Procedure for production of high purity tungsten for sputtering target

FIELD: metallurgy.

SUBSTANCE: procedure consists in refining solution of ammonia paratangstate with sulphate of ammonia from molybdenum impurity. Further, refining is carried out with ion exchange on anionite AM-n and with thermal decomposition of ammonia paratangstate at temperature 600-800°C till production of tungsten trioxide. Tungsten trioxide is refined with zone sublimation at temperature 900-950°C in a continuous flow of oxygen. Further, trioxide of tungsten is heterogeneous reduced with hydrogen at temperature 700-750°C till production of powder of tungsten. Powder is compressed to tungsten rod which is subjected to electronic vacuum zone re-crystallisation till production of tungsten crystal. Tungsten crystals are melt in electron vacuum in a flat crystalliser with melt of flat ingot of tungsten on each side at total depth not less, than twice. A tungsten rod is treated with chlorine prior to zone re-crystallisation at rate of chlorine supply 100 ml/min and temperature 300°C during 1 hour.

EFFECT: raised purity of tungsten designed for thin film metallisation by magnetron target sputtering and improved electro-physical parametres of applied thin layers.

1 ex

 

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

A method of obtaining high-purity tungsten for sputtering targets, which includes cleaning solution parabolicamara ammonium from impurities by ammonium sulfide and ion exchange for the anion S-n. Then carry out thermal decomposition of parabolicamara ammonia at a temperature of 600-800°C to obtain the tungsten trioxide and purification of tungsten trioxide zone sublimation at a temperature of 900-950°C in a constant flow of oxygen. After sublimation spend heterogeneous hydrogen reduction of tungsten trioxide at a temperature of 700-750°C. before the formation of tungsten powder and pressing the powder of tungsten to receive the rod. Then conduct electronic vacuum zone recrystallization to obtain a crystal of high-purity tungsten and electronic vacuum melting the required number of crystals in a flat mold with a penetration of flat bar with each hand at the depth not less than twice [RF Patent №2375480]. This method adopted by us for the prototype. In principle, there is a method allows to obtain the target high-purity tungsten, which satisfy the main requirements to the purity of the obtained films. However, the presence of such targets is quite high concentrations of heavy metals (copper, iron, cobalt, Nickel, lead, vanadium, molybdenum, etc.) stimulated the search for methods to make additional fine purification of tungsten.

Technical problem - increasing purity tungsten for sputtering targets used for thin-film metallization, and, as a consequence, the improvement of the electrophysical parameters of the applied thin layers.

This is achieved by the known method of production of high-purity tungsten for sputtering targets, including cleaning solution parabolicamara ammonium sulfide ammonium due to the transfer of impurities molybdenum tocomplex [S42-], cleaning solution ion exchange of the anion S-n, thermal decomposition of parabolicamara ammonia at a temperature of 600-800°C to obtain tungsten trioxide, cleaning trioxide tungsten zone sublimation at a temperature of 900-950°C in a constant oxygen flow, heterogeneous hydrogen reduction of tungsten trioxide at a temperature of 700-750°C. before the formation of tungsten powder, pressing tungsten powder to obtain a rod of tungsten, electronic vacuum zone recrystallization of the tungsten rod to obtain a crystal of tungsten and electronic vacuum melting of crystals of tungsten in a flat mold with propla the population of flat bar with each hand on the depth of not less than two times moreover, the rod of tungsten zone before the recrystallization process chlorine in the feed rate of chlorine 100 ml/min and a temperature of 300°C for 1 hour.

Method of production of high-purity tungsten for sputtering targets is as follows. The solution parabolicamara ammonium purified by ammonium sulfide due to the transfer of impurities molybdenum tocomplex [MoS42-]. Then make a clearance from other impurities by means of ion exchange on the anion S-n and thermal decomposition of parabolicamara ammonia at a temperature of 600-800°C to obtain the tungsten trioxide. Purification of tungsten trioxide using zone sublimation is carried out at a temperature of 900-950°C in a constant flow of oxygen. Heterogeneous recovery of tungsten trioxide with hydrogen at a temperature of 700-750°C lead to the formation of the tungsten powder, which is then pressed to obtain a rod of tungsten. Then the tungsten rod is treated with chlorine at a feed rate of the chlorine 100 ml/min at a temperature of 300°C for 1 hour. Electronic vacuum zone recrystallization of the tungsten rod is carried out to obtain a crystal of tungsten. Electronic vacuum melting the required number of crystals of tungsten is produced in a flat mold with a penetration of flat bar of tungsten with each side on the depth of not less than two times. the main feature of additional purification steps tungsten, what happens chlorination of the surface of the rod of tungsten to form tungsten chloride WCl2. During the subsequent electronic vacuum zone recrystallization of the tungsten rod by passing the molten zone, in addition to crystallization treatment processes, there is an interaction between the impurities of metals and chloride of tungsten with the formation of volatile chlorides of the impurities (such as FeCl2, CoCl2, NiCl2, CuCl2, rl3, PbCl2, SnCl2, MoCl5and others)that are removed from the tungsten evaporation.

An example implementation of the method.

As the source materials used solution parabolicamara ammonium, which was purified by ammonium sulfide due to the transfer of impurities molybdenum tocomplex [MoS42-] and from other impurities by ion exchange of the anion S-n. Then paraformat ammonium subjected to thermal decomposition at a temperature of 600-800°C and received trioxide of tungsten, which was subjected zone sublimation on a special setup with a quartz reactor zone heater, resulting in a received purified tungsten trioxide. The flow rate of oxygen 50-60 ml/min, the velocity of zone 20 mm/h, the temperature of 900-950°C. Was made ten passes of the steam zone. The tungsten trioxide were subjected to heterogeneous hydrogen recovery is on a standard installation at a temperature of 700-750°C. The duration of the restoration process was 3-5 hours at a loading of 0.5-1 kg of the Obtained fine powder of tungsten extruded into a rod of tungsten, which were placed in a quartz reactor and processed in the stream drained from moisture chlorine with a feed rate of chlorine 100 ml/min at a temperature of 300°C with a holding time in the furnace for 1 hour, resulting happened saturation of the surface of the rod tungsten chlorine. Processed chlorine in the tungsten rod was subjected to vacuum zone recrystallization by the standard technology in the e-beam zone melting, resulting in the obtained crystals of tungsten, which was molded in a flat mold in vacuum e-beam melting. Flat tungsten ingot was Poplawski using axial electron gun with each hand on the depth of not less than two times. According to mass spectral analysis of the content of impurities in the tungsten was as follows (ppm): si<0,01; N<0,01; Fe<0,05; Ni<0,01;<0,05; Cr<0,01; Nb<0,05; V<0,05; Mo<0,1.

Thus, the introduction of additional purification steps in obtaining for tungsten sputtering targets, with some complication of the process, can significantly reduce the content of heavy metals.

Method of production of high-purity tungsten for sputtering targets, VK is uchumi cleaning solution parabolicamara ammonium sulfide ammonium due to the transfer of impurities molybdenum tocomplex [MoS 42-], treatment with ion exchange resin S-n, thermal decomposition of parabolicamara ammonia at a temperature of 600-800°C to obtain tungsten trioxide, cleaning trioxide tungsten zone sublimation at a temperature of 900-950°C in a constant oxygen flow, heterogeneous hydrogen reduction of tungsten trioxide at a temperature of 700-750°C. before the formation of tungsten powder, pressing tungsten powder to obtain a rod of tungsten, electronic vacuum zone recrystallization of the tungsten rod to obtain a crystal of tungsten and electronic vacuum melting of crystals of tungsten in a flat mold with a penetration of flat bar of tungsten on each side on the depth of not less than two times, characterized in that rod of tungsten zone before the recrystallization process chlorine in the feed rate of chlorine 100 ml/min and a temperature of 300°C for 1 h



 

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EFFECT: selective extraction of tungsten from concentrate due to lowered sintering temperature without crust formation.

1 tbl

FIELD: metallurgy.

SUBSTANCE: procedure consists in purification of solution of ammonia paramolybdate form impurities by ion exchange in neutral and sub-alkali mediums on hydrated oxide of tin and on sub-basic anionite AN-106. Further, ammonia paramolybdate is thermally decomposed at temperature 600-800°C to production of molybdenum oxide and is refined by zone sublimation at temperature 750-800°C in continuous flow of oxygen. Molybdenum oxide is heterogeneous reduced with hydrogen at temperature 700-750°C till production of powder of molybdenum. Powder is compressed to a rod which is subjected to electronic vacuum zone re-crystallisation till production of high purity molybdenum crystal. Molybdenum crystals are melt in electron vacuum in a flat crystalliser with melt of flat ingot of high purity molybdenum on each side at total depth not less, than twice. A molybdenum rod is treated with chlorine prior to zone re-crystallisation at rate of chlorine supply 100 ml/min and temperature 300°C during 1 hour.

EFFECT: great rise of molybdenum purity.

1 ex

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