Invited Paper TF+EM+NS+PS+SM-ThM1
Atomic Layer Deposition of Silicon Dielectrics: Precursors, Processes, and Plasmas

Thursday, October 22, 2015, 8:00 am, Room 114

As the dimensions of modern semiconductor devices continue to shrink below the current 14 nm technology node, novel processes for the deposition of highly conformal, low temperature, silicon based dielectrics will be needed for applications that include sidewall spacers, barriers, and patterning layers. Atomic layer deposition (ALD) is an ideal method for achieving the high conformality and has been used in high volume manufacturing (HVM) to deposit high-k dielectric materials (HfO₂, ZrO₂, etc.) for several technology generations. Plasma assisted ALD is the best known method to meet low temperature (<500⁰C) requirements and is now being used for depositing conformal silicon dielectrics such as silicon oxide (SiO₂) and silicon nitride (Si₃N₄).

In this presentation, we discuss the current state of the art of precursors, plasmas, and process conditions required to deposit conformal silicon dielectrics by plasma ALD. Theoretical and experimental data will be presented in order to explain the observed reaction characteristics for the plasma ALD of silicon oxide (SiO₂), silicon nitride (Si₃N₄), and the lack (so far) of silicon carbide (SiC). Generic to all ALD processes is the high cost of the precursors relative to traditional chemical vapor deposition (CVD); in the case of silicon dielectric ALD, this is exacerbated by the relative low “reactivity to cost ratio” of available silicon precursors. Although plasmas enable low temperature deposition, they pose challenges for achieving isotropic film properties over the complex topography on today’s semiconductor devices.