Subcritical water was used to selectively remove Si3N4 layers in the 3D NAND fabrication. Various fluorine compounds were added to subcritical water. When sulfonyl fluoride-based additives were added to subcritical water, the dissolution of Si3N4 was accelerated by F-, and the Si3N4-to-SiO2 removal selectivity increased owing to the high [F-]/[HF2-] ratio and low OH- concentration. Furthermore, the addition of H2SiO3 to the subcritical water resulted in selective and uniform Si3N4 removal without the loss of SiO2 layers in the 128-layer Si3N4/SiO2 stack structure. However, the addition of ammonium fluoride compounds to subcritical water could not achieve selective removal of Si3N4. The addition of HCl to the ammonium fluoride-containing subcritical water suppressed the dissolution of Si and SiO2. Further addition of H2SiO3 and optimization of the additive concentrations led to selective and uniform Si3N4 removal in the 128-layer Si3N4/SiO2 stack structure without the loss of the Si substrate and SiO2 layers.
|Journal||Journal of Supercritical Fluids|
|Publication status||Published - 2022 Oct|
Bibliographical noteFunding Information:
This research was supported by MOTIE (Ministry of Trade, Industry & Energy ( 20020276 )) and KSRC (Korea Semiconductor Research Consortium) support programs for the development of future semiconductor devices.
© 2022 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Condensed Matter Physics
- Physical and Theoretical Chemistry