| 摘要 |
A method for measuring linewidths of microelements or lines on wafers or masks in which the line is held in a selected fixed position and a magnified real image of a small area field containing the line is projected on a predetermined focal plane. The magnified image is scanned along a flat path with a moving slit that is substantially parallel to the edges of the line. The slit is sized to vary the light transmitted therethrough in accordance with the optical properties of the line in contrast to the background on the wafer or mask. Transmitted light through the slit is directed onto a photosensitive device moving with the slit which is responsive to the relatively light and dark regions defined by the line and the adjacent area. The distance of movement of the slit and the output signal from the photosensitive device are both monitored and both edges of the image of the line are located by identifying characteristic changes in the output signal. The spacings between the line edges as determined by the amount of slit movement and the characteristic output signal changes are used to generate a digital output that is proportional to the width of the line.
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