RU2061786C1 - Method for application of coatings in vacuum and vacuum plant evaporator for its embodiment - Google Patents

Abstract

FIELD: vacuum and gas-discharge electronics, particular, technology of application of thin films, applicable in growing of epitaxial layers in vacuum for modification of various coatings in the process of their growing and for application of thin films. SUBSTANCE: after evaporation, pores are formed in a row of molecular flows overlapping one another. Pores of substances having complex compounds simultaneously with formation into a row of molecular flows dissociate into components. Introduced coaxially into evaporator of vacuum plant at the outlet of crucible 1 is former 3 of molecular flows in form of metal cylinder accommodating tubes 7 parallel to its longitudinal axis and presenting a thermal tube 8. Former 3 has heater 9. Evaporated substance 13 is placed into crucible 1. Created in chamber 10 is vacuum. Whenever required, complex compounds of initial substance are dissociated into components by raising the temperature of former 3 with the help of thermal tubes 8 and their heater 9. EFFECT: higher efficiency. 3 cl, 1 dwg

Description

 The invention relates to the field of vacuum and gas discharge electricians, in particular, to the technology of applying thin films, and can be used for growing epitaxial layers in a vacuum to modify various coatings during their growing and for applying thin films.

 A known method of coating in vacuum, which consists in the thermal evaporation of the applied substance and the subsequent condensation of vapors on the substrate / 1 /.

 Also known is the evaporator of a vacuum installation for coating, containing a crucible with a heater and thermal screens / 2 /.

The disadvantage of the method and the evaporator of the vacuum installation for coating include:
uneven deposition of films on a large area substrate, due to the fact that the diameter of a single vapor stream of the deposited material is smaller than the size of the substrate, and the distribution of the flow intensity over its cross section is close to conical;
deposition and condensation of the applied substance on the walls of the outlet and the tube forming the flow due to their low temperatures, which leads to overgrowth of the outlet and the channel of the tube;
insufficient directivity of the flow, due to its spatial divergence, due to the small thickness of the wall of the hole;
inertia of flow rate control;
low growth rate of films of complex composition due to insufficient chemical activity of molecules or atoms.

 The technical result of the claimed inventions is the ability to obtain uniform coatings on substrates of a large area and the ability to synthesize coatings from the products of dissociation of complex compounds of substances.

 This is achieved by the fact that in the method of coating in vacuum, which consists in the thermal evaporation of the applied substance and the subsequent condensation of vapors on the substrate, according to the invention, after evaporation, the vapors are formed into a series of overlapping molecular flows.

 Pairs of substances having complex compounds, simultaneously with the formation of a series of molecular flows, dissociate into components.

 In the evaporator of a vacuum coating system comprising a crucible with a heater and heat shields according to the invention, a molecular flow former in the form of a metal cylinder is inserted coaxially at the outlet of the crucible, inside of which metal pipes are installed parallel to its longitudinal axis, and its internal cavity is a heat pipe, moreover, the shaper is equipped with a heater.

 The invention is illustrated in the drawing, which shows the evaporator of a vacuum installation for coating.

 Inside the crucible 1 with the heater 2 is placed applied / evaporated / substance. Thermal screens 4 and flat screens 5 are mounted on holder 3. At the outlet of crucible 1 and coaxial to it, a molecular flow former 6 is introduced in the form of a metal cylinder, inside of which metal tubes 7, dissociators and molecular flow former are installed parallel to its longitudinal axis, and the internal cavity the shaper 6 is a heat pipe 8, and the shaper has a heater 9. In the vacuum chamber 10, pumped continuously by the evacuation system 11, the substrate 12 is fixed.

 The method is implemented as follows.

 The evaporated substance 13 is placed in the crucible 1, the crucible is closed by the molecular flow former 3 and placed inside the chamber 10. A vacuum is created in the chamber using the vacuum system 11. The heat radiation is reduced by screens 5 and 4. Molecular flows are formed by the shaper 3. If necessary, increasing the temperature of the shaper 3 using heat pipes 8 and their heater 9, dissociate complex compounds of the starting material into components.

An example of a specific installation. The vacuum chamber is a sealed volume pumped by steam-oil and fore-vacuum pumps. Helical crucible heater with direct current flow through the spiral. Thermal cylindrical screens are made of tantalum foil with a thickness of 50 μm, and flat screens of sheet nickel with high reflectivity. The applied substance is placed in the crucible. The molecular flow former is a metal cylinder inside which a series of metal tubes are installed parallel to its longitudinal axis. Vapors of substance dissociate on the inner walls of these tubes. The cavity formed by the outer walls of the tubes and the inner wall of the former is a heat pipe. The shaper is equipped with a heater. The diameter of the multi-channel angle is 150 mm, the diameter of the dissociator tubes is 0.5 mm. The height of the multi-channel assembly is 50 mm. The cavity of the heat pipe to 0.9 volume is filled with a tin-lead solder melt / POS /. Overheating to any ^o # temperature in the range of 300-700 ^o From this melt is carried out by a tube heater with a power of 100 watts. The heater is made of a 0.3 mm thick nichrome wire insulated electrically from the walls of the heat pipe 5 with a layer of alunda.

 Example 1 of the method.

To obtain T8 vinyl films, 200 mg of the applied powder is loaded into the crucible. The vacuum in the chamber is created at 10 Pa. Vinyl was evaporated at an evaporator temperature of 110 ^{° C.} for 10 minutes. In this mode, shaper 3 was used only for the formation of molecular flows. At a film thickness of 0.3 μm, the non-uniformity did not exceed 2% over the area of the substrate with a diameter of 150 mm.

 Example 2

To obtain films of polyparaxylylene / PPC / provided vapor pressure inside the crucible at a level of 10 PA. This vapor pressure required heating the crucible to a temperature of 400 ^o C. To control the processes of film growth and stop it in a given coating thickness, a heat pipe heater was switched on. The temperature of their walls was raised to 430 ^o C. At this temperature on the walls there is a dissociation of VAP vapors into gaseous components pumped out by a vacuum system. The film growth process stops and can only be resumed after the temperature of the tube drops below 400 ^o C. Due to the low inertia of the heat pipe, the process of controlling the flow intensity is fast.

 Example 3

A molecular vapor stream of potassium iodide was formed, which in addition to the molecules contains the products of dissociation of this compound, i.e. iodine and potassium, as well as ions of these elements. 5 g of the starting material was loaded into the crucible, then the crucible was heated to 600 ^° C, and the former was heated to 800 ^° C. On the inner walls of the channels, the vapor molecules partially dissociate, and some of the dissociation products turn into ions due to surface ionization. When an accelerating voltage of 100 V is applied to the substrate holder, the positive K + ions contribute to the formation of a defect-free KJ film on the substrate with an increased speed. It has equal thickness over the entire area with a diameter of 150 mm. The loaded mass of the applied compound is sufficient for 7 hours of continuous operation of the source.

 The application of this invention allows to obtain uniform coatings over large areas, and the use of a molecular flux former allows controlling the process of film growth and synthesizing coatings from the products of dissociation of complex compounds of substances.

Claims (3)

 1. The method of coating in vacuum, which consists in the thermal evaporation of the applied substance and the subsequent condensation of vapors on the substrate, characterized in that after evaporation the vapors are formed into a series of overlapping molecular flows.  2. The method according to claim 1, characterized in that the pairs of substances having complex compounds, simultaneously with the formation of a series of molecular flows, dissociate into components.  3. The evaporator of the vacuum coating system, comprising a crucible with a heater and heat shields, characterized in that the molecular flow former in the form of a metal cylinder is coaxially inserted at the outlet of the crucible, inside of which metal tubes are installed parallel to its longitudinal axis, and its internal cavity represents a heat pipe and the shaper is equipped with a heater.