Hydrogen Selenide (H2Se) Dopant Gas for Selenium Implantation

With the continued scaling of semiconductor devices, controlling contact resistance becomes more and more challenging. Selenium (Se) ion implantation is noted in the literatures to effectively reduce contact resistance in NMOS transistors by lowering the electron Schottky barrier height (SBH). A suitable selenium source feed material is required and can be in solid form, such as selenium oxide (e.g. SeO2), or in gas form, such as hydrogen selenide (H2Se). Solid source materials in general suffer from relatively longer setup times and concern of re-deposition of the dopant, whereas hydrogen selenide gas stored at high pressure poses safety and handling issues. In this paper, we present performance and usage data associated with a subatmospheric source of H2Se, including beam setup, Se+ beam current, beam stability, and source conditions. Material properties, as well as the subatmospheric delivery source are also described.