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US4619695A
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Process for producing high-purity metal targets for LSI electrodes
Assignee: Nihon Kogyo KK
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Filing: 1984-07-26
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Granted: 1986-10-28
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Expires: 2004-07-26
Abstract
Abstract A high-purity high-melting metal target or high-purity high-melting metal silicide target for LSI electrodes having an alkali metal content of not more than 100 ppb and a radioactive element content of not more than 10 ppb is provided by a wet purification process followed by a series of dry processings. Preferably the high-melting metal is molybdenum, tungsten, titanium, niobium or tantalum. More preferably, the high-melting metal is molybdenum.
Inventors
- 👤 Hideo Oikawa
- 👤 Takao Amazawa
- 👤 Nakahachiro Honma
- 👤 Hideo Miyazaki
- 👤 Iwao Kyono
- 👤 Nobuyuki Mori
- 👤 Yoshiharu Katoh
- 👤 Masami Kuroki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:33
CPC Classifications
C; C22; C22B; C22B34/00; C22B34/30; C22B34/34; H; H10; H10D; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01316; H10D64/01318; H10D64/0132; H10D64/60; H10D64/66; H10D64/665; H10D64/667; H10D64/668; H10P; H10P14/00; H10P14/40; H10P14/42; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12528; Y10T428/12674; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12833
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
150 words
A process for producing a high-purity metal target for the formation of LSI electrodes, in which the target has an alkali metal content of not more than 100 ppb and a radioactive element content of not more than 10 ppb, comprising the steps of dissolving a metal or metal compound, the metal selected from the group consisting of molybdenum and tungsten, into an acid or ammonia to form an aqueous metal-containing solution, filtering the aqueous solution causing the aqueous metal-containing solution to form metal-containing crystals by adjusting temperature and composition of the solution, collecting the crystals by solid-liquid separation, washing and drying the collected crystals, reducing the dried crystals by heating in the presence of high-purity hydrogen to prepare a high-purity metal powder, compacting the powder, sintering the compact, electron beam melting the sintered compact to produce a high-purity metal ingot, and thereafter plastically working the ingot with subsequent machining.
Claim 2
Dependent Claim
150 words
A process for producing a high-purity metal target for the formation of LSI electrodes, in which the target has an alkali metal content of not more than 100 ppb and a radioactive element content of not more than 10 ppb, comprising the steps of dissolving a metal or metal compound, the metal selected from the group consisting of molybdenum and tungsten, into an acid or ammonia to form an aqueous metal-containing solution, filtering the aqueous solution causing the aqueous metal-containing solution to form metal-containing crystals by adjusting temperature and composition of the solution, collecting the crystals by solid-liquid separation, washing and drying the collected crystals, reducing the dried crystals by heating in the presence of high-purity hydrogen to prepare a high-purity metal powder, compacting the powder, sintering the compact, electron beam melting the sintered compact to produce a high-purity metal ingot, and thereafter plastically working the ingot with subsequent machining.
Claim 3
Dependent Claim
11 words
The process according to claim 1 wherein the metal is molybdenum.
Claim 4
Dependent Claim
28 words
The process according to claim 1 wherein the acid is selected from the group consisting of hydrochloric, nitric, hydrofluoric, sulfuric or a combination of two or more acids.
Claim 5
Dependent Claim
23 words
The process according to claim 1 which further includes the step of redissolving said crystals followed by recrystallizing to obtain further purified crystals.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-10-27 | 1990-04-28 | 1990-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-27 | 1994-04-28 | 1994-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-27 | 1998-04-28 | 1998-10-28 | $7700.00 | Window Closed / Lapsed |