Microscopic observation of Cu damascene interconnect grains using x-ray microbeam

Abstract

Microscopic observation and imaging of Cu damascene interconnect grains were carried out using the x-ray microbeam of the BL-16XU at SPring-8. The x-ray focusing system of the beamline consists of a bent-cylindrical prefocusing mirror and elliptical mirrors with a Kirkpatric–Baez configuration. Diffraction spots from the microscopic area irradiated by the intense x-ray microbeam (7×6 μm full width at half maximum) at the boundary between the metal line and the dielectric were observed. The diffraction spots observed show that Cu(111) grains grow normally on the sidewall and Cu(200) grain orientation distribution is quite broad, suggesting that crystallographic texture near the trench is quite disordered. Two-dimensional images of grains with a specific orientation angle were also obtained. Grains as large as about 10 μm caused by self-annealing were observed.