Mura-detection method by using a slit-beam ellipsometer

— A slit‐beam ellipsometer which performs sensitive mura detection of thin films on transparent substrates has been developed. Mura is a Japanese term which means the non‐uniformity of the thin‐film thickness, the dielectric constant, etc. The mura thickness of polyimide films and the mura thickness of the surface of polyimide films caused by rubbing along a 30‐mm‐long slit beam was observed. This ellipsometer only detects the reflected light from the rubbed polyimide films onto the transparent substrates. As a result, sensitive MURA detection is achieved. The slit beam generated by a cylindrical lens is irradiated onto a sample. The reflected light from the sample becomes collimated light passing through another cylindrical lens and is detected by a 2048‐pixel CCD liner sensor. In addition, the in‐line use of slit‐beam ellipsometer was examined. When the slit‐beam ellipsometer is set up during the rubbing process, the optimum set up, where rubbing mura‐detection becomes highly sensitive, was determined.