CS248976B1 - Method of tungsten thin layers formation on solid substrate - Google Patents

Abstract

The solution determines how thin it is created of tungsten layers on a solid substrate plasma vacuum. Tungsten on the surface of the solid of the substrate is applied from the plasma into which it is \ t is obtained by sublimation of tungsten hexacarbonyl and its subsequent cleavage.

Description

The invention relates to a method of forming a thin film of tungsten on a solid substrate.

Currently, there are a number of methods of preparing tungsten layers on the solid surface. The most important of these methods are methods of vacuum vapor deposition of tungsten, which is directly vaporized, for example by electron beam, chemical methods and CVD methods.

The methods used so far based on direct evaporation of tungsten by electron beam under vacuum are energy intensive and associated with difficulties caused by the high evaporation temperature of tungsten and its low evaporation rate. The disadvantages of chemical processes include the relatively unsatisfactory purity of the tungsten layers due to the light oxidation of the tungsten and in many cases also the content of chemically aggressive substances in the layer. By way of example, the presence of Fa and HF in the tungsten layers during their preparation by the CVD method of WFe. The disadvantages of the tungsten layers used hitherto on the basis of the thermal decomposition of tungsten hexacarbonyl are mainly due to their unsatisfactory purity, due to the high pressure Ar (of the order of 10 ⁵ Pa) in the reaction chamber and high content of carbon and its oxides in the layer. on the substrate surface at high pressure.

The above drawbacks are eliminated by a method of forming thin films of tungsten on a solid substrate, according to the invention, which is characterized in that the solid substrate, heated to a temperature above 170 DEG C., is treated in a vacuum chamber at a pressure of 10 ^-3 Pa to 10 ² Pa is a plasma consisting of an inert gas (usually Ar 1) and a tungsten hexacarbonyl pair that sticks on the surface of a solid substrate and in the tungsten plasma at birth and CO.

It is furthermore advantageous according to the invention that the plasma in which the sublimating tungsten hexacarbonyl is cleaved is stimulated by the electron flux emitted by the cathode towards the anode and by the magnetic fields in that direction.

The advantages of tungsten thin film formation on a solid substrate, under vacuum conditions in plasma by cleavage of tungsten hexacarbonyl, are that the tungsten layers thus formed can be achieved with high purity, with the possibility of achieving a high layer growth rate and controlling the layer structure and size. The grain of the grains by means of electrical deposition parameters, the process can be carried out at solid substrate temperatures as low as 170 ° C, which in the case of most solid substrates is lower than the temperature of the light structural changes or lower than the damage temperature. A further advantage of the method of applying tungsten thin layers to a solid substrate is that the decomposition products of tungsten hexacarbonyl, tungsten, and the CO molecule do not cause corrosion damage to the substrate and the vacuum device.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in more detail with the aid of the accompanying drawing, in which an example of a process for the treatment of a process is shown schematically. The vacuum chamber 1 is pumped by the vacuum system 2 to a pressure of the order of 10 &^lt; ^-1 > Pa to 10 ^-5 Pa. The solid substrate 4 placed on the holder S is heated with a heater 5 to a temperature of at least 170 ° C. An inert gas (usually Arj through a valve 7 at a pressure in the range of 10 ^{: 1} to 10 ² Pa) is introduced into the thus prepared and still pumped vacuum chamber 1 and by the electron flow from the cathode 8 to the anode 9 in the magnetic field created by The tungsten hexacarbonyl vapor is released from the vacuum chamber 1 by sublimation from the vaporizer 3, wherein the tungsten hexacarbonyl sublimates by heating to the sublimation temperature, either by transferring heat from the heater or by connecting the vaporizer 3 to a positive electrical potential. against cathode 8, whereby the heating of tungsten hexacarbonyl to the sublimation temperature is effected by electron impact from the plasma space 11. Tungsten hexacarbonyl vapors cleave into the tungsten at birth and CO in the plasma space 11 and on the surface of the solid substrate 4, thereby on the surface of the solid substrate 4 The rate of growth of the tungsten layer is dependent on the rate of growth tungsten hexacarbonyl sublimation, the magnetic field strength in space 11 and the electrical potentials at the electrodes 8, 9, the vaporizer potential 3, and the substrate temperature 4. In the case of the tungsten layers thus prepared, a stop is placed on their maximum conductivity , it is expedient to anneal them with a heater 5 at a temperature of 850 ° C to 950 ° C for at least one hour.

This method has been verified in the deposition of tungsten layers on high-speed steel substrates, aluminum alloys, and silicon substrates. Tungsten hexacarbonyl sublimated into the plasma space formed from Ar by resistive heating at a pressure in a vacuum chamber of 10 ¹ Pa. The substrates were heated to 200 ° C. These processes, which lasted 20 minutes on the surface of solid substrates, resulted in layers of tungsten having a depth of 0.7 ₍ µm).

The tungsten layers prepared according to the invention can be used as high-adhesion interlayers applied to a solid substrate and forming a substrate for functionally hard and abrasion-resistant layers, for example TiN, TiCl 3, TiC, and as a substitute for aluminum layers in microelectronics applications.

Claims (3)

1. Process for forming a thin film on a solid substrate volírámu, characterized in that the solid substrate, heated to a temperature above 170 DEG C. is treated in a vacuum chamber at a pressure of 10 ³ to 10 ² Pa plasma, consisting of an inert gas, usually Ar, and a pair of tungsten hexacarbonyl that cleave on the surface of the solid substrate and in the plasma, on the tungsten at birth and the CO molecule. ¹ INVENTION 2. The method of claim 1, wherein the tungsten hexacarbonyl pairs are cleaved into tungsten and CO in the plasma, which is stimulated by the flow of electrons emitted by the cathode towards the anode and magnetic fields in that direction. 3. A process according to claim 1, characterized in that the hexacorbonyl of tungsten sublimes into the vacuum chamber.