Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2001-10-12
2004-02-24
Young, Christopher G. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S275100, C430S302000, C430S320000, C101S473000
Reexamination Certificate
active
06696220
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to imprint lithography templates. More particularly, to imprint lithography templates for use in micro- and nano-imprint lithography processes.
2. Description of the Relevant Art
Optical lithography techniques are currently used to make most microelectronic devices. However, it is believed that these methods are reaching their limits in resolution. Sub-micron scale lithography has been a critical process in the microelectronics industry. The use of sub-micron scale lithography allows manufacturers to meet the increased demand for smaller and more densely packed electronic components on chips. It is expected that in the coming years, the microelectronics industry will pursue structures that are smaller than about 50 nm. Further, there are emerging applications of nanometer scale lithography in the areas of opto-electronics and magnetic storage. For example, photonic crystals and high-density patterned magnetic memory of the order of terabytes per square inch require nanometer scale lithography.
For making sub-50 nm structures, optical lithography techniques may require the use of very short wavelengths of light (e.g., about 13.2 nm). At these short wavelengths, many common materials may not be optically transparent and therefore imaging systems typically have to be constructed using complicated reflective optics. Furthermore, obtaining a light source that has sufficient output intensity at these wavelengths may be difficult. Such systems may lead to extremely complicated equipment and processes that may be prohibitively expensive. It is believed that high-resolution e-beam lithography techniques, though very precise, may be too slow for high-volume commercial applications.
Imprint lithography processes have demonstrated the ability to replicate high-resolution (sub-50 nm) images on substrates using templates that contain images as topography on their surfaces. It is believed that imprint lithography may be an alternative to optical lithography for use in patterning substrates in the manufacture of microelectronic devices, optical devices, MEMS, opto-electronics, patterned magnetic media for storage applications, etc. Imprint lithography techniques may be superior to optical lithography for making three-dimensional structures such as micro lenses and T-gate structures.
For production-scale imprint lithography, it may be desirable to place patterned regions as close as possible to each other without interfering with subsequent imprints. This effectively maximizes the patternable area on the substrate. In order to accomplish this goal, the location of the any excess fluid that is expelled from the patterned area should be well confined and repeatable. As such, the individual components, including the template, substrate, fluid and any other materials that may affect the physical properties of the system, including but not limited to surface energy, interfacial energies, Hamacker constants, Van der Waals' forces, viscosity, density, opacity, etc., should be engineered properly to accommodate a repeatable process. Accordingly, a need exists for a way of controlling the spread of excess fluid outside desired patterning regions that can facilitate production-scale imprint lithography.
SUMMARY OF THE INVENTION
The embodiments described herein include imprint lithography templates, methods for forming and using imprint lithography templates, and template holders.
In an embodiment, an imprint lithography template may be substantially transparent to activating light (e.g., ultraviolet light). Such a template may include a body having a first surface. The template may further include a plurality of recesses on the first surface. In various embodiments, the first surface may be substantially planar, parabolic, or spherical. At least a portion of the recesses may have a feature size of less than about 250 nm. In some embodiments, the template may further include at least one alignment mark on the body. In some embodiments, the template may further include a gap sensing area.
In various embodiments, the body may be formed in whole, or in part of silicon, silicon dioxide, silicon germanium carbon, gallium nitride, silicon germanium, sapphire, gallium arsinide, epitaxial silicon, poly-silicon, gate oxide, quartz, indium tin oxide or combinations thereof. In some embodiments, at least a portion of the body may be formed of SiO
x
, where X is less than 2. For example, X may be about 1.5.
In an embodiment, the plurality of recesses on the first surface may include first recesses, having a first depth; and second recesses, having a second depth. The second depth may be greater than the first depth. For example, the first depth may be less than about 250 nm. In addition to the plurality of recesses on the first surface, the template may include at least one recess on a second surface opposite the first surface. In an embodiment, at least a portion of the recesses may have a width that varies in a direction normal to the first surface. Such recesses may be configured to accommodate changes in material properties of a light curable liquid that may be used with the template in an imprint lithography process. For example, the light curable liquid may contract or expand upon curing.
In an embodiment, a template may include an excess fluid relief structure formed in a portion of the body. For example, such a structure may be formed in a kerf area of a template.
In some embodiments, at least a portion of the first surface of the template may have a surface free energy measured at 25° C. of less than about 40 dynes/cm. In some of these embodiments, the portion of the first surface of the template may have a surface free energy measured at 25° C. of less than about 20 dynes/cm. For example, at least the portion of the first surface may have a surface treatment layer. The surface treatment layer may include a reaction product of an alkylsilane, a fluoroalkylsilane, or a fluoroalkyltrichlorosilane with water. For example, the surface treatment layer may include a reaction product of tridecafluoro-1,1,2,2-tetrahydrooctyl trichlorosilane with water. The surface treatment layer may reduces the surface free energy of the first surface measured at 25° C. to less than about 40 dynes/cm, or in some cases, to less than about 20 dynes/cm.
In some embodiments, an alignment mark on the template may be substantially transparent to activating light. The alignment mark may be substantially opaque to analyzing light. In such embodiments, the analyzing light may include visible light or infrared light. The alignment mark may be formed of a material different than the material of the body. For example, the alignment mark may include SiO
x
where x is less than 2. For example, x may be about 1.5. Alternately, the alignment mark may include a plurality of lines etched on a surface of the body. The lines may be configured to substantially diffuse activating light, but produce an analyzable mark under analyzing light.
In some embodiments, the template may have a planarity of less than about 500 nm. In some of these embodiments, the template may have a planarity of less than about 250 nm.
In some embodiments, the template may include a conductive coating or reflective coating on at least one edge of the body. In other embodiments, the template may include a mirror coupled to at least one edge of the body.
In an embodiment, the template may include a template blank coupled to the body. For example, the body may be bonded to the template blank using a bonding agent. The template blank and the bonding agent may be substantially transparent to activating light. In some embodiments, a gap sensing area may include at least one recess having a known depth. The gap sensing area may be in the first surface or the second surface. In an embodiment, the gap sensing area may have a depth greater than about 100 nm.
In an embodiment, an imprint lithography template, as described above, may be formed by obtaining a material that is substantially transparent t
Bailey Todd
Choi Byung J.
Colburn Matthew
Ekerdt John
Sreenivasan S. V.
Board of Regents , The University of Texas System
Brooks Kenneth C.
Young Christopher G.
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