Patent GB-1031136-A (GB)
Title: A method of producing monocrystalline silicon carbide
IPC: C30B15/16
Filed: 1964-12-04
Abstract: Monocrystalline silicon carbide is produced by heating silicon carbide and chromium to produce a melt, inserting a seed crystal of silicon carbide into a growth region of said melt so that the silicon carbide starts to grow on the crystal, further heating a selected region of the melt spaced from the crystal to between 1700 DEG  C. and 1800 DEG  C. so that the chromium-enriched melt in the growth region moves towards the selected region, and withdrawing the seed crystal from the melt as the crystal grows.  The silicon carbide and chromium may be heated in a crucible made of silicon carbide.  The means <PICT:1031136/C1/1> for further heating may be a laser or an electron beam.  The crucible may be heated to between 1550 DEG  and 1650 DEG  C. with the temperature of the growth region between 1650 DEG  and 1750 DEG  C.  As shown, silicon carbide crucible 1 containing a melt 2 comprising 87% chromium and 13% silicon carbide is heated to 1600 DEG  C. by induction furnace 5.  An annular selected region 4 of the melt 2 is further heated to 1750 DEG  C. by electron beams 13 and 14 emitted by electron sources 6 and 7. Silicon carbide seed crystal 11 is dipped into a growth region surrounded by selected region 4 and is clamped in clamp 10 mounted at the end of lead screw 9 rotating in a threaded hole of block 8.  The seed grows in the form of bar 12 and is pulled out of the melt 2 by rotating screw 9.  The temperature of the growth region is 1700 DEG C.  Part of the chromium vaporizes at the selected region.  The temperature of the crucible is controlled such that sufficient silicon carbide is transferred from the crucible into the melt to keep a constant quantity of silicon carbide in the melt.ALSO:Monocrystalline silicon carbide is produced by heating silicon carbide and chromium to produce a melt, inserting a seed crystal of silicon carbide into a growth region of said melt so that the silicon carbide starts to grow on the crystal, further heating a selected region of the melt spaced from the crystal to between 1700 DEG C. and 1800 DEG C. so that the chromium-enriched melt in the growth region moves towards the selected region, and withdrawing the seed crystal from the melt as the crystal grows.  The silicon carbide and chromium may be melted in a crucible made of silicon carbide. The crucible may be heated to between 1550 DEG C. and 1650 DEG C. with the temperature of the growth region between 1650 DEG C. and 1750 DEG C.  According to the Fig. (not shown) silicon carbide crucible 1 containing a melt 2 comprising 87% chromium and 13% silicon carbide is heated to 1600 DEG C. by induction furnace 5.  An annular selected region 4 of the melt 2 is further heated to 1750 DEG C. by electron beams 13 and 14 of lasers.  Silicon carbide seed crystal 11 is dipped into a growth region surrounded by selected region 4 and is clamped in clamp 10 mounted at the end of lead screw 9 rotating in a threaded hole of block 8.  The seed grows in the form of bar 12 and is pulled out of melt 2 by rotating screw 9.  The temperature of the growth region is 1700 DEG C.  Part of the chromium vapourises at the selected region. The temperature of the crucible is controlled such that sufficient silicon carbide is transferred from the crucible into the melt to keep a constant amount of silicon carbide in the melt.