Drop-in test structure chip to visualize residual stress of Ru/Cu film grown by atomic layer deposition and supercritical fluid deposition

We propose a drop-in test structure chip to evaluate residual stress. The structure was applied to evaluate supercritical fluid deposition (SCFD) Cu film over atomic layer deposition (ALD) Ru/TiO
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film. In an early development stage of such emerging technology, researchers make experiments with a small sample chip in a small chamber. Small chips make classical stress evaluation methods such as wafer curvature radius measurement inappropriate due to high chip stiffness. We propose to “dropin” altogether the sample chip and an additional tiny test chip equipped with free-standing MEMS test structure. The MEMS directly visualizes stress of the deposited material for both tensile and compressive ones. Researchers can continue the device fabrication process on the sample chip while obtaining stress information of the deposited layer by test structure chip. In this paper, in-plane rotating stress sensors were utilized for stress visualization. We proceeded SCFD with two different conditions. The results revealed that SCFD Cu film had tensile stress at the low-temperature condition and compressive stress at the hightemperature condition.