Ion sputtering deposition

Ion sputtering to form an interference film is a new method to enhance the contrast between the white and the white.

Ion beam sputtering deposition is in a partial vacuum sputtering chamber glow discharge, gas ions produces a positive; under the accelerating effect of the voltage between the cathode (the target) and anode (sample), a positively charged ion bombardment cathode surface, the cathode material surface atomic; the formation of neutral atoms, from every direction slop, set over the sample surface, so on the specimen surface formation a uniform layer of film. So this method form the interference film with similar evaporation Hof Peng pai.

The surface of the cathode hit material is mainly due to the neutral atoms, if the ion impact energy is low, namely under low acceleration voltage, hit the number of atoms is considerably less can be neglected; under the impact of energetic ions accelerated voltage exceeding 500V actually each ion can from the surface of the target hit an atom. From the target surface spills the atomic velocity, mainly depends on the target, accelerating voltage, pressure and atmosphere of the nature. The growth rate of the film on the surface of the sample depends on the relative position of the sample and the target as well as the velocity of the atom. The specimen of the sputtered atoms reached, decreased with increasing distance between the sample and the target square and. When the position of the sample is close to and parallel to the surface of the target, the growth rate reaches the maximum, which is the order of magnitude of 100nm/m. Therefore, the control of sputtering film thickness can be used in the following relationships:

T=d2/v

Type

T- to reach a certain thickness of the time;

The distance between the d- sample and the target;

Voltage used by v-;

K- constant, determined by the experiment.

Ion sputtering and cathodic ion etching instead, ion sputtering, sample circuit anode.

Figure 1 Schematic principle of ion sputtering equipment

Ion sputtering coating requires dry cleaning of sample. In order to make the sample surface clean, when necessary, the sample and the cathode are replaced, and the surface of the spark discharge cleaning surface is used. And then the sample recovery, and then sputter coating. Obviously, a new cathode is to be changed when the coating is started. In order to avoid cleaning the surface of the sample, the impurities deposited on the cathode surface, and then deposited on the surface of the sample.

Due to the different effects of the gas and the cathode sputtering atoms in the sputtering chamber, there are two kinds of neutral sputtering and reactive sputtering. If the sputtering chamber, the vacuum chamber vacuum to 10-3 mercury column, and then open the inlet valve, so that the pure argon gas into a vacuum chamber, then vacuum pump operation regulation, gas pressure in the sputtering chamber maintained at 2 mm to 1 mm Hg, or oxidizing atmosphere and cathode material is not easy to be oxidized, sputter deposited film is cathode material, which is neutral sputter coating. If the oxygen or air enters the sputtering chamber, the atomic oxygen and the oxygen function of the cathode are deposited on the sample to form an oxide film, which is the reactive sputtering coating. In recent years, it has been used to test the surface of polished steel samples and the surface of copper treated by iron cathode and oxygen in the sputtering chamber. Also, the sample with Ni Pb as cathode lead oxide formation. With gold as cathode materials, the film to produce gold. These results clearly pointed out: (1) cathode material was sputtered on the specimen surface; (2) oxygen cathode sputtering atoms and atmosphere is sufficiently high affinity when the oxide film is formed if the cathode sputtering atoms and atmosphere of oxygen affinity small or under an inert atmosphere, only the formation of pure metal coating.

Ion sputtering deposition, mostly in the presence of reactive gases, the stability of the deposition film and optical constants, depends on the type of gas and cathode materials. Commonly used reactive gas for oxygen, the commonly used cathode material is iron, nickel, copper and lead, and sometimes gold, platinum, palladium, indium and other metals. The oxide formed by reactive sputtering is a coating material which is not very high in absorption and refractive index.

The operation of sputtering coating is closely related to the sputtering coating equipment. Commercially available equipment has been installed in the position of the platform under the microscope. When sputtering coating, the polished specimen is placed on the design head, and is transferred to the position of the electron gun (cathode) to adjust the pressure in the sputtering chamber, the glow discharge, the cathode sputtering, the reactive sputtering deposition. Some time after, interrupt sputtering, the sputter deposition of the specimen surface, turn back to the position of the objective lens face, observing the color of a surface of the specimen, to evaluate the thickness of the deposited film, when the requirements of color, coating operation stop.

Figure 2 Schematic diagram of sputtering and observation equipment