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

Abstract

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.

Failure mechanism of a multilayer (TiN/Al/TiN) diffusion barrier between copper and silicon

“…17 We have suggested that the improved barrier performance is probably due to the formation of Al 2 O 3 in the TiN grain boundaries with the help of HRTEM and EDS analysis, which also could be explained by Ti-N-O-Al quaternary phase diagram. 33 In this study, with the Al interlayer of 1 nm, the significant improvement of the barrier performance of the TiN film has also been obtained. By increasing the Al thickness, the amount of the Al available to form the Al 2 O 3 is increased too.…”

The determination of phases formed in AlSiCu/TiN/Ti contact metallization structure of integrated circuits by x-ray diffraction

“…Some peaks in the following figures could be explained by the formation of several phases. Only the most probable compounds formed as predicted by quaternary phase diagrams 16,17 are indicated. The possibility that other phases were observed are also discussed.…”

“…These products can be predicted with the help of the Al-Ti-O-N, 16 the Al-Ti-Si-N and the Al-Ti-Si-O quaternary phase diagrams. 17 The Al-Ti-O-N diagram predicts that the Ti oxides formed on the TiN barrier during air exposure could react with the Al during the sintering and result in the formation of Al 2 O 3 , TiAl 3 , and AlN.…”

Novel multilayered Ti/TiN diffusion barrier for Al metallization

“…It is important to note that the formation of TiAl 3 is more likely to occur in the Al-Ti system than in the Al-TiN system after thermal processing, since thermal stability between Al and Ti layers is lower than that between Al and TiN layers. [22][23][24] Increased thickness of the inserting Ti interlayer will enhance the formation of TiAl 3 compounds, resulting in increased contact resistance. Table I, to explore effects of distribution of inserting Ti interlayer on barrier properties of multilayered Ti/TiN barriers.…”