Advanced plasma etching of novel materials

The chalcogenide materials, incorporating chalcogens such as S, Se, or Te, are blended with diverse elements like Zn, Si, Ge, Sb, and As to create alloys spanning from binary to quaternary compositions. These chalcogenide-based alloys are used in Phase-Change Memories (PCMs) and Ovonic Threshold Switching (OTS) based devices. Enhancing these chalcogenide alloys through the addition of more elements or doping contributes to improved structural, and thermal stability and their electrical properties.

A significant challenge in integrating these metal alloys into practical schemes is the precise nano-scale patterning without compromising their intrinsic properties. Typically, dry etch techniques are preferred for achieving high scalability. The crucial aspect lies in studying the interaction between plasma and metal-based film systems. The chemical reaction during the etch process is intricate and may lead to undesired collateral effects. Potential outcomes include doping in the material with the etchant or chemical modification of the material surface post-etching. Additionally, the choice of specific chemical etch techniques and plasma parameters (voltage, power, and pressure) may impact the film's electrical properties by changing roughness. Therefore, it is paramount to thoroughly understand and control the interactions between the plasma and novel metal systems to ensure that their intrinsic properties remain unaltered for their respective technological applications.

The goal of this study is to expose the chalcogenide material to different plasma chemistries and try to understand the impact of these chemistries on the surface morphology, stoichiometry, or crystallography of the deposited chalcogenide. These are crucial aspects to understand as any change in the chalcogenide during its patterning into memory devices can impact its electrical performance.

The following steps will be carried out and repeated to understand what an optimized etching condition for chalcogenides is.

1. Literature review on plasma etching of chalcogenides, and characterization techniques.
2. Expose samples to different plasma chemistry (etchant) and conditions.
3. Doing physical and chemical characterization to see physical and chemical changes on the surface.
4. Analysis of the results and learnings
5. Find a suitable etch chemistry and condition that doesn't impact the material physically and chemically.

Type of work: 20% of literature related to materials, plasma etch, and metrology, 20% to reporting, presenting, and writing publications, and 60% to experimental work and data analysis.