Method for production of highly pure molybdenum for spattering targets and device for its realisation

FIELD: technological processes.

SUBSTANCE: invention is related to production of highly pure molybdenum for spattering targets. Method includes cleaning of ammonium paramolybdate in the form of solution from admixtures with ion exchange in neutral and alkalescent mediums on hydrated tin oxide and on weakly-basic anion-exchange resin AN-106. Then thermal decomposition of ammonium paramolybdate is executed at the temperature of 600-800°C to produce molybdenum oxide, as well as cleaning of molybdenum oxide by zone sublimation at the temperature of 750-800°C in continuous flow of oxygen. After cleaning, heterogeneous recovery of molybdenum oxide is carried out by hydrogen at the temperature of 700-750°C to produce molybdenum powder, as well as its pressing to produce bar. Then electronic vacuum zone recrystallisation of pressed bars is carried out to produce crystals of highly pure molybdenum, as well as electronic vacuum melting in flat crystalliser with melting of flat bars of highly pure molybdenum from each side to the whole depth at least twice. Device is also suggested for cleaning of molybdenum oxide by zonal sublimation.

EFFECT: sharp increase in purity of molybdenum intended for thin-film metallisation by magnetron spattering of targets, since purity of molybdenum to a large degree defines electrophysical parametres of applied thin layers.

2 cl, 2 dwg, 1 tbl, 1 ex

 

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

There is a method of ion-exchange purification of obtaining high-purity molybdenum, in accordance with which you can clear solutions paramolybdate ammonium from two - and trivalent impurities, as well as to solve a complex problem purification of compounds of molybdenum from tungsten.

The disadvantage of this method is that used for this purpose are known physico-chemical methods are either very time consuming or ineffective, whereby the content, for example, tungsten raw materials qualification CHP is usually located at the level of 4.10-2%. In the study of electoral properties of ion-exchange materials of different nature with respect to the impurities that adversely affect the physical properties of molybdenum, when sorption from solution paramolybdate ammonium established that the highest selectivity to ions of divalent or trivalent metals are aminocarboxylate the ampholytes. The study of sorption of tungsten from solutions of paramolybdate ammonium was found to be increased selectivity to tungsten. Also, do not doubt the fact that high-purity molybdenum cannot receive the th using only one, albeit powerful, method of cleaning, and the most reasonable application of complex chemical and metallurgical methods.

Technical problem - increasing purity molybdenum for sputtering targets used for thin-film metallization, as the purity molybdenum largely determines the electrophysical parameters of the applied thin layers.

This is achieved by the proposed method of obtaining high-purity molybdenum for sputtering targets, which includes cleaning paramolybdate ammonium in the form of a solution of impurity ion exchange in neutral and alkaline environments hydrated tin oxide and the weakly basic anion exchange resin an-106, thermal decomposition of paramolybdate ammonia at a temperature of 600-800°C to obtain a molybdenum oxide, purification of molybdenum oxide zone sublimation at a temperature of 750-800°C in a constant stream of oxygen, with the highest volatile oxides of molybdenum is collected in the far part of the reactor, and non-volatile oxides impurities collect in the initial part of the reactor, heterogeneous recovery of molybdenum oxide with hydrogen at the temperature of 700-750°C prior to the formation of molybdenum powder, pressing the powder of molybdenum to receive a rod, electronic vacuum zone recrystallization extruded rods to obtain crystals of high purity is of olindina and electronic vacuum melting in a flat mold with a penetration of flat ingots of high-purity molybdenum on each side on the depth of not less than two times.

This is achieved by a device for the purification of molybdenum oxide zone sublimation to extract high-purity molybdenum for sputtering targets, including the reactor, the floating heater, oxygen system and movable along backfill of molybdenum oxide zone width of 50 mm at a speed of 20 mm/h and the length of the backfill 500 mm

Figure 1 shows the laboratory device for zone sublimation of molybdenum oxide in the beginning of the process: 1-quartz reactor, 2-zone heater, 3-oxide of molybdenum. Figure 2 presents a laboratory device for zone sublimation of molybdenum oxide at the end of the process: 1-quartz reactor, 2-zone heater, 3-oxide of molybdenum.

Method of production of high-purity molybdenum for sputtering targets is as follows. The solution paramolybdate ammonium clear from the various impurities in neutral and alkaline environments hydrated tin oxide and tungsten on the weakly basic anion exchange resin an-106, produce thermal decomposition of paramolybdate ammonia at a temperature of 600-800°C to obtain a molybdenum oxide, molybdenum oxide 3 (Figure 1) is subjected to zone sublimation in the reactor 1 at a temperature of 750-800°C, the speed of movement of the heater 2 to 20 mm/h and ten passages zone, resulting in the material being processed, exposed zone cleaning,moving from the nearest part of the reactor 1 in the direction of travel of the band heater 2 in a distant part of the reactor 1, and in the process zone sublimation occurs purification from volatile oxides of impurities, molybdenum oxide is subjected to heterogeneous reduction with hydrogen at a temperature of 700-750°C to obtain a fine powder of metallic molybdenum, molybdenum powder pressed into rods and subjected to electronic vacuum zone recrystallization to obtain crystals of molybdenum, crystals of molybdenum smelting in a cooled flat mold in vacuum with an axial electron beam, and a flat bar with each hand proplast on the depth of not less than two times.

An example implementation of the method.

As the source materials used paramolybdate ammonium, which was subjected to purification from tungsten in neutral and alkaline environments hydrated tin oxide (IV) and the weakly basic anion exchange resin an-106, selectively absorbing tungsten. The resulting paramolybdate ammonium subjected to thermal decomposition at a temperature of 600-800°C and received molybdenum oxide, which was subjected to zone sublimation at the facility with a quartz reactor and the band moved horizontally by the heater, resulting in a received purified molybdenum oxide. The flow rate of oxygen 50-60 ml/min, the velocity of zone 20 mm/h, the temperature of 750-800°C. the molybdenum Oxide was subjected to heterogeneous vos is the establishment of hydrogen at a temperature of 700-750°C for 3-5 hours at a loading of 0.5-1 kg The result has been fine metal powder of molybdenum, which is extruded into rods for electron-beam zone melting. Vacuum zone melting was conducted in installing LSP with pre-vacuum annealing of extruded rod in the same setup. The results of the analysis of impurity content at different stages of processing are presented in the table.

From the results of the analysis shows that the use of adsorption on hydrated tin oxide in combination with other chemical and vacuum metallurgical methods allows to obtain a high purity molybdenum. As far as we know, while in the literature there are no reports on molybdenum such high purity for the manufacture of sputtering targets for modern nano - and microelectronics: samples of crystals before manufacture of sprayed target had indicators residual electrical resistance at the level of 50,000 and above.

The content of impurities in high purity molybdenum. The impurity concentration is given in ppm (particles per million), corresponding to ~10-4m%.
ImpurityThe original solutionThe purified solution Cleared of Moo3Mo powder pureMo crystal clean
Chrome-0,50<1,000,20<0,05
Copper10,005,00<1,000,20<0,06
Aluminum20,004,00-0,50<0,03
Magnesium20,000,305,005,00<0,02
Manganese5,000,30<1,000,10<0,06
Lead8,001,00-0,30<0,20
W is let 4,008,001,00-<0,06
Nickel6,000,50<1,000,50<0,05
Cobalt10,002,00-<0,06
Silicon60,0010,00--<0,30
Vanadium---0,50<0,05
Niobium--<5,00<5,00<1,00
Tin----<2,00
Wolf is s 150,00-<10,002,001,00
R300K/R4,2K≥50000

1. Method of production of high-purity molybdenum for sputtering targets, which includes cleaning paramolybdate ammonium in the form of a solution of impurity ion exchange in neutral and alkaline environments hydrated tin oxide and the weakly basic anion exchange resin an-106, thermal decomposition of paramolybdate ammonia at a temperature of 600-800°C to obtain a molybdenum oxide, purification of molybdenum oxide zone sublimation at a temperature of 750-800°C in a constant stream of oxygen, with the highest volatile oxides of molybdenum is collected in the far part of the reactor, and non-volatile oxides impurities collect in the initial part of the reactor, heterogeneous recovery of molybdenum oxide with hydrogen at a temperature of 700-750°C to education the molybdenum powder, pressing the powder of molybdenum to receive a rod, electronic vacuum zone recrystallization extruded rods to obtain crystals of high-purity molybdenum and electronic vacuum melting in flat crystallized the re with the penetration of flat ingots of high-purity molybdenum per side on the depth of not less than two times.

2. Device for purification of molybdenum oxide zone sublimation to extract high-purity molybdenum for sputtering targets, including the reactor, the floating heater, oxygen system and movable along backfill of molybdenum oxide zone width of 50 mm at a speed of 20 mm/h with the length of the backfill 500 mm



 

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FIELD: metallurgy.

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FIELD: metallurgy.

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FIELD: metallurgy.

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2 cl, 1 tbl, 1 ex

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2 tbl, 1 ex

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1 tbl

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EFFECT: enhanced efficiency of determination of soluble molybdenum amount; optimization of process.

12 cl, 5 dwg, 2 tbl, 3 ex

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2 tbl, 4 ex

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EFFECT: avoidance of reagents due to oxidizer-fluorine cycle; avoidance of thermal and chemical contamination of surrounding medium.

3 cl, 2 dwg, 4 ex

FIELD: chemistry.

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EFFECT: reduced content of thiocyanates in recycled water with simultaneous reclamation of cyanide.

3 dwg, 1 ex

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