Thermally stable, low specific resistance (1.30×10−5 Ω cm2) TiC Ohmic contacts to n-type 6Hα-SiC

Abstract

An array of transfer length measurement (TLM) structures was formed on an electrically isolated (0001) n+6Hα-SiC epilayer. The n+6Hα-SiC epilayer contained an in situ incorporated nitrogen concentration of 4×1019 cm−3. The specific contact resistance (ρc), sheet resistance (Rs), contact resistance (Rc), and transfer length (LT) were calculated from resistance (RT) versus contact spacing (d) measurements obtained from 17 TLM structures. The linear curves used for these calculations were fit to the RT versus d data by calculating the standard error of linear regression of RT on d; where, the average correlation coefficient with a straight line was 1.0000 and the average standard error of linear regression of RT on d was 0.08 Ω. The resulting average values were: ρc=1.30×10−5 Ω cm2, Rs=14.4 Ω/square, Rc=1.6 Ω, and LT=9.5 μm. The (111) TiC contacts, epitaxially grown by chemical vapor deposition, were thermally and chemically stable at 1400 °C. The TiC contacts could not be scratched with a tungsten carbide scriber, nor delaminated from the 6Hα-SiC substrate.

Time-dependent characteristics of titanium-silicide contacts to 6H-silicon carbide

“…18,19 TiC has been used as a contact to 6H-SiC, but its contact resistivity was large. 20 In this paper, the microstructural development result- ing from the deposition of Ti and Si layers onto SiC is examined to determine how to obtain contacts of the low-resistivity C54-TiSi 2 phase on 6H-SiC. The approach followed is to use a silicon buffer layer to suppress the formation of TiC, and to examine structures with different Ti/Si layer thickness ratios.…”

CVD-based tungsten carbide schottky contacts to 6H-SiC for very high-temperature operation

“…An exception is Re, which has been proven to be thermally stable up to at least 1373 K, 8 but no electrical characteristics were presented. Refractory metal silicides [9][10][11] have been suggested because of their thermal stability and metal carbides 12 because of their outstanding adhesion properties.…”

Thin film solid-state reactions forming carbides as contact materials for carbon-containing semiconductors

“…Bushmer and Crayton 22 studied the self-diffusion of 14 C into WC, and obtained an activation energy E a b.d. = 3.82 eV for bulk diffusion, and E a g.b.d.…”

“…Examples of carbides used as contact materials are already available in the literature: WC was examined as a schottky contact to 6H-SiC ͑Ref. 12͒ and to diamond; 13 TiC was used as an Ohmic contact to 6H-SiC, 14 but also as an Ohmic contact to diamond 15 and CNTs. 16 Contact materials are usually evaluated on ͑a͒ their thermodynamic stability in contact with the semiconductor, ͑b͒ their electric conductivity ͑as high as possible͒, ͑c͒ their formation temperature ͑as low as possible͒, and ͑d͒ their contact resistance ͑as low as possible͒.…”