KR20040057115A - Field emission device manufacturing method - Google Patents

Abstract

PURPOSE: A field emission device fabrication method is provided to lengthen a lifetime and improve the reliability by minimizing a damage of a tunnel oxidation film. CONSTITUTION: A field emission device fabrication method comprises a step of forming an anode oxidation film at a lateral side of a bottom electrode after protecting a territory to be formed on a tunnel oxidation film and forming a hard mask(13) pattern at a top center part of the bottom electrode formed on a plate, a step of forming a field insulating film(15), a top electrode bus(16), and a top insulating film(17) in order at a top part of a structure formed at a former step, a step of excluding finally the hard mask by etching in order and forming an aperture part at the structure, and a step of forming a highest top electrode at a top part of the structure and forming the tunnel oxidation film by oxidizing a bottom electrode in results of excluding the hard mask.

Description

Field emission device manufacturing method {FIELD EMISSION DEVICE MANUFACTURING METHOD}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a field emission device, and more particularly, to a method for manufacturing a field emission device suitable for extending the reliability and lifespan of a field emission device by minimizing damage to tunnel oxide of a metal insulating metal (MIM) cathode.

Display elements have been rapidly developed in accordance with the demands of various display elements. Recently, as devices using field emission have been applied to the display field, development of thin film displays capable of providing high resolution while reducing size and power consumption has been actively developed.

The field emission devices have been studied in various forms. Among them, the field emission devices using MIM (Metal Insulating Metal) as electron emission sources are much larger than the field emission devices using micro tips or carbon nanotubes as electron emission sources. It is widely used because of the advantages of easy area fabrication and simple process.

The field emission device includes a lower plate having an electron emission source, an upper plate emitting light by an electron emission source, and a spacer for supporting the upper plate and the lower plate and maintaining the inside in a vacuum state.

This article discusses the bottom plate applying MIM as an electron emission source.

The field emission device using the bottom plate applied with MIM has the advantages of easy large area and simple process, but its life is governed by the tunnel oxide film between the lower electrode and the upper electrode. The thickness of the tunnel oxide film is generally about 100 GPa, and the loss of the tunnel oxide film is closely related to the life of the entire panel.

Conventionally, the tunnel oxide film was generated at an early stage of the process, which will be described in detail with reference to the accompanying drawings.

1A to 1G are cross-sectional views of a conventional field emission device fabrication process, forming a lower electrode 2 on an upper portion of the lower plate glass 1 as shown therein (FIG. 1A); Forming a photoresist (PR) pattern in the center of the lower electrode (2), and then forming an anode oxide film (3) on top of the exposed lower electrode (2); Removing the photoresist PR and forming a tunnel oxide film 4 on the exposed lower electrode 2 (FIG. 1C); Sequentially depositing and patterning the field insulating film 5 and the upper electrode bus 6 on the upper surface of the structure to block the exposure of the tunnel oxide film 4 and the anodizing film 3 (FIG. 1D); Depositing an upper insulating film 7 on top of the structure and patterning the upper insulating film 7 and the lower upper electrode bus 6 to expose the upper field insulating film 5 of the tunnel oxide film 4 ( 1e); Etching the field insulating film 5 and over-etching the side surface of the upper electrode bus 6 (FIG. 1F); Depositing a metal on top of the structure to form top electrodes 8, 9 on the upper insulating film 7, the exposed tunnel oxide film 4 and the field insulating film 5 (FIG. 1G). .

Hereinafter, an embodiment of the conventional field emission device manufacturing method configured as described above will be described in more detail.

First, as shown in FIG. 1A, aluminum is deposited on an upper portion of the lower plate glass 1, and the deposited aluminum is wet-etched to form a lower electrode 2 on an upper portion of the lower plate glass 1.

Next, as shown in FIG. 1B, after forming a photoresist (PR) pattern in the center of the lower electrode 2, the exposed lower electrode 2 is oxidized by anodizing to produce anodized film 3 of aluminum oxide. ).

Then, as shown in Fig. 1C, the photoresist PR is removed, and a tunnel oxide film 4 is formed on the center of the lower electrode 2 exposed by the removal of the photoresist PR.

Then, as shown in FIG. 1D, tungsten and aluminum are deposited on the entire upper surface of the structure to form the field insulating film 5 and the upper electrode bus 6.

Next, the formed field insulating film 5 and the upper electrode bus 6 are patterned so as to be selectively positioned only on the upper side of the tunnel oxide film 4 and the anodic oxide film 3.

Then, as shown in FIG. 1E, a silicon nitride film (SiNx) is deposited on top of the structure to form an upper insulating film 7.

The upper insulating film 7 and the lower upper electrode bus 6 are then patterned to expose the upper field insulating film 5 of the tunnel oxide film 4.

Next, as shown in FIG. 1F, the field insulating film 5 is etched and the side surface of the upper electrode bus 6 is excessively etched.

Then, as shown in Fig. 1G, Ir / Pt / Au is deposited on top of the structure, so that the top electrode (on the top insulating film 7, the exposed tunnel oxide film 4 and the field insulating film 5) is formed. 8, 9).

Through this process, the bottom plate of the field emission device manufactured, that is, the cathode is formed.

As described above, in the conventional field emission device manufacturing method, since the tunnel oxide film is formed at the beginning of the process, chemical damage due to in-process etching, electrical damage in the thin film deposition process, and mechanical damage due to the stress of the thin film may occur. There was a problem that the life is shortened.

In view of the above problems, the present invention provides a method for manufacturing a field emission device which can extend the reliability and lifespan of a field emission device by minimizing damage to the tunnel oxide film by a lower plate forming process by forming the tunnel oxide film later in the process. The purpose is.

1A to 1E are cross-sectional views of a manufacturing process of a conventional field emission device.

2A to 2L are cross-sectional views of a manufacturing process of the field emission device of the present invention.

* Description of the symbols for the main parts of the drawings *

11: Lower glass 12: Lower electrode

13: Hard mask 14: Anodic oxide film

15: Field insulating film 16: Upper electrode bus

17: upper insulating film 18: tunnel oxide film

19: top electrode

The present invention for achieving the above object is to form a hard mask on the upper center of the lower electrode to protect the upper portion of the lower electrode to be formed tunnel oxide film; And removing the hard mask and forming the tunnel oxide layer on the exposed lower electrode prior to forming the top electrode.

The present invention provides a method of manufacturing a semiconductor device, comprising: forming a hard mask pattern on an upper center of a lower electrode formed on a substrate to protect a region where a tunnel oxide film is to be formed, and then forming an anodized film on a side of the lower electrode; Forming a field insulating film, an upper electrode bus, and an upper insulating film on the structure in order; Forming openings in the structure and etching sequentially to finally remove the hard mask; And oxidizing the lower electrode exposed by the removal of the hard mask to form a tunnel oxide layer, and forming a top electrode on the structure.

The hard mask may have a sufficient thickness so as not to transmit oxygen ions in the anodic oxide film and the field insulating film forming step.

The hard mask is formed using a thickness of 0.1 ~ 0.5㎛ using WO ₃ , Ta ₂ O ₅ or SiO ₂ .

When described in detail with reference to the accompanying drawings an embodiment of the present invention configured as described above are as follows.

2A to 2L are cross-sectional views of a process of manufacturing the field emission device according to the present invention, as shown in this step, in order to form the lower electrode 12 and the hard mask 13 on top of the lower plate glass 11 (Fig. 2a); Etching the hard mask layer 13 using a photoresist pattern to form a hard mask 13 (FIG. 2B); Wet etching the lower electrode 12 using a photoresist pattern (FIG. 2C); Forming an anodic oxide film (14) on the side surface of the lower electrode (12); Depositing a field insulating film 15 and an upper electrode bus 16 layer on the upper front surface of the structure in turn (FIG. 2E); Patterning the formed field insulating film 15 and the upper electrode bus 16 using a photoresist (FIG. 2F); Forming an upper insulating film 17 on the upper front surface of the structure (FIG. 2G); Patterning the upper insulating film 17 to form an opening using a photoresist pattern (FIG. 2H); Etching the upper electrode bus 16 exposed through the opening by wet etching to form an opening (FIG. 2I); Forming a photoresist pattern on the formed structure so that a part of the upper field insulating film 15 of the hard mask 13 is exposed (FIG. 2J); Removing a portion of the exposed field insulating film 15 and the hard mask 13 by using the toporesist pattern to form a tunnel oxide film 18 on the exposed lower electrode 12 (FIG. 2K); Forming a top electrode 19 on the upper surface of the formed structure (Fig. 2l).

Hereinafter, the present invention having the above configuration will be described in more detail.

First, as shown in FIG. 2A, a lower electrode 12 and a hard mask 13 layer are sequentially formed on the lower plate 11. The lower glass 11 advantageously has the same surface roughness as that of the silicon substrate. An aluminum thin film is formed to a thickness of 0.1 to 0.5 μm on the lower plate 11 by wireless magnetron sputtering or chemical vapor deposition to form a lower electrode 12 layer, and a hard mask on the upper portion of the lower glass 11. 13) A layer is formed to a thickness of 0.1 ~ 0.5㎛ using WO ₃ , Ta ₂ O ₅ or SiO ₂ . The hard mask 13 layer should have a sufficient thickness such that oxygen ions are permeated through the lower electrode 12 when the field insulating film and the anodic oxide film to be formed in a later process are not formed to form an aluminum oxide film.

Subsequently, as shown in FIG. 2B, the hard mask 13 is patterned by an etching process after spin coating, exposing and developing the photoresist.

Next, as shown in FIG. 2C, after spin coating, exposing and developing the photoresist, the aluminum lower electrode 12 is etched and wet-etched using a mixed solution of nitric acid, phosphoric acid, and acetic acid.

Next, as shown in FIG. 2D, an anodization film 14 is formed on the side surface of the lower electrode 12 exposed through anodization. In this case, the hard mask 13 is also exposed to an anodization process so that the aluminum underneath it is exposed. Do not allow oxygen ions to permeate. The anodic oxidation is an anodic oxide film of Al ₂ O ₃ by oxidizing aluminum by applying a DC voltage of about 30 to 160 V at both ends using a specimen in which aluminum is deposited in a phosphoric acid or oxalic acid solution as the anode and platinum as the opposite cathode. ).

Subsequently, as shown in FIG. 2E, the field insulating film 15 and the aluminum upper electrode bus 16, such as SiO ₂ and SiNx, are deposited to have a thickness of 10 to 50 nm and 100 to 500 mm, respectively, by wireless magnetron sputtering or chemical vapor deposition. do.

Next, as shown in FIG. 2F, the upper electrode bus 16 and the field insulating film 15 are etched through the photoresist pann, and the aluminum upper electrode bus 16 is wet etched with a mixed solution of phosphoric acid, nitric acid, and acetic acid. do.

Then, as shown in Figure 2g to form an upper insulating film 17 on the upper surface of the formed structure, this also deposits SiO ₂ to 100 ~ 500nm thickness by wireless magnetron sputtering or chemical vapor deposition method.

Next, as illustrated in FIG. 2H, an opening is formed by performing reactive ion etching (RIE) on the upper insulating film 17 in a mixed atmosphere of CF ₄ and O ₂ using a photoresist pattern.

Next, the upper electrode bus 16 exposed as shown in FIG. 2I is wet-etched with a mixed solution of phosphoric acid, nitric acid, and acetic acid to form an opening.

Next, as shown in Fig. 2J, a photoresist pattern is formed so that a part of the field insulating film 15 is exposed.

Next, as shown in FIG. 2K, a portion of the exposed field insulating film 15 is removed through reactive ion etching (RIE) in a mixed atmosphere of CF ₄ and O ₂ to form an opening, and the hard mask 13 is removed. As a result, the lower electrode 12 is exposed to form a tunnel oxide film 18 formed on the upper surface of the aluminum lower electrode 12 through anodization. The anodic oxidation is Al ₂ O ₃ tunnel oxide film (18) by oxidizing aluminum by applying a DC voltage of about 30 to 160V at both ends with a specimen in which aluminum is deposited in a phosphoric acid or oxalic acid solution as an anode and platinum as an opposite cathode. ) Is formed. The tunnel oxide film 18 is formed intact because aluminum, which is a forming base material, is intact because it is protected by the hard mask 13 during the last process.

Then, as shown in FIG. 2L, the top electrode 19 is deposited by a wireless magnetron sputtering or chemical vapor deposition method, and the top electrode 19 uses a continuous film of Ir, Pt, Au.

Since the tunnel oxide film 18 is formed immediately before the top electrode 19 is deposited on the aluminum lower substrate 12 without damaging the tunnel oxide film 18 through the above-described method, chemical damage due to in-process etching, Electrical damage, mechanical damage caused by thin film stress, etc. can be minimized.

As described above, the method of manufacturing the field emission device of the present invention protects the upper portion of the lower electrode where the tunnel oxide film is to be formed by using a hard mask pattern, and then forms the tunnel oxide film at the end of the process to damage the tunnel oxide film by the lower plate forming process. By minimizing this, the reliability and lifespan of the field emission device can be extended, and ultimately, the reliability and lifespan of the display panel can be improved.

Claims (4)

Forming a hard mask on an upper center of the lower electrode to protect a part of the upper part of the lower electrode on which the tunnel oxide film is to be formed; Removing the hard mask and forming the tunnel oxide film on the exposed lower electrode prior to forming a top electrode. The method of claim 1, wherein the hard mask has a sufficient thickness so as not to transmit oxygen ions in the anodic oxide film and the field insulating film forming step. The method of claim 1, wherein the hard mask is formed to a thickness of 0.1 μm to 0.5 μm using WO ₃ , Ta ₂ O _5, or SiO ₂ . Forming a hard mask pattern on an upper center of the lower electrode formed on the substrate to protect a region where the tunnel oxide film is to be formed, and then forming an anodized film on the side of the lower electrode; Forming a field insulating film, an upper electrode bus, and an upper insulating film on the structure in order; Forming openings in the structure and etching sequentially to finally remove the hard mask; And oxidizing the lower electrode exposed by the removal of the hard mask to form a tunnel oxide film, and forming a top electrode on the structure.