Abstract: A thermal activated SACVD method for depositing a phosphorus oxide layer onto a silicon oxide wafer comprising the steps of: loading an SACVD device with a silicon oxide wafer; depositing a phosphorus doped oxide (PSG) layer on the USG layer using pure oxygen and a phosphorus and silicon source; purging the SACVD device; and depositing a boron and phosphorus doped oxide (BPSG) layer on the PSG layer.