KR19980048923A - Method of manufacturing field emission device having self-aligned focusing electrode - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a field emission device having a focusing electrode, wherein a cathode tip (7) is formed on a substrate (1), and a gate insulating film (8) and an electrode metal film or a conductive film are sequentially formed. After that, the gate film is patterned by a CMP method to expose the upper portion of the cathode tip 7 to a predetermined width to define the gate electrode 6, and the focusing electrode insulating film 10 and the focusing electrode metal film on the exposed substrate. Alternatively, after the conductive film 11a is formed, the focusing electrode film 11a is patterned by a CMP method to form a focusing electrode, and the focusing electrode insulating film 10 and the gate insulating film exposed through the focusing electrode 11 are formed. 6) is etched to expose the cathode tip 7 into the air to produce a field emission device.

The field emission device of the present invention can form the cathode tip, the gate electrode and the focusing electrode symmetrically, and can improve the focusing speed of the electron beam, thereby manufacturing a high-definition device when manufacturing a flat panel display.

Description

Fabrication method of FED with self-aligned focusing electrode

The present invention relates to a field emission device, and in particular, a focusing electrode for focusing electrons emitted from the cathode tip of the field emission device can be formed on the upper side of the gate electrode to improve the focusing speed of the electrons emitted from the cathode tip. A method for manufacturing a field emission device.

Field emission devices (field emission displays) are attracting attention as display devices having the advantages of a thin image such as a cathode ray tube and a light and thin element such as a flat panel display.

As shown in FIG. 1, the field emission device includes an insulator or semiconductor substrate 1 on which the cathode tip 7 is formed, and a cathode tip 7 on the substrate 1 via an insulating film 8. Substrate 1 as a lower plate, an ITO electrode 31 as an upper electrode, and red, green, and blue phosphors formed thereon, formed with a gate electrode 6 formed so as to surround an upper end of a predetermined space. And a spacer 33 for maintaining a predetermined space between the substrate 1 and the upper plate 30, and a transparent glass upper plate 30 including the pixel 32.

In the planar structure of the field emission device having such a configuration, as shown in Fig. 5, the well 20, which is a high concentration impurity region for forming a cathode electrode traveling in a predetermined direction, is formed on the substrate. A plurality of cathode tips 7 are formed in a portion of the area 20, and the gate electrode 6 and the focusing electrode which are formed at an angle of 90 ° with the well 20 above the cathode tips 7. (11) is formed.

The well 20 is connected to an external power source through an electrode 21 and a contact portion 22, and the electrode 21 is connected to a power source through a pad 23, and a gate electrode 6. It is connected via the pad 24, and has the structure which external power is applied.

The field emission device having such a configuration maintains a constant distance between the cathode and anode electrodes using a spacer 33 at a constant height in order to accelerate electrons emitted from the cathode tip as shown in FIG. As the spacing increases, the emitted electrons are accelerated, but the emitted electron beam spreads away from the cathode tip 7, resulting in a lower resolution of the pixels of the display.

Therefore, although the height of the spacer 33 may be reduced to some extent in order to improve the resolution of pixels of the display, reducing the height reduces the distance from which electrons receive acceleration energy, vacuum packaging, and uniformity of the spacer. It is necessary to maintain a certain interval by, for example.

As one of the methods for solving the problem of electron spreading, there is a method of forming a focusing electrode on the top of the gate electrode when collecting the cathode tip array of the field emission device.

For example, in the field emission device, electrons are emitted by a high voltage applied to the cathode tip 7, and electrons are accelerated and focused by applying a positive voltage to the ITO electrode 31 and the gate electrode 6, and thus the ITO electrode. The phosphor of the pixel 32 formed on the (31) is blown, and the image is displayed using the principle that the excited phosphor material receives energy from electrons and emits light.

Therefore, the display efficiency of the field emission device is determined by the energy of the electrons emitted from the cathode tip 7 striking the phosphor of the pixel. As a method for accelerating and focusing the emitted electrons, the edge of the cathode tip is sharpened. To prevent the electrons emitted from spreading widely, to minimize the diameter of the opening formed by the gate electrode, to improve the focusing force of the emitted electrons, and to further form a focusing electrode as described above. There is a method of focusing electrons in the costume again.

2A and 2B are schematic diagrams for explaining the difference between the electron collecting speeds when the focusing electrode is not used and when the focusing electrode is used.

As shown in FIG. 2A, when the focusing electrode is not used, the electrons emitted from the cathode tip 7 are focused only by the gate electrode 6, so that the electrons move away from the emitter electrode 7. Spread out.

On the contrary, as shown in FIG. 2B, when the focusing electrode 11 is further formed on the top of the gate electrode 6, the electron beam emitted from the emitter electrode 7 is formed on the top of the gate electrode 6. By focusing once again by the electric field of the formed focusing electrode 11, it is possible to prevent the spread of electrons as shown in Figure 2a.

In the conventional method of manufacturing the field emission device having the focusing electrode 11, the silicon tip or the silicon film is isotropically etched to make the tip of the cathode tip 7 sharp, and then subjected to e-beam evaporation. As a result, the gate oxide film and the metal for forming the gate electrode were sequentially deposited two times, and the oxide film was etched by a lift-off method to simultaneously fabricate the field emission gate electrode 6 and the electron focusing electrode 11.

3A to 3F are cross-sectional views illustrating a method of manufacturing a field emission device according to the related art.

The method of forming the focusing electrode according to the related art will be described with reference to FIGS. 3A to 3F as follows.

First, as shown in FIG. 3A, an insulating film pattern 4 made of a nitride film having a predetermined width, for example, a width designed according to the size of a cathode tip, is formed on a semiconductor substrate 1 such as silicon, amorphous silicon, polycrystalline silicon, or the like. To form.

Subsequently, as shown in FIG. 3B, the exposed semiconductor substrate 1 is etched using the insulating layer pattern 4 as an etch mask to form a precursor of a cathode tip having a conical shape.

3C, the oxide substrate 5 is formed on the surface of the exposed substrate and the precursor of the cathode tip by thermally oxidizing the semiconductor substrate 1. Therefore, by the thermal oxidation, the tip of the upper end of the precursor of the cathode tip is pointed to form the cathode tip 7.

Subsequently, as shown in FIG. 3D, a gate insulating film 8 is formed as a thick oxide film on the surface of the semiconductor substrate 1 and on the insulating film pattern 4, and polysilicon, silicide, metal, or the like is formed on the gate insulating film 8. The electrode thin film 6a is formed.

3E, a focusing electrode insulating film 8 is formed on the electrode thin film 6a as an oxide film, and polysilicon, silicide, and metal are deposited thereon to form the focusing electrode metal film 11a. To form.

Subsequently, as shown in FIG. 3F, the oxide film 5 on the surface of the cathode tip 7, the nitride film pattern 4, the gate insulating film 8 and the focusing electrode insulating film 10 formed thereon; The electrode thin film 6a and the focusing electrode metal film 11a are removed to form the gate electrode 6 and the focusing electrode 11.

The disadvantages of the conventional field emission device made by this manufacturing method are that the gate insulating film 8 and the focusing electrode insulating film 11 are deposited by the electron beam into the oxide film, so that the leakage current of the gate oxide film is large and the shape of the tip depending on the position. This asymmetry, the thicker the oxide film, the greater the distance between the cathode tip 7 and the gate electrode 6, and the oxide film deposited by the electron beam deposition method during the lift-off process. Since the etching rate is large in Foshan, it is difficult to control the lift-off process.

The present invention has proposed a method of forming a focusing electrode by a self-aligned method to secure the symmetry between the cathode tip and the gate electrode and improve the focusing speed of the emitted electrons.

The object of the present invention is to provide a method of manufacturing a field emission device capable of precisely controlling the symmetry between the cathode tip and the electrode and the aperture ratio of the electrode in forming a focusing electrode capable of increasing the focusing speed of the electron beam.

In accordance with an aspect of the present invention, there is provided a method of manufacturing a field emission device, which includes: forming an insulating film pattern having a predetermined width on a substrate, and using the insulating film pattern as an etching mask, a cathode tip having a conical shape on the substrate. Forming an oxide film by thermally oxidizing the exposed substrate to form an oxide film to sharpen the tip, and then removing the oxide film to form a cathode tip on the substrate; and a gate insulating film on the entire surface of the exposed substrate. Forming a thin film for a gate electrode; and removing a convex upper portion of the cathode tip of the gate electrode thin film at a predetermined width with a high selectivity to form an exposed gate insulating film higher than the gate electrode; A step of sequentially forming an electrode insulating film and a focusing electrode metal film, and a convex upper portion of the cathode tip of the focusing electrode metal film Removing a predetermined width and is characterized in that the step of forming the hole of the focusing electrode, removing the focusing electrode insulating film and the gate insulating film exposed through the focusing electrode including a step of exposing the cathode tip in the air.

1 is a cross-sectional view of a field emission display (FED).

2 is a cross-sectional view illustrating a principle of using an electron focusing electrode.

3 is a cross-sectional view illustrating a method of manufacturing a cathode tip of a field emission display (FED) having a conventional focusing electrode.

Figure 4 is a cross-sectional view showing a method of manufacturing a cathode tip of the FED having a focusing electrode of the present invention.

5 is a layout diagram of an FED having a focusing electrode.

Explanation of symbols on the main parts of the drawings

1 semiconductor substrate 2 insulating film pattern

3: photosensitive film pattern 5: oxide film

6a: thin film for electrode 6: gate electrode

7: cathode tip 8: gate insulating film

10. Focusing electrode insulating film 11a: Focusing electrode metal film

11: focusing electrode

The present invention is characterized in that the gate electrode and the focusing electrode are manufactured by a chemical mechanical polishing (CMP) method, and after etching the gate electrode with CMP, the height of the gate insulating film is formed higher than that of the gate electrode and the focusing electrode is subsequently processed. When the insulating layer and the focusing metal film are deposited and the focusing metal film is etched by the CMP method, the opening of the focusing electrode can be easily manufactured since the tip is higher than the other parts.

For example, the present invention is to form the gate electrode and the focusing electrode by the CMP method to form the focusing electrode by a self-aligned method in order to prevent the electrons emitted from the cathode tip in the field emission device to spread widely.

Accordingly, the manufacturing method is easier than in the conventional manufacturing method, and uniformity and symmetry are high.

Therefore, since the electron beam can be easily focused by using the manufactured focusing electrode, such a manufacturing process may be used in various ways, and a device of high definition may be manufactured when manufacturing a flat panel display.

Types of field emission devices include the use of silicon, polysilicon, amorphous silicon, the use of metal tips, and the use of low work function materials such as carbonaceous metals such as diamond.

Among them, in the case of using silicon tips, amorphous silicon, or polysilicon, many advantages have been developed due to the advantages of using semiconductor processing equipment and the advantages of making them compatible with integrated circuit processes.

The present invention provides a manufacturing process in which the gap between the cathode tip and the gate electrode can be reduced and the openings of the cathode tip and the gate electrode can be self-aligned more than in the conventional method of manufacturing the field emission device. .

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

4A to 4H show sectional views of the manufacturing process of the field emission device according to the present invention.

FIG. 4A illustrates a process of forming an etch mask for defining a region of forming a cathode tip on a substrate. First, a cathode is formed on a substrate 1 on which amorphous silicon or polysilicon is deposited on a semiconductor substrate or a glass substrate. After a well masking operation for forming, on a semiconductor substrate 1 such as monocrystalline silicon, polycrystalline silicon and amorphous silicon doped at high concentration (1 × 10 ¹⁹ / cm 3) by an ion implantation method or a high temperature doping method After forming an insulating film made of an oxide film, a nitride film, or an oxide film / nitride film having a thickness of 50 nm to 300 nm, a photosensitive film pattern 3 having a predetermined width is formed on the insulating film, and then the photosensitive film pattern 3 is etched and masked. The insulating film is patterned to form an insulating film pattern 2, and the photosensitive film pattern 3 is removed.

Subsequently, as shown in FIG. 4B, the exposed semiconductor substrate 1 is etched in two steps using the insulating layer pattern 2 as an etching mask to form a precursor of a cathode tip having a conical shape.

At this time, in the etching process, isotropic etching was performed by a wet or dry method in the first step, and anisotropic dry etching was performed in the second step.

This two-step etching method independently adjusts the thickness and height of the precursor of the cathode tip having a conical shape formed into the cathode tip by a subsequent process by adjusting the first isotropic etching and the second anisotropic etching time, respectively. It is to be able to adjust.

In other words, using this two-step etching process, the cathode tip can be made higher than the size of a given insulating film pattern 2. If the tip is high, an etch-back process for forming a gate electrode is performed in a subsequent process. When the CMP process is performed, the size of the opening of the gate electrode to be etched is uniform, the size of the electric field applied to the cathode tip is increased, and the parasitic capacitance between the gate electrode and the cathode is reduced, thereby reducing the RC delay time of the device. do.

In addition, when the height of the cathode tip is high, the thickness of the insulating film (dielectric) under the gate insulating film and the focusing electrode can be thickened, thereby effectively preventing the leakage current.

Subsequently, as shown in FIG. 4C, the entire surface of the exposed substrate 1 is thermally oxidized to form an oxide film 5 on the surface.

Next, as illustrated in FIG. 4D, the cathode tip 7 is formed by wet etching the insulating film pattern 2 and the oxide film 5.

Next, as shown in FIG. 4E, an oxide film is deposited to a thickness of 50 nm to 2000 nm on the entire surface of the exposed substrate by CVD to form a gate insulating film 8.

Next, a thin film for electrodes such as polysilicon or silicide or W, TiW, Mo, Au, etc. is formed on the gate insulating film 8, and then the thin film for electrodes is patterned by etching to form an upper side of the cathode tip 7. The gate electrode 6 is formed by etching the negative electrode thin film to form an opening.

In this case, the process of patterning the electrode thin film uses a process of polishing using the CMP method, it may be patterned using a photosensitive film etch back process.

The etch ratio of the electrode thin film and the gate insulating film 8 is increased (10: 1) so that the profile of the gate insulating film 8 remains as it is.

At this time, after the electrode thin film 6 is etched by CMP, the gate insulating film 8 exposed through the opening is formed higher than the gate electrode 6. As such, the reason for forming the gate insulating film 8 higher than the gate electrode 6 is that in the subsequent process, the tip electrode of the opening is different when the focusing electrode insulating film and the focusing metal film are deposited and the focusing metal film is etched by the CMP method. It is higher than the portion to easily etch the focusing electrode.

Therefore, when forming the opening of the gate electrode by CMP, the height of the gate insulating film must be formed higher than the gate electrode 6.

Next, as shown in FIG. 4F, an insulating film having a thickness of 100 nm to 3000 nm is deposited on the exposed gate electrode 6 and the gate insulating film 8 by CVD to form the focused electrode insulating film 10. Next, a silicide or focusing electrode metal film 11a such as W, TiW, Mo, Au, or the like is formed thereon.

4G, the focusing electrode 11 is defined by polishing the portion of the focusing electrode metal film 11a that protrudes upward by the CMP method.

In this CMP process, the etching selectivity of the focusing electrode metal film 11a and the focusing electrode insulating film 10 is 20: 1 or more, so that the focusing electrode metal film is etched first or the etching selectivity is close to 1: 1. The electrode metal film and the focusing electrode insulating film 10 are simultaneously etched.

Further, in the process of patterning the focusing electrode, an SOG or a photoresist pattern (not shown) from which an upper portion of the cathode tip 7 is removed is formed on the focusing electrode metal film 11a, and then the exposed focusing electrode is exposed. The metal film 11a may be patterned by etch back.

Next, as shown in FIG. 4H, portions of the focusing electrode insulating film 10 and the gate insulating film 8 exposed through the focusing electrode 11 are etched by wet etching to expose the cathode tip 7. Let's do it.

As described above, the field emission device of the present invention, which manufactures the gate electrode and the focusing electrode by the CMP process, can precisely control the symmetry between the cathode tip and the electrode as compared with the conventional art.

In addition, the diameter of the opening of the focusing electrode for focusing the electrons emitted from the cathode tip can be narrowed, and the gate electrode and the edge of the opening side of the focusing electrode are bent upward to be emitted to the cathode tip. By maximizing the effect of the electric field on the electrons, the acceleration and focusing performance of the electrons can be significantly improved.

Therefore, the field emission device manufactured by the manufacturing process as described above can easily focus the emitted electrons, and thus can not only use a variety of electron sources, but also can manufacture devices with high clarity when manufacturing flat panel displays, and have low voltage. A high voltage FED can be easily produced using a conventional high voltage phosphor without using a phosphor for the purpose.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a field emission device capable of improving the concentration rate of electrons emitted from the cathode tip of the field emission device.

Claims (14)

Forming an insulating film pattern 2 having a predetermined width on the substrate 1 and forming a precursor of a cathode tip having a conical shape on the substrate using the insulating film pattern as an etching mask; Thermally oxidizing the exposed substrate to form an oxide film 5 to sharpen the tip, and then removing the oxide film to form a cathode tip 7 on the substrate; Forming a gate insulating film 8 and an electrode thin film 6a on the entire exposed substrate; Removing the convex upper portion of the cathode tip 7 of the gate electrode thin film at a predetermined width at a high selectivity to form an exposed gate insulating film 8 higher than the gate electrode 6; Sequentially forming a focusing electrode insulating film 10 and a focusing electrode metal film 11a on the front surface; Removing the convex upper portion of the cathode tip of the focusing electrode metal film to a predetermined width to form a hole of the focusing electrode 11; Fabrication of a field emission device having a self-aligned focusing electrode comprising removing the focusing electrode insulating film and the gate insulating film exposed through the focusing electrode 11 to expose the cathode tip 7 into the air. Way. The method of claim 1, The patterning process of the gate electrode (6) is a method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that performed by the CMP method. The method of claim 1, The patterning process of the focusing electrode (11) is a method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that performed by the CMP method. The method of claim 1, The etching process of the substrate (1) for forming the precursor of the cathode tip is a method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that performed by isotropic etching and anisotropic etching. The method of claim 1, The substrate (1) is a method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that using one of single crystal silicon, polysilicon or amorphous silicon. The method of claim 1, A method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that the opening side portion of the gate electrode (6) is bent upward so that the upper layer portion is convex when the focusing electrode film is later deposited. The method of claim 1, The method of manufacturing a field emission device having a self-aligned focusing electrode, wherein the electrode thin film 6a and the gate insulating film 8 have an etching selectivity of 10: 1 or more. The method of claim 1, The gate insulating film (8) is a method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that formed in a thickness of 50nm-2000nm. The method of claim 1, The focusing electrode insulating film (10) is a method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that formed to a thickness of 100 to 3000nm. The method of claim 1, The electrode thin film is a method of manufacturing a field emission device having a self-aligned focusing electrode, characterized in that it has a self-aligned focusing electrode, characterized in that formed of any one of polysilicon, silicide, W, TiW, Mo, Au. . The method of claim 1, The focusing electrode metal film 11a has a self-aligned focusing electrode characterized in that it is formed of any one of polysilicon, silicide, W, TiW, Mo, Au. Method of manufacturing the device. The method of claim 1, The forming of the focusing electrode 11 may include removing the focusing electrode metal film 11a exposed on the upper portion of the cathode tip 7 on the surface of the focusing electrode metal film 11a. A method of manufacturing a field emission device having a self-aligned focusing electrode. The method of claim 1, And the mask pattern is formed by etching back SOG. The method of claim 1, The focusing electrode metal film (11a) and the focusing electrode insulating film (10) has an etching selectivity of 10: 1 manufacturing method of the field emission device having a self-aligned focusing electrode.