JPS6252020B2 - - Google Patents
Info
- Publication number
- JPS6252020B2 JPS6252020B2 JP12275185A JP12275185A JPS6252020B2 JP S6252020 B2 JPS6252020 B2 JP S6252020B2 JP 12275185 A JP12275185 A JP 12275185A JP 12275185 A JP12275185 A JP 12275185A JP S6252020 B2 JPS6252020 B2 JP S6252020B2
- Authority
- JP
- Japan
- Prior art keywords
- tantalum
- melting point
- purity
- anion exchange
- point metals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 229910052751 metal Inorganic materials 0.000 claims description 21
- 239000002184 metal Substances 0.000 claims description 21
- 238000002844 melting Methods 0.000 claims description 20
- 150000002739 metals Chemical class 0.000 claims description 18
- 230000008018 melting Effects 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 14
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 claims description 14
- 229910052700 potassium Inorganic materials 0.000 claims description 13
- 229910052715 tantalum Inorganic materials 0.000 claims description 12
- 239000003957 anion exchange resin Substances 0.000 claims description 11
- 239000011591 potassium Substances 0.000 claims description 11
- 239000002994 raw material Substances 0.000 claims description 8
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 7
- 229910001385 heavy metal Inorganic materials 0.000 claims description 5
- 150000003109 potassium Chemical class 0.000 claims description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 238000000746 purification Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 6
- 230000015654 memory Effects 0.000 description 6
- 229910052750 molybdenum Inorganic materials 0.000 description 6
- 229910052721 tungsten Inorganic materials 0.000 description 6
- 239000010408 film Substances 0.000 description 5
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 239000012046 mixed solvent Substances 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 239000011347 resin Substances 0.000 description 4
- 229920005989 resin Polymers 0.000 description 4
- 229910052726 zirconium Inorganic materials 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 3
- 238000010828 elution Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 238000000638 solvent extraction Methods 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012776 electronic material Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052735 hafnium Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- -1 vacuum tubes Substances 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910017855 NH 4 F Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- LDDQLRUQCUTJBB-UHFFFAOYSA-N ammonium fluoride Chemical compound [NH4+].[F-] LDDQLRUQCUTJBB-UHFFFAOYSA-N 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 229910021563 chromium fluoride Inorganic materials 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- QHEDSQMUHIMDOL-UHFFFAOYSA-J hafnium(4+);tetrafluoride Chemical compound F[Hf](F)(F)F QHEDSQMUHIMDOL-UHFFFAOYSA-J 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- SHXXPRJOPFJRHA-UHFFFAOYSA-K iron(iii) fluoride Chemical compound F[Fe](F)F SHXXPRJOPFJRHA-UHFFFAOYSA-K 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- DBJLJFTWODWSOF-UHFFFAOYSA-L nickel(ii) fluoride Chemical compound F[Ni]F DBJLJFTWODWSOF-UHFFFAOYSA-L 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910021332 silicide Inorganic materials 0.000 description 1
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910001936 tantalum oxide Inorganic materials 0.000 description 1
- YRGLXIVYESZPLQ-UHFFFAOYSA-I tantalum pentafluoride Chemical compound F[Ta](F)(F)(F)F YRGLXIVYESZPLQ-UHFFFAOYSA-I 0.000 description 1
- FTBATIJJKIIOTP-UHFFFAOYSA-K trifluorochromium Chemical compound F[Cr](F)F FTBATIJJKIIOTP-UHFFFAOYSA-K 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- NXHILIPIEUBEPD-UHFFFAOYSA-H tungsten hexafluoride Chemical compound F[W](F)(F)(F)(F)F NXHILIPIEUBEPD-UHFFFAOYSA-H 0.000 description 1
- OMQSJNWFFJOIMO-UHFFFAOYSA-J zirconium tetrafluoride Chemical compound F[Zr](F)(F)F OMQSJNWFFJOIMO-UHFFFAOYSA-J 0.000 description 1
Description
＜産業上の利用分野＞
本発明は、高密度LSIに適用するTa薄膜Ta2O5
等の素材となるTa（タンタル）を高純度に精製
するタンタルの精製法に関し、更に詳言すると、
特に素子特性を劣化させるジルコニウム、ハフニ
ウム、タングステン、モリブデン等の高融点、金
属を除去するように工夫したものである。
＜従来の技術＞
従来よりTaは化学工業での耐酸容器、蓄電
器、真空管等の電子材料に用いられている。この
従来用いられているTaは溶媒抽出法で精製され
ており、また従来はフアイブ−ナイン以上の高純
度が要求されなかつた。
ところが、最近半導体工業、特にMOSメモリ
の製作において超高純度Taの必要性がクローズ
アツプされてきた。この理由を以下に詳述する。
MOSメモリの高密度化に伴い、メモリ内のキ
ヤパシタの占有面積を縮小しなければならない
が、このときキヤパシスタンスが減少してしまう
と回路構成が困難である。よつて従来用いられて
いるSiO2の５〜７倍の誘電率を有するTa2O5が注
目されてきた。ところが、従来入手できる有機溶
媒抽出によるTaターゲツトで作製したTa2O5は
純度が悪い（後述の実施例中の表参照）のため、
リーク電流が大きく実用にならない。第３図は、
Ta2O5のリーク電流特性図を示し、同図中Ａが従
来入手できるTa2O5の特性曲線である。
そこで、本発明者らは、上記市販のTaをEBメ
ルト精製して高純度化を図つた。この精製Taタ
ーゲツトでTa2O5膜を形成して、同様にリーク電
流を測定したところ、第３図にＢで示す特性曲線
のようにリーク電流が格段に小さくなつている
が、曲線の傾き自体はＡ曲線とそれ程差がない。
これは、このような精製Taを用いたTa2O5も、
上述の市販のTaを用いたTa2O5と同タイプの伝
導による電流が流れることを示している。このた
め前述の如きEBメルト精製によるTaをターゲツ
トとして形成したTa2O5膜は高密度化MOSメモ
リには実用上適用できない。これは後述の実施例
中の表に示すように、精製Taの中に不純物とし
て高融点金属が１〜50ppm残留していることに
起因する。
さらに、近年、ゲート電極配線材料としてTa
のシリサイドが注目されている。この場合にも、
Taの純度が低いため高純度なTaSi2膜が形成でき
ず、素子の信頼性が問題となつている。
以上述べたように、従来市販されている有機溶
媒抽出によるTa、およびこのTaをEBメルト精製
したTaは、不純物が多いためMOSメモリ製作な
どの半導体工業には用いることができない。
よつて本発明は、特に高融点金属を効率よく除
去して上記用途に用いることができる高純度Ta
を得る高純度タンタルの精製法を提供することを
目的とする。
＜問題点を解決するための手段＞
上記目的を達成する本発明の構成は、HF溶液
としたタンタル原料を強塩基性陰イオン交換樹脂
に通して先に重金属および高融点金属を溶離し、
上記強塩基性陰イオン交換樹脂に吸着されたタン
タルをフルオロタンタル酸アンモニウムとして溶
離したのちフルオロタンタル酸カリウムとして分
離し、このフルオロタンタル酸カリウムを還元し
てタンタル金属としたのちEBメルト精製するこ
とを特徴とする。すなわち、本発明は、発明の本
質であるTa以外の高融点金属をTaより完全に除
きTaをフルオロタンタル酸カリウムとして化学
分離する第１の工程と、このフルオロタンタル酸
カリウムを還元してタンタル金属とする第２の工
程と、このタンタル金属をEBメルトで精製する
第３の工程とを組合せたものである。
＜作用＞
上記構成において、第１の工程における陰イオ
ン交換樹脂での処理により、Fe、Ni、Co等の重
金属はもちろんのことMo、Ｗなどの高融点金属
が効率よく除去される。また、第３の工程におけ
るEBメルトにより第１及び第２工程中での汚染
により混入したNa、Ｋ、Fe、Ｃ等が完全に除去
される。
＜実施例＞
以下、本発明の好適な一実施例を図面を参照し
ながら説明する。
第１図は、本実施例の工程図、第２図は本実施
例の溶離曲線である。両図に示すように、まず
Ta原料（市販の素Ta）１ｇを10〜20MのHF10ml
と酸化剤であるHNO32mlとの混合溶媒に溶解
し、蒸発乾固してフツ化タンタルとした後、再び
IMのHFで溶解してTaのHF溶液とする。このTa
のHF溶液を、予め調製して1MのHFを流してコ
ンデイシヨニングしてあるHF形強塩基性陰イオ
ン交換樹脂に通す。このとき、Fe、Al、Ni等の
重金属は全く吸着されないで、1M HF30mlによ
りフツ化鉄、フツ化クロム、フツ化ニツケルなど
にして流出される。なお、本実施例では強塩基性
陰イオン交換樹脂を6meq（ほぼ６mlに相当）使
用した。このように強塩基性陰イオン交換樹脂は
Ta1ｇに対して５〜6meq使用するのが経済的で
ある。
次に、3molHCl−0.15molHF混合溶媒を流して
Zr、Hf、Ｗ、Mo、Nb等の高融点金属を溶離す
る。本実施例では、第２図に示すように、HCl−
HF混合溶媒180mlでTa以外の金属はすべてフツ
化ジルコニウム、フツ化ハフニウム、フツ化タン
グステンなどとして溶離され、これにより強塩基
性樹脂にはTaだけが吸着されている。なお、こ
れらTa以外の高融点金属の溶離に使用できる混
合溶媒は１〜5molHCl−0.1〜1molHFである。
次いで、強塩基性陰イオン交換樹脂に吸着され
ているTaは2.7molNH4Cl−1.2molNH4F溶液60ml
により、フルオロタンタル酸のアンモニウム塩の
形で溶離した。なお、このTaの溶離には２〜
3molNH4Cl−１〜2molNH4F溶液を使用すること
ができる。
このようにして得たフルオロタンタル酸アンモ
ニウムを含む溶液にKOHを加えてフルオロタン
タル酸カリウムを析出させた。このフルオロタン
タル酸カリウムの析出にはKOHを必要最低限使
用する必要がある。これはKOHを過剰に用いる
と再溶解して好ましくないからである。
このフルオロタンタル酸カリウムを水洗、浄
過、乾燥して精製Taの原料であるフルオロタン
タル酸カリウムの白色粉末を1.9ｇ得た。
以上の強塩基性陰イオン交換樹脂による分離操
作においてはTaのロスはほとんどないが、最後
に残つたTaを100％溶出させるには溶出液がさら
に60〜120ml必要になる。よつて、この後、
1MHFで処理して樹脂をくりかえし使用するのが
好ましい。
このようにして得たフルオロタンタル酸カリウ
ムとNaとを10：３の割合で鉄製の容器中に積層
充填し、NaClを充満させた後密封し、10-3mmHg
下、100〜900℃で４〜５分加熱した。放冷して
NaClを除去した後、Naをメチルアルコール、さ
らに水に溶解除去するとともにFeを王水で溶解
除去し残つたTaを十分水洗し、60℃で乾燥して
粉末Taを得た。
この粉末Taを静水圧にて十分固めた後、石英
容器内に高温高圧で更に十分固めてTa電極をつ
くる。このTa電極を負極とし、核となるTa電極
を正極としこれらの間に10-4〜10-5mmHg下、高
電圧をかけことによりEBメルト精製し、Ta電極
から核となるTa電極上に高純度Taをドリツプさ
せて、高純度Taを得た。なお、このEBメルト精
製においても核となるTa電極をくりかえし使用
することにより90％以上、100％に近い回収率を
確保することができる。なお、このEBメルト精
製により、Ｃ、Na、Ｋ、Fe等の汚染元素を除去
することができる。
このようにして得たTaの分析結果を次表に示
す。また、従来技術にかかる有機溶媒抽出による
Ta、および有機溶媒抽出した後EBメルトに精製
したTaの分析結果も併せて示す。
<Industrial Application Field> The present invention is a Ta thin film Ta 2 O 5 applied to high-density LSI.
In more detail, regarding the tantalum refining method for refining Ta (tantalum), which is a material such as
In particular, it is designed to remove high melting point metals such as zirconium, hafnium, tungsten, and molybdenum, which degrade device characteristics. <Prior art> Ta has been used in the chemical industry for acid-resistant containers, capacitors, vacuum tubes, and other electronic materials. This conventionally used Ta is purified by a solvent extraction method, and conventionally, a purity higher than five-nine was not required. However, recently the necessity of ultra-high purity Ta has been highlighted in the semiconductor industry, especially in the production of MOS memories. The reason for this will be explained in detail below. As the density of MOS memories increases, the area occupied by capacitors within the memory must be reduced, but if the capacitance decreases, circuit configuration becomes difficult. Therefore, Ta 2 O 5 , which has a dielectric constant 5 to 7 times that of SiO 2 used conventionally, has attracted attention. However, Ta 2 O 5 prepared using conventionally available Ta targets extracted with organic solvents has poor purity (see the table in Examples below).
The leakage current is so large that it is not practical. Figure 3 shows
A leakage current characteristic diagram of Ta 2 O 5 is shown, and A in the figure is a characteristic curve of Ta 2 O 5 that is conventionally available. Therefore, the present inventors attempted to purify the commercially available Ta by EB melt purification. When a Ta 2 O 5 film was formed using this purified Ta target and the leakage current was similarly measured, the leakage current was significantly smaller as shown in the characteristic curve B in Figure 3, but the slope of the curve was The curve itself is not that different from the A curve.
This means that Ta 2 O 5 using such purified Ta also
This shows that a current flows due to the same type of conduction as in Ta 2 O 5 using commercially available Ta mentioned above. For this reason, the Ta 2 O 5 film formed using Ta as a target by EB melt purification as described above cannot be practically applied to high-density MOS memories. This is because, as shown in the table in Examples below, 1 to 50 ppm of high melting point metal remains as an impurity in purified Ta. Furthermore, in recent years, Ta has been used as a gate electrode wiring material.
silicide is attracting attention. Also in this case,
Due to the low purity of Ta, it is not possible to form a high-purity TaSi 2 film, and the reliability of the device has become a problem. As mentioned above, conventional commercially available Ta obtained by extraction with an organic solvent and Ta obtained by EB melt purification of this Ta contain many impurities and cannot be used in the semiconductor industry such as MOS memory production. Therefore, the present invention provides high-purity Ta that can be used for the above-mentioned applications by efficiently removing high-melting point metals.
The purpose of the present invention is to provide a method for purifying high-purity tantalum to obtain tantalum. <Means for Solving the Problems> The structure of the present invention to achieve the above object is to pass the tantalum raw material made into an HF solution through a strong basic anion exchange resin to first elute heavy metals and high melting point metals,
The tantalum adsorbed on the above strongly basic anion exchange resin is eluted as ammonium fluorotantalate, then separated as potassium fluorotantalate, and this potassium fluorotantalate is reduced to tantalum metal, which is then subjected to EB melt purification. Features. That is, the present invention consists of the first step of completely removing high melting point metals other than Ta from Ta, which is the essence of the invention, and chemically separating Ta as potassium fluorotantalate, and reducing this potassium fluorotantalate to tantalum metal. This is a combination of the second step of refining this tantalum metal using EB melt. <Function> In the above configuration, high melting point metals such as Mo and W as well as heavy metals such as Fe, Ni, and Co are efficiently removed by the treatment with the anion exchange resin in the first step. Furthermore, the EB melt in the third step completely removes Na, K, Fe, C, etc. that were contaminated during the first and second steps. <Example> Hereinafter, a preferred example of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram of this example, and FIG. 2 is an elution curve of this example. As shown in both figures, first
1g of Ta raw material (commercially available raw Ta) and 10ml of 10-20M HF
It was dissolved in a mixed solvent of 2 ml of HNO3 , an oxidizing agent, and evaporated to dryness to obtain tantalum fluoride, and then dissolved again.
Dissolve IM in HF to make a Ta HF solution. This Ta
The HF solution is passed through an HF type strongly basic anion exchange resin that has been prepared in advance and conditioned by flowing 1M HF. At this time, heavy metals such as Fe, Al, and Ni are not adsorbed at all, but are flushed out as iron fluoride, chromium fluoride, nickel fluoride, etc. using 30 ml of 1M HF. In this example, 6 meq (equivalent to approximately 6 ml) of strongly basic anion exchange resin was used. In this way, strongly basic anion exchange resins
It is economical to use 5 to 6 meq per 1 g of Ta. Next, flow 3molHCl−0.15molHF mixed solvent.
Elutes high melting point metals such as Zr, Hf, W, Mo, and Nb. In this example, as shown in FIG.
With 180 ml of HF mixed solvent, all metals other than Ta are eluted as zirconium fluoride, hafnium fluoride, tungsten fluoride, etc., and as a result, only Ta is adsorbed on the strong basic resin. The mixed solvent that can be used to elute these high melting point metals other than Ta is 1 to 5 mol HCl-0.1 to 1 mol HF. Next, the Ta adsorbed on the strongly basic anion exchange resin was mixed with 60 ml of a 2.7 mol NH 4 Cl−1.2 mol NH 4 F solution.
eluted in the form of the ammonium salt of fluorotantalic acid. In addition, for the elution of Ta, 2~
A 3 mol NH4Cl -1 to 2 mol NH4F solution can be used. KOH was added to the thus obtained solution containing ammonium fluorotantalate to precipitate potassium fluorotantalate. For precipitation of potassium fluorotantalate, it is necessary to use the minimum necessary KOH. This is because if KOH is used in excess, it will re-dissolve, which is undesirable. This potassium fluorotantalate was washed with water, purified, and dried to obtain 1.9 g of white powder of potassium fluorotantalate, which is a raw material for purified Ta. Although there is almost no loss of Ta in the above separation operation using the strongly basic anion exchange resin, an additional 60 to 120 ml of eluate is required to elute 100% of the Ta remaining at the end. So, after this,
It is preferable to treat with 1MHF and use the resin repeatedly. Potassium fluorotantalate and Na thus obtained were layered in an iron container at a ratio of 10:3, filled with NaCl, and then sealed .
Then, the mixture was heated at 100 to 900°C for 4 to 5 minutes. Leave it to cool
After removing NaCl, Na was dissolved and removed in methyl alcohol and then water, Fe was dissolved and removed in aqua regia, and the remaining Ta was thoroughly washed with water and dried at 60°C to obtain powdered Ta. This powdered Ta is sufficiently solidified using hydrostatic pressure, and then further solidified at high temperature and pressure in a quartz container to form a Ta electrode. Using this Ta electrode as the negative electrode and the core Ta electrode as the positive electrode, a high voltage of 10 -4 to 10 -5 mmHg is applied between them to purify the EB melt, and from the Ta electrode to the core Ta electrode. High-purity Ta was obtained by dripping high-purity Ta. In addition, even in this EB melt purification, by repeatedly using the core Ta electrode, it is possible to secure a recovery rate of 90% or more, close to 100%. Note that by this EB melt purification, contaminant elements such as C, Na, K, and Fe can be removed. The analysis results of Ta obtained in this way are shown in the following table. In addition, organic solvent extraction according to conventional technology
The analysis results of Ta and Ta purified into EB melt after organic solvent extraction are also shown.
【表】
表に示すように従来技術にかかるTaは、１〜
50ppmの高融点金属を含有しているが、本発明
方法によるTaは、高融点金属も検出限界
（0.1ppm）以下で検出されなかつたがppbオーダ
まで低減していると予測される。
なお、上記実施例ではTa原料として素Taを用
いたがこの他Ta原料として酸化タンタルを用い
ても同様に処理することができる。
また、上述した実施例では、Ta原料をHF溶液
とする場合に用いた酸化剤であるHNO3を除去し
た後、強塩基性陰イオン交換樹脂を通している。
このHNO3は、Taの樹脂への吸着性を低下させる
ので、HNO3を除去しない場合には、カラム効率
が低下し、樹脂が多量に必要となる。
このように、本発明方法によれば高融点金属も
効率よく除去されるので、不純物を含まないTa
ターゲツトを作製することができ、MOSメモリ
の製造にも適用できる。
また、上述したように、本発明方法によれば、
Zr、Nb、Mo、Ｗなどの貴重な高融点金属が、
Fe、Alなどの卑金属とは別に分離できるので、
これらの高融点金属の精製が容易かつ安価にな
る。
なお、高融点金属を分離する必要がない場合に
は、初めから例えばHCl−HFを流すことによ
り、重金属、高融点金属が同時に溶離され、Ta
の精製手順はさらに簡単になる。
＜発明の効果＞
以上実施例とともに具体的に説明したように、
本発明方法によれば、Mo、Zr、Nb、Ｗなどの高
融点金属も効率よく除去できて高純度Taを得る
ことができ、この高純度Taを用いてスパツタリ
ングターゲツト等の膜形成原料を製作すれば、従
来にない高純度ターゲツト等を実現できる。この
Taターゲツトを用いて形成したTa2O5膜は、Ta
ターゲツトが高純度であり、特に問題となる
Mo、Ｗ等の高融点金属が除去されているので、
リーク電流が大幅に低減されており、LSIの高密
度化に適用できる。また、本発明方法によるTa
を用いれば、TaSi2ゲート電極の改善もでき、超
小形C.R（コンデンサ・抵抗）部品等の各種薄膜
電子材料へ与える効果も大きい。
さらに、本発明方法によれば、不純物である貴
重な高融点金属が容易にかつ安価に分離できるの
で、これらの高融点金属の用途が拡大される。例
えば高純度Nbの超伝導薄膜材料への適用が考え
られる。[Table] As shown in the table, Ta related to the conventional technology is 1 to
Although it contains 50 ppm of high melting point metals, it is predicted that Ta by the method of the present invention has been reduced to ppb order, although the high melting point metals were also below the detection limit (0.1 ppm) and were not detected. In the above embodiment, bare Ta was used as the Ta raw material, but tantalum oxide may also be used as the Ta raw material to perform the same treatment. Furthermore, in the above-mentioned example, after removing HNO 3 , which is an oxidizing agent used when converting the Ta raw material into an HF solution, the solution is passed through a strongly basic anion exchange resin.
This HNO 3 reduces the adsorption of Ta to the resin, so if HNO 3 is not removed, the column efficiency will decrease and a large amount of resin will be required. In this way, according to the method of the present invention, high-melting point metals are also efficiently removed, so that impurity-free Ta can be removed.
Targets can be created and it can also be applied to the manufacture of MOS memories. Furthermore, as mentioned above, according to the method of the present invention,
Valuable high melting point metals such as Zr, Nb, Mo, W, etc.
Because it can be separated separately from base metals such as Fe and Al,
Purification of these high melting point metals becomes easier and cheaper. If it is not necessary to separate the high melting point metal, for example, by flowing HCl-HF from the beginning, the heavy metal and the high melting point metal will be eluted at the same time, and the Ta
The purification procedure becomes even simpler. <Effects of the Invention> As specifically explained above with the examples,
According to the method of the present invention, high-melting point metals such as Mo, Zr, Nb, and W can be efficiently removed and high-purity Ta can be obtained, and this high-purity Ta can be used as a raw material for forming films such as sputtering targets. By producing this, it is possible to create targets of unprecedented purity. this
The Ta 2 O 5 film formed using Ta target is
This is especially problematic when the target is of high purity.
Since high melting point metals such as Mo and W are removed,
Leakage current is significantly reduced, making it suitable for increasing the density of LSIs. Moreover, Ta by the method of the present invention
By using this method, it is possible to improve the TaSi 2 gate electrode, and it will also have a large effect on various thin film electronic materials such as ultra-small CR (capacitor/resistor) parts. Furthermore, according to the method of the present invention, valuable high-melting point metals as impurities can be separated easily and inexpensively, so that the uses of these high-melting point metals are expanded. For example, the application of high-purity Nb to superconducting thin film materials can be considered.
第１図は、本発明の一実施例にかかる高純度タ
ンタルの精製法の工程図、第２図はその溶離曲線
を示す説明図、第３図は従来技術にかかるTa2O5
のリーク電流特性図である。
FIG. 1 is a process diagram of a method for purifying high-purity tantalum according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing its elution curve, and FIG. 3 is a diagram showing a Ta 2 O 5 according to the prior art.
FIG. 3 is a leakage current characteristic diagram of FIG.
Claims (1)
オン交換樹脂に通して先に重金属および高融点金
属を溶離し、上記強塩基性陰イオン交換樹脂に吸
着されたタンタルをフルオロタンタル酸アンモニ
ウムとして溶離したのちフルオロタンタル酸カリ
ウムとして分離し、このフルオロタンタル酸カリ
ウムを還元してタンタル金属としたのちEBメル
ト精製することを特徴とする高純度タンタルの精
製法。1 The tantalum raw material made into an HF solution was passed through a strong basic anion exchange resin to first elute heavy metals and high melting point metals, and the tantalum adsorbed on the strong basic anion exchange resin was eluted as ammonium fluorotantalate. A method for purifying high-purity tantalum, which is characterized in that it is then separated as potassium fluorotantalate, and this potassium fluorotantalate is reduced to tantalum metal, which is then purified by EB melt.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12275185A JPS61281831A (en) | 1985-06-07 | 1985-06-07 | Method for refining high-purity tantalum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12275185A JPS61281831A (en) | 1985-06-07 | 1985-06-07 | Method for refining high-purity tantalum |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61281831A JPS61281831A (en) | 1986-12-12 |
| JPS6252020B2 true JPS6252020B2 (en) | 1987-11-02 |
Family
ID=14843698
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12275185A Granted JPS61281831A (en) | 1985-06-07 | 1985-06-07 | Method for refining high-purity tantalum |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61281831A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100220881B1 (en) * | 1990-05-17 | 1999-09-15 | 마싸 앤 피네간 | Method of producing high surface area low metal impurity tantalum powder |
| WO2001096620A2 (en) | 2000-05-22 | 2001-12-20 | Cabot Corporation | High purity niobium and products containing the same, and methods of making the same |
-
1985
- 1985-06-07 JP JP12275185A patent/JPS61281831A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61281831A (en) | 1986-12-12 |
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