METHOD OF PREPARING MONOISOTOPIC SILICON Si Russian patent published in 2000 - IPC

FIELD: microelectronics. SUBSTANCE: described is method of preparing highly pure monoisotopic silicon Si²⁸. Highly pure Si²⁸H₄ is prepared by reducing tetrafluoride Si²⁸F₄ with calcium hydride at 180-200 C. Silicon is isolated by thermal decomposition of silane and at silicon growth rate of not higher than 0.5 mm/h. Isolation is carried out in two stages, first on metallic substrate and monoisotropic silicon resulting from first stage is then used as substrate. Ingot is cleaned by using method of zone smelting without crucibles. Substrate material at first silane decomposition stage includes preferably metals with melting temperature of not lower than 1500 C. The claimed method is useful for preparing other stable isotopes of silicon Si²⁹ and Si³⁰. EFFECT: high yield of silicon without isotopic dilution. 2 cl, 1 ex, 1 tbl