摘要:
In photolithographic exposure, a feature (144) of an optical mask is projected onto a dark area (160). The light intensity inside the dark area is reduced by providing a non-printable clear cutout (410) inside the feature. The optical mask has the same optical pathlength outside the feature (144) adjacent to the entire outer boundary of the feature as at the cutout, the optical pathlength being measured along the optical mask's thickness.
摘要:
Alignment targets include optically resolvable regions and SEM resolvable regions. SEM measurements taken of the SEM resolvable regions produce correction factors that can be applied to optical measurements taken of the optically resolvable regions where the correction factors improve the accuracy of the optical measurements. When one or more batches of wafers from a continuous production run are to be measured, a small sub-sample is measured with use of an SEM scan of their SEM resolvable regions. Then the correction factors developed from the SEM scans are applied to optical measurements taken of others of the wafers in the same mass production run.
摘要:
An overlay measurement recipe is checked for reliability as follows. A first pair of overlay layers (130, 150) is formed (610), and the recipe is used to obtain alignment measurements for the two layers. Then another pair of overlay layers (130, 150) is obtained (630), possibly using the same masks, but this time at least one of the layers (150) is offset from its previous position. The overlay measurement recipe is used again to obtain alignment measurements (640). The two sets of measurements are checked against the offset of the layers from their previous positions to validate the recipe. Other embodiments are also provided.
摘要:
In photolithographic exposure, a feature (144) of an optical mask is projected onto a dark area (160). The light intensity inside the dark area is reduced by providing a non-printable clear cutout (410) inside the feature. The optical mask has the same optical pathlength outside the feature (144) adjacent to the entire outer boundary of the feature as at the cutout, the optical pathlength being measured along the optical mask's thickness.
摘要:
A pillar array is printed in positive photoresist using an optical mask (108) having an array of features (310) corresponding to the pillars. The pillars' width/length dimensions are below the exposure wavelength. Superior results can be achieved (less peeling off of the pillars and less overexposure at the center of each pillar) if the mask features (310) are downsized relative to the pillars' target sizes, and the exposure energy is reduced. Negative photoresist (with a dark field mask) can be used, and can provide good results (in terms of pillars peeling-off) if the combined area of the features (410) corresponding to the pillars is smaller than the area between the features (410).
摘要:
In photolithographic exposure, the illumination pattern (120R) formed on a photosensitive surface (106) is a reverse of the pattern (130) on the optical mask (124). The reverse pattern (120R) is obtained using off-axis illumination when the photosensitive surface is at other than the best focus position.