Effect of reactive ion etch-induced damage on the performance of 4H-SiC schottky barrier diodes

Abstract

The effect of reactive ion etch (RIE) induced damage on 4H-SiC surfaces etched in fluorinated plasmas has been investigated and characterized using Ni Schottky diodes and x-ray photoelectron spectroscopic surface analysis. The diodes were characterized using current-voltage, current-voltage-temperature, and capacitance-voltage measurements with near ideal forward characteristics (n = 1.07) and forward current density as high as 9000 A/cm 2 from the control (unetched) devices. High current handling capability was observed in diodes with etched surfaces as well. Diodes with surfaces etched in CHF 3 containing plasmas showed a significant reduction in the barrier height compared to the diodes with surfaces etched in CF 4 containing plasma. Control devices exhibited high leakages when reverse biased, which is attributed to the presence of a thin (~2 nm) oxide layer at the metal-semiconductor interface. However, under reverse bias diodes with CHF 3 -etched surfaces showed improvement in leakage current compared to diodes with CF 4 -etched surfaces and the control diodes.

Ohmic contact formation on inductively coupled plasma etched 4H-silicon carbide

“…The induced damaged could exist as dislocation, vacancy, or recombination centers. 20 Our recent results 8 and those of others 10 using the electrical characterization of Schottky diodes on 4H-SiC also indicate that this etch-induced damage significantly affects the performance of the Schottky diode. In order to check the surface damage induced by energetic ions of ICP, the roughness of the silicon-carbide surface was measured by AFM for each etched sample (A2, A3, and A4) and the unetched reference sample (A1) prior to the metal deposition.…”

Inductively coupled plasma etch damage in 4H−SiC investigated by Schottky diode characterization

“…The increased series resistance with increasing temperature is explained by a decreasing mobility. 9 The samples E5-E8 have Schottky contacts of type Ti-b, and typical IV characteristics at 25°C for all of these samples can be seen in Fig. 3, and in Fig.…”

“…Even with the lower ICP damage etching the electrical properties of SiC are changed during etching, and annealing or removal of the damage region is needed. [7][8][9] High temperature oxidation of the etched surface passivates the etch damage, but a device can only be exposed to such ambients early in the processing. This has to be taken into account when making heterojunctions with GaN on SiC.…”

Degradation mechanism of Schottky diodes on inductively coupled plasma-etched n-type 4H-SiC

“…2 However, ICP etching still causes degradation of the electrical properties, depending on the type of etch gas and plasma power. 3 The degradation of electrical properties of SiC Schottky contacts on etched surfaces has been attributed to surface contamination resulting from the reaction of the residual etching gas with SiC. A significant amount of chemical bonds associated with etching gas elements was found on the etched surface.…”

“…1,4 Another possible origin of the degradation in electrical characteristics could be the generation of microstructural imperfections on the etched surface or carrier traps. 3 Current-voltage (I -V) measurement is a common method for monitoring the effects of dry etching damage of the electrical properties of Schottky diodes, namely, the Schottky barrier height ( B ), ideality factor ͑ ͒ and reverse leakage current (I R ). However, it is not improper for the quantitative evaluation of dry-etching-induced traps.…”