KR20000026858A - Field emission device and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A field emission device and a manufacturing method thereof are provided to enhance the bonding characteristic with a resistor layer, thereby enhancing an aspect ratio and a current density. CONSTITUTION: A field emission device comprises front and rear substrates(1,11,31) opposing each other, stripe type cathodes(2,12,32) formed on the rear substrate, resistor layer(3,13,33) formed on the cathodes, conical type micro tips(2,30), insulating layer(4,14,34), stripe type gates(5,15,35), stripe type anodes(39), and fluorescent layers(39a). The micro tips are formed on the resistor layer in array shape. The insulating layer has holes for inserting the micro tips and is formed on the cathodes and the substrates. The gates have openings corresponding to the holes and cross with the cathodes. The anodes cross with the cathodes on the front substrate. The fluorescent layers are separated in constant gap from both electrodes.

Description

Field emission display device and manufacturing method thereof

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a field emission display, which is a flat panel display. Specifically, the present invention relates to a field emission display device having a micro tip having a dense electric field distribution and an increased current density. The manufacturing method is related.

Currently, the development of a flat image display device as an image display device that can replace the CRT (cathode ray tube) of the existing television receiver is being actively studied, and the development is in progress for the purpose of applying the image display device for wall-mounted television and HDTV It is becoming.

Such flat image display apparatuses include liquid crystal displays, plasma display panels, and field emission devices, among which are electric fields in terms of brightness and low power consumption of the screen. Emission display devices have attracted much attention.

1 is a vertical cross-sectional view taken from a general field emission display device.

As shown in FIG. 1, in the conventional field emission display device, a plurality of cathodes 2 on a stripe are provided on the rear substrate 1, and resistor layers 3 are formed on the cathodes 2. . On the resistor layers 3, a plurality of microtips 2 'are formed in an array form.

These micro tips 2 'are provided in the holes 4a of the insulator layer 4 formed on the cathodes 2. The gates 5 having the openings 4a corresponding to the holes 4a are stacked on the insulator layer 4. As the material of the resistor layer 3, generally, a heat resistant alloy such as amorphous silicon (a-Si) or Cr-SiO ₂ is mainly used.

A method of manufacturing a field emission display device having such a configuration is as follows.

2A through 2E are vertical cross-sectional views of manufacturing the field emission display device of FIG.

As shown in FIG. 2A, the cathodes 2 are formed on the back substrate 1 in a stripe shape, the resistor layer 3 is stacked thereon, and nicked into a specific shape by a photolithography process. The insulator layer 4 and the gate layer 5 'are laminated sequentially.

Next, in a photolithography process, as shown in FIG. 2B, a photoresist mask 6 is formed on the gate layer 5 ′ and etched to form a gate 5 having an opening 5 a.

Next, as shown in FIG. 2C, the photoresist mask 6 is removed and the insulator layer 4 is etched using the gate 5 as a mask to form holes 4a in the insulator 4. do.

Next, as shown in FIG. 2D, the partition layer 7 is deposited on the gate 5, and as shown in FIG. 2E, the molybdenum (Mo) and the molybdenum (Mo) are formed by electron beam deposition while rotating the substrate. The micro tip 2 'is deposited from the same high melting point material.

The dividing layer 7 is then etched away so that the micro tip byproduct 2a is also removed. In this way, the field emission display device as shown in FIG. 1 is completed.

In the conventional field emission display device as described above, the micro tip 2 ', which is usually made of a high melting point material such as molybdenum (Mo), has an aspect ratio that is a ratio of the height of the tip to the bottom diameter of the tip. 1 to 1.3.

Accordingly, metals such as tungsten (W) are generally used as the material of the micro tip in order to have an aspect ratio larger than that of molybdenum (Mo) to improve the efficiency and current density of the field emission.

However, in forming the micro tip from a metal such as tungsten (W), tungsten (W) has a fine void at the interface with the resistor layer 13, so that the adhesive property is poor, so that the formation of the tip is not uniform or formed. Even if it is, the field emission is not achieved.

In addition, when the tip is formed of molybdenum (Mo) as in the prior art, there is a problem that the field emission efficiency and the current density are relatively low due to a low aspect ratio.

SUMMARY OF THE INVENTION The present invention has been made to improve the above problems, and has a strong adhesive force with a resistor layer, a high aspect ratio, and a field emission display device having a micro tip for densely distributing electric field distribution to improve current density; The object is that the manufacturing method is provided.

1 is a vertical cross-sectional view taken from a general field emission display device;

2A through 2E are vertical cross-sectional views of manufacturing the field emission display device of FIG.

3 is a vertical cross-sectional view of a field emission display device according to the present invention;

4A to 4G illustrate vertical cross-sectional views of manufacturing the field emission display device of FIG. 3.

<Description of the symbols for the main parts of the drawings>

1,11,31 ... back substrate 2,12,32 ... cathode

2 ', 30 ... micro tips 2a ... micro tips by-products

3,13,33 ... resistor layer

4,14,34 ... insulator layer 4a, 14a, 34a ... hole

5,15,35 ... Gate 5 ', 15' ... Gate Layer

5a, 15a, 35a ... opening

16 ... mask 7,21 ... divided layer

22. By-product of the first metal layer

23 The second metal layer by-product 30a ... The first metal layer

30b ... Second metal layer 36 ... spacer

37. Emissions 38. Front substrate

39.Anode 39a ... Phosphor layer

In order to achieve the above object, the field emission display device according to the present invention includes: a front substrate and a rear substrate spaced apart from each other at regular intervals; Cathodes formed in a stripe shape on the rear substrate; A resistor layer continuously formed on the cathodes; A plurality of conical micro tips formed in an array on the resistor layer; An insulator layer formed on the cathodes and the substrate exposed portion to have holes for receiving the plurality of micro tips, respectively; Gates formed on a stripe in a direction crossing the cathodes on the insulator layer to have openings corresponding to the holes; Anodes formed on the front substrate on a stripe in a direction crossing the cathodes; And a phosphor layer formed at regular intervals on the anodes, the field emission display device comprising:

The micro tip has a double layer structure in which a lower first metal layer and an upper second metal layer of different metal materials are stacked.

The first metal layer is made of one of molybdenum (Mo) to chromium (Cr), and the second metal layer is preferably made of tungsten (W) having a larger aspect ratio than the first metal layer.

In addition, in order to achieve the above object, the method of manufacturing a field emission display device according to the present invention, (A) sequentially depositing a cathode layer, a resistor layer, an insulator layer, and a gate layer on a stripe on a glass substrate, Etching the gate layer to form a gate having an opening having a predetermined diameter; (B) etching to form holes corresponding to the openings in the insulator layer; (C) forming a partition layer on the gate by electron beam deposition while rotating the substrate; (D) while depositing a predetermined thickness of the first metal layer continuously by electron beam deposition while rotating the substrate, and depositing a predetermined thickness of the second metal layer different from the first metal layer by a double layer formed by the first metal layer and the second metal layer. Forming a micro tip of the structure; And (e) removing the micro tip byproduct layers by etching the partition layer.

The first metal layer is made of one of molybdenum (Mo) to chromium (Cr), it is preferable that the second metal layer is made of tungsten.

Here, the aspect ratio of the second metal layer is preferably larger than the first metal layer.

Hereinafter, a field emission display device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a vertical cross-sectional view of the field emission display device according to the present invention.

As shown in FIG. 3, the back substrate 31 and the front substrate 38 are spaced apart from the spacer 36 so as to face each other so as to maintain a constant distance. The cathode 32 is formed on the rear substrate 31 in parallel with the stripe. The resistor layer 33 is formed on the cathode 32.

On the resistor layer 33, a plurality of micro tips 30 having a double layer structure in which the first metal layer 30a and the second metal layer 30b of different materials are successively deposited are formed in an array structure.

Here, the micro tip 30 having the structure of the double layer is formed with a first metal layer (30a) made of any one of molybdenum (Mo) and chromium (Cr), the tungsten on the first metal layer (30a) A second metal layer 30b made of (W) is deposited.

An insulator layer 34 having holes 34a respectively accommodating the micro tips 30 is formed on the exposed portions of the resistor layer 33 and the rear substrate 31, and the insulator layer 34 is formed on the insulator layer 34. A gate 35 having an opening 35a corresponding to the hole 34a of 34 is formed in a stripe shape in a direction crossing the resistor layer 33.

Here, the micro tip 30 according to the present invention is formed to have a structure of a double layer, unlike the conventional, has a sharp tip tip portion having a large aspect ratio. That is, the first metal layer 30a of molybdenum (Mo) having good adhesion to the resistor layer 13 described later is first deposited on the resistor layer 13, and the tungsten (W) having a large aspect ratio thereon is deposited thereon. The second metal layer 30b is successively secondary deposited to have a micro tip 30 having a double layer structure.

Unlike the conventional field emission display device having a single conical micro tip (2 'in FIG. 1), the micro tip 30 having such a double layer structure has a large aspect ratio, and the tip portion of the tip is sharper. The height of the micro tip 30 is greater, so that the electric field distribution is more densely distributed, thereby improving the current density, and the resistor layer tends to occur when forming a sharper tungsten (W) tip. The adhesion property to the interface between the 13 and the micro tip 30 can be increased.

In addition, the anodes 39 are formed on the front substrate 38 in a stripe shape, and the phosphor layer 39a is coated on the anodes 39. In addition, a vacuum space is provided between the phosphor layer 39a and the gate 35 to facilitate emission of the emission electrons 37 from the micro tips 30 to the anodes 39.

The field emission display device according to the present invention having such a structure applies a voltage of about 70V to 100V between the cathode 32 and the gate 35, and has a potential difference of about 300V between the cathode 32 and the anode 39. When maintaining, the emission electrons 37 are emitted from the micro tip 30 to pass through the vacuum region and collide with the phosphor layer 39a on the anode 39 to start to emit light.

Since the resistor layer 33 and the gate 35 on the cathode 32 have XY matrix structures facing each other with the insulator layer 34 interposed therebetween at a predetermined interval and on a stripe, only the selected region emits light. do.

At this time, the distance between the back substrate 31 on which the field emitter array (FEA) is formed and the front substrate 38 on which the phosphor layer 39a is formed can be maintained by the high-definition spacer 36. At this time, the holding interval is formed to about 200㎛.

As described above, the current density of Fowler-Nordheim shows that the current density of the discharge current is proportional to the square of the intensity of the electric field.

Therefore, the strength of the electric field and the current density with respect to the electric field are closely related to the shape of the tip for discharging the current.

That is, the tip of the micro tip 30 is formed more sharply, the height of the micro tip 30 is formed larger, and the distribution of the emission current is denser, so that the field emission efficiency is improved to improve the uniformity of the current density. Panel characteristics are improved.

Such a method of manufacturing the field emission display device according to the present invention will be described in detail with reference to the accompanying drawings.

4A to 4G are vertical cross-sectional views after the step-by-step process of manufacturing the field emission display device of FIG. 3. Like reference numerals in the drawings shown above indicate the same components.

First, referring to FIG. 4A, the cathode 12 is formed in a stripe shape on the glass substrate 11.

The resistor layer 13 is formed on the cathode 12, and the insulator layer 13 and the gate layer 15 ′ are sequentially stacked on the resistor layer 13.

At this time, the insulator layer 14 is interposed between the resistor layer 13 and the gate layer 15 'so as to have an X-Y matrix shape on a stripe in a direction crossing each other.

Next, in a photolithography process, as shown in FIG. 4B, a photoresist 16 ′ is formed on the gate layer 15 ′. As illustrated in FIG. 4C, the photoresist 16 ′ is exposed to an exposure apparatus having an ultraviolet wavelength, and then etched to form a photoresist mask 16.

Then, as shown in FIG. 4D, by etching with a wet etching method using the photoresist mask 16 described above to form the holes 14a of the insulator layer 14, the corresponding openings 15a are formed. A hole 14a having a predetermined diameter is formed. Next, the mask 16 is removed.

Thereafter, as shown in FIG. 4E, the divided layer 21 of aluminum (Al) is formed on the gate 15 while rotating the substrate by the electron beam deposition method. Here, the partition layer 21 surrounds the gate 15 over the gate 15 due to the rotation of the substrate and the electron beam deposition.

Next, the step of forming a micro tip 30 having a bilayer structure characterizing the present invention.

As shown in FIG. 4F, the first metal layer 30a is formed as a lower portion of the micro tip 30 having a double layer structure, which will be described later. The material of the first metal layer 30a is molybdenum (Mo). ) To chromium (Cr).

In the present invention, the material of the first metal layer 30a is preferably made of molybdenum (Mo). Accordingly, a tip is formed on the resistor layer 13 by electron beam deposition while rotating the substrate by using a molybdenum (Mo) source for electron beam deposition while maintaining a vacuum state with a vacuum evaporator. Molybdenum first metal layer 30a is deposited. Then, the first metal layer by-product 22 of the first metal layer 30a is deposited on the partition layer 21 so as to surround the partition layer 21.

Next, as shown in Figure 4g, as the upper portion of the micro tip 30 having a bilayer structure described later on top of the first metal layer (30a), the second metal layer so that a sharp tip for electric field emission is formed In the step of forming 30b, the material of the second metal layer 30b is preferably made of tungsten (W) having a high aspect ratio.

Accordingly, the first metal layer may be formed by electron beam deposition while rotating the substrate using a tungsten (W) source for electron beam deposition while maintaining a vacuum state using a vacuum evaporator as in the process of forming the first metal layer 30a. A second metal layer 30b of tungsten (W) is continuously deposited on 30a so that a sharp tip is formed. Then, the second metal layer by-product 23 is deposited on the first metal layer by-product 22 deposited on the partition layer 21 to surround the first metal layer by-product 22.

Here, the first metal layer 30a has physical, chemical, and electrical properties similar to those of the second metal layer 30b, for example, a thermal expansion coefficient, etc., and the aspect ratio of the first metal layer 30a is the second metal layer. It should be relatively smaller than (30b). The reason is that the height of the tip to be formed and the tip of the tip of the second metal layer 30b are high and sharply formed.

In addition, the partition layer 21 made of aluminum (Al) is removed by performing a wet etching process using a chemical solution, and the first and second metal layer by-products 22 and 23 stacked on the partition layer 21 are together. 4, the manufacturing process of the micro-tip array having a double layer structure having a sharp tip according to the present invention is completed.

The field emission display device manufactured by the above process first deposits the first metal layer 30a of molybdenum (Mo), and continuously deposits the second metal layer 30b of tungsten (W) having a large aspect ratio thereon. Subsequent deposition forms a micro tip 30 having a double layer structure having a larger aspect ratio than the conventional micro tip formed only of the first metal layer 30a.

That is, the first metal layer 30a of molybdenum (Mo) is formed in order to improve the adhesive property with the resistor layer 13, and in order to improve the density of the electric field distribution, improve the current density, and form the tip of the sharp tip. A second metal layer 30b of tungsten (W) having a high aspect ratio is deposited on the first metal layer 30a to form a micro tip 30 having a bilayer structure having a large aspect ratio as a whole. Subsequently, after assembling the FEA (field emitter array) fabricated as described above and the front substrate (38 in FIG. 3) on which the phosphor layer (39a in FIG. 3) is formed, the glass of low melting as a heat melting process The vacuum container is formed using glass powder, and the inside of the field emission display device is evacuated to a high vacuum of about 10 ^-7 to 10 ^-8 torr using a heating exhaust device (not shown).

At this time, in order to improve the degree of vacuum and maintain the degree of vacuum inside the display element, the exhaust process is performed while releasing various residual gases that may be generated from the inside of the display element by heating to about 320 to 340 ° C.

Next, when the inside of the display element reaches a vacuum degree of about 10 ^-7 to 10 ^-8 torr, the glass exhaust pipe is thermally fused so that the inside of the display element can be maintained in a high vacuum state. When a flashing of a barium (Ba) getter film, which is a chemical substance, is performed inside a display device by using a high frequency induction heating device to increase the degree of vacuum inside the display device by adsorption, the field emission display device according to the present invention Manufacturing is complete.

As described above, the field emission display device and the method of manufacturing the same according to the present invention are provided with a micro-tip having a double layer structure, and thus have excellent adhesion characteristics with the resistor layer, and have a high aspect ratio. There is an advantage in improving the current density by densely distributing the electric field distribution.

Claims (7)

A front substrate and a rear substrate spaced apart from each other at regular intervals; Cathodes formed in a stripe shape on the rear substrate; A resistor layer continuously formed on the cathodes; A plurality of conical micro tips formed in an array on the resistor layer; An insulator layer formed on the cathodes and the substrate exposed portion to have holes for receiving the plurality of micro tips, respectively; Gates formed on a stripe in a direction crossing the cathodes on the insulator layer to have openings corresponding to the holes; Anodes formed on the front substrate on a stripe in a direction crossing the cathodes; And A field emission display device comprising: a phosphor layer formed at regular intervals on the anodes; The micro tip has a double layer structure in which a lower first metal layer and an upper second metal layer of different metal materials are stacked. The method of claim 1, The first metal layer is formed of any one of molybdenum to chromium field emission display device The method of claim 1, And the second metal layer is formed of tungsten (W) having a larger aspect ratio than the first metal layer. (A) sequentially depositing a cathode layer, a resistor layer, an insulator layer, and a gate layer on a stripe on the glass substrate, and etching the gate layer to form a gate having an opening having a predetermined diameter; (B) etching to form holes corresponding to the openings in the insulator layer; (C) forming a partition layer on the gate by electron beam deposition while rotating the substrate; (D) depositing a predetermined thickness of the first metal layer continuously by electron beam deposition while rotating the substrate, and then depositing a predetermined thickness of the second metal layer different from the first metal layer to form a double layer by the first metal layer and the second metal layer. Forming a micro tip of the structure; And (E) removing the micro tip byproduct layers by etching the partition layer. The method of claim 4, wherein In the step (d), The first metal layer is a method of manufacturing a field emission display device, characterized in that made of any one of molybdenum to chromium. The method of claim 4, wherein In the step (d), And the second metal layer is made of tungsten. The method of claim 4, wherein And an aspect ratio of the second metal layer is greater than that of the first metal layer.