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A METHOD OF FORMING HIGH PRESSURE SILICON OXYNITRIDE (OXYNITRIDE) GATE DIELECTRICS FOR METAL OXIDE SEMICONDUCTOR (MOS) DEVICES WITH P+ POLYCRYSTALLINE SILICON (POLYSILICON) GATE ELECTRODES
A METHOD OF FORMING HIGH PRESSURE SILICON OXYNITRIDE (OXYNITRIDE) GATE DIELECTRICS FOR METAL OXIDE SEMICONDUCTOR (MOS) DEVICES WITH P+ POLYCRYSTALLINE SILICON (POLYSILICON) GATE ELECTRODES
A silicon oxynitride (oxynitride) dielectric layer is presented using a process in which nitrogen is incorporated into the dielectric as it is grown upon a silicon substrate. The oxynitride layer is grown at elevated temperature and pressure in an ambient containing N2O and/or NO. An MOS gate dielectric is advantageously formed from the oxynitride dielectric layer with a sufficient nitrogen concentration near the interface between a boron-doped polysilicon gate electrode and the gate dielectric as to prevent boron atoms from penetrating into the gate dielectric. Further, the oxynitride layer contains a sufficient nitrogen concentration near the interface between the gate dielectric and a silicon substrate as to reduce the number of high-energy electrons injected into the gate dielectric which become trapped in the gate dielectric. Nitrogen atoms in the gate dielectric near the interface between the boron-doped polysilicon gate electrode and the gate dielectric physically block boron atoms, preventing them from penetrating into the gate dielectric. Nitrogen atoms and silicon atoms form strong Si-N bonds at the interface between the gate dielectric and the silicon substrate, helping ensure injected electrons are not easily trapped in the oxynitride dielectric layer.
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