KR0135940B1 - Manufacturing method of silicon tip field emitter for field emission display - Google Patents

Abstract

By using ZMR (Zone Melting Recrystallization) process, single crystal silicon is formed on the cathode electrode to form a silicon tip field emitter for field emission display, which can simplify the manufacturing process and reduce the manufacturing cost. .

Description

Method for manufacturing silicon tip field emitters for field emission displays

1 is a schematic diagram illustrating a Zone Melting Recrystallization (ZMR) process.

2 (a) to (f) are cross-sectional views sequentially showing a process for manufacturing the silicon tip field emitter of the present invention using the ZMR process of FIG.

* Explanation of symbols for the main parts of the drawings

1,11 silicon substrate 2: upper focusing heat source

3: recrystallized thin film 4: melting zone

12. cathode electrode 13: polycrystalline silicon thin film

14 capping oxide film 15 single crystal silicon thin film

16: tip protective oxide film 17 silicon tip

18 oxide film 19 tungsten thin film

20 gate electrode 21 silicon nitride film

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a field emitter manufacturing method for cold cathode devices of field emission displays (FEDs), and in particular to solve the difficulty of forming a cathode electrode under a silicon tip, Zone Melting Recrystallization It relates to a method of manufacturing a field emitter in the form of a silicon tip using a) process.

Field emission displays are displays that emit a strong electric field on a metal surface at room temperature, typically using a silicon tip form as a field emitter.

Field emitters in the form of conventional silicon tips require the formation of a silicon tip on top of the metal used as the cathode electrode material, which is a great challenge.

That is, anisotropic etching of single crystal silicon is required to form a silicon tip on the cathode electrode, but it is not easy to form single crystal silicon on the metal.

In general, in order to grow (epitaxial growth) a thin film having a single crystal structure of a certain material, it must have very demanding conditions, the most important of which is that the crystal structure of the substrate material is similar to the crystal structure of the thin film to be grown. Should be.

However, there is no problem in forming a silicon tip directly on a single crystal silicon wafer, but a problem arises in the field emission display because the silicon tip must be formed on the metal used as the cathode electrode.

That is, since the metal used as the cathode electrode is a polycrystalline structure, it is not easy to directly grow a silicon single crystal thin film thereon.

In addition, there is a manufacturing method of forming a metal tip instead of forming a silicon tip as a field emitter on top of the cathode electrode, but a process of manufacturing a field emitter in the form of a metal tip is more difficult than a process of manufacturing a silicon tip. have.

That is, in order to manufacture a field emitter in the form of a metal tip, a metal tip is formed on the substrate, followed by a general semiconductor manufacturing process of forming an alumina insulator and a molybdenum anode electrode on a metal tip, followed by a metal tip. To form a metal tip source, a metal tip source is deposited in a direction perpendicular to the substrate to form a field emitter in the form of a metal tip, wherein the anode is formed before forming the metal tip to remove unnecessary portions deposited on top of the anode electrode. There is a difficulty in forming a parting layer (parting layer), such as alumina on the electrode.

In addition, as a method, before forming the silicon tip, a method of increasing the electrical conductivity by N-type doping in the portion where the silicon tip is formed is also used, but the cathode electrode is formed by N-type doping in the portion where the silicon tip is formed. In order to form N-type doping, the ion implantation process and the drive-in process of the dopant must be additionally included, so that the manufacturing process becomes complicated, the manufacturing cost increases, and the electrical conductivity of the metal tip is also increased. There is a drawback to not getting it.

Therefore, in order to solve the above-mentioned problems, the present invention not only forms a field emitter in a simple process by using a silicon melting recrystallization (ZMR) method but also forms a silicon tip on top of the cathode electrode, thereby manufacturing costs. You can also save.

In order to achieve the above object, the present invention is to form a cathode electrode on a predetermined portion on the silicon wafer, and to form a polycrystalline silicon thin film on the silicon wafer and the cathode electrode by low pressure deposition method, the capping (capping) on the Forming a silicon oxide film and then locally heating it with a focused energy source and moving the heat source to transform the polycrystalline silicon thin film on the cathode electrode into a single crystal silicon thin film, and etching a predetermined portion of the capping oxide film on the single crystal silicon thin film Next, the remaining portions of the single crystal silicon thin film except for the single crystal silicon thin film on the cathode electrode are etched and removed, the tip protection oxide is formed on the single crystal silicon thin film on the cathode electrode, and then anisotropic etching is performed on the cathode electrode. Forming a silicon tip, and the whole sphere After forming an insulating layer from the top of the semiconductor film, depositing an oxide on the silicon tip surface, forming a conductive film on the insulating layer, and removing the silicon oxide film on the silicon tip and the insulating film and the conductive film on the silicon tip. Characterized in that it comprises a.

Hereinafter, the present invention will be described in detail with the accompanying drawings.

1 is a schematic diagram for explaining a zone melting recrystallization (ZMR) process.

In general, it is very difficult to form a single crystal silicon thin film on the electrical insulation layer. In particular, since SiO _{2, which} is frequently used as a semiconductor device, has an amorphous structure, it is almost impossible to epitaxially grow a single crystal thin film thereon.

Therefore, the substrate on which the amorphous or polycrystalline silicon thin film is deposited on the amorphous insulator (SiO ₂ ) is locally heated with a heat source of focused energy, and a small melt is formed on the silicon thin film to move the heat source. There is a ZMR (Zone Melting Recrystallization) method in which a thin film solidifies in one direction and grows into a single crystal.

Representative heat sources used in ZMR include laser beams, electron beams and graphite rods, arc lamps and tungsten halogen lamps.

Next, a detailed description of the ZMR process is as follows.

First, as shown in FIG. 1, the temperature of the whole board | substrate 1 is maintained at 900 degreeC or more by uniform preheating from the silicon substrate 1 lower part. In this state, as the upper focusing heat source 2, the thin film 3 to be recrystallized is melted by localized heating, and a melting zone having a length corresponding to the diameter of the silicon substrate 1 and a narrow width (3 mm or less) ( 4) form.

At this time, as the upper focusing heat source 2 is scanned, the melting zone 4 is formed, and the melting zone 4 moves the substrate 1 laterally, so that the polycrystalline silicon 3 becomes the single crystal silicon 5. The thin film 3 of the whole upper part of the board | substrate 1 is single-crystallized by unidirectional solidification.

(A) to (f) of FIG. 2 are cross-sectional views sequentially showing a process for manufacturing the silicon tip field emitter of the present invention using the ZMR process described in FIG. 1, and FIG. It is sectional drawing which shows the process of forming the chromium (Cr) electrode 12 for the cathode electrode in the predetermined part on the wafer 11, FIG. 2 (b) is after the process shown by FIG. 2 (a) is completed, After the polycrystalline silicon thin film 13 is formed on the chromium cathode electrode 12 by low pressure vapor deposition (LPCVD), the capping oxide film 14 is sequentially deposited on the chromium cathode electrode 12, and then by ZMR (Zone Melting Recrystallization) method. It is sectional drawing which shows the process of changing the polycrystalline silicon thin film 13 on the chromium cathode electrode 12 into a single crystal silicon thin film.

In other words, when a halogen lamp, not shown as a focused heat source, is connected from above, a specific portion of polycrystalline silicon is solidified while melting to form a single crystal silicon film. When the single crystal silicon is seeded and moved laterally, the polycrystalline silicon thin film 13 on the chromium electrode 12 is changed into a single crystal silicon thin film.

After the above process, as shown in FIG. 1C, after removing all the capping oxide film 14 on the single crystal silicon thin film 15, the remaining single crystal silicon except for the single crystal silicon on the chromium electrode 12 is subsequently removed. Is removed by etching.

FIG. 1D illustrates a tip protection oxide film 16 formed on the single crystal silicon thin film 15 illustrated in FIG. 1C, and then anisotropically etches the single crystal silicon thin film 15 to form a silicon tip. It is sectional drawing which shows the process of forming (17).

(E) of FIG. 1 shows that after the above-described process, a silicon nitride film (Si ₃ N ₄ ) is deposited from the top of the entire structure by a plasma enhanced CVD (PECVD) method, and an oxide film 18 is formed around the silicon tip 17. It is sectional drawing which shows the process of forming the gate electrode 20 by depositing the tungsten thin film 19 from the upper part of the whole structure by E-beam vapor deposition process.

FIG. 1F is a silicon oxide film 21 formed on the silicon nitride film 21 over the silicon tip 17 and the tungsten 19 and silicon tip 17 formed thereon after the process shown in FIG. 18) is a cross sectional view showing the completed state of the silicon tip field emitter.

Next, the operation of the silicon tip field emitter of the present invention will be described. That is, when an appropriate voltage is applied between the cathode electrode 12 and the gate electrode 20, the distance between the gate electrode 20 and the silicon tip 17 is very small, such as several micrometers, so that a strong electric field is formed therebetween. do. Thus, electrons are emitted from the silicon tip 17. At this time, the field emitter in the form of the silicon tip 17 is a key component of the cold cathode device.

As described above, the present invention, in which a silicon tip is formed on a chromium electrode by using a ZMR process to form a field emitter, not only forms a silicon single crystal on the cathode but also reduces the manufacturing cost and the manufacturing cost. Can be.

Claims (4)

In a method of manufacturing a silicon tip field emitter for a field emission display (FED), forming a cathode electrode on a predetermined portion on a silicon wafer, forming a polycrystalline silicon thin film on the silicon wafer and the cathode electrode, and capping on the silicon wafer. forming a silicon oxide film for capping), and locally heating a heat source of focused energy and moving the heat source to transform the polycrystalline silicon thin film on the cathode electrode into a single crystal silicon thin film, and a predetermined portion of the capping oxide film on the single crystal silicon thin film After etching, the remaining portions of the single crystal silicon thin film except for the single crystal silicon thin film on the cathode electrode are etched and removed, the tip protective oxide is formed on the single crystal silicon thin film on the cathode electrode, and then the cathode is anisotropically etched. Forming a silicon tip on top of the electrode Forming an insulating layer from the top of the entire structure, depositing an oxide on the silicon tip surface, forming a conductive film over the insulating layer, and forming a silicon oxide film over the silicon tip, an insulating film and a conductive film over the silicon tip. Method for manufacturing a silicon tip field emitter comprising the step of removing. 2. The method of claim 1 wherein the cathode comprises chromium. The method of claim 1, wherein the insulating layer comprises a silicon nitride film (Si ₃ N ₄ ). 4. The method of claim 3 wherein the conductive film over the insulating layer comprises a tungsten thin film.