Nitride encapsulated thin film transistor fabrication technique

摘要

A thin film transistor includes a thin film transistor body above a gate electrode. The thin film transistor body is hydrogenated to prevent the transistor body from apparently capturing and releasing electrons. The transistor body itself is coated with an upper and lower layer of silicon nitride to prevent the trapped hydrogen from migrating out of the transistor body over time. This is formed by depositing a layer of silicon dioxide, then a layer of silicon nitride over the gate electrode, followed by deposition of a polysilicon layer which is then etched to form the transistor body. This is hydrogenated after threshold adjustment implant and source/drain implant and subsequently coated with an upper sealing layer of silicon nitride. This enables the establishment of relatively high Ion/Ioff ratio and improves the reliability of the transistor.