Silicon dioxide-polysilicon multi-layered stack etching with plasma etch chamber employing non-corrosive etchants
First Claim
1. A method of etching a stack of silicon and dielectric layers disposed over a substrate, the method comprising:
- loading the substrate into a plasma etch chamber, the substrate having a mask layer disposed over the stack of silicon and dielectric layers;
introducing process gases into the chamber, wherein the process gases comprise one part SF6, 2-30 parts CH4, 0.4-4 parts O2, 1-30 parts N2 and 1-20 parts NF3 at a chamber pressure between 20 and 50 mT;
energizing the process gases into a plasma with RF energy of at least one frequency, wherein the RF energy is pulsed over time between an RF on state and an RF off state; and
etching, with the plasma, portions of the stack not covered by the mask layer, the etching having a selectivity to the mask layer of at least 1;
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Accused Products
Abstract
Multilayered stacks having layers of silicon interleaved with layers of a dielectric, such as silicon dioxide, are plasma etched with non-corrosive process gas chemistries. Etching plasmas of fluorine source gases, such as SF6 and/or NF3 typically only suitable for dielectric layers, are energized by pulsed RF to achieve high aspect ratio etching of silicon/silicon dioxide bi-layers stacks without the addition of corrosive gases, such as HBr or Cl2. In embodiments, a mask open etch and the multi-layered stack etch are performed in a same plasma processing chamber enabling a single chamber, single recipe solution for patterning such multi-layered stacks. In embodiments, 3D NAND memory cells are fabricated with memory plug and/or word line separation etches employing a fluorine-based, pulsed-RF plasma etch.
18 Citations
12 Claims
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1. A method of etching a stack of silicon and dielectric layers disposed over a substrate, the method comprising:
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loading the substrate into a plasma etch chamber, the substrate having a mask layer disposed over the stack of silicon and dielectric layers; introducing process gases into the chamber, wherein the process gases comprise one part SF6, 2-30 parts CH4, 0.4-4 parts O2, 1-30 parts N2 and 1-20 parts NF3 at a chamber pressure between 20 and 50 mT; energizing the process gases into a plasma with RF energy of at least one frequency, wherein the RF energy is pulsed over time between an RF on state and an RF off state; and etching, with the plasma, portions of the stack not covered by the mask layer, the etching having a selectivity to the mask layer of at least 1;
1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of forming a three dimensional (3D) NAND memory device, the method comprising:
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loading a substrate into a plasma etch chamber, the substrate having a mask layer disposed over a stack of silicon word line gate electrode layers electrically isolated from each other by an intervening silicon-based dielectric layer; introducing process gases into the chamber, wherein the process gases comprise one part SF6, 2-30 parts CH4, 0.4-4 parts O2, 1-30 parts N2 and 1-20 parts NF3, at a chamber pressure between 20 and 50 mT; energizing the process gases into a plasma with RF energy of at least one frequency, wherein the RF energy is pulsed over time between an RF on state and an RF off state; and etching, with the plasma, vias or trenches through the thickness of the stack in regions not covered by the mask layer, the etching having a selectivity to the mask layer greater than 1;
1. - View Dependent Claims (10, 11, 12)
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Specification