Search

In this paper, patterning challenges that led to the fabrication of a first Spin Torque Majority Gate (STMG) device are explored. We have highlighted key process module developments from the Magnetic Tunnel Junctions (MTJs) pillar patterning to dual damascene scheme wiring module. Spin devices such as STMG have already been proposed as a replacement for conventional CMOS transistors. The main challenge to their experimental demonstration remains the successful fabrication of connected MTJs through a ferromagnetic layer, allowing spin transport across the gate. We propose a new etching approach utilizing Ion Beam Etching (IBE), to be able to pattern the MTJs with high precision and with less damage to the magnetic layers. Furthermore, we have introduced Electron-beam lithography to further scale down the device geometries. This development paves the way towards a fully integrated STMG device for Spin Logic applications.

Extreme ultraviolet (EUV) materials are deemed as critical to enable and extend the EUV lithography technology. Currently both chemically amplified resist (CAR) and metal-oxide resist (MOR) platforms are candidates to print tight features on wafer, however patterning requirements, process tonality (positive or negative), illumination settings and reticle tonality (dark or bright) play a fundamental role on the material performance and in consequence on the material choice. In this work we focus on the patterning of staggered pillars using a single EUV exposure, and this by looking at the lithographic and etching performance of CAR and MOR platforms, using metrics as process window, local critical dimension uniformity (LCDU), pillar edge roughness (PER), pillar placement error (PPE) and (stochastic) nano-failures. As a bright field reticle shows a lower aerial image contrast to print pillars compared to the aerial image of contact holes using a dark field reticle, we also investigate alternative patterning solutions such as the tone reversal process (TRP) to pattern pillars from contact holes.