KR100546581B1 - Fabrication Method of Field Emission Device - Google Patents

Abstract

The present invention relates to a method of manufacturing a field emission device capable of low voltage driving.

The method of manufacturing a field emission device of the present invention comprises the steps of: stacking a cathode and a structure thin film on an arbitrary substrate; forming a structure by inclining the structure thin film using a hard mask pattern; and forming a emitter thin film; Removing the hard mask pattern, sequentially forming the insulating film and the gate film, and removing the insulating film and the gate film on the structure.

According to the present invention, the distance between the emitter and the gate can be minimized by removing the hard mask used for etching the structure and then depositing the insulating film and the gate film, thereby reducing the driving voltage.

Description

Fabrication Method of Field Emission Device {Fabrication Method of Field Emission Device}             

1 is a cross-sectional view showing the basic structure of the field emission display.

2 is a cross-sectional view of a tip-shaped field emission device manufactured by a conventional spin method.

3 is a cross-sectional view of a conventional volcanic field emission device.

4 is a cross-sectional view illustrating a method of manufacturing the volcanic field emission device shown in FIG.

5 is a cross-sectional view illustrating a method of manufacturing a field emission device in accordance with an embodiment of the present invention.

<Brief description of symbols for the main parts of the drawings>

10: lower substrate 12: cathode

14 emitter tip 16, 16A insulating film

18, 18A: gate film 20: upper substrate

22: anode 24: phosphor

26: vacuum space 28: electron

30: visible light 32, 32B: structure

32A: structure thin film 34, 34A: emitter thin film

36: hardmask pattern

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a field emission device used for field emission display or other electron emission in vacuum, and more particularly to a method for manufacturing a field emission device capable of low voltage driving.

Today, with the development of multimedia, the interest and importance of the display (play), which plays an important role, is increasing. In response to this, various flat panel displays, such as liquid crystal displays (LCDs) and plasma display panels (PDPs), have been developed and put into practical use. However, they have not yet achieved a satisfactory display in terms of viewing angle, high-speed response, high brightness, high definition, power consumption, and thinness. Currently, except for problems such as thinness, weight, and power consumption, cathode ray tube (CRT) This is close to the ideal display.

In recent years, field emission displays (hereinafter referred to as FEDs), which are attracting attention as next-generation displays, use phosphor emission by electron beams similarly to cathode ray tubes (CRTs). Accordingly, the FED is likely to be implemented as a flat panel display having low power consumption without distortion of the image while maintaining excellent characteristics of the cathode ray tube (CRT). In general, the FED is a triode like a conventional vacuum tube, but concentrates the high electric field on a sharp cathode, that is, an emitter, without using a hot cathode, and thus the electrons are attracted by a quantum mechanical tunnel effect. The cold cathode which emits is used. The electrons emitted from the emitter are accelerated by the voltage applied between the anode and the cathode and collide with the phosphor film formed on the anode to emit the phosphor. In other words, it is the same principle as the cathode ray tube (CRT) in that the phosphor emits light by electron collision.

1 is a cross-sectional view showing the basic structure of the FED, the FED shown in FIG. 1 is a cathode 12 formed on the lower substrate 10, an emitter tip 14 formed on the cathode 12, and the emitter tip (14) The insulating film 16 and the gate film 18 sequentially stacked on the cathode 12 around the upper substrate, the upper substrate 10 disposed to face the lower substrate 10, and the upper substrate 10. And a phosphor 24 coated on the surfaces of the anode 22 and the upper substrate 10. In addition, the space 26 provided inside the FED maintains a high vacuum state. In the FED shown in FIG. 1, the emitter tip 14 emits electrons into the vacuum by a high electric field formed with a voltage applied to the gate film 18 positioned adjacent to the sharp part. As such, the electrons 28 emitted from the emitter tip 14 are accelerated by the voltage applied between the cathode 12 and the anode 22 to collide with the phosphor 24 formed on the anode 12 to emit visible light. 30 will be released.

As such, as the field emission device applied to the FED, a tip shape as shown in FIG. 1 is representative. This tip type field emission device has a spint type emitter, which is formed of molybdenum (Mo) material by electron beam deposition, and a dry or wet type of silicon (Si) substrate (eg wafer or thin film). After forming the tip shape using an etching process, the surface of the silicon tip is oxidized at high temperature (1000 ° C.) to form a thermal oxide film, and then the silicon oxide (SiO 2) etching solution is used to remove the thermal oxide film to form the tip. There is a ruins. Here, silicon type emitters require high temperature thermal oxidation during the tip sharpening process, which makes it impossible to use large sized substrates such as glass, which limits the size of the display. Thermal stress is concentrated at the tip of the tip, so that the tip is easily broken and the surface of the silicon is easily changed by the residual gas, thereby deteriorating the electron emission characteristic of the tip. In addition, in the case of a spin type emitter in which a high melting point molybdenum (Mo) is formed by an electron beam deposition method, the tip has a longer life than the silicon tip, but there is a problem in that the manufacturing process is complicated.

Referring to Fig. 2, a cross-sectional view of a tip-shaped field emission device manufactured by the spin method (i.e., rotary deposition method) is shown.

Referring to the manufacturing process of the field emission device by the spin method, first, the cathode 12, the insulating film 16, and the gate film 18 are sequentially formed on the lower substrate 10, and then the gate film ( 18) and the insulating film 16 are sequentially etched to provide a tip formation space. Subsequently, molybdenum (Mo) material is deposited while rotating the lower substrate 10 to form the emitter tip 14 in the tip forming space. Then, the molybdenum material deposited on the gate film 18 is removed to complete the field emission device.

As such, the spin type emitter requires an angle adjustment of the beam when the molybdenum (Mo) film is deposited on the electron beam, and thus the tip shape is uneven when the device is implemented on a large substrate. In this case, since electron emission is concentrated only on a specific tip, there is a high possibility that the tip may be broken, and thus there is a limitation in applying to a large display. In addition, the tip-type emitter described above is limited to materials such as molybdenum (Mo) and silicon (Si) as a material of the emitter in the process, so that the application of low work function materials such as TiN and LaB6 is impossible. There is a limit to improvement.

In order to solve the shortcomings of the tip type field emission device, a volcanic field emission device as shown in FIG. 3 has emerged. The volcanic field emission device can use a low-cost, large-area glass substrate, etch the emitter structure 34 by etching without sputtering, and by sputtering the side surface of the structure, low work function and high Forming an emitter 32 by forming a material having a melting point and forming an insulating film 16 and a gate film 18 by a self-alignment method by electron beam deposition can easily produce a triode-type field emission device. There is a characteristic. Such volcanic emitters have a higher electron emission area compared to tip-type emitters, resulting in higher emission currents, which makes it possible to manufacture devices with high efficiency, and when chemical / mechanical stability materials are used as emitters (32) for a long time. There is an advantage that can be produced a stable field emission device having a lifetime of.

Referring to FIG. 4, a method of manufacturing the volcanic field emission device shown in FIG. 3 is illustrated in stages.

As shown in FIG. 4A, an electrode such as aluminum (Al) is formed on the lower substrate 10 using a thin film deposition method such as sputtering or electron beam deposition. On the cathode 12, a structure thin film 32A made of metal such as silicon (Si) and molybdenum (Mo) is formed. A hard mask pattern 36 for etching the structure thin film 32A is formed on the structure thin film 32A. The hard mask pattern 36 is formed by applying a hard mask thin film and then using a lithography process to pattern the film to a desired size and shape. As the material of the hard mask pattern 44, each material constituting the device, SiO 2, Si 3 N 4, or a metal material having a large etching selectivity is used. Next, the sidewall is inclined as shown in (b) by etching the structure thin film 32A exposed through the hard mask pattern 36 so that the side is inclined by using reactive ion etching (RIE) or wet etching. To form the structure (32B). The emitter thin films 34 and 34A are formed on the surface of the structure 32B and the hard mask pattern 36 by the sputtering method as shown in (c). In this case, the thickness of the emitter foils 34 and 34A is adjusted by adjusting sputtering conditions such as pressure and power. The materials of the emitter thin films 34 and 34A are conductive as well as a TiN thin film having a low work function (for example, 2.9 eV for TiN and 4.3 eV for molybdenum) and high melting point (for example, 3000 ° C.). Various materials such as nitrides such as ZrN and HfN, carbides such as ZrC and HfC, or metals such as molybdenum (Mo), chromium (Cr), and tantalum (Ta) may be used. As shown in (d) on the emitter thin films 34 and 34A, the insulating films 16 and 16A made of SiO2 and the like, and the gate thin films 18 and 18A made of chromium (Cr) and molybdenum (Mo). Are sequentially deposited using an electron beam deposition method. Subsequently, as shown in (e), the hard mask pattern 364 on the structure 32B is wet-etched together with the emitter thin film 34A, the insulating film 16A, and the gate thin film 18A stacked thereon. Will be removed. As a result, the triode form is completed by self-alignment without the need for a separate lithography process. Finally, by etching the structure 32B inside the emitter thin film 34 with SiO 2 etchant, the final triode type field emission device as shown in (f) is completed.

As described above, the conventional volcanic field emission device fabrication process is easily triode using an electron beam characteristic that is not deposited on the lower portion of the hard mask pattern used for etching the insulating film and the gate thin film by the electron beam deposition method. There is an advantage in that the structure can be manufactured. In the field emission device of such a structure, the driving voltage becomes lower as the distance d between the emitter and the gate is narrowed. However, in the conventional field emission device manufacturing method, the distance between the emitter and the gate depends on the size of the hard mask pattern used to etch the structure. However, there is a limitation in reducing the gap, which leads to a high driving voltage. In addition, even when the size of the conventional hard mask pattern for structure etching is uniform, the distance between the emitter and the gate becomes uneven when the shape between the structures becomes uneven due to the problem of the etching process, so that the characteristics of the field emission device become uneven. .

Accordingly, it is an object of the present invention to provide a method of manufacturing a field emission device which enables low voltage driving and has a uniform electron emission characteristic.

In order to achieve the above objects, the method for manufacturing a field emission device according to the present invention comprises the steps of laminating a cathode and a structure thin film on any substrate, and forming a structure by inclining the structure thin film using a hard mask pattern, Forming an emitter thin film, removing a hard mask pattern, sequentially forming an insulating film and a gate film, and removing the insulating film and the gate film on the structure.

Other objects and advantages of the present invention in addition to the above object will be apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIG. 5.

Referring to FIG. 5, a method of manufacturing a volcanic field emission device according to an embodiment of the present invention is illustrated in stages.

First, as shown in (a), a cathode 12 made of aluminum (Al) or the like is formed on the lower substrate 10 by using a thin film deposition method such as sputtering or electron beam deposition. On the cathode 12, a structure thin film 32A made of metal such as silicon (Si) and molybdenum (Mo) is formed. The hard mask pattern 36 is formed on the structure thin film 32A for etching the structure thin film 32A in a later process. The hard mask pattern 36 is formed by applying a hard mask thin film and then using a lithography process to pattern the film to a desired size and shape. As the material of the hard mask pattern 36, SiO ₂ , Si ₃ N ₄ , or a metal material having a high etching selectivity is used so as not to be etched when the structure thin film 32A is etched.

Next, the sidewalls are inclined as shown in (b) by etching the structure thin film 32A exposed through the hard mask pattern 36 to be inclined by side using reactive ion etching (RIE) or wet etching. To form the structure (32B). In this case, the inclination of the structure 32B can be optimally set by adjusting the etching conditions. For example, in case of using reactive ion etching (RIE), the gas type and concentration ratio, power and vacuum degree of reactive ion etching (RIE) are controlled, and in case of wet etching, the type and concentration ratio of etching solution, etching time, etc. 32B) has an optimal shape.

The emitter thin films 34 and 34A are formed on the surface of the structure 32B and the hard mask pattern 36 by the sputtering method as shown in (c). In this case, the thickness of the emitter foils 34 and 34A is adjusted by adjusting sputtering conditions such as pressure and power. The materials of the emitter thin films 34 and 34A are conductive as well as a TiN thin film having a low work function (for example, 2.9 eV for TiN and 4.3 eV for molybdenum) and high melting point (for example, 3000 ° C.). Various materials such as nitrides such as ZrN and HfN, carbides such as ZrC and HfC, or metals such as molybdenum (Mo), chromium (Cr), and tantalum (Ta) may be used.

Subsequently, as shown in (d), the hard mask pattern 36 used to etch the structure thin film 32A is removed using a wet etching method. In this case, the emitter thin film 34A deposited on the hard mask 36 is also removed.

As shown in (e), the insulating films 16 and 16A and the gate thin films 18 and 18A are sequentially deposited on the emitter thin film 34 and the structure 32B. In this case, the insulating films 16 and 16A may be deposited using electron beam deposition, sputtering, chemical vapor deposition (CVD), etc., but the gate thin films 18 and 18A may be deposited by electron beam deposition having a high linearity of particles during deposition. Alternatively, the deposition may be performed using any one of thermal deposition. When the gate thin films 18 and 18A are deposited, the slope of the side of the structure 32B is severe and the step 32 of the structure 32B is large. Since a discontinuous portion is generated at regular intervals between the gate thin films 18, the distance between the emitter 34 and the gate 16 is also maintained at a constant interval. In this case, the distance between the emitter 34 and the gate 16 is a very short distance compared to the distance between the emitter and the gate when the insulating film and the gate thin film are deposited with the conventional hard mask pattern 36 remaining. In addition, the distance between the emitters is maintained regardless of the etching shape of the structure. As a result, the driving voltage can be reduced by reducing the emitter and gate spacing, and the uniformity of the electron emission characteristic is improved because the emitter and gate spacing are kept constant. As the material of the insulating film, a conventional insulating material such as SiO 2, Al 2 O 3, Ta 2 O 5, or the like is used. As the gate material, a metal such as Ta, Mo, Nb, Cr, W, etc., which has a large selectivity in wet etching and a high chemical and thermal stability, is used as the gate material.

Subsequently, as shown in (f), the insulating film 16A and the gate thin film 18A stacked on the structure 32B are removed using the etchant of the insulating film 16A. At the same time, a portion of the insulating film deposited around the emitter is etched to reduce the leakage current flowing through the insulating film surface to the gate. Finally, the structure 32B inside the emitter thin film 34 is etched with SiO 2 etchant to form the volcanic structure 32 as shown in (f) to complete the triode type field emission device. Done.

As described above, in the conventional manufacturing method of the volcanic emission device, the insulating film and the gate film are deposited by the electron beam deposition method to remove the hard mask used for etching the structure, whereas the method of manufacturing the field emission device according to the present invention is a structure. After removing the hard mask used for etching, the insulating film and the gate film are formed by electron beam deposition. As a result, since the distance limitation between the emitter and the gate due to the hard mask pattern is eliminated, the distance between the emitter and the gate can be minimized.

As described above, according to the method of manufacturing the field emission device according to the present invention, by removing the hard mask used for etching the structure and depositing an insulating film and a gate film, the distance between the emitter and the gate is not limited by the distance between the emitter and the gate by the hard mask pattern. Since the distance can be minimized, the driving voltage can be reduced. In addition, according to the method for manufacturing a field emission device according to the present invention, since the distance between the gate and the emitter can be made constant, a device having a uniform electron emission characteristic can be manufactured.                     

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (5)

Stacking a cathode and a structure thin film on any substrate; Diagonally etching the structure thin film using a hard mask pattern to form a structure; Depositing an emitter thin film, Removing the hard mask pattern; Sequentially applying the entire insulating film and the gate film; And removing the insulating film and the gate film on the structure. The method of claim 1, And said emitter thin film is formed by a sputtering method. The method of claim 1, The gate film is a field emission device manufacturing method characterized in that the film is formed by any one of the electron beam evaporation method and thermal evaporation method having a large linearity of the particles during deposition. The method of claim 1, Removing the insulating film and the gate film Etching a portion of the insulating film formed around the emitter thin film; And etching the tip of the emitter thin film inner structure. The method of claim 1, The material of the gate thin film manufacturing method of the field emission device, characterized in that the structure and the insulating film and the wet etching selectivity, a metal film having a large chemical and thermal stability is used.

Images