Method and system of lithography using masks having gray-tone features
AssigneeMassachusetts Institute of Technology
InventorsMichael Fritze, Brian Tyrrell
Life of this patent
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Abstract
A method forms patterns on a substrate by exposing the substrate a first time and exposing the substrate a second time using a mask containing gray-tone features. The gray-tone features locally adjust an exposure dose in regions corresponding to features defined in the primary exposure. Moreover, the gray-tone features enable the forming of features having different critical dimensions on a substrate. The gray-tone features may be sub-resolution features and formed by pixellation. The trim mask containing gray-tone features may have regions with different transmissivities.
Claims135
A method of forming a pattern on a substrate, comprising:
- (a) forming patterns on a substrate;
- and
- (b) exposing the substrate using a mask containing gray-tone features.
A method of designing a mask in which a primary exposure is assumed, comprising:
- (a) placing gray-tone features on a layout of the mask to locally adjust an exposure dose in regions corresponding to features defined in the primary exposure;
- and
- (b) placing other features on the layout of the mask.
A trim mask comprising gray-tone features.
A method of forming a feature having a critical dimension on a substrate, comprising:
- (a) exposing the substrate using a trim mask containing gray-tone features.
A mask set for a process for providing patterns on a substrate comprising:
- a fine feature mask containing a pattern of dense features;
- and
- a trim mask containing gray-tone features to produce multiple trimmed patterns of fine features.
A method of forming a random contact array on a substrate comprising:
- (a) exposing the substrate to provide a pattern of dense contact features of a predetermined pitch and critical dimension;
- and
- (b) exposing the substrate with a trim mask containing gray-tone features to provide multiple trimmed patterns on the substrate, the trimmed patterns including both densely populated and sparsely populated regions of features, the critical dimension of the features in the densely populated regions and sparsely populated regions being substantially independent of feature density.
A mask set for a process for providing patterns on a substrate comprising:
- a fine feature mask;
- and
- a trim mask containing gray-tone features to produce multiple trimmed patterns of fine features.
A computer aided design method for designing a mask, comprising:
- (a) specifying, through an input of a user, a geometric property of a desired substrate feature;
- and
- (b) determining automatically, based upon the user specified geometric property of the desired substrate feature, mask features for a gray-tone mask.
A method of forming a pattern on a substrate, comprising:
- (a) imprinting a pattern on a substrate;
- and
- (b) exposing the substrate to change the imprinted pattern.
Dependencies are inferred from the claim text.