ALD Approach toward Electrodeposition of Sb[sub 2]Te[sub 3] for Phase-Change Memory Applications

Abstract

This paper describes various studies undertaken to devise a deposition cycle for the formation of normalSb2normalTe3 , a phase-change memory material, by electrochemical atomic layer deposition (EC-ALD). The importance of deposition potentials to the formation of deposits of Sb and Te, were investigated. The resulting potentials were then used in an EC-ALD cycle to form deposits one atomic layer at a time, using a sequence of surface limited reactions. The optimal deposition potentials for the normalSb2normalTe3 EC-ALD cycle, on a Au substrate, consisted of −0.22V for Sb deposition, and −0.35V for Te. Bulk Te stripping at was performed at −0.70V . The conditions using a TiN substrates included Sb deposition at −0.20V , Te deposition, and bulk stripping at −0.35 and −0.70V , respectively. The deposits obtained were stoichiometric, with a Te∕Sb atomic ratio of 1.5 from electron probe microanalysis. Glancing angle X-ray diffraction studies showed a (015) preferred orientation for the deposit. normalSb2normalTe3 was shown to grow successfully on patterned TiN substrates with 200nm vias.

Deposition of Sb2Se3 thin films on Pt substrate via electro-chemical atomic layer epitaxy (EC-ALE)

“…The concentrations of Sb2O3 and SeO2 were chosen based on both literature data and experimental observations. The concentration used in literature for Sb2O3 solutions [20,[24][25][26][27][28][29][30] ranges from 0.01 mM to 0.05mM, and we can confirm from experiment that 0.05 mM which is the most often used concentration, is higher than the solubility limit of antimony oxide in sulfuric acid solution. The concentration used in literature for SeO2 solutions [22,[31][32][33][34][35][36][37][38][39][40][41][42][43] ranges from 0.05 mM to 2 mM, with 0.5 mM as the most often used one.…”

Single‐Source Precursor‐Based Deposition of Sb2Te3 Films by MOCVD**

“…Bulk Sb 2 Te 3 finds widespread technical applications in minipower‐generation systems and micro‐coolers, charge coupled device (CCD) technology, and infrared detectors . Since nanostructuring is expected to further enhance the figure of merit due to reduction of the thermal conductivity, Sb 2 Te 3 films and nanostructures with well‐defined morphologies have been fabricated both via solution phase and gas phase processes such as solvothermal processes, microwave heating, vapor transport growth, vapor‐liquid‐solid growth, electrochemical atomic layer epitaxy, electrochemical deposition, DC and RF sputtering, and molecular beam epitaxy (MBE) processes . In addition, MOCVD using trialkylstibanes SbR 3 (R = Me, Et) and dialkyltellanes TeR′ 2 (R = Et, i Pr) have been successfully employed …”

Experimental and theoretical investigations on effects of hydrostatic pressure on the electrical properties of rhombohedral Sb2Te3

“…Sb 2 Te 3 exhibits the growth-dominated crystallization process and the set operation speed is faster than that of Ge 2 Sb 2 Te 5 in which the crystallization process is nucleation dominated. [7][8][9] Several studies [10][11][12][13] have been performed to date the phase transformation achieved within nanosecond between the amorphous phase and crystalline phase.…”