VT 2024_Etching.pdf

VLSI Technology (EC 323) Dr. Vivek Garg Department of Electronics Engineering S. V. National Institute of Technology (SVNIT) Surat email: [email protected]; [email protected]  Course Outline...

VLSI Technology (EC 323) Dr. Vivek Garg Department of Electronics Engineering S. V. National Institute of Technology (SVNIT) Surat email: [email protected]; [email protected]  Course Outline 9/8/2024 2  Course Text and Materials Additional: Relevant Journals and Conferences Materials and Sources shared in the lectures 9/8/2024 3  Etching Techniques Etching is the process of using strong acid or etchant to remove the unprotected parts. In fabrication, it to used to remove the specific layers. Etching: a) Wet etching b) Dry etching 9/8/2024 4  Etching Techniques In wafer production, after slicing from ingot to remove any damaged and contaminated regions. In photolithography, to remove unnecessary photoresist, or material. In metallization, to remove unnecessary metal surface between the devices. 9/8/2024 5  Etching Techniques 9/8/2024 6  Etching Techniques Yellow: to be removed, Blue: layer to remain 1. Poor selectivity etch removes the layer but also attacks the underlying material 2. A highly selective etch leaves the underlying material unharmed Red: masking layer, Yellow: layer to be removed 1. A perfectly isotropic etch produces round side walls 2. A perfect anisotropic etch produces vertical sidewalls 9/8/2024 7  Etching Techniques Etch Profiles 9/8/2024 8  Etching Techniques 9/8/2024 9  Etching Techniques Under Cut and Over Etch 9/8/2024 10  Etching Techniques 9/8/2024 11  Etching Techniques Wet Etching 9/8/2024 12  Etching Techniques Dry Etching Dry etching refers to any method of etching that uses gas instead of chemical etchants. Dry etching is capable of producing critical geometries that are very small. Plasma Etching, Reactive Ion Etching Inductively Coupled Plasma Etching 9/8/2024 13  Etching Techniques Plasma and Reactive Ion Etching It uses the gas that is subjected to an intense Electrons electric field to create plasma. Ions There are two different versions of plasma Radicals etching based on the shape of chamber a) Barrel type b) Parallel Plate Reactor Reactive ion Etching 9/8/2024 14  Etching Techniques Typical Components Electrons Ions Radicals 9/8/2024 15  Etching Techniques 9/8/2024 16  Etching Techniques Barrel Type Coil is wrapped around the chamber. Wafers are placed sitting up and gas is flowed over the wafers 9/8/2024 17  Etching Techniques Parallel Plate Reactor Two parallel plates are used to provide the electric field Wafers are placed sitting up and gas is flowed from below the wafers 9/8/2024 18  Etching Techniques Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE) 9/8/2024 19  Etching Techniques 9/8/2024 20  Comparison 9/8/2024 21  Comparison 9/8/2024 22  Etching Techniques Video Demonstration 9/8/2024 23  Etching Techniques Deep Reactive Ion Etching Ion Beam Etching Reactive Ion Beam Etching Chemically Assisted Ion Beam Etching Atomic Layer Etching 9/8/2024 24