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One of the most challenging issues in the metal hard mask process for copper interconnects is controlling the residual stress in TiN mask. The relationship between the residual stress and the feature size of the trench was investigated using a mechanical simulation. It was found that the trench deformation at a specific pattern due to the residual compressive stress in TiN film resulted in void formation in Cu. To overcome this problem, the correlation between the residual stress and the film properties of TiN was investigated and a potential TiN mask in the metal hard mask process was studied. The residual stress in TiN film and the etching performance were correlated with the composition and the crystal structure of TiN. The grain growth was suppressed by reducing the energy of sputtered atoms during the deposition of TiN, resulting in low residual stress in TiN film with keeping the etching performance for TiN. By applying low stress TiN mask which had a fiber-textured structure, the trench deformation at a specific pattern could be suppressed and thus Cu filling was perfectly achieved. The metal hard mask process using TiN film which had a fiber-textured structure was demonstrated to be high performance. As the wiring pitches in copper (Cu) interconnect continue to become smaller, resistive-capacitive (RC) delay due to the increase in the capacitance between Cu lines becomes a critical problem. Therefore, the low k-value dielectric materials have been studied to reduce the capacitance between Cu lines.1-8 However, the low-k materials are known to be easily damaged by the post-processes such as the resist ashing process with oxygen (O 2 ) plasma 9-11 because of their low mechanical strength, and it results in k-value increasing.To suppress the damage of interlayer dielectric by the ashing process during the removal of the trench resist, the metal hard mask (MHM) process has been studied instead of the conventional resist mask process.12-24 As a hard mask in the MHM process, Titanium nitride (TiN) has been investigated. [20][21][22][23][24][25][26][27][28][29][30][31] This is because the alignment pattern for photolithography can be easily recognized through TiN film compared to other metal films such as Tantalum nitride (TaN) film. However, the serious problems occurred in the MHM process due to high residual stress in TiN mask. One of the problems is that the trench deformation after the etching process, which is known as the wiggling phenomenon.32 This is due to the stress relaxation of TiN film after the trench formation with the etching process, and it results in the buckled structure. Therefore, the approaches to reduce the residual stress in TiN film used as a hard mask have been also studied. One approach to reduce the residual stress is to reduce the thickness of TiN mask. However, thinner TiN mask tends to result in worse property of a hard mask in the self-aligned via process, and the shrink of the pitches between via and trench occurs. It results in degrading the device yield or the reliability per...