Post-annealing processes to improve inhomogeneity of Schottky barrier height in Ti/Al 4H-SiC Schottky barrier diode

Sinsu Kyoung, Eun Sik Jung, Man Young Sung

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

To improve the high resistance and low breakdown voltage (BV) of a 4H-SiC Schottky barrier diode (SBD), the metal annealing process is conventionally used; this process stabilizes the Schottky barrier height (SBH). In this paper, we apply a post-metal annealing process to 4H-SiC Ti-SBD chips and verify the effect of the changes on electrical characteristics based on the post-annealing process. The results of experiments show that the condition of 873 K/30 min annealing created a stable SBH and a low value of on-resistance (Ron), which improved inhomogeneity. Based on the results of EDX and TEM analysis, the cause of improved SBH at the condition of 30 min was attributed to the generation of TiSix (which has a higher SBH than Ti). On the other hand, the improved value of Ron at the condition of 30 min was attributed to the change to γ-phase Ti3Al (which has a low resistance because diffused Al is present) caused by proper annealing. However, when more heat is applied in the cases of 773 K/60 min and 873 K/60 min, Ron increased and the SBH decreased. The results of EDX and TEM analysis showed that the low SBH was caused by Al spiking, which created an Al Schottky junction with a lower SBH than that of the Ti Schottky junction. Higher Ron resulted from the change to α-TiAl phase at the Al-Ti interface layer because of excessive diffusion of Ti and Al, which is due to the overly applied heat. From the results produced by this work, we can enhance the Al-Ti 4H-SiC SBD electrical characteristics by applying a suitable post-annealing process.

Original languageEnglish
Pages (from-to)69-73
Number of pages5
JournalMicroelectronic Engineering
Volume154
DOIs
Publication statusPublished - 2016 Mar 25

Fingerprint

Schottky barrier diodes
Schottky diodes
inhomogeneity
Annealing
annealing
Energy dispersive spectroscopy
Metals
Transmission electron microscopy
heat
spiking
transmission electron microscopy
Electric breakdown
low resistance
high resistance
electrical faults
metals
chips
causes

Keywords

  • 4H-SiC Schottky barrier diode
  • Diffusion
  • Inhomogeneity
  • Post-annealing
  • Schottky barrier height
  • Transformation

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics

Cite this

Post-annealing processes to improve inhomogeneity of Schottky barrier height in Ti/Al 4H-SiC Schottky barrier diode. / Kyoung, Sinsu; Jung, Eun Sik; Sung, Man Young.

In: Microelectronic Engineering, Vol. 154, 25.03.2016, p. 69-73.

Research output: Contribution to journalArticle

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AB - To improve the high resistance and low breakdown voltage (BV) of a 4H-SiC Schottky barrier diode (SBD), the metal annealing process is conventionally used; this process stabilizes the Schottky barrier height (SBH). In this paper, we apply a post-metal annealing process to 4H-SiC Ti-SBD chips and verify the effect of the changes on electrical characteristics based on the post-annealing process. The results of experiments show that the condition of 873 K/30 min annealing created a stable SBH and a low value of on-resistance (Ron), which improved inhomogeneity. Based on the results of EDX and TEM analysis, the cause of improved SBH at the condition of 30 min was attributed to the generation of TiSix (which has a higher SBH than Ti). On the other hand, the improved value of Ron at the condition of 30 min was attributed to the change to γ-phase Ti3Al (which has a low resistance because diffused Al is present) caused by proper annealing. However, when more heat is applied in the cases of 773 K/60 min and 873 K/60 min, Ron increased and the SBH decreased. The results of EDX and TEM analysis showed that the low SBH was caused by Al spiking, which created an Al Schottky junction with a lower SBH than that of the Ti Schottky junction. Higher Ron resulted from the change to α-TiAl phase at the Al-Ti interface layer because of excessive diffusion of Ti and Al, which is due to the overly applied heat. From the results produced by this work, we can enhance the Al-Ti 4H-SiC SBD electrical characteristics by applying a suitable post-annealing process.

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