fields of microelectronics, optics, paint industries, electroplating industries, coatings, biology, medicine and pharmaceutical, having information in the form of two-dimensional profile is sufficient; so there is no need to use AFM as an expensive and time-consuming topography method.
Most profilometers consist of four main parts: sensor, probe, sample stage, and software module. The profilometer functional mechanism is very similar to AFM contact mode. At first, a probe moves vertically along the surface, touches the surface and applies a certain force to it. Then, sample stage starts to move the sample along a straight line. Surface features lead to the partial displacements of the probe. These probe displacements result in the production of analog signals by sensor, which are subsequently converted into quantifying data using software module and stored; these data are adapted with probe longitudinal position and finally plotted in the form of a two-dimensional profile. The surface features height which this device can measure varies from 10 nm to 1 mm. The probe tip radius can also vary from 20 nm to 50 micrometers. Besides, the horizontal resolution depends on scan rate and the sampling rate of the signals. The applied force from the probe to the sample surface can change from 1 to 50 milligrams. The noticeable feature of this device is that knowing the layer and substrate materials is not necessary because this device works in contact mode.
Profilometer is an effective and practical tool for achieving the surface roughness information and thickness of nanometer and micrometer layers. Most of surface roughness standards in the world are based on the contact mode. Details of technical specifications are presented in the following Table.
Profilometer is one of the most essential devices in thin film laboratories. In this method, the coatings thickness or surface roughness can be measured by moving a probe along the surface. The employed technology in profilometers makes the measurement of Z with a precision of 50 nm possible.