Patent US3423206A successfully refreshed from Google Patents.
Patent US3004835A successfully refreshed from Google Patents.
US3004835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing silicon rods
Assignee: Mallinckrodt Chemical Works
•
Filing: 1958-11-20
•
Granted: 1961-10-17
•
Expires: 1978-11-20
Abstract
No abstract record available.
Inventors
- 👤 Verner Harry Grey
- 👤 Jr John R Kuebler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:40
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/02; C01B33/021; C01B33/027; C01B33/035; C23; C23F; C23F1/00
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
80 words
THE METHOD OF PRODUCING SILICON IN THE FORM OF ZONE-REFINABLE RODS WHICH COMPRISES DEPOSITING SILICON ON A TANTALUM FILAMENT, LEACHING THE DEPOSIT TOGETHER WITH THE EMBEDDED FILAMENT IN HOT AQUEOUS HYDROFLUORIC ACID TO DISSOLVE A SUBSTANTIAL PORTION OF THE TANTALUM FILAMENT AND ENABLE ITS REMOVAL, ETCHING THE RESULTING ROD OF SILICON, FROM WHICH THE TANTALUM HAS BEEN REMOVED, IN NITRIC ACID CONTAINING A MINOR PROPORTION OF HYDROFLUORIC ACID, AND THEN RINSING AND DRYING THE RESULTING ZONE-REFINABLE ROD OF PURE SILICON.
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) | 1964-10-16 | 1965-04-17 | 1965-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1968-10-16 | 1969-04-17 | 1969-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1972-10-16 | 1973-04-17 | 1973-10-17 | $7700.00 | Window Closed / Lapsed |