Al-neal Degrades Al2O3 Passivation of Silicon Surface

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Abstract

Atomic layer deposited (ALD) aluminum oxide (Al2O3) has emerged as a useful material for silicon devices due to its capability for effective surface passivation and ability to generate p+ region underneath the oxide as active or passive component in semiconductor devices. However, it is uncertain how Al2O3 films tolerate the so-called Al-neal treatment that is a necessary process step in devices that also contain silicon dioxide (SiO2) passivation layers. Herein, it is reported that the Al-neal process is harmful for the passivation performance of Al2O3 causing over eightfold increase in surface recombination velocity (SRV) (from 0.9 to 7.3 cm s−1). Interestingly, it is also observed that the stage at which the so-called activation of Al2O3 passivation is performed impacts the final degradation strength. The best result is obtained when the activation step is done at the end of the process together with the Al-neal thermal treatment, which results in SRV of 1.7 cm s−1. The results correlate well with the measured interface defect density, indicating that the Al-neal affects defects at the Si/SiOx/Al2O3 interface. The root causes for the defect reactions are discussed and possible reasons for the observed phenomena are suggested.

Original languageEnglish
Article number2100214
Number of pages5
JournalPhysica Status Solidi (A) Applications and Materials Science
DOIs
Publication statusE-pub ahead of print - 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • Al-neal
  • aluminum oxide
  • silicon devices
  • surface passivation

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