DUV scanner linewidth control by mask error factor compensation
Linewidth variations and bias that result from MEF changes and reticle linewidth variations in a printed substrate are controlled by correcting exposure dose and partial coherence at different spatial locations. In a photolithographic device for projecting an image of a reticle onto a photosensitive substrate, an adjustable slit is used in combination with a partial coherence adjuster to vary at different spatial locations the exposure dose received by the photosensitive substrate and partial coherence of the system. The linewidth variance and horizontal and vertical or orientation bias are calculated or measured at different spatial locations with reference to a reticle, and a corrected exposure dose and partial coherence is determined at the required spatial locations to compensate for the variance in linewidth and bias on the printed substrate. Improved printing of an image is obtained, resulting in the manufacture of smaller feature size semiconductor devices and higher yields.
1. A photolithographic device comprising:
a partial coherence adjuster receiving electromagnetic radiation from a source;
an adjustable slit receiving electromagnetic radiation from said partial coherence adjuster;
a reticle stage that holds a reticle;
a substrate stage; and
projection optics between said reticle stage and said substrate stage,
whereby a dose of electromagnetic radiation received at said substrate stage is controlled by said adjustable slit, and a partial coherence of said electromagnetic radiation is modified at selected portions of said reticle by said partial coherence adjuster to control linewidth variation.
2. The photolithographic device of claim 1 , wherein said partial coherence adjuster comprises an array optical element.
3. The photolithographic device of claim 2 , further comprising a region selector associated with said array optical element, whereby a partial coherence may be changed at any predetermined spatial location.
4. The photolithographic device of claim 2 , wherein said array optical element has a plurality of emerging numerical aperture modifying regions.
5. A scanning photolithographic device comprising:
an array optical element having a plurality of emerging numerical aperture modifying regions that receive electromagnetic radiation;
an adjustable slit that receives electromagnetic radiation emerging from said array optical element;
a reticle stage that holds a reticle;
a substrate stage;
projection optics between said reticle stage and said substrate stage; and
an controller coupled to said adjustable slit,
whereby a dose of electromagnetic radiation directed towards said substrate stage is controlled by said controller, and said array optical element modifies an emerging numerical aperture at selected portions of the reticle to control linewidth variation.
6. The scanning photolithographic device of claim 5 , further comprising a region selector associated with said array optical element for changing said emerging numerical aperture and resulting partial coherence at predetermined spatial locations.
7. The scanning photolithographic device of claim 5 , wherein said adjustable slit has a variable width along a longitudinal length.
8. The scanning photolithographic device of claim 5 , further comprising a test reticle having a plurality of line pattern portions with lines of different linewidths and orientations spatially positioned.
9. The scanning photolithographic device of claim 5 , further comprising means, associated with a substrate mounted on said substrate stage, for determining the variations of linewidth on said substrate when processed.
10. A scanning photolithographic device comprising:
an optical element having a plurality of emerging numerical aperture modifying regions and comprising a gradient, said optical element receiving electromagnetic radiation from an illumination source and providing a predetermined partial coherence at selected locations on a reticle that is mounted on a reticle stage;
a region selector that redirects said plurality of emerging numerical aperture modifying regions at predetermined locations;
an adjustable slit that receives electromagnetic radiation from said optical element and having a variable width along its longitudinal dimension;
a reticle stage that holds said reticle;
a substrate stage that holds a substrate thereon;
projection optics between said reticle stage and said substrate stage;
a stage control coupled to said reticle stage and said substrate stage;
an adjustable slit control coupled to said adjustable slit; and
a system control coupled to said stage control, said region selector, and said adjustable slit control,
whereby a dose of electromagnetic radiation received by said substrate is controlled by said adjustable slit, and said optical element modifies said selected partial coherence at predetermined spatial locations on said reticle to control linewidth variation.
11. The photolithographic device of claim 10 , further comprising a region selector associated with said optical element, whereby a partial coherence may be changed at any predetermined spatial location.
12. The photolithographic device of claim 10 , wherein said optical element is an array optical element.