Beyond 10 μm Depth Ultra-High Speed Etch Process with 84% Lower Carbon Footprint for Memory Channel Hole of 3D NAND Flash over 400 Layers

A novel High-Aspect-Ratio (HAR) dielectric etch technology which is capable of etching beyond $10 \mu \mathrm{m}$ depth memory channel hole for future generations of 3D NAND flash memory has been successfully developed for the first time. Ten micron depth etching is not practical with conventional etching technology, but our novel technology using cryogenic wafer stage and new gas chemistry can achieve not only $10 \mu \mathrm{m}$ etch capability but also quite short process time (33 minutes) with 84% carbon footprint reduction of greenhouse gases. Etched profile was also confirmed to be excellent. Thus, this is a key technology for highly productive, cost effective and sustainable manufacturing of 3D NAND flash memory device.