RU2377331C1 - Method to produce high-purity nickel for dispersed targets and device to this end - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy. Proposed method comprises zone chlorination of nickel metal in gaseous chlorine flow at 940 to 970°C to produce nickel chloride powder. Then, one-stage sublimation of nickel chlorides powder in atmosphere of humid argon at 940 to 970°C is carried out to produce nickel chloride vapors and diffusion recovery of nickel chloride vapors in dehydrated hydrogen at 950 to 980°C to produced compact recovered nickel. Now, said foil and crystals are pressed and vacuum zone re-crystallization is effected to produce ingots. The latter are remelted in cooled flat crystalliser in vacuum to produce flat ingot to be remelted on both sides for complete depth, at least, two times. Invention covers also device to produce nickel chloride powder for dispersed targets and device for sublimation and homogeneous recovery of nickel chloride.

EFFECT: sharp increase in nickel purity.

3 cl, 2 dwg, 1 tbl, 1 ex

Description

The invention relates to the field of metallurgy of non-ferrous metals and can be used in the production of sputtered magnetron targets in the production technology of silicon integrated circuits in microelectronics.

The prior art method is known (GB 1381036, IPC C22B 23/04, 01/22/1975) for producing high-purity nickel by reducing nickel chloride with hydrogen. A device is known (WO 02102533 A1, C22B 23/04, 2002) for producing nickel by reduction of nickel chloride with hydrogen, containing a reactor and reactant supply systems.

A disadvantage of the known method and device is that in the chloride process, the removal of impurities strongly depends on the choice of material and capacity of the reaction vessel, the ratio of chlorine to the starting metal, the selection of temperature for precipitation and the purity of the starting product. In addition, in the initial product, for example in carbonyl nickel, there are gas impurities that adversely affect the efficiency of this process, and impurities that are close in their chemical properties to nickel, such as cobalt and iron, are removed extremely inefficiently. Vacuum melting and purification of the initial powders of nickel chloride obtained by the chloride technology is not always accompanied by the achievement of the desired result, and the ingots at the final stage contain an excess of impurities and, as a result, a poor macrostructure. The growth of single crystals from such starting materials is greatly complicated due to the presence of impurities.

The technical problem is a sharp increase in the purity of nickel to obtain single crystals and sputtering targets used for thin-film metallization by various spraying methods, since the purity of nickel largely determines the electrophysical parameters of the applied thin layers.

This is achieved by using a method for producing high-purity nickel for sputtering targets, which includes zone chlorination of nickel metal powder in a stream of chlorine gas at a temperature of 940-970 ° C to obtain nickel chloride powder, its sublimation in wet argon at a temperature of 940-970 ° C diffusion recovery of nickel chloride vapors in a stream of dried hydrogen at a temperature of 950-980 ° C to obtain compact reduced nickel; vacuum zone recrystallization to obtain nickel crystals; in the required mass amount of nickel crystals in a cooled flat mold in vacuum to obtain a flat ingot melted on each side to a full depth of at least two times. This is achieved by using a device for zone chlorination of metallic nickel for sputtering targets, including a reactor made of refractory material, a zone heater configured to move from top to bottom at a given speed along metallic nickel when it is heated to a temperature of 940-970 ° C counterflow of chlorine. This is achieved by using a device for reducing nickel chloride to produce high-purity nickel for sputtering targets, including a reactor made with a reduction zone in the form of a narrowed middle part and with a sublimation zone designed to supply argon to it to transfer nickel chloride vapors to the reduction zone , a heater, and a thin-walled nickel tube located on the central axis of the reactor to supply hydrogen to the reduction zone and to deposit reduced nickel on its outer surface STI

Figure 1 and Figure 2 presents a device for implementing the proposed method. Figure 1 shows a laboratory device for zone chlorination: 1 - processed material; 2 - reactor; 3 - movable zone; 4 - zone heater; 5 - chlorine supply system; 6 - argon feed system. Figure 2 presents a laboratory device for sublimation and diffusion recovery: 7 - processed material; 8 - sublimation zone; 9 - recovery zone; 10 - precipitated nickel; 11 - Nickel tube for supplying hydrogen and deposition; 12 - reactor; 13 - heater.

The method of producing high-purity nickel to obtain crystals and targets is as follows (Figure 1). The processed material 1 in the form of a metal nickel powder is placed in the reactor 2, heated to a temperature of 700-750 ° C using a zone heater 4, chlorine gas is passed through the reactor 2, the zone heater 4 is moved vertically down along the processed material 1, moving the heating zone 3 and producing chlorination, fill the reactor 2 with wet argon, quickly move the zone heater 4 to its initial upper position and repeat the zone chlorination until complete transfer of metallic nickel to nickel chloride. To remove carbon impurities and use the differences in the ability to high-temperature hydrolysis of nickel chlorides and impurity elements (Figure 2), in the sublimation zone 8, the processed material 7 is evaporated in the form of nickel chloride at a temperature of 940-970 ° С and a carrier gas stream ( argon) chloride vapors are fed into the reduction zone 9. A diffusion reduction zone 9 is created by narrowing the reactor 12 to form an annular diaphragm, which is necessary to create an excess of nickel chloride vapors compared to diffusing in portly that prevents recovery of chloride in the volume and on the walls of the reactor in the reduction zone. Diffusion recovery of chloride vapors is carried out using hydrogen supplied to the reduction zone through a nickel tube 11 located along the central axis of the reactor 12, and the reduced nickel 10 is deposited on the outer surface of the nickel tube 11. During the recovery process, the hydrogen pressure inside the nickel tube is increased from 1 to 15 at. The processed material in the form of a compact hollow core is subjected to vacuum zone recrystallization to obtain crystalline nickel ingots. To obtain a target, the processed material in the form of nickel ingots is placed in a cooled flat mold and vacuum remelted to obtain a flat ingot, melting it from each side to full depth.

An example implementation of the method.

As a starting material, OCPh grade carbonyl metal nickel powder was used. Zone chlorination of metallic nickel was carried out in a vertical container of fused silica in a stream of chlorine. The zone heated to a temperature of 700-750 ° C was moved from top to bottom at a speed of 50 mm / h, gaseous chlorine was passed through the backfill material towards the movement of the zone heater. The height of the zone is 50 mm. The result of zone chlorination of metallic nickel was the production of stoichiometric nickel chloride powder, while chlorination occurred without sintering. Zone chlorination of carbonyl nickel was carried out in 2-3 passes of the heated zone; as a result, metallic nickel was completely converted into nickel chloride powder. The duration of chlorination was 8-10 hours per 1 kg of chloride, the yield of pure product 90-95%. Diffusion recovery of chloride was carried out on the installation, schematically depicted in Figure 2, a feature of which is the separation of the reactor into two zones: a sublimation zone of nickel chloride and a zone of diffusion recovery of chloride vapor by hydrogen. The optimal heating conditions in the evaporation zone are 940-970 ° С, in the recovery zone - 950-980 ° С. The yield of reduced nickel was 85-90%. A study of the behavior of impurities (see table) showed that the proposed process is a highly effective method of purification from impurities and allows to obtain a metal with a content of controlled impurities at the level of 0.1-1.0 ppm.

Thus, the proposed method for producing high-purity nickel allows high-purity purification of starting materials of reduced purity and, finally, for the preparation of magnetron targets to use a nickel product of record purity.

Table
Impurity content in nickel obtained by diffusion reduction of nickel chloride (ppm) Element NiCl ₂ (OSH) Ni after the differential. recovery NiCl ₂ after sublimation Ni after subl. and differential. rest. Na 5,0 <0.3 <0.3 <0.1 TO 5,0 0.3 0.3 <0.1 Mg 10.0 0.3 0.3 <0.1 Al 10.0 <0.1 <0.1 <0.1 Ca 10.0 0.3 <0.3 <0.1 Mn 30,0 <0.01 <0.01 <0.01 With 30,0 0.3 <0.3 <0.1 Fe 30,0 0.3 <0.3 <0.1 Cu 5,0 0.3 0.3 <0.1 Ba 30,0 0.3 0.3 <0.1 Si 10.0 1,0 0.3 <0.1 Li <0.1 <0.1 <0.1 <0.1 Zn <0.1 <0.1 <0.1 <0.1 Pb <0.1 <0.1 <0.1 <0.1 S 0.3 <0.1 <0.1 <0.1 Cr <0.1 <0.1 <0.1 <0.1 As <0.1 <0.1 <0.1 <0.1 Sb <0.1 <0.1 <0.1 <0.1 Sn <0.1 <0.1 <0.1 <0.1 Bi <0.1 <0.1 <0.1 <0.1 P <0.1 <0.1 <0.1 <0.1 FROM 10.0 <5.0 <5.0 <5.0

Claims (3)

1. A method of producing high-purity nickel for sputtering targets, which includes chlorinating metallic nickel in a stream of chlorine gas at a temperature of 940-970 ° C to obtain nickel chloride powder, sublimating it in wet argon at a temperature of 940-970 ° C, diffusion recovery of nickel chloride vapor in a stream of dried hydrogen at a temperature of 950-980 ° C to obtain compact reduced nickel, vacuum zone recrystallization to obtain nickel crystals, remelting the required number of nickel crystals by weight I in the planar cooled crystallizer in vacuo to give a flat ingot fusion with each side at the full depth of not less than two times. 2. A device for the chlorination of metallic nickel, designed to produce high-purity nickel for sputtering targets, comprising a reactor made of refractory material, a zone heater, configured to move from top to bottom at a given speed along metallic nickel when it is heated to a temperature of 940-970 ° C in counterflow of chlorine. 3. A device for the recovery of nickel chloride, designed to produce high-purity nickel for sputtering targets, including a reactor made with a reduction zone in the form of its narrowed middle part and with a sublimation zone intended for sublimation of nickel chloride powder and feeding argon to transfer chloride vapor nickel in the reduction zone, the heater and a thin-walled nickel tube located on the central axis of the reactor for supplying hydrogen to the reduction zone and for the deposition of reduced nickel and its outer surface.

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