Water re-absorption into hygroscopic film in interlayer dielectrics and its impact on hot-carrier immunity

We clarified the behavior of water molecules in interlayer dielectrics that contain a hygroscopic film, BPSG, prepared by APCVD using TEOS and ozone. Some of the water molecules move through the following path: water diffuses from the BPSG to the gate oxide and is later re-absorbed into the BPSG itself. The hygroscopic BPSG can act as a desiccating agent to pump water molecules out of the gate oxide. This result demonstrates the improvement of water-related hot-carrier immunity.