Tom Dillinger
Member
To achieve an aggressive lithographic pitch in advanced process nodes, foundries have employed self-aligned double patterning (SADP), using sidewall spacers as the final masking layer. In the future, another iteration of this method will offer quad patterning, or SAQP.
The team at UC-Berkeley has been investigating an alternative approach to realizing an aggressive masking pitch, known as Tilted Ion Implantation (TII). As illustrated below, the approach uses "shadowing" of an Ar+ implant into an SiO2 layer, using a base pattern of a Hard Mask (HM) material as the implant block.
View attachment 18617
The implanted SiO2 areas will have a different (wet HF) etch rate than the unimplanted regions, allowing the final SiO2 masking material to be patterned between and undercut below the base HM material. The final SiO2 etch pattern and linewidth tolerances are a function of many parameters -- e.g., HM height and profile, implant angle, implant dose/energy, SiO2 layer thickness, etch selectivity between implanted and unimplanted regions.
A thorough description of the TII approach can be found in a recent IEEE Transactions on Electron Devices paper:
Sub-lithographic Patterning via Tilted Ion Implantation for Scaling Beyond the 7-nm Technology Node - IEEE Xplore Document .
-chipguy
The team at UC-Berkeley has been investigating an alternative approach to realizing an aggressive masking pitch, known as Tilted Ion Implantation (TII). As illustrated below, the approach uses "shadowing" of an Ar+ implant into an SiO2 layer, using a base pattern of a Hard Mask (HM) material as the implant block.
View attachment 18617
The implanted SiO2 areas will have a different (wet HF) etch rate than the unimplanted regions, allowing the final SiO2 masking material to be patterned between and undercut below the base HM material. The final SiO2 etch pattern and linewidth tolerances are a function of many parameters -- e.g., HM height and profile, implant angle, implant dose/energy, SiO2 layer thickness, etch selectivity between implanted and unimplanted regions.
A thorough description of the TII approach can be found in a recent IEEE Transactions on Electron Devices paper:
Sub-lithographic Patterning via Tilted Ion Implantation for Scaling Beyond the 7-nm Technology Node - IEEE Xplore Document .
-chipguy
Last edited: