Formation of conductive templates employing indium tin oxide
The present invention is directed to a method forming conductive templates that includes providing a substrate; forming a mesa on the substrate; and forming a plurality of recessions and projections on the mesa with a nadir of the recessions comprising electrically conductive material and the projections comprising electrically insulative material. It is desired that the mesa be substantially transparent to a predetermined wavelength of radiation, for example ultraviolet radiation. As a result, it is desired to form the electrically conductive material from a material that allows ultraviolet radiation to propagate therethrough. In the present invention indium tin oxide is a suitable material from which to form the electrical conductive material.
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The field of invention relates generally to imprint lithography. More particularly, the present invention is directed to reducing the time required to fill the features of a template with imprinting material during imprint lithography processes.
Micro-fabrication involves the fabrication of very small structures, e.g., having features on the order of micro-meters or smaller. One area in which micro-fabrication has had a sizeable impact is in the processing of integrated circuits. As the semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, micro-fabrication becomes increasingly important. Micro-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which micro-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like.
An exemplary micro-fabrication technique is shown in U.S. Pat. No. 6,334,960 to Willson et al. Willson et al. disclose a method of forming a relief image in a structure. The method includes providing a substrate having a transfer layer. The transfer layer is covered with a polymerizable fluid composition. A mold makes mechanical contact with the polymerizable fluid. The mold includes a relief structure, and the polymerizable fluid composition fills the relief structure. The polymerizable fluid composition is then subjected to conditions to solidify and to polymerize the same, forming a solidified polymeric material on the transfer layer that contains a relief structure complimentary to that of the mold. The mold is then separated from the solid polymeric material such that a replica of the relief structure in the mold is formed in the solidified polymeric material. The transfer layer and the solidified polymeric material are subjected to an environment to selectively etch the transfer layer relative to the solidified polymeric material such that a relief image is formed in the transfer layer. The time required and the minimum feature dimension provided by this technique are dependent upon, inter alia, the composition of the polymerizable material.
It is desired, therefore, to provide a technique that decreases the time required to fill a feature of an imprint lithography template.
SUMMARY OF THE INVENTIONThe present invention is directed to a conductive template and of a method forming conductive templates that includes providing a substrate; forming a mesa on the substrate; and forming a plurality of recessions and projections on the mesa with a nadir of the recessions comprising electrically conductive material and the projections comprising electrically insulative material. It is desired that the mesa be substantially transparent to a predetermined wavelength of radiation, for example ultraviolet radiation. As a result, it is desired to form the electrically conductive material from a material that allows ultraviolet radiation to propagate therethrough. In the present invention indium tin oxide is a suitable material from which to form the electrical conductive material. However, indium tin oxide is difficult to pattern due to its resistance to etch. Nonetheless, the present method provides a manner in which to form a conductive template with indium oxide suitable for use in imprint lithography. These other embodiments are discussed more fully below.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to both
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To facilitate filling of recessions 28a, material 36a is provided with the requisite properties to completely fill recessions 28a while covering surface 32 with a contiguous formation of material 36a. In the present embodiment, sub-portions 34b of imprinting layer 34 in superimposition with protrusions 28b remain after the desired, usually minimum, distance “d”, has been reached, leaving sub-portions 34a with a thickness t1 and sub-portions 34b with a thickness t2. Thicknesses “t1” and “t2” may be any thickness desired, dependent upon the application. Typically, t1 is selected so as to be no greater than twice the width u of sub-portions 34a, i.e., t1≦2u, shown more clearly in
Referring to
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Referring to
n=Vt/Vu (1)
where Vt and Vu, are defined above. Assume a square array of droplets 36 where the total number, n, of droplets 36 is defined as follows:
n=n1×n2 (2)
where n1 is that number of droplets along a first direction and n2 is the number of droplets along a second direction A spacing S1 between adjacent droplets 36 along a first direction, i.e., in one dimension, may be determined as follows:
S1=L1/n1 (3)
where L1 is the length of region 40 along the first direction. In a similar fashion, a spacing S2 between adjacent droplets 36 along a second direction extending transversely to the first direction may be determined as follows:
S2=L2/n2 (4)
where L2 is the length of region 40 along the second direction.
Considering that the unit volume of imprinting material 36a associated with each of droplets 36 is dependent upon the dispensing apparatus, it becomes clear that spacings S1 and S2 are dependent upon the resolution, i.e., operational control of the droplet dispensing apparatus (not shown) employed to form droplets 36. Specifically, it is desired that the dispensing apparatus (not shown) be provided with a minimum quantity of imprinting material 36a in each of droplets 36 so that the same may be precisely controlled. In this fashion, the area of region 40 over which imprinting material 36a in each droplet 36 must travel is minimized. This reduces the time required to fill recessions 28 and cover substrate with a contiguous layer of imprinting material 36a.
Another problem that the present invention seeks to avoid is the trapping of gases in imprinting layer 34 once patterned surface 34c is formed. Specifically, in the volume 44 between spaced-apart droplets 36 of matrix array 42, there are gases present, and droplets 36 in matrix array 42 are spread over region 40 so as to avoid, if not prevent, trapping of gases therein. To that end, in accordance with one embodiment of the present invention, a subset of droplets 36 in matrix array 42 that are compressed along a first direction by mold 28 along a first direction and subsequently compressing the remaining droplets 36 of matrix array 42 along a second direction, extending transversely to the first direction. This is achieved by cantilevering impingement of mold 28 onto droplets 36, shown in
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Assuming body 150 is formed from fused-silica, a suitable etching technique would involve a buffered oxide etch (BOE). This occurs for a sufficient amount of time to provide a desired height, h, for mesa 133, as measured from surface 112 of body 150, shown in
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The embodiments of the present invention described above are exemplary. Many changes and modifications may be made to the disclosure recited above, while remaining within the scope of the invention. For example, the use of electromagnetic filed may prove beneficial in ensuring that imprint material fully fill the features on the mold, thereby avoiding discontinuities in the imprinting layer. Such discontinuities occur when imprinting material fails to fill the recessions of the mold. This may be due to various environment and material based parameters, such as capillary attraction between a protrusion and a surface in superimposition therewith. Applying an electromagnetic field to attract imprinting material to the mold will overcome these properties. Therefore, the scope of the invention should not be limited by the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.
Claims
1. A method for forming a conductive template, the method comprising:
- providing a substrate;
- forming a mesa on the substrate; and
- forming a plurality of recessions and projections on the mesa with a nadir of the recessions comprising electrically conductive material and the projections comprising electrically insulative material.
2. The method as recited in claim 1 wherein the mesa is substantially transparent to a predetermined wavelength of radiation.
3. The method as recited in claim 1 wherein forming further includes fabricating a plurality of spaced-apart electrically conductive region on the mesa.
4. The method as recited in claim 1 wherein forming the plurality of recessions further includes depositing a layer of conductive material on the substrate and depositing a layer of insulative material on the layer of conductive material; and patterning the insulative layer to form said plurality of recessions, with said plurality of projections extending from a surface of the substrate.
5. The method as recited in claim 1 wherein forming the plurality of recessions further includes depositing a layer indium tin oxide on the substrate and depositing a layer of insulative material on the layer of indium tin oxide.
6. The method as recited in claim 1 wherein forming the plurality of recessions further includes forming a plurality of spaced apart conductive regions on the substrate, with regions of the substrate not in superimposition with the spaced-apart conductive regions being exposed, defining exposed regions, and forming, on the exposed regions, electrically insulative material, with the electrically insulative material and the conductive regions forming a patterned layer having a plurality of vias.
7. The method as recited in claim 1 wherein forming further includes depositing a layer of patterning material on the template and patterning the patterning material to expose regions of the substrate disposed, defining a patterned layer, depositing a layer of conductive material on the patterned layer, and removing the patterned layer, thereby leaving a plurality of spaced-apart electrically conductive regions on the mesa and covering the plurality of spaced-apart electrically conductive regions with an electrically insulative layer and patterning the layer to expose the plurality of spaced-apart electrically conductive regions.
8. The method as recited in claim 1 wherein providing further includes forming the substrate from a material selected from a set of materials consisting essentially of quartz, fused-silica, silicon, sapphire, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, and metal.
9. The method as recited in claim 8 wherein the mesa allows ultraviolet radiation to propagate therethrough.
10. A method for forming a conductive template, the method comprising:
- providing a substrate;
- forming a mesa on the substrate, with the mesa consisting of material that is substantially transparent to a predetermined wavelength of radiation;
- forming a plurality of recessions and projections on the mesa with a nadir of a subset of the recessions including electrically conductive material to form a plurality of electrical conductive regions.
11. The method as recited in claim 10 wherein forming the plurality of recessions further includes forming the plurality of recessions from depositing a layer of indium tin oxide on the substrate, followed by depositing a layer insulative material on the layer on indium tin oxide.
12. The method as recited in claim 10 wherein forming the plurality of recessions further includes providing the plurality of electrically conducting regions to be selectively activated.
13. The method as recited in claim 10 wherein forming the plurality of recessions further includes depositing a layer of conductive material on the substrate and depositing a layer of insulative material on the layer of conductive material; and patterning the insulative layer to form a plurality of vias therein extending from a surface of the insulative layer and terminating in the layer of conductive material.
14. The method as recited in claim 10 wherein forming the plurality of recessions further includes forming a plurality of spaced apart conductive regions on the substrate, with regions of the substrate not in superimposition with the spaced-apart conductive regions being exposed, defining exposed regions, and forming, on the exposed regions, electrically insulative material, with the electrically insulative material and the conductive regions forming a patterned layer having a plurality of vias.
15. The method as recited in claim 10 wherein providing further includes forming the substrate from a material selected from a set of materials consisting essentially of quartz, fused-silica, silicon, sapphire, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, and metal.
16. A method for forming a conductive template, the method comprising:
- providing a substrate;
- forming a plurality of recessions and projections on the substrate with a nadir of a subset of the recessions including electrically conductive material to form a plurality of electrically conductive regions by depositing a plurality of spaced-apart conductive regions on the substrate, followed by depositing a layer insulative material on the layer on plurality of electrically conductive regions.
17. The method as recited in claim 16 wherein forming the plurality of recessions further includes providing the plurality of electrically conducting regions to be selectively activated.
18. The method as recited in claim 16 wherein forming the plurality of recessions further includes depositing the layer of indium tin oxide on the substrate and depositing a layer of insulative material on the layer of indium tin oxide; and patterning the insulative layer to form a plurality of vias therein extending from a surface of the insulative layer and terminating in the layer of indium tin oxide.
19. The method as recited in claim 16 wherein forming the plurality of recessions further includes forming the layer of indium tin oxide as a plurality of spaced apart conductive regions on the substrate, with regions of the substrate not in superimposition with the spaced-apart conductive regions being exposed, defining exposed regions, and forming, on the exposed regions, electrically insulative material, with the electrically insulative material and the conductive regions forming a patterned layer having a plurality of vias.
20. The method as recited in claim 16 wherein providing further includes forming the substrate from a material selected from a set of materials consisting essentially of quartz, fused-silica, silicon, sapphire, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, and metal.
21. A template, comprising:
- a substrate; and
- a plurality of spaced-apart electrically conductive regions disposed on the substrate, with the substrate and the electrically conductive regions both being substantially transparent to a predetermined wavelength of energy.
22. The template as recited in claim 21 wherein said predetermined wavelength of energy is ultra-violet radiation.
23. The template as recited in claim 21 where said substrate further includes a mesa, with a subset of said plurality of spaced-apart electrically conductive regions are disposed on said mesa.
24. The template as recited in claim 21 wherein said substrate if formed from fused-silica.
25. The template as recited in claim 21 wherein said plurality of spaced-apart conductive regions are formed from Indium Tin Oxide.
26. The template as recited in claim 21 further including a power supply connected to a subset of said plurality of spaced-apart conductive regions.
27. The template as recited in claim 26 further including a processor connected to said power supply to direct the operation thereof to apply electrical energy so said plurality of spaced-apart electrically conductive regions in a predetermined manner.
28. The template as recited in claim 26 further including a processor connected to said power supply to direct the operation thereof to apply electrical energy so said plurality of spaced-apart electrically conductive regions to sequentially apply electrical energy thereto.
29. The template as recited in claim 23 wherein said subset further includes all of said plurality of spaced-apart electrically conductive regions.
30. A method of creating a pattern on a body, said method comprising:
- arranging a liquid to be between a template and said body;
- orientating said template proximate to said liquid; and
- applying an electrical field between said template and said body move a portion of said liquid to avoid to spread said liquid over said body to form a film, while preventing discontinuities in said film.
31. The method as recited in claim 30 wherein applying further includes applying an electric field of sufficient magnitude to overcome capillary forces of said liquid between said template and said body.
32. The method as recited in claim 30 further including providing said template with an electrically conductive layer that is transparent to radiation that causes said liquid material to polymerize and cross-link and, with applying said electric field further including applying a voltage to said conductive layer.
33. The method as recited in claim 32 further including forming said template from fused-silica and including an electrically conductive layer that is transparent to radiation that causes said liquid material to polymerize and cross-link and, with applying said electric field further including applying a voltage to said conductive layer.
34. The method as recited in claim 33 wherein said radiation includes ultra-violet light.
35. The method as recited in claim 32 wherein providing further includes providing said template with a said electrically conductive layer that is contiguous in a region in superimposition with said liquid.
36. The method as recited in claim 35 wherein providing further includes providing said template with a plurality of spaced apart electrically conductive layers in a region in superimposition with said liquid.
37. The method as recited in claim 35 wherein providing further includes providing said template with a plurality of spaced apart electrically conductive layers in a region in superimposition with said liquid and consecutively applying a voltage to a subset of said plurality of spaced-apart electrically conductive layers.
38. The method as recited in claim 35 wherein providing further includes providing said template with a plurality of spaced apart electrically conductive layers and concurrently applying a common voltage level to a subset of said plurality of electrically conductive layers.
39. The method as recited in claim 35 wherein providing further includes providing said template with a plurality of spaced apart electrically conductive layers and concurrently applying differing voltage levels to a subset of said plurality of electrically conductive layers.
Type: Application
Filed: Nov 12, 2003
Publication Date: May 12, 2005
Applicant: MOLECULAR IMPRINTS, INC. (Austin, TX)
Inventors: Sidlgata Sreenivasan (Austin, TX), Ian McMackin (Austin, TX), Byung-Jin Choi (Round Rock, TX), Ronald Voisin (Austin, TX)
Application Number: 10/706,537