Selective photoresist hardening to facilitate lateral trimming
First Claim
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1. A method of trimming a feature patterned on a photoresist layer, the photoresist layer disposed over a substrate and the feature including a top portion and lateral surfaces, the method comprising the steps of:
- modifying the top portion of the feature patterned on the photoresist layer in an ion-dominated environment to form a modified top portion by flood exposing the feature to ions or by fluorinating the top portion to undergo a reduction in reactivity; and
trimming the feature patterned on the photoresist layer to form a trimmed feature, wherein a vertical trim rate and a lateral trim rate are associated with the feature and the vertical trim rate is slower than the lateral trim rate due to the modified top portion.
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Abstract
A process for forming sub-lithographic features in an integrated circuit is disclosed herein. The process includes modifying a photoresist layer after patterning and development but before it is utilized to pattern the underlying layers. The modified photoresist layer has different etch rates in the vertical and horizontal directions. The modified photoresist layer is trimmed with a plasma etch. A feature included in the trimmed photoresist layer has a sub-lithographic lateral dimension.
435 Citations
24 Claims
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1. A method of trimming a feature patterned on a photoresist layer, the photoresist layer disposed over a substrate and the feature including a top portion and lateral surfaces, the method comprising the steps of:
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modifying the top portion of the feature patterned on the photoresist layer in an ion-dominated environment to form a modified top portion by flood exposing the feature to ions or by fluorinating the top portion to undergo a reduction in reactivity; and
trimming the feature patterned on the photoresist layer to form a trimmed feature, wherein a vertical trim rate and a lateral trim rate are associated with the feature and the vertical trim rate is slower than the lateral trim rate due to the modified top portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An integrated circuit fabrication process, the process comprising:
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developing a patterned photoresist layer, the patterned photoresist layer including at least one feature;
modifying the patterned photoresist layer to form a top portion and a bottom portion of the at least one feature, the top portion having a top etch rate and the bottom portion having a bottom etch rate, wherein the top etch rate is different from the bottom etch rate; and
trimming the patterned photoresist layer by plasma etching to change the at least one feature to have a sub-lithographic lateral dimension, whereby a sufficient vertical thickness exists to maintain pattern integrity, wherein the modifying step is performed after the developing step and before the trimming step. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A process of forming an integrated circuit having a feature of sub-lithographic dimension, the process comprising steps of:
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patterning the feature on a photoresist layer disposed over a substrate, the feature patterned in accordance with a radiation at a lithographic wavelength and a pattern provided on a mask or a reticle;
developing the feature patterned on the photoresist layer;
changing at least a portion of the photoresist layer, wherein a top portion of the feature patterned on the photoresist layer is changed to have a different etch rate from a bottom portion of the feature patterned on the photoresist layer;
trimming the feature patterned on the photoresist layer to a sub-lithographic dimension wherein the trimming does not entirely remove the top portion;
removing the top portion from the feature; and
transferring the trimmed feature patterned on the photoresist layer to the substrate, wherein the feature in the substrate has the sub-lithographic dimension. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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Specification