| 摘要 |
PROBLEM TO BE SOLVED: To produce a pyrolytic boron nitride (PBN) crucible having a long service life by controlling peeling and limiting peeling to a single selected PBN layer of controlled thickness for each crystal growth run. SOLUTION: A method for forming a pyrolytic boron nitride article comprises the steps of introducing vapors of ammonia and a gaseous boron halide in a suitable ratio into a heated furnace reactor to cause boron nitride to be deposited in layers on a substrate, injecting at least one gaseous contaminant into the furnace at controlled periodic intervals such that at least two selected layers of boron nitride are doped with the gaseous contaminant at a minimum concentration level of above 2 atomic % at a depth ranging from about 1,000 to 2,000 angstroms in each selected layer, controlling the interval of injection to space the selected layers between about 1 micron and 100 microns apart, and separating the article from the substrate. |
