Advanced thermal management via an insulation plate design for uniform and void-free Ge2Sb3Te5 deposition

Ge2Sb3Te5 (GST) has attracted significant attention as a promising material for next-generation phase-change memory owing to its fast switching and excellent nonvolatile characteristics. However, GST thin films are highly sensitive to processing temperature fluctuations owing to the high vapor pressures of Sb and Te. In a GST deposition system, openings in the chamber are required for wafer transfer, rendering the use of auxiliary heat sources difficult and inevitably causing heat loss. In this study, we report the effect of a non-annular U-shaped thermal insulation plate installed beneath the electrostatic chuck (ESC) heater to suppress heat loss through a slit door and improve heat uniformity. Heat retention increased markedly when the insulation plate was positioned within 1 cm beneath the heater, reducing the temperature deviation on the GST thin film to ∼2 °C. Numerical simulation demonstrated effective thermal insulation by blocking radiative heat loss to the chamber. Consequently, the thermal insulator plate significantly improves the compositional uniformity of the GST films. The compositional variations in Sb and Te decreased from 1.9 to 2.7 at. % to 0.5 and 0.5 at. %, respectively. Furthermore, the uniformity of the GST film thickness improved from 91.2% to 99.3%. In addition, void-free cells were fabricated using a thermal insulator plate to reduce thermal loss. Consequently, higher productivity and more reliable phase-change memory devices can be achieved by employing this novel design for GST deposition.