Impact of Ar+ bombardment of 4H–SiC substrates on Schottky diode barrier heights. (1st March 2021)

• Record Type: Journal Article
• Authors: Pfusterschmied, G.; Triendl, F.; Schneider, M.; Schmid, U.
• Is Part Of: Materials science in semiconductor processing. Volume 123(2021)
• Publication Date: 2021-03-01
• Subjects: Schottky contact -- Diode -- SiC -- Ion bombardment; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2020.105504
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: In this paper, we investigate the impact of plasma power and plasma exposure time on the Schottky barrier height (SBH) and the ideality factor of silicon carbide (SiC) Schottky diodes. N-doped 4H–SiC Schottky diodes with molybdenum nitride (MoN) top metallization are fabricated. The plasma power PISE is varied from 0 up to 300 W at a constant plasma time of 300 s. High resolution transmission electron microscopy is performed showing a ~6 nm thin amorphous layer formed at the MoN/4H–SiC interfaces after ion bombardment. Current-Voltage-Temperature measurements are conducted in a wide temperature range from 50 K up to 500 K. SBHs are extracted using standard techniques, showing a significant influence of PISE on the SBH. A SBH of about 1 V is measured for diodes without ion pretreatment (PISE = 0 W). The highest SBH of 1.1 V is extracted for the diode with PISE = 50 W, followed by a continuous decrease of the SBH at higher plasma powers. At a PISE = 300 W, a SBH of 1.02 V is obtained, which is close to the SBH at PISE = 0 W. These results show that, ion bombardment increases the SBH. However, similar SBHs can be obtained by optimizing the plasma power when ion bombardment is required. Additionally, the plasma time is varied from 0 s up to 420 s by simultaneously holding the plasma power constant at 300 W. The activation energy of the investigated Schottky diodes is extracted from Arrhenius plots obtained at different voltages from −1 to −5 V. These results are in good agreement SBH evaluation. The influence of ion bombardment on SBH homogeneity on wafer level is presented. It is shown that the standard deviation of SBH on 4-inch wafers can be reduced by a factor of 2.7 when ion bombardment is used, compared to diodes fabricated without ion bombardment.