KR100325075B1 - Field emission display device and manufacturing method - Google Patents

Abstract

The present invention discloses a field emission display device and a method of manufacturing the same. According to the present invention, there is provided a method of forming a cylindrical sacrificial layer on a silicon substrate, using the sacrificial layer as a mask, isotropically etching the silicon substrate by a predetermined depth, and forming polysilicon on the silicon substrate surface and the sacrificial layer surface. Depositing a film, forming a protective film on the surface of the polysilicon film, and anisotropically etching the protective film and the polysilicon film to form a spacer of polysilicon film and a protective film on the sidewalls of the sacrificial layer and the sidewalls of the silicon substrate. And forming a gate oxide layer and a gate electrode on both sides of the polysilicon and the protective layer, and removing the sacrificial layer and the protective layer to form a cylinder spacer type tip of the polysilicon layer.

Description

Field emission display device and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission display device and a manufacturing method, and more particularly, to a tip of a field emission display device capable of lowering an operating voltage while increasing emission current and a method of manufacturing the same.

As is well known, the field emission display device is an indicator using a matrix address capable of matrix addressing a field emission array (FEA), and an electron beam stimulates a phosphor to cause cathode light emission, such as a CRT.

Such field emission display devices have opposing cathode and anode plates and vacuum gaps therebetween. Here, the cathode plate is provided with a gate electrode and a plurality of emitter tips for emitting electrons. On the other hand, the anode plate facing the cathode plate is provided with a phosphor to realize colorization of the field emission display device.

Here, the brightness of the field emission display device is determined by the electron emission capability of the emitter tip, and the electron emission capability of the emitter tip is determined by how low the work function of the material constituting the emitter tip has.

Conventionally, emitter tips are formed of materials such as silicon (Si), molybdenum (Mo), and tungsten (W) having a work function of about 4 to 5 eV.

Referring to FIG. 1, a method of forming a tip from silicon is described below.

In the conventional tip forming method, as shown in FIG. 1, a predetermined pattern (not shown) is formed on the silicon substrate 1, and then a silicon pattern (not shown) is used as a mask. Isotropically etch 1). In this case, the silicon under the pattern is conical by performing overetching during the isotropic etching. Here, the etched portion formed in the shape of a cone is called the tip 4.

Next, the silicon oxide film and the molybdenum layer are formed on both sides of the tip 2 by electron beam evaporation to form the gate oxide film 2 and the gate electrode 3.

However, the cone-shaped tip formed as described above has the following problems.

In general, the tip must be pointed to release a large amount of current. However, according to the prior art, it is practically difficult to make a silicon tip in the form of a cone, which makes it difficult to sharpen the tip of the tip. In addition, when manufacturing the tip in the form of a cone like this there is a lot of loss of material constituting the tip.

In addition, according to the above method, since the shapes of the plurality of tips are not all formed uniformly, the uniformity is very poor.

For the above reasons, the field emission display device has a smaller amount of emission current and a higher operating voltage.

Accordingly, an object of the present invention is to provide an electroluminescent display device capable of increasing the amount of emission current and lowering the operating voltage.

Another object of the present invention is to provide a method of manufacturing the field emission display device.

[Technical Challenges to Invent]

According to an aspect of the present invention for achieving the above object, in the field emission display device comprising an emitter tip for emitting electrons to emit a phosphor, the emitter tip is a cylindrical spacer form formed to surround the outer wall of the cylinder And a polysilicon film.

In addition, according to another aspect of the invention, forming a sacrificial layer of a cylindrical shape on the silicon substrate, using the sacrificial layer as a mask, isotropic etching the silicon substrate by a predetermined depth, the surface of the silicon substrate and Depositing a polysilicon film on the surface of the sacrificial layer, forming a protective film on the surface of the polysilicon film, anisotropically etching the protective film and the polysilicon film, and forming a polysilicon film and a protective film on the sidewalls of the sacrificial layer and the sidewalls of the silicon substrate. Forming a spacer, forming a gate oxide film and a gate electrode on both sides of the polysilicon and the passivation spacer, and removing the sacrificial layer and the passivation layer to form a cylinder spacer tip made of the polysilicon layer. Steps.

According to the present invention, by forming a tip in the form of a cylinder spacer using a doped polysilicon film, the amount of discharge current can be increased, and thus the operating voltage can be lowered.

(Example)

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

2A to 2E are cross-sectional views of respective processes for explaining a method of manufacturing a field emission display device according to an exemplary embodiment of the present invention.

First, in the preferred embodiment of the present invention, as shown in FIG. 2A, the sacrificial layer 12 is formed on the silicon substrate 11 on which the doping of impurities is performed and the well drive-in is performed. To the extent deposited.

In this case, the sacrificial layer 12 is formed of a PSG (phosphorus silicate glass) material which is a material having a different etching rate from that of the silicon substrate 11 and which can be selectively etched.

Subsequently, the sacrificial layer 12 is patterned into a disk shape, and then the silicon substrate 11 is isotropically etched to a depth of about 5500 to 6500 하여 using the sacrificial layer 12 as a mask. At this time, an under cut is generated in the silicon substrate 11 below the sacrificial layer 12 by isotropic etching. In the isotropic etching, SF ₆ gas is used as an etching gas.

Next, as shown in FIG. 2B, the polysilicon film 13 and the silicon oxide film 14 are sequentially deposited on the surfaces of the silicon substrate 11 and the sacrificial layer 12 which have been etched. At this time, the polysilicon film 13 is deposited by about 900 to 1100 kPa by low pressure chemical vapor deposition (LPCVD), and the polysilicon film 13 is preferably a film doped with impurities.

Subsequently, as shown in FIG. 2C, the silicon oxide layer 14 and the doped polysilicon layer 13 are anisotropically etched by reactive ion etching (RIE) to form sidewalls of the sacrificial layer 12 and the silicon substrate ( In the undercut portion of 11), a spacer 15 having a laminated structure of the silicon oxide film 14 and the polysilicon film 13 is formed. In this case, the silicon oxide layer 14 is formed to prevent the surface of the polysilicon layer 13 from being etched during the etching process for forming the spacer 15.

Next, as shown in FIG. 2D, gate oxide films 16 and gate electrodes 17 are formed on both sides of the sacrificial layer 12 structure by electron beam deposition. At this time, a silicon oxide film is used for the gate oxide film 16, and a molybdenum metal film is used for the gate electrode 17. When the gate oxide layer 16 and the gate electrode 17 are formed by the electron beam deposition method, the gate oxide material 16a and the gate electrode 17a are also stacked on the sacrificial layer 12.

Subsequently, as shown in FIG. 2E, the gate oxide material 16a and the gate electrode 17a stacked on the sacrificial layer 12 are removed by a known method. In this process, the silicon oxide film 14 covering the surface of the sacrificial layer 12 and the polysilicon 13 is simultaneously removed. This method is called a lift off method.

Accordingly, only the polysilicon film 15 remains. At this time, the remaining polysilicon film 15 is a cylinder spacer type and becomes the tip 13a in the present invention. The tip 13a is in the form of a cylindrical shape and has a pointed spacer shape, so that an area through which current is emitted is larger than a conventional cone.

Thus, the amount of field emission current is increased. In addition, the cylinder spacer tip 15a can be easily formed by known anisotropic etching, and since the silicon oxide film 14 is covered on the surface when the tip 13a is formed, the tip 13a is uniformly etched. can do.

Furthermore, since the spacer is formed of a doped polysilicon film having an electron transfer capability superior to that of the silicon film, the conductive properties are superior to those of the conventional tip.

1 is a cross-sectional view of a conventional field emission display device.

2A to 2E are cross-sectional views of respective processes for explaining a method of manufacturing a field emission display device according to the present invention.

(Explanation of symbols for the main parts of the drawing)

11-silicon substrate 12-sacrificial layer

13-polysilicon film 14-silicon oxide film

15-spacer 16-gate insulating film

17-gate electrode

As described above, according to the present invention, by forming the tip of the cylinder spacer form using the doped polysilicon film, it is possible to increase the amount of emission current, thereby lowering the operating voltage.

The present invention is not limited to the above embodiment. In the present invention, a polysilicon film doped with a tip is used, but after forming the tip with a pure polysilicon film, the same effect can be obtained even by injecting impurities.

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (13)

A field emission display device comprising an emitter tip for emitting electrons to emit phosphors, And the emitter tip is formed of a polysilicon film in the form of a cylinder spacer formed to surround a cylindrical outer wall. The field emission display device of claim 1, wherein the polysilicon film is a polysilicon film doped with impurities. Forming a cylindrical sacrificial layer on the silicon substrate; Isotropically etching the silicon substrate by a predetermined depth using the sacrificial layer as a mask; Depositing a polysilicon film on the silicon substrate surface and the sacrificial layer surface; Forming a protective film on a surface of the polysilicon film; Anisotropically etching the passivation layer and the polysilicon layer to form spacers of the polysilicon layer and the passivation layer on the sidewalls of the sacrificial layer and the sidewalls of the silicon substrate; Forming a gate oxide film and a gate electrode on surfaces of the silicon substrate on both sides of the polysilicon and the protective film; And And removing the sacrificial layer and the protective film to form a cylinder spacer type tip made of a polysilicon film. The method of claim 3, wherein, in the forming of the gate oxide layer and the gate electrode, a gate oxide layer and a gate electrode are formed on the sacrificial layer to remove the gate oxide layer and the gate electrode on the sacrificial layer. And the protective film is removed at the same time. The method of manufacturing a field emission display device according to claim 3 or 4, wherein the sacrificial layer is a PSG film. The method of claim 5, wherein the protective film is a silicon oxide film. The method of claim 5, wherein the sacrificial layer has a thickness of 4500 to 5500 kPa. The method of claim 3, wherein in the etching of the silicon substrate using the sacrificial layer as a mask, the gas used for etching is SF ₆ gas. The method of claim 8, wherein in the etching of the silicon substrate using the sacrificial layer as a mask, the etching depth of the silicon substrate is about 5500 to 6500 Å. 4. The method of claim 3, wherein the polysilicon film is a polysilicon film doped with impurities. The method of manufacturing a field emission display device according to claim 10, wherein the polysilicon film is formed by LPCVD. The method of claim 11, wherein the polysilicon film is deposited at about 900 to about 1100 GHz. The method of claim 3, wherein the gate oxide layer and the gate electrode are formed by an electron beam deposition method.