Specific contact resistivity measurement by a vertical Kelvin test structure

A vertical Kelvin test structure is used to measure the specific contact resistivity of the Al (1-percent Si)/Si and Al (1-percent Si)/TiSi 2 /Si contact system. For the vertical test structure, the driving current flows "vertically," thus the current crowdings and sheet resistance effects are eliminated and measurement on the true specific contact resistivity becomes possible. Experimental works show that results obtained by using this vertical structure are closer to the true specific contact resistivities than those obtained by using the conventional six-terminal Kelvin method. It is also found that R sd , the sheet resistance directly underneath the contact pad, is much less than that of the conduction bar without the contact pad. A value of (1.17 ± 0.17) × 10 -7 Ω . cm 2 specific contact resistivity is obtained for the Al (1-percent Si) /TiSi 2 (direct reaction) /Si system.