Sub-critical-dimension integrated circuit features
First Claim
1. A method of forming a patterned structure in an integrated circuit at a semiconductor surface of a substrate, comprising the steps of:
- forming a first layer over the surface;
applying a layer of photosensitive masking material over the first layer;
exposing the photosensitive masking material to light through a photomask having an elongated feature, the feature having a plurality of first sections along its length of a width at or greater than a critical photolithographic dimension, and having at least one second section disposed between adjacent ones of the first sections of the feature, the at least one second section having a width less than the critical photolithographic dimension;
after the exposing step, removing the photosensitive masking material from locations not corresponding to the location at which the patterned structure is to be formed; and
etching the first layer to form the patterned structure.
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Abstract
A method of photolithographically forming an integrated circuit feature, such as a conductive structure, for example a gate electrode (15), or such as a patterned insulator feature, is disclosed. A critical dimension (CD) for a photolithography process defines a minimum line width of photoresist or other masking material that may be patterned by the process. A photomask (20, 30, 40, 50, 60) has a mask feature (25, 35, 45, 55, 65) that has varying width portions along its length. The wider portions have a width (L1) that is at or above the critical dimension of the process, while the narrower portions have a width (L2) that is below the critical dimension of the process. In the case of a patterned etch of a conductor, photoexposure and etching of conductive material using the photomask (20, 30, 40, 50, 60) defines a gate electrode (15) for a transistor (10) that has a higher drive current than a transistor having a uniform gate width at the critical dimension.
10 Citations
23 Claims
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1. A method of forming a patterned structure in an integrated circuit at a semiconductor surface of a substrate, comprising the steps of:
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forming a first layer over the surface;
applying a layer of photosensitive masking material over the first layer;
exposing the photosensitive masking material to light through a photomask having an elongated feature, the feature having a plurality of first sections along its length of a width at or greater than a critical photolithographic dimension, and having at least one second section disposed between adjacent ones of the first sections of the feature, the at least one second section having a width less than the critical photolithographic dimension;
after the exposing step, removing the photosensitive masking material from locations not corresponding to the location at which the patterned structure is to be formed; and
etching the first layer to form the patterned structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A transistor formed at a semiconductor surface of a substrate, comprising:
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a gate electrode extending along the surface for a length, the gate electrode having at least one second section disposed between adjacent ones of the first sections of the gate electrode, the at least one second section having a width that is narrower than the width of the adjacent ones of the first sections of the gate electrode; and
source and drain doped regions in the surface, and disposed on opposing sides of the gate electrode;
wherein the gate electrode is formed by a process comprising the steps of;
forming a conductive layer over the surface;
applying a layer of photosensitive masking material over the conductive layer;
exposing the photosensitive masking material to light through a photomask having an elongated feature, the feature having a plurality of first sections along its length of a width at or greater than a critical photolithographic dimension, and having at least one second section disposed between adjacent ones of the first sections of the feature, the at least one second section having a width less than the critical photolithographic dimension, the first sections and at least one second section of the feature defining the first sections and at least one second section of the gate electrode;
after the exposing step, removing the photosensitive masking material from locations not corresponding to the location of the gate electrode; and
etching the conductive layer to form the gate electrode. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification