Specific Process Knowledge/Thin film deposition/Deposition of Silicon Nitride: Difference between revisions

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+=Silicon Nitride (Si₃N₄)=
+Silicon nitride (Si₃N₄) is a wide‑bandgap (~5 eV) ceramic prized for its high mechanical strength, low intrinsic stress, chemical inertness, and excellent dielectric properties, making it a workhorse insulator in microelectronics and MEMS.
+It is deposited by reactive magnetron sputtering for dense, low‑defect films, and by low‑pressure CVD (LPCVD) or plasma‑enhanced CVD (PECVD) to obtain highly uniform, conformal layers over large wafers or temperature‑sensitive substrates.
+Within semiconductor process flows, Si₃N₄ serves as a hard mask, etch stop, stress liner, diffusion barrier, gate or capacitor dielectric, shallow‑trench‑isolation liner, and robust passivation layer for logic, memory, and power devices.
+Optically, its moderate refractive index (~2.0) and low propagation loss enable high-Q integrated-photonics waveguides, resonators, frequency-comb sources, filters, and durable anti-reflection coatings spanning the visible to the mid-IR.
+Beyond electronics and photonics, Si₃N₄’s high fracture toughness, fatigue resistance, and chemical stability support MEMS pressure sensors, accelerometers, and resonators, as well as protective barriers in solar cells, Li‑ion batteries, and high‑temperature or corrosive‑environment components, underscoring its versatility across semiconductor, optical, and engineering applications.
 == Deposition of silicon nitride ==
-Deposition of silicon nitride can be done by either LPCVD (Low Pressure Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition). Stoichiometric nitride or silicon rich (low stress) LPCVD nitride is deposited on a batch of wafers in a LPCVD nitride furnace. PECVD nitride (or oxynitride) is deposited on a few samples at a time in a PECVD system. LPCVD nitride has a good step coverage and a very good uniformity. Using PECVD it is possible to deposit a much lower temperature and a thicker layer of nitride on different types of samples, but the nitride does not cover sidewalls very well.
+Deposition of silicon nitride can be done by either LPCVD (Low Pressure Chemical Vapor Deposition) or PECVD (Plasma Enhanced Chemical Vapor Deposition). Stoichiometric nitride or silicon-rich (low stress) LPCVD nitride is deposited on a batch of wafers in an LPCVD nitride furnace. PECVD nitride (or oxynitride) is deposited on a few samples at a time in a PECVD system. LPCVD nitride has a good step coverage and a very good uniformity. Using PECVD, it is possible to deposit a much lower temperature and a thicker layer of nitride on different types of samples, but the nitride does not cover the sidewalls very well.
 It is also possible to deposit silicon nitride and oxynitride by reactive sputtering.