RU188584U1 - Device for the manufacture of nanometer transparent films - Google Patents

Abstract

The invention relates to devices for the manufacture of nanometer transparent films of semiconductors, dielectrics and metal oxides and can be used for vacuum deposition of films of ZnS, ZnSe, MgF, CaF, SiO, GeO, WO, MoO, SnO. The technical result of the proposed solution is to simplify the method of manufacturing nanometer transparent films. This technical result is achieved by the fact that the proposed device for the manufacture of nanometer transparent films containing a vacuum chamber, a radiation source, an evaporator material, a control substrate, an optical window of the vacuum chamber, a working substrate, while the radiation source of the visible wavelength range is installed inside the vacuum chamber below the plane of the hole of the evaporator material, and the control substrate, is located above the plane of the hole of the evaporator material and is available as for the deposition of evaporated mat rial, and for observing the surface through the optical window of the vacuum chamber, the control substrate is fixed on a cylindrical quartz member and is made of an iron foil. For the implementation of the process of manufacturing nanometer transparent films with thicknesses in the range of 9.6 ÷ 19.5 nm using the proposed device does not require the use of additional sophisticated equipment other than the traditional installation for producing thin films using the method of thermal vacuum deposition UVN-2M1, in which the distance from the evaporator to working substrate is 250 mm.

Description

The invention relates to devices for the manufacture of nanometer transparent films of semiconductors, dielectrics and metal oxides and can be used for vacuum deposition of films of ZnS, ZnSe, MgF2, CaF2, SiO, GeO, WO3, MoO3, SnO2.

A device for vacuum deposition of nanometer transparent films is known, for example, TiO2 and SiO2, used in the RF patent No. 2527670, this device is the closest in technical essence to the claimed utility model and is taken as a prototype. The device contains: a radiation source; fiber optic cables; lens for placing radiation into the camera; lens for outputting radiation from the camera; vacuum chamber housing; evaporators of materials with different refractive indices; input / output optical window of the deposition chamber; working substrates on which the target multilayer coating is applied; control substrate available for spraying; hidden from the deposition of the control substrate; spectrometer.

The disadvantage of this device is the complexity of its manufacture and functional complexity, as well as the complexity of its application for the case of single-layer nanometer transparent films.

The technical problem of the proposed solution is to simplify the design of the device.

The technical result of the proposed solution is to simplify the method of manufacturing nanometer transparent films.

This technical result is achieved by the fact that the proposed device for the manufacture of nanometer transparent films containing a vacuum chamber with an optical window and located in it: the radiation source of the visible wavelength range, the material evaporator, the control substrate and the working substrate, according to the decision, the radiation source is installed below the plane holes of the material evaporator, and the control substrate is installed above the plane of the holes of the material evaporator, ensuring deposition of the material to be evaporated and its surface through the optical window of the vacuum chamber, while the control substrate is fixed on a cylindrical quartz element and made of iron foil.

FIG. 1 shows a general view of the device for the manufacture of nanometer transparent films.

Device for manufacturing nanometer transparent films, contains a vacuum chamber - 1, a source of radiation of the visible wavelength range - 2, a material evaporator - 3, a control substrate - 4, an optical window of a vacuum chamber - 5, a working substrate - 6, while the radiation source of a visible range wavelengths, installed inside the vacuum chamber - 1 below the plane of the evaporator opening of the material - 4, and the control substrate - 4, is located above the plane of the evaporator opening of the material - 3 and is available both for deposition of the evaporated material and for observation of its surface through the optical window of the vacuum chamber - 5.

FIG. 2 is a detailed view of the device in the composition of the vacuum unit. The inventive device operates as part of a vacuum unit, which also contains: the frame - 7, on which the vacuum chamber - 1 and the vacuum pumping system are mounted. The vacuum pumping system consists of: a mechanical foreline pump - 8, a high-vacuum steam-oil pump - 9 with an electric heater - 10 and a switch of pumping lines - 11, which connects with pipelines - 12 a fore vacuum pump - 8 or with a steam-oil pump - 9, or with a vacuum chamber - 1. Between the base plate - 13 and the upper flange of the steam-oil pump - 9 an oil vapor trap - 14 is installed, containing a cooling system. The vacuum chamber - 1 consists of a base plate - 13 and a cylindrical cap. The cap is equipped with an optical window - 5. Air inlet into the working chamber is performed with a vacuum valve - 15. In the lowered state of the cap, the vacuum chamber is sealed on the base plate - 13 with a sealing ring - 16 made of vacuum rubber. Pressure sensors - 17 residual gases are connected to the holes in the base plate and in the vacuum pipelines. In addition, in the vacuum chamber - 1 installed: movable damper - 18, which in one of two positions blocks the flow of evaporated particles in the directions towards the surface of the working substrate 6; the substrate holder - 19, mounted above the flap - 18; electric heater - 20 substrates, located above the substrate - 6; thermocouple - 21, located between the heater and the substrate; high-voltage cathode electrode - 22, used in the ionic cleaning of the substrate surface - 6 in the plasma of an independent gas discharge; metal screen - 23; for convenience of mounting, the control substrate is mounted on a cylindrical quartz composite; the substrate is mounted on a cylindrical quartz element - 24 in the form of a quartz tube section, which is installed in a vacuum chamber so that its lower base is in the plane of the material evaporator opening - 3, while the control the substrate - 4, made of iron foil, is located inside the quartz element - 24 above the plane of the evaporator opening of the material and is available both for deposition of the evaporated material and for I observation of its surface through an optical window - 5 of the vacuum chamber, and a source of visible wavelength radiation range - 2 installed inside the vacuum chamber below the plane of opening of the evaporator material - 3 and consists of a tungsten bulb - 25 and the metallic reflector radiation - 26; metal screen - 27 blocks the flow of light and molecules of evaporated material in the directions from the evaporator - 3 to the window - 5.

Example

Devices for the manufacture of nanometer transparent films of the evaporator - 3, fixed in massive contact clamps, has the shape of a tube with a diameter of 6 ÷ 6.5 mm and a length of 4.5 ÷ 5 mm with a hole with a diameter of 4 ÷ 4.5 mm on the surface of the tube at equal distances from its ends and is made of tantalum foil with a thickness of 0.1 mm. The evaporated material is silicon monoxide (SiO) in the form of granules with a diameter of 3 ÷ 4 mm. The distance between the evaporator hole - 3 and the center of the working substrate - 16 is 200 ÷ 250 mm, while the evaporator hole - 3 is located perpendicular to the center of the substrate - 6. The cylindrical quartz element - 24 is made in the form of a piece of quartz pipe 35 ÷ 36 mm long inner diameter 66 ÷ 67 mm and outer diameter 71 ÷ 72 mm. The control substrate - 4 is made of iron foil with a thickness of 0.2 ÷ 0.25 mm, obtained from tin-coated iron foil (used in the food industry) by removing tin layers in a 40% aqueous solution of potassium hydroxide (KOH) at a temperature (80 ÷ 90) ° С to which (in the process of tin removal) 30% hydrogen peroxide (H ₂ O ₂ ) is added. The surface of the control substrate - 4, facing the evaporator - 3, is a cylindrical surface with a radius equal to the radius of the inner cylindrical surface of the quartz element - 24. The height of the control substrate - 4 is 50 ÷ 52 mm, and the distance between its linear borders is 60 ÷ 62 mm . The control substrate - 4 is equipped with at least two elements for its fastening inside the quartz element - 24, which are made by cutting the control substrate - 4 parallel to its linear borders at a distance of 5 ÷ 6 mm from the borders to a depth of 15 ÷ 16 mm and subsequent bending undercut areas of the substrate - 4 relative to the upper edge of the quartz element - 24.

A device for the manufacture of nanometer transparent films works as follows. Before starting work, fix the evaporator - 3 in massive contact clamps providing transmission through the evaporator - 3 electric currents with a measured value of 50 ÷ 200 A, and fill the evaporator with 3 granules of evaporated material (SiO). The prepared working substrates - 6 are placed in the substrate holder - 19. A cylindrical quartz element - 24 with its control substrate fixed inside - 4 is installed in a vacuum chamber so that the bases of the quartz element - 24 and the substrate - 6 are in the plane of the material evaporator opening - 3, and the control substrate - 4 was available both for deposition of the evaporated material, and for observing its surface through the optical window - 5 of the vacuum chamber. After that, the air from the vacuum chamber is pumped to a pressure of (10 ^-3 ÷ 10 ^-4 ) Pa, the radiation source of the visible wavelength range is installed inside the vacuum chamber below the plane of the material evaporator opening - 3, the flap - 18 is opened and the evaporated material is heated to its evaporation temperature: in the case of SiO - (1050 ÷ 1100) ° C. In this case, the evaporated molecules of the evaporated material are condensed both on the surface of the control substrate - 4 facing the evaporator - 3, and on the working substrates - 6, forming nanometer transparent films on them.

The process of deposition of nanometer films is controlled by observing the emerging color of the surface of the control substrate - 4, facing the evaporator - 3, through the optical window - 5 of the vacuum chamber. The beginning of the deposition of a nanometer film of evaporated material is fixed by the occurrence of interference color (reddish-brown color) of the film on the surface area (in the form of a strip) in the lower region of the control substrate - 4. As the deposition and thickness of the deposited transparent film increases, 4 change the colors of the interference color of the transparent film in the sequence: brown-violet-blue-green-yellow-orange-red. As a reference point for measuring the thickness, choose the film thickness, which corresponds to the green color of the film, since this color corresponds to the maximum of the visibility curve of the average normal human eye, which takes place at the radiation wavelength λ = 0.55 μm. To calculate the thickness of the transparent film in the green color area, you can use the formula for the maximum intensity of the radiation reflected from the medium optically more dense:

where h is the thickness of the transparent film,

n is the refractive index of the material of the transparent film, i ₁ is the angle of radiation incidence on the film,

λ ₀ - radiation wavelength,

m is an integer, which is called the order of the interference maximum.

For a specific example of the implementation of the proposed device for the manufacture of nanometer transparent films, this formula leads to a film thickness h = 147 nm with the values of the remaining parameters in this formula: λ ₀ = 0.55 μm, m = 1, n _SiO = 1.996, i ₁ = 45 °. In the case of using a small flat evaporator, the thickness h of the deposited film is calculated by the formula:

Where

M _e - the mass of the evaporated material, ρ is the density of the evaporated material,

r is the distance from the hole of the evaporator to the considered point on the substrate,

α is the evaporation angle (between the normal to the plane of the evaporator opening and the direction to the point on the substrate under consideration),

β is the angle of incidence of evaporating molecules on the substrate at the point under consideration (measured from the normal to the substrate at this point).

Using formula (2) for the claimed device, it is possible to obtain a formula for the ratio of the thickness h _{2 of the} film in the center of the working substrate - 6 to the thickness h _{1 of the} film at the considered point on the control substrate - 4:

where r ₂ is the distance between the evaporator opening 3 and the center of the working substrate 6, r ₁ is the distance from the evaporator opening 3 to the point under consideration on the control substrate 4,

α ₁ and β ₁ - the angles of evaporation and incidence (respectively) for the control substrate - 4.

When obtaining the formula (3), it was taken into account that for the working substrate - 6 the evaporation angle α ₂ = 0 and the angle of incidence β ₂ = 0, and therefore there are equalities: cosα ₂ = 1 and cosβ ₂ = 1.

If to estimate the thickness h _{2 of the} film in the center of the working substrate 6, use the green interference color band corresponding to the first interference order (m = 1) on the surface of the control substrate — 4 in its lower region, then in this region the film thickness h ₁ = 147 nm . If b is the distance from the middle of the green strip to the bottom base of the substrate - 4, ar is the radius of the substrate - 4, then the distance r ₁ from the evaporator opening - 3 to the middle of the green strip on the substrate - 4 can be determined by the formula:

Formula (3) leads to the value of the film thickness h ₂ = 19.5 nm in the center of the working substrate - 6 with the following values of the other parameters in this formula: r ₁ = 33.84 mm (if b = 7.5 mm, r = 33 mm), cosα = 0.2216, cosβ = 0.9751, r ₂ = 200 mm, h ₁ = 147 nm. If in this example of calculating the thickness h _{2 of the} film in the center of the working substrate - 6, increase the value of r ₂ to the value of r ₂ = 250 mm, without changing the values of the other parameters, then the value of h ₂ will be reduced to the value of h ₂ = 12.5 nm.

When reducing the inner radius of the reference substrate - 4 to 30 mm, the calculation by the formula (3) gives the value of the film thickness h ₂ = 14.9 nm in the center of the working substrate - 6 with the following values of the other parameters in this formula: r ₁ = 30.92 mm (if b = 7.5 mm, r = 30 mm), cosα = 0.2425, cosβ = 0.9701, r ₂ = 200 mm, h ₁ = 147 nm. This reduction of the inner radius r of the control substrate - 4 can be performed either by replacing the quartz element - 24 with the control substrate - 4 with an inner radius of 33 mm with another quartz element - 24 with the control substrate - 4 having an inner radius of 30 mm, or by shifting the quartz element - 24 with the control substrate - 4, having r = 33 mm, on the horizontal surface of the metal screen - 27 in the direction of decreasing the distance from the evaporator opening - 3 to the control substrate - 4 by an amount equal to 3 mm. If in the second example of calculating the thickness h _{2 of the} film in the center of the working substrate - 6, increase the value of r ₂ to the value of r ₂ = 250 mm without changing the values of the other parameters, then the value of h ₂ will be reduced to the value of h ₂ = 9.6 nm.

Thus, from the given examples of estimating the thickness h _{2 of the} film in the center of the working substrate 6, it follows that the inventive device for producing nanometer transparent films allows 6 nanometer films to be deposited on the working substrate with thicknesses in the range of 9.6 ÷ 19.5 nm if to control the thickness of the film on the working substrate - 6 use a green band of interference color, corresponding to the first order interference (m = 1), on the surface of the control substrate - 4 in its lower region. In order to obtain thicker nanometer transparencies on the working substrate - 6, deposition of the evaporated material should be continued, controlling the deposition process and increasing the film thickness by observing changes in the colors of the interference color of the transparent film on the surface of the control substrate - 4. At the same time, a green band of interference color will appear periodically the surface of the control substrate - 4 in its lower region, corresponding to the second, third and fourth order of the interference maximum (m = 2, m = 3, m = 4) in the formula (1).

It should be noted that the implementation of the above-described process of manufacturing nanometer transparent films does not require the use of additional complex equipment other than the traditional installation for producing thin films using the UVN-2M1 type thermal vacuum deposition method, in which the distance from the evaporator to the working substrate is 250 mm.

Claims (2)

1. Device for the manufacture of nanometer transparent films containing a vacuum chamber with an optical window, a source of visible radiation in a vacuum chamber, an evaporator of a material with an opening, a working substrate, a control substrate, characterized in that the radiation source is installed below the surface of the evaporator opening and the control substrate is higher than the plane of the aforementioned hole with the provision of deposition of the evaporated material and observation of its surface through the optical window of the vacuum cameras. 2. The device according to p. 1, characterized in that the control substrate is made of iron foil.

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