Patent Number: 
Section: description

Korean Patent Application No. 2001-31125, filed on Jun. 4, 2001, and entitled: xe2x80x9cElectron Emission Lithography Apparatus and Method Using Selectively Grown Carbon Nanotube,xe2x80x9d is incorporated by reference herein in its entirety. FIG. 1 illustrates a sectional view of an electron emission lithography apparatus using a carbon nanotube as an electron emission source according to an embodiment of the present invention. The structure of the electron emission lithography apparatus using a selectively grown carbon nanotube as an electron emission source according to an embodiment of the present invention will now be described. A sample 14, on which an e-beam resist 15 to be patterned is formed, is disposed above and a predetermined distance apart from a substrate 12, on which carbon nanotubes 11 acting as electron emission sources are formed, within a chamber. The substrate 12 and the sample 14 are positioned between magnetic field generators 13 and 13xe2x80x2 for controlling the paths of electrons emitted from the carbon nanotubes 11. A voltage apply unit 16, which applies voltage to emit electrons from the carbon nanotubes, is provided separately. The magnetic field generators 13 and 13xe2x80x2 are designed to precisely control a magnetic field according to the distance between the carbon nanotubes 11 and the sample 14 to be patterned so that the electrons 17 emitted from the carbon nanotubes 11 can reach corresponding positions on the sample 14. The following description relates to an electron emission lithography method using a carbon nanotube as an electron emission source. As shown in FIG. 1, if voltage is applied from the voltage apply unit 16 to each of the carbon nanotubes 11, an electron 17 is emitted from the tip of the carbon nanotube 11. Here, the emitted electron 17 must reach a desirable position 15xe2x80x2 on the sample 14 on which the e-beam resist 15 is formed. A track of the movement of the electron 17 emitted from the carbon nanotube 11 is controlled by a magnetic field precisely controlled by the magnetic field generators 13 and 13xe2x80x2. The electron 17 spirals one time and reaches a desirable position 15xe2x80x2 on the surface of the sample 14 coated with the e-beam resist 15. In other words, the electron 17 emitted from the carbon nanotube 11 reaches a predetermined position 15xe2x80x2, which corresponds to the carbon nanotube 11 on the sample 14 coated with the e-beam resist 15, due to a magnetic field. Consequently, the shape of the carbon nanotube 11 formed on the substrate 12 can be projected upon the sample 14. Accordingly, a lithography process is performed on the sample 14 in a desired pattern. Thereafter, if a developing process is performed, portions of the e-beam resist 15 exposed to an electron beam (i.e., 15xe2x80x2) remain when the e-beam resist 15 is negative, while portions of the e-beam resist 15 not exposed to an electron beam remain when the e-beam resist 15 is positive. FIGS. 2A and 2B illustrate perspective views of two embodiments of an electron emitter formed by selectively growing carbon nanotubes using nano templates and patterning them in a desired shape in an electron emission lithography apparatus using a carbon nanotube as an electron emission source according to the present invention. In FIG. 2A, carbon nanotubes 11 are selectively grown from desired portions on a porous substrate 12. In FIG. 2B, an insulator thin film 18 is deposited on the top portions of the carbon nanotubes 11 grown on the substrate 12 in order to emit electrons from the carbon nanotubes 11 in a desired pattern. FIGS. 3A and 3B illustrate an electron emission lithography method using a carbon nanotube as an electron emission source according to an embodiment of the present invention. In FIGS. 3A and 3B, electron beams have reached the desired position of an e-beam resist 15xe2x80x2, and the desired positions of the e-beam resist 15xe2x80x2 have been developed and patterned. In this case, the e-beam resists 15 and 15xe2x80x2 are negative. Alternatively, if the e-beam resists 15 and 15xe2x80x2 were positive, the exposed e-beam resist 15xe2x80x2 would be removed, as described above. A method of manufacturing an electron emission lithography array using a selectively grown carbon nanotube as an electron emission source according to the present invention will be described with reference to FIGS. 4A through 4E. FIGS. 4A through 4E illustrate the steps of a manufacturing process of the electron emission lithography array according to an embodiment of the present invention. Holes 19 are formed at positions where carbon nanotubes 11 are to be grown in a substrate 12 by an anodizing process. As shown in FIG. 4A, a first anodizing process is performed on the substrate 12, for example, an aluminum (Al) substrate. As a result, the holes 19 where the carbon nanotubes 11 are to be grown are formed in the substrate 12. Next, as shown in FIG. 4B, a second anodizing process is performed to deepen the holes 19, thereby forming nano templates 20. The nano templates 20 define positions where the carbon nanotubes 11 are to grow and preferably have a diameter of about 1000 nm or less. After the first and second anodizing processes are completed, the Al substrate is oxidized into Al2O3. Next, as shown in FIG. 4C, a carbon nanotube growth gas 21 is injected into the substrate 12 having the nano templates 20, thereby growing the carbon nanotubes 11. Preferably, methane is used as the carbon nanotube growing gas, and preferably, argon or nitrogen gas is used as a diluent gas. As shown in FIG. 4D, the carbon nanotubes 11 can be grown in a desired pattern and directly used as electron emission sources. Alternatively, as shown in FIG. 4E, a nonconductive layer 18, for example, an SiO2 layer, is formed on the substrate 12 having the grown carbon nanotubes 11 and is patterned using an electron beam to have a desired pattern. FIGS. 5A and 5B are transmission electron microscope (TEM) photos of carbon nanotube electron emission arrays formed by vertically growing carbon nanotubes 11 as electron emission sources in the substrate 12 according to the method illustrated by FIGS. 4A through 4E using an electron emission lithography apparatus according to the present invention. A carbon nanotube electron emission array can be very precisely manufactured through the above-described process. As described above, according to the present invention, since carbon nanotubes are used as electron emission sources, a lithography process can be performed with a precise critical dimension. In addition, since electrons emitted from carbon nanotubes depreciate portions of an e-beam resist corresponding to the carbon nanotubes, a deviation between the center of a substrate and the edge thereof can be prevented. Preferred embodiments of the present invention have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.