KR100199295B1 - Method of manufacturing field emission device - Google Patents

Abstract

[Technical field to which the invention described in the claims belong]

Field emitter

[Technical Problem to Solve]

This facilitates the alignment of the cathode emitting electrons and the gate controlling it.

[Summary of the solution of the invention]

The cathode is formed of diamond-like carbon, but diamond-like carbon is formed by laser ablation to achieve a fine position alignment so that the gate metal film is close to the diamond-like carbon cathode.

[Important Uses of the Invention]

Electronic communication field using field emission device

Description

Field emission device manufacturing method

The present invention relates to a method of manufacturing a field emission device having a triode structure, in which a diamond-like carbon film serves as an electron emission source per unit pixel, and a gate is attached to control the field emission. A method for manufacturing a field emission device for facilitating the alignment thereof.

When a strong electric field is applied to a semiconductor, electrons are released through a potential barrier and discharged into a vacuum, which is called field emission. The electron emission time is ^10-15 seconds, so this phenomenon can be used for amplifying microwaves for communication. The flat electron display can also be manufactured by making the electrons collide with the fluorescent film. In addition, the field emission device may be used for pressure sensors, infrared detection, particle acceleration devices for nuclear reactions, and various sensors in harsh environments such as space development.

In the conventional field emission device, molybdenum or silicon was processed into a sharp needle shape, and a gate was formed at a close distance to control the field emission current. However, in order to make molybdenum or silicon into needles, a complicated process is required and field emission characteristics are not uniform for each needle type. However, recently, it is known that electric field emission is possible in a flat diamond-like carbon film rather than a needle shape, and studies are being actively made to use this material for field emission devices. This is because the use of diamond-like carbon eliminates the need to make the cathode, the source of field emission, into a needle shape, making the process much simpler and improving device reliability.

The disadvantage of this material, however, is that it is difficult to pattern and thus difficult to form gates at close range. In order to obtain a field emission current by applying a voltage to the anode located far away from the diamond-like carbon thin film, which is a cathode, a high voltage must be applied. In this case, the use range of the field emission device will be particularly limited.

In addition, chemical vapor deposition (Chemical Vapor Deposition) has been generally used to form the diamond-like carbon film. In this case, the diamond-like carbon film covers all sides of the structure forming the device without distinguishing the shape of the desired device. it's difficult.

An object of the present invention is to provide a method for manufacturing a field emission device in which a diamond-like carbon film is patterned into each pixel and a gate is formed at a distance of micrometers so that the field emission current can be obtained even at a low voltage applied to the gate.

In order to achieve the above object, the present invention deposits a diamond-like carbon film by a laser ablation method so that carbon flies a straight line to the substrate as a target, so that a diamond-like film is used only on the cathode part using a shadow mask. By forming the carbon film, the desired device shape can be patterned, and the gate and cathode portions are disconnected, thereby improving the performance of the device.

1a to 1l is a manufacturing process chart of the field emission device according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

101 silicon substrate 102 oxide film

103 nitride film 104 molybdenum film

105 nickel film 106 photoresist

107: diamond-like carbon film

1A to 1L show a field emission device manufacturing process chart according to an embodiment of the present invention, with reference to this one embodiment of the present invention will be described in detail.

First, as shown in FIG. 1A, the crystal direction is (100), and a 4 inch n-type unity silicon substrate 101 having a resistivity of 5 to 10? 102) grow.

Subsequently, a nitride film (Si ₃ N ₄ ) 103 is formed on the oxide film 102 by a low pressure chemical vapor deposition method at 850 ° C as shown in FIG.

Next, as shown in FIG. 1C, a molybdenum (Mo) film 104 to be used as the gate metal film is deposited on the nitride film 103 by an electron beam deposition method.

Next, as illustrated in FIG. 1D, a nickel (Ni) film 105 to be used as a sacrificial layer is deposited on the molybdenum film 104 by an electron beam deposition method.

Next, as shown in FIG. 1E, a spinner is rotated on the nickel film 105 for 5 seconds at a low speed of 500 rpm and 35 seconds at a high speed of 4000 rpm to apply the photoresist 106.

Subsequently, as in 1f, the applied photoresist is soft baked at 95 ° C. for 30 minutes, followed by selective exposure using an aligner for 9.5 seconds, and then water and AZ-500MIF developer are subjected to 1 exposure. : It is developed for 70 second in the developer mixed with 6 :, and the photoresist pattern 106a is formed. This photoresist pattern 106a is a gate mask for gate patterning.

Next, as shown in FIG. 1G, the nickel film 105 is dry-etched using the photoresist pattern 106a as a mask to form the nickel film pattern 105a, and the photoresist pattern is removed.

Subsequently, as shown in FIG. 1H, the molybdenum film 104, which is a gate metal film, is wet-etched in a wet etching solution in which HNO ₃ , HF, and CH ₃ COOH solutions are mixed to form the molybdenum film pattern 104a.

Next, as shown in FIG. 1L, the nitride film 103 is etched by a dry etching method to form the nitride film pattern 103a.

Subsequently, as in the first j, the oxide film 102 is wet-etched by dipping the wafer into a buffered-oxide-etchant (BOE), wherein the degree of wet etching is controlled to virtually remove the wafer from the sidewall of the nickel film pattern 105a. The sidewalls of the oxide layer pattern 102a are further etched at the vertical extension line to serve as a shadow mask during subsequent laser ablation deposition of diamond-like carbon.

Subsequently, as in 1k, the diamond-like carbon film 107 is deposited on the entire structure by a laser ablation deposition method. At this time, since the carbon flows straight from the target, the diamond-like carbon film 107 is formed on the sidewall of the pattern pillar. It is deposited only on the portions exposed on one side without being deposited.

Next, as shown in FIG. 11, the nickel film pattern 105a is lifted off to remove the nickel film pattern 105a and the diamond-like carbon film 107 deposited thereon. As a result, as shown in the drawing, the diamond-like carbon film 107 serving as the field emission source and the molybdenum film pattern 104a serving as the gate are formed to be close to each other.

According to the present invention, when the diamond-like carbon film is used as the field emission device, the material shortcomings of the silicon field emission device can be compensated. The application range of the device can be extended.

In addition, since the diamond-like carbon film is deposited by the laser ablation method, since the diamond-like carbon film does not adhere to the gate side surface, electrical separation between the gate and the cathode portion can be easily performed.

Claims (10)

Sequentially forming a first insulating film, a second insulating film, a gate metal film, and a sacrificial film on the semiconductor substrate; Forming a gate mask pattern on the sacrificial layer, etching the sacrificial layer, and then removing the gate mask pattern; Etching the gate metal layer exposed by etching the sacrificial layer; Etching the second insulating layer exposed by etching the gate metal layer; Etching the first insulating layer exposed by the etching of the second insulating layer, wherein the sidewalls of the first insulating layer are etched at a vertical extension line imaginary from the sidewalls of the etched and patterned nickel film; Forming a diamond-like carbon film by laser ablation deposition; And removing the patterned nickel film and the diamond-like carbon film on the patterned nickel film by lifting off the patterned nickel film. The method of claim 1, wherein the semiconductor substrate is a silicon substrate. The method of claim 2, wherein the first insulating film is an oxide film grown on an oxide furnace under a condition of 4.5 sccm of oxygen and a temperature of 1050 ° C. 4. 4. The method of claim 3, wherein the second insulating film is a nitride film by chemical vapor deposition. The method of claim 1, wherein the gate metal layer is molybdenum (Mo). The method of claim 1, wherein the sacrificial film is nickel (Ni). The method of manufacturing a field emission device according to claim 5 or 6, wherein the gate metal film and the sacrificial film are formed by an electron beam deposition method. The method of claim 1, wherein the gate mask pattern is a photoresist pattern. The method of claim 5, wherein the HNO ₃ , HF, and CH ₃ COOH solutions, which are etching the molybdenum film, are wetted in a mixed wet etching solution. The method of claim 4, wherein the etching of the oxide layer is performed by wet etching in a BOE.