Patent Application
20070221624
This application claims priority to and the benefit of Korean Patent Application No. 10-2006-0026524 filed on Mar. 23, 2006 in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an electron emission device, and more particularly, to an electron emission device having openings formed through a second electrode and an insulating layer, a method of manufacturing the electron emission device, and an electron emission display having the electron emission device.
2. Description of Related Art
A typical electron emission device using Field Emission Array (FEA) elements includes a first substrate on which first electrodes, an insulating layer, and second electrodes are successively formed. Openings are formed through the second electrodes and the insulating layer at each crossed region of the first and second electrodes to partly expose the surfaces of the first electrodes. The electron emission regions are formed on the exposed surfaces of the first electrodes through these openings.
These openings are usually formed through the second electrodes and the insulating layer through a wet-etching process using a mask layer. In this process, a mask layer is formed on the substrate and covers the second electrodes. Openings in the mask layer expose portions of the second electrodes. These exposed portions are etched to form the openings in the second electrodes. Then, the portions of the insulating layer that are exposed by the openings in the second electrodes are etched to form the openings in the insulating layer.
The second electrodes have a thickness in the range of thousands of angstrom (Å) while the insulating layer has a thickness of several micrometers (μm). In addition, the upper widths (or diameters) of the openings in the insulating layer increase as the etching depth increases due to the isotropic nature of the wet-etching process. As a result, when the wet-etching process is finished, the upper widths of the openings in the insulating layer, on which the second electrode is formed, become greater than those of the corresponding openings in the second electrodes.
Therefore, portions of the second electrodes may be suspended above the openings in the insulating layer, thereby decreasing shape stability and pattern preciseness. In addition, in the course of forming the electron emission regions through the openings of the insulating layer, the portions of the second electrodes that lie above the openings in the insulating layer, may be broken away. When the broken pieces contact the electron emission regions or the first electrodes, a short circuit may occur between the first and second electrodes. This may cause product defectiveness.
One embodiment of the present invention provides an electron emission device in which openings formed through a second electrode are precisely aligned with corresponding openings formed through an insulating layer, a method of manufacturing the electron emission device, and an electron emission display including the electron emission device.
According to an embodiment of the present invention, a method is provided for manufacturing an electron emission device including a first electrode disposed on a first substrate, an electron emission region disposed on the first electrode, and a second electrode disposed on the first electrode with an insulating layer interposed between the first and second electrodes, the insulating layer and the second electrode being provided with openings for exposing the electron emission region, the method including forming a mask layer having an opening on the second electrode; forming the opening in the second electrode by etching the second electrode using the mask layer; forming the opening in the insulating layer by wet-etching the insulating layer wherein a width of the opening in the insulating layer at an upper portion is greater than a width of the opening in the second electrode; enlarging the opening in the second electrode by etching an exposed portion of the second electrode exposed to the opening in the insulating layer; and removing the mask layer.
The etching of the exposed portion of the second electrode may be a wet-etching performed by filling the opening in the insulating layer with a first etching solution for etching the second electrode.
After the opening in the second electrode is enlarged by etching the exposed portion of the second electrode, the width of the opening in the second electrode may be greater than the width of the opening in the insulating layer.
The first electrode may be formed of a conductive material having a corrosion-resistance against the first etching solution.
The method may further include, after the removing of the mask layer, forming the electron emission region on the first electrode, wherein the electron emission region is formed of a material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbon, C60, silicon nanowires, and combinations thereof.
In one embodiment, there is provided an electron emission device manufactured by the above-described method, wherein a distance between a center of the opening in the insulating layer and a center of the opening in the second electrode is less than 0.5 μm.
According to still another embodiment, there is provided an electron emission display including: an electron emission device manufactured by the above-described method, a second substrate facing the first substrate with a vacuum region formed between the first and second substrates, and phosphor layers disposed on a surface of the second substrate facing the first substrate, an anode electrode disposed on the phosphor layers, wherein a distance between a center of the opening in the insulating layer and a center of the opening in the second electrode is less than 0.5 μm.
In another embodiment, there is provided a method of manufacturing an electron emission device including a first electrode disposed on a first substrate, an electron emission region disposed on the first electrode, a second electrode disposed on the first electrode with a first insulating layer interposed between the first and second electrodes, and a third electrode disposed on the second electrode with a second insulating layer interposed between the second and third electrodes, wherein the first insulating layer, the second electrode, the second insulating layer, and the third electrode are provided with openings for exposing the electron emission region, the method including: forming a first mask layer having an opening on the third electrode; forming the opening in the third electrode by etching the third electrode using the first mask layer; forming the opening in the second insulating layer by wet-etching the second insulating layer, wherein a width of the opening in the second insulating layer at an upper portion is greater than a width of the opening in the third electrode; enlarging the opening in the third electrode by etching an exposed portion of the third electrode exposed to the opening in the second insulating layer; removing the first mask layer; forming a second mask layer having an opening on the second electrode; and forming the opening in the second electrode by etching the second electrode using the second mask layer.
The method may further include: forming the opening in the first insulating layer by wet-etching the first insulating layer, wherein a width of the opening in the first insulating layer at an upper portion is greater than a width of the opening in the second electrode; enlarging the opening in the second electrode by etching an exposed portion of the second electrode exposed to the opening in the first insulating layer; and removing the second mask layer.
The etching of the exposed portion of the third electrode may be a wet-etching performed by filling the opening in the second insulating layer with a second etching solution for etching the third electrode.
After the opening in the third electrode is enlarged by etching the exposed portion of the third electrode, a width of the opening in the third electrode may be greater than a width of the opening in the second insulating layer.
The second electrode may be formed of a conductive material having a corrosion-resistance against the second etching solution.
According to yet another embodiment of the present invention, there is provided an electron emission device manufactured by the above method, wherein a distance between a center of the opening in the second insulating layer and a center of the opening in the third electrode may be less than 0.5 μm.
According to yet another embodiment of the present invention, there is provided an electron emission display, including: an electron emission device manufactured by the above method; a second substrate facing the first substrate with a vacuum region formed between the first and second substrates; and phosphor layers disposed on a surface of the second substrate facing the first substrate; and an anode electrode disposed on the phosphor layers, wherein a distance between a center of the opening in the second insulating layer and a center of the opening in the third electrode is less than 0.5 μm.
The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention.
In the following description, only certain exemplary embodiments of the present invention are shown and described, by way of illustration. As those skilled in the art would recognize, the described exemplary embodiments may be modified in various ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not restrictive.
Referring first to
Another conductive layer is formed on the insulating layer 14 and processed to form second electrodes 16 having a stripe pattern crossing the first electrodes 12 at right angles. The first electrodes 12 may be formed of a transparent material such as indium tin oxide (ITO) while the second electrodes 16 may be formed of a metal material such as Chromium (Cr) or Molybdenum (Mo).
Referring to
Referring to
Referring to
At this point, since the upper widths of the openings 141 in the insulating layer 14 gradually increase as the etching depths increase due to the isotropic nature of the wet-etching process, the upper widths of the openings 141 in the insulating layer 14, on which the second electrodes 16 are formed, become greater than those of each of the corresponding openings 161 in the second electrodes 16. Therefore, portions of the second electrodes 16 may be suspended above the openings 141 in the insulating layer 14, thereby decreasing shape stability and pattern preciseness.
Referring to
At this point, by controlling the dipping time of the substrate structure in the first etching solution, the widths of the openings 161 in the second electrodes 16 can be adjusted. That is, when the dipping time is relatively long, the first etching solution permeates between the mask layer 18 and the insulating layer 14 to etch the openings 161 in the second electrodes 16 such that the widths of the openings 161 in the second electrodes 16 are greater than those of the corresponding openings 141 in the insulating layer 14.
In the above process, since portions of the first electrodes 12 are exposed to the first etching solution, the first electrodes 12 are formed of a material different from that of the second electrodes 16. That is, the first electrodes 12 are formed of a material having a corrosion-resistance against the first etching solution so as not to be etched when the second electrodes 16 are etched.
Next, the mask layer 18 is removed and, as shown in
The electron emission regions 20 may be formed of a material such as a carbonaceous material or a nanometer-sized material. For example, the electron emission regions 20 can be formed of a material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbon, C60, silicon nanowires, and combinations thereof.
The electron emission regions 20 can be formed by preparing a paste mixture by mixing vehicles, binder and the like, screen-printing the paste mixture on the exposed portions of the first electrodes 12, and drying and firing the printed mixture.
The first electrodes 12 may be cathode electrodes for applying electric current to the electron emission regions 20 while the second electrodes 16 may be gate electrodes for inducing electron emission by forming an electric field around the electron emission regions.
As described above, since the second electrodes 16 are etched again after the openings 141 of the insulating layer 14 are formed, no portion of the second electrodes 16 is suspended above the openings 141 in the insulating layer 14. As a result, the shape stability of the second electrodes 16 can be improved and a short circuit between the first and second electrodes 12 and 16 can be prevented during the forming of the electron emission regions 20.
In addition, referring to
In the electron emission device shown in
Referring to
The first electrodes 12 are formed on the first substrate 22 and the insulating layer 14 is formed on the first substrate 22 to fully cover the first electrodes 12. The second electrodes 16 are formed on the insulating layer 14, crossing the first electrodes 12 at right angles. The openings 161 and 141 are formed respectively through the insulating layer 14 and the second electrodes 16 at each crossed region of the first and second electrodes 12 and 16 to expose the electron emission regions 20.
At this point, the openings 161 and 141 are formed in the second electrodes 16 and the insulating layer 14, respectively, using the above described method illustrated with reference to
Phosphor layers 26 such as red (R), green (G) and blue (B) phosphor layers 26R, 26G and 26B are formed on a surface of the second substrate 24 opposite to the first substrate 22, and black layers 28 are arranged between the phosphor layers 26. Each crossed region of the first and second electrodes 12 and 16 corresponds to a single color phosphor and define a pixel region.
An anode electrode 30 is formed of a conductive material such as aluminum, and is formed on the phosphor and black layers 26 and 28. The anode electrode 30 increases the screen luminance by receiving the high voltage required to accelerate the electron beams traveling from the first substrate 22 toward the second substrate 24 and by reflecting the visible light rays radiated from the phosphor layer 26, toward the first substrate 22 to the second substrate 24, thereby increasing the screen's luminance.
Disposed between the first and second substrates 22 and 24 are spacers (not shown) for uniformly maintaining a gap against outer forces between the first and second substrates 22 and 24. The spacers are arranged on the black layers 28 and do not trespass onto the phosphor layers 26.
The above-described electron emission display is driven when a certain (e.g., predetermined) voltage is applied to the first, second and anode electrodes 12, 16 and 30.
For example, referring to
Electric fields are formed around the electron emission regions 20 of pixels where a voltage difference between the first and second electrodes 12 and 16 is equal to or greater than a threshold value, and thus, the electrons are emitted from the electron emission regions 20. The high voltage applied to the anode electrode 30 causes the emitted electrons to strike the phosphor layers 26 of the corresponding pixel, thereby exciting the phosphor layers 26.
Referring to
Another conductive layer is formed on the first insulating layer 38 and processed to form second electrodes 40 having a stripe pattern crossing the first electrodes 36 at right angles. Another insulating material is deposited on the first insulating layer 38 to cover the second electrodes 40 to form a second insulating layer 42. Another conductive layer is formed on the second insulating layer 42 to form a third electrode 44.
Referring to
Referring to
Referring to
Referring to
In the above process, since portions of the second electrodes 40 are exposed to the first etching solution, the second electrodes 40 are formed of a material different from that of the third electrodes 44. That is, the second electrodes 40 are formed of a material having a corrosion-resistance against the first etching solution so as not to be etched when the third electrodes 44 are etched.
Next, the first mask layer 46 is removed and, referring to
Referring to
Referring to
Referring to
In the above process, since portions of the first electrodes 36 are exposed to the third etching solution, the first electrodes 36 can be formed of a material different from that of the second electrodes 40. That is, the first electrodes 36 can be formed of a material having a corrosion-resistance against the third etching solution so as not to be etched when the second electrodes 40 are etched.
Next, the second mask layer 48 are removed and, referring now to
According to this embodiment, since the third electrodes 44 are secondarily etched after the openings 421 in the second insulating layer 42 are formed and the second electrodes 40 are secondarily etched after the openings 381 in the first insulating layer 38 are formed, the shape stability of the third and second electrodes 44 and 40 can be improved and the shape preciseness of the openings 441 and 401 can also be improved.
An electron emission display according to this embodiment of the present invention includes first and second substrates 22′ and 24′ facing each other and spaced apart by a certain (e.g., predetermined) distance. A sealing member (not shown) is provided at the peripheries of the first and the second substrates 22′ and 24′ to seal them together.
The first insulating layer 38 is formed on the first substrate 22′ to cover the first electrodes 36 and the second insulating layer 42 is formed on the first insulating layer 38 to cover the second electrodes 40. The third electrode 44 is formed on the second insulating layer 42.
One opening 441 is formed on the third electrode 44 at each crossed region of the first and second electrodes 36 and 40 to generally focus the electrodes emitted from one pixel region. Alternatively, one opening is formed on the third electrode 44 to correspond to one electron emission region 50 to individually focus the electrons emitted from one electron emission region 50. The former is applied to this embodiment.
The third electrode 44 receives 0V or a negative DC voltage of several to tens of volts. Therefore, the third electrode 44 converges the electrons to a central portion of bunched electron beams by applying repulsive force to the electrons.
As the method depicted in
In addition, the difference between the upper circumference of each of the openings 441 in the third electrode 441 and the upper circumference of the corresponding opening 421 in the second insulating layer 42 is less than 1 μm. The difference between the upper circumference of each of the openings 401 in the second electrodes 40 and the upper circumference of the corresponding opening 381 in the first insulating layer 38 is also less than 1 μm.
While the invention has been described in connection with certain exemplary embodiments, it is to be understood by those skilled in the art that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications included within the spirit and scope of the appended claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0026524 | Mar 2006 | KR | national |
