A method and apparatus for controlling dopant concentration during
borophosphosilicate glass film deposition on a semiconductor wafer to
reduce consumption of nitride on the semiconductor wafer. In one
embodiment of the invention, the method starts by placing a substrate
having a nitride layer in a reaction chamber and providing a silicon
source, an oxygen source and a boron source into the reaction chamber
while delaying providing a phosphorous source into the reaction chamber
to form a borosilicate glass layer over the nitride layer. The method
continues by providing the silicon, oxygen, boron and phosphorous sources
into the reaction chamber to form a borophosphosilicate film over the
borosilicate glass layer.