To test the actual thickness of a filter layer supplied in the stage where a chip is still a part of a wafer.

The semiconductor chip 10 being employed in a chip array assembly for scanning a hard copy image comprises arrays of photodetector 20 each comprising a polyimide filter layer 22R, 22G, 22B for passing one primary color. In addition to the photodetector 20, the chip 10 is provided with a reflective region 30 on which a filter part 32 is provided. The filter part 32 is formed simultaneously with formation of the filter layer on the photodetector 20. Optical transmittance of the filter layer on the photodetector 20 can be determined using the filter part 32 provided in the reflective region 30 as a test site.