Review on recent progress in patterning phase change materials

Abstract

This review discusses critical aspects of patterning phase change materials (PCMs), including dry etching, wet clean, and encapsulation, as they dictate the reliability and functionality of the phase change random access memory devices. Specifically, alloys of germanium–antimony–tellurium are used as a model system, and the importance of PCM composition control, critical dimension control, high fidelity pattern transfer, and a system level of ambient control to avoid oxidation that can alter the materials’ functionality are highlighted. The research findings motivate the development of a state-of-the-art integrated system that combines dry etch, wet clean, and encapsulation into one platform to realize consistent and successful patterning of PCMs for future generations of the memory devices.

Composition control of conformal crystalline GeSbTe films by atomic layer deposition supercycles and tellurization annealing

“…There is also a need for an improved dry etching process that reduces the patterning damage of memory cells in which phase change material, selector material, and electrodes are stacked. 6 Like three-dimensional (3D) vertical NAND flash memory devices, 3D vertical PCRAM devices can expand storage capacity significantly by increasing the number of memory layers without adopting advanced lithography equipment. The advantage becomes evident as the number of layers increases.…”

“…There is also a need for an improved dry etching process that reduces the patterning damage of memory cells in which phase change material, selector material, and electrodes are stacked. 6…”

Identifying new absorber materials for EUV photomasks

“…Notably, the reactions happening in a plasma environment are complex and often involve multistep intermediate reactions with transient species. Instead, this paper explores very simple reactions (example reactions d, e, f in Table 1), where the metal is in its atomic solid standard state (M), gases are in their atomic states (F, Cl, H, O, C), bromine is in its atomic liquid state (Br), and methyl is in its molecular gas state (CH3) [16,[24][25][26][27]. From these general reactions, ΔGrxn can be calculated using the standard molar enthalpies of formation ΔfH°and the standard molar entropies S°.…”

“…of SPIE Vol. 12751, Thermodynamic analysis serves as the fundamental basis for predicting if a reaction can potentially occur [16]. Under thermodynamic equilibrium, the Gibbs free energy can be calculated for a given surface reaction [16].…”

“…12751, Thermodynamic analysis serves as the fundamental basis for predicting if a reaction can potentially occur [16]. Under thermodynamic equilibrium, the Gibbs free energy can be calculated for a given surface reaction [16]. Furthermore, the reaction product's boiling point can also be calculated based on reaction conditions, such as pressure.…”