Calculation of a Al–Ti–O–N quaternary isotherm diagram for the prediction of stable phases in TiN/Al alloy contact metallization

We have calculated a quaternary phase diagram of the Al–Ti–O–N system, valid in the range of temperatures between 450 and 550 °C. In particular, the respective composition ranges of all the binary compounds were taken into account and are listed along with their composition and structure. The four simplified ternary diagrams (Ti–Al–O, Ti–N–O, Ti–Al–N, and Al–N–O) were first calculated to constitute the four faces of the tetrahedron representing the quaternary phase diagram. The interior tie lines of the quaternary diagram were calculated with the same proposed procedure that was used to obtain the ternary diagram. Two of these tie lines are important, one of which links TiN and Al2O3 and one which links AlN and TiO2. The utility of this diagram is illustrated by predicting the phases that are likely to occur during the reaction between Al and TiN layers, the latter compound being oxydized or not.