Silicon dioxide-polysilicon multi-layered stack etching with plasma etch chamber employing non-corrosive etchants
First Claim
1. An etch system, comprising:
- a process chamber;
a chuck disposed in the process chamber to support a substrate while being etched;
a plurality of RF generators to energize the process gases into a plasma with a plurality of RF frequencies;
a pulse controller coupled to the plurality of RF generators, the pulse controller to pulse each of the plurality of RF generators over time between an RF on state and an RF off state synchronously to haw all generators in the RF off state concurrently for at least some period of time;
a first gas source plumbed to the process chamber, the first gas source comprising SF6;
a second gas source plumbed to the process chamber, the second gas source comprising NF3, wherein the first gas source and the second gas source have a common mass flow controller;
a third gas source plumbed to the process chamber, the third gas source comprising CH4;
a fourth gas source plumbed to the process chamber, the fourth gas source comprising 02;
a fifth gas source plumbed to the process chamber, the fifth gas source comprising N2, wherein each of the third gas source, the fourth gas source, and the fifth gas source has its own respective mass flow controller;
and a controller coupled to the process chamber, the controller configured to execute a method comprising;
loading the substrate into the process chamber, the substrate having a mask layer disposed over a stack of silicon and dielectric layers;
introducing process gases into the process 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.
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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.
26 Citations
6 Claims
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1. An etch system, comprising:
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a process chamber; a chuck disposed in the process chamber to support a substrate while being etched; a plurality of RF generators to energize the process gases into a plasma with a plurality of RF frequencies; a pulse controller coupled to the plurality of RF generators, the pulse controller to pulse each of the plurality of RF generators over time between an RF on state and an RF off state synchronously to haw all generators in the RF off state concurrently for at least some period of time; a first gas source plumbed to the process chamber, the first gas source comprising SF6; a second gas source plumbed to the process chamber, the second gas source comprising NF3, wherein the first gas source and the second gas source have a common mass flow controller; a third gas source plumbed to the process chamber, the third gas source comprising CH4; a fourth gas source plumbed to the process chamber, the fourth gas source comprising 02; a fifth gas source plumbed to the process chamber, the fifth gas source comprising N2, wherein each of the third gas source, the fourth gas source, and the fifth gas source has its own respective mass flow controller; and a controller coupled to the process chamber, the controller configured to execute a method comprising; loading the substrate into the process chamber, the substrate having a mask layer disposed over a stack of silicon and dielectric layers; introducing process gases into the process 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)
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Specification