JP2001126608A - Semiconductor device for emitting electrons and method of fabricating it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of the electrons emitted from a semiconductor device with stability. SOLUTION: A needle emitter electrode 5 has a leasing end surrounded by an enclosure emitter electrode 9 with crown-shaped edges 13 and 15, which serves as electron emission surfaces together with the needle emitter electrode 5. Instead of the enclosure emitter electrode 9 or in its outside may be installed a conductive film for drawing the electrons. The conductive film is surrounded by a focusing electrode. The needle silicon body is surrounded by a conductive layer to form a mountain-like structure of which summit is removed by etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electron-emitting semiconductor device used for a flat panel display or the like and a method of manufacturing the same.

[0002]

2. Description of the Related Art A semiconductor device having an electron-emitting device can be used for a field emitter array of a flat panel display, and can be used for a small vacuum tube, a high-frequency device, and the like, and its application range is wide.
FIG. 1 shows a typical conventional structure of an electron-emitting device as Sp
5 shows an indt type element. A structure having a sharp tip is provided as an emitter. The emitter emits electrons into a vacuum due to electric field concentration from the surrounding electron extraction electrode (gate electrode).

For example, when an electron-emitting device is used in a flat panel display, an anode coated with a fluorescent material is arranged above the emitter, and the emitted fluorescent material emits light. This is a so-called FED (Field Emission Display).

[0004]

The characteristics required of such an electron-emitting device include a large amount of electron emission (current density) and stable electron emission.

However, in the prior art, as shown in FIG. 1, the electron emission surface is shaped like a <dot>, the area is small, the electron emission amount is relatively small, and the electron emission stability is high. I can't say. For example, oxygen gas and carbon dioxide gas are contained in a vacuum that emits electrons, and those gas molecules are adsorbed on the emitter surface, and the work function of the emitter surface fluctuates. It can cause instability. In addition, application to a flat panel display may cause a decrease in stability of emission of a fluorescent material, and application to a switching element such as a vacuum tube may cause a decrease in stability of a signal output.

Further, it is desired for the electron-emitting device to reduce the driving voltage for emitting electrons as much as possible from the viewpoint of reducing power consumption and improving operation speed.

[0007] Further, it is desired for the electron-emitting device to appropriately control the electron emission direction. For example, when applied to a flat panel display, electrons emitted from an emitter are distributed at a finite angle, so that not only the fluorescent material to be emitted but also another adjacent fluorescent material may emit light. In addition, pixel control cannot be performed properly. In order to avoid such a phenomenon, it is necessary to increase the pixel interval, which is disadvantageous in providing a highly accurate display.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and one of its objects is to provide a semiconductor device capable of increasing the amount of emitted electrons and stabilizing the emission of electrons.

Another object of the present invention is to provide a semiconductor device capable of reducing a driving voltage for emitting electrons.

It is still another object of the present invention to provide a semiconductor device capable of appropriately controlling the direction of emitting electrons.

Still another object of the present invention is to provide a preferable method for manufacturing a semiconductor device which can achieve the above-mentioned object.

[0012]

(1) In order to achieve the above object, an electron emission semiconductor device according to one embodiment of the present invention is a needle-like emitter electrode formed of a needle-like silicon body, and the needle-like emitter electrode. A surrounding emitter electrode comprising at least a single conductive film covering the periphery of the electrode, and having a crown-shaped edge surrounding the tip of the silicon needle on the conductive film;
including.

According to the present invention, a crown-shaped edge is formed on the conductive film covering the periphery of the silicon needle-shaped body, and the crown-shaped edge in addition to the tip of the needle-shaped body functions as an electron emission surface. Therefore, the electron emission surface can be enlarged, thereby stabilizing the electron emission and increasing the electron emission amount.

According to one embodiment of the present invention, there is provided an electron emission semiconductor device comprising: a needle-like emitter electrode formed of a silicon needle-like body;
An electron extraction electrode formed of a conductive film that covers the periphery of the surrounding emitter electrode via an insulating film.

According to the present invention, the emitter electrode and the electron extraction electrode (gate electrode) can be brought close to each other.
For example, a conductive film as an electron extraction electrode is formed around an acicular emitter electrode via an oxide film as an insulating film. In this case, the distance between the electrodes can be set with nano-order accuracy. The drive voltage can be reduced by the proximity of the electrodes.

The electron-emitting semiconductor device according to one aspect of the present invention further comprises a conductive film covering the periphery of the electron extraction electrode with an insulating film interposed therebetween, and the electron for focusing the electrons emitted from the emitter electrode. Includes focusing electrode.

According to the present invention, since the electron focusing electrode is provided so as to surround the electron extracting electrode, the emitted electrons can be focused. For example, in a flat panel display, it is possible to suppress a phenomenon that emitted electrons cause not only a fluorescent material to be emitted but also an adjacent fluorescent material to emit light. This can reduce the pixel interval.

(2) In the method of manufacturing an electron-emitting semiconductor device according to the present invention, a step of forming a silicon needle as a needle emitter electrode and at least a single conductive film surrounding the needle surrounding the silicon needle are provided. And exposing the needle-like emitter electrode by removing a conductive film portion on the top of the chevron structure covering the silicon needle-like body with the conductive film around the needle.

Preferably, in the step of removing the conductive film portion on the top, an etching process is performed, and the conductive film portion on the top is selectively formed by utilizing the fact that a resist film thickness is hardly formed on the top of the chevron structure. Is removed. Preferably, the resist film is formed by spin coating.

In one embodiment of the present invention, the needle surrounding conductive film is formed as a surrounding emitter electrode surrounding the needle-like emitter electrode, and when the top conductive film portion is removed by etching, the silicon needle conductive film is formed on the etched removed portion. A crowned edge is formed surrounding the tip of the body. Preferably, a double crowned edge is formed on the inner and outer peripheral sides of the etched portion.

In one embodiment of the present invention, the needle surrounding conductive film is formed as an electron extraction electrode. Preferably,
Another conductive film surrounding the needle that covers the electron extraction electrode via an insulating film is formed as an electron focusing electrode that focuses electrons emitted from the needle-like emitter electrode. More preferably, by forming a mountain-shaped structure that covers the periphery of the silicon needle-shaped body with a double needle- circumference conductive film, and then removing the needle-side conductive film inside from the outer needle- circumference conductive film to a deep position. Forming the electron extraction electrode and the electron focusing electrode at the same time.

According to the present invention, it is possible to easily manufacture a semiconductor device in which a silicon needle-shaped body is covered with a conductive film and the conductive film functions as an emitter electrode, an electron extraction electrode or a focusing electrode. In particular, the present invention focuses on the difficulty in forming a resist film on the top of a mountain-shaped structure in which a silicon needle-like body is covered with a conductive film, and selectively etches away the top. Thereby, a suitable semiconductor device can be easily manufactured.

In the present invention, the silicon needle-like body is
Preferably, an impurity deposition region formed in a silicon substrate or a silicon layer is used as a micromask, and the silicon substrate or the silicon layer is anisotropically etched at a high selectivity to form a cone type formed with the micromask as an apex. It is a structure. As a result, an elongated needle-like body having a sharp tip is obtained. The aspect of the needle-shaped body can also be increased.
Then, in a semiconductor device in which a conductive film is formed around a needle-like body, a needle-like body having an appropriate shape can be provided at a central portion thereof.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings.

<Embodiment 1> FIG. 2 is a cross-sectional view showing the electron-emitting semiconductor device of the present embodiment. A concave portion 3 is provided in the silicon substrate 1, and the concave portion 3 is kept in a vacuum state. A needle-like emitter electrode 5 composed of a silicon needle-like body protrudes from the bottom surface of the concave portion 3.

The periphery of the needle-shaped emitter electrode 5 is covered with the surrounding emitter electrode 9 via the insulating film 7. For example, the insulating film 7 is a thermal oxide film, and the surrounding emitter electrode 9 is a conductive film of polycrystalline silicon doped with phosphorus.

The upper end of the insulating film 7 is at an appropriate position lower than the tip of the needle-shaped emitter electrode 5, and the lower end reaches the root of the needle-shaped emitter electrode 5. And the surrounding emitter electrode 9
Is provided with a gap 11 between it and the needle-like emitter electrode 5. The gap 11 can be formed by removing a part of the insulating film 7 as described later.

The tip of the surrounding emitter electrode 9 has
Two ring-shaped crown edges 13, 15 are formed. The crown-shaped edges 13 and 15 are formed along the outer circumference and the inner circumference of the surrounding emitter electrode 9, respectively. These coronal edges 13 and 15 form concentric circles surrounding the tip of the needle-like emitter electrode 5. These coronal edges 1
As described later, 3 and 15 are formed on the outside and inside of the removed portion by removing the tip of the polycrystalline silicon of the surrounding emitter electrode 9 by etching.

On the other hand, on the upper surface of the silicon
, An electrode (gate electrode) 19 for extracting electrons is formed via an insulating film 17. For example, insulating film 1
Reference numeral 7 denotes a thermal oxide film, and the electron extraction electrode 19 is made of polycrystalline silicon.

FIGS. 3A and 3B show an example of a configuration in which the above-described semiconductor device for emitting electrons is applied to a flat panel display. As shown in FIG. 3A, the above-mentioned electron-emitting devices are respectively formed in a plurality of opening regions of a gate electrode (electrode for extracting electrons). FIG. 3 (b)
As shown in (2), a plurality of electron-emitting devices may be arranged in each opening region (each concave portion). Then, a substrate on which an RGB fluorescent material layer is formed is arranged so as to face the emission element array structure. The fluorescent material emits light by the electrons emitted from the electron-emitting device. By forming an anode electrode in place of the above-described fluorescent material in addition to the flat panel display, the semiconductor device of this embodiment can be used for a small vacuum tube or the like.

According to the semiconductor device of this embodiment, the tip of the needle-like emitter electrode 5 and the crown-shaped edges 13 and 15 of the surrounding emitter electrode 9 function as an electron emission surface. Therefore, the electron emission area per element occupied area of one electron emission element increases, and as a result, the electron emission amount can be increased and the emission current can be stabilized.

Next, an example of a method of manufacturing the semiconductor device according to the present embodiment will be described with reference to FIGS. Note that various conditions, numerical values, and the like in each step are examples.

In this embodiment, it is important that the needle-shaped emitter electrode located at the core of the electron-emitting device is very thin.
An important point is how to make a structure having this needle-like projection. In this regard, the inventor has devised a preferred method of making suitable needle-like protrusions on a silicon wafer.
In this method, the impurity deposition region formed in the single-crystal silicon substrate or the single-crystal silicon layer is used as a micromask, and the silicon substrate or the silicon layer is anisotropically etched at a high selectivity to obtain a weight having the micromask at the top. The body structure is formed to protrude. The above-described needle-like crystal and a method of manufacturing a semiconductor device using the same are disclosed in Japanese Patent Application No. 10-313976 by the present applicant, and this application is incorporated herein by reference.

Steps (1) to (5) in FIG.
4 shows a process for producing a needle-shaped emitter electrode according to the above principle.

In the steps (1) to (3), a nano-order compound of Si and N is formed in a silicon substrate. In step (1), an n-type Si substrate (impurity phosphorus, ρ =
0.011 Ωcm, concentration 3 × 10 ¹⁸ cm ^-3 )
A thermal oxide film of nm is grown. In the step (2), nitrogen is ion-implanted. The ion implantation conditions are acceleration energy 10
0 keV (Rp = 0.22 μm), dose amount is 1 × 10
¹⁵ cm ^-2 . In the step (3), 1000 ° C., 6
Heat treatment for 0 minutes in atmospheric oxygen. Thus, it is considered that nitrogen ions implanted into the substrate combine with silicon atoms to form a nano-order SiN compound.

In steps (4) and (5), silicon needle crystals are formed using the above-mentioned SiN compound. In step (4), the oxide film in the region where the silicon needle crystal is to be formed is wet-etched with BHF (buffered hydrofluoric acid). In the step (5), high selectivity dry etching in which silicon is easily etched is performed using SiN as a mask. As a dry etching gas, NF ₃ , HBr,
He and O ₂ are utilized. Thereafter, wet etching is performed for 30 seconds with BHF at 20 ° C. to remove deposits during etching.

As described above, a silicon needle crystal having a very thin shape, a sharp pointed end, and a large aspect ratio is formed. In the example of FIG. 4, the root diameter of the needle is about 0.35 μm, the height is about 2.5 μm, the tip angle is about 10 degrees, and the aspect ratio (aspect ratio) is about 7.1. Depending on the etching conditions, the needle height can be increased by about 10 μm while keeping the aspect ratio constant.

Next, in steps (6) to (10), a surrounding emitter electrode is formed around the needle-like crystal to manufacture the semiconductor device of this embodiment.

In the step (6), a thermal oxide film is formed on the silicon needle crystal. As the processing conditions, the oxidation temperature is 900
C., the oxidation time was 15 minutes, and the atmosphere was pyrogenic (a mixed gas of hydrogen and oxygen). Further, the thermal oxide film is processed and patterned by photolithography and wet etching using hydrofluoric acid. Here, only the thermal oxide film of the silicon needle crystal and the region where the electron extraction electrode (gate electrode) is formed is left.

In the step (7), a method having good coverage is used.
A polycrystalline silicon film is formed, and needle-like crystals are converted to polycrystalline silicon.
Obtain a chevron structure covered with a membrane. In the present embodiment, the decompression CV
Polycrystalline silicon is deposited by D method. The film thickness is 40
It is set to 0 nm. After that, the polysilicon
Doping (diffusion). Phosphorus concentration is 10²¹cm
^-3It is about.

In the step (8), a resist is spin-coated under a condition that the thickness is slightly smaller than the height of the silicon needle crystal. The resist is of standard specification with a viscosity of 11 cp and the spin speed is 5350 rpm. here,
As described below, the nature of the resist is used to prevent the resist from being applied to the top of the chevron structure (the portion where the needle crystal is covered with silicon).

That is, the resist has a property that it is difficult to apply the resist to the top of the chevron due to its viscosity. The higher the peak and the smaller the area of the top, the more difficult it is to apply the resist to the top. The resist film thickness becomes thinner at the upper part of the step, and the film thickness at the top becomes smaller than that at the foot and side.

In the present embodiment, since the silicon needles are very elongated, when the needles are covered with polycrystalline silicon, the peaks become high and the peaks become narrow. Therefore, by utilizing the properties of the resist, it is possible to apply the resist only to portions other than the tops of the chevron portions as shown in the figure. The resist film becomes thinner as going upward.

Further, in the step (8), the resist in the region excluding the vicinity of the gate electrode and the silicon needle crystal is removed by photolithography.

Referring to FIG. 6, in the step (9), dry etching is performed under conditions where polycrystalline silicon is easily etched. As the gas, Cl ₂ or HBr is used. Since resist is not applied to the tip of the silicon needle crystal,
The polycrystalline silicon at the tip is etched. here,
Etching is performed until a thermal oxide film covering the needle-like crystals can be seen.

In step (10), the resist is removed by Carros cleaning. Further, the thermal oxide film between the polycrystalline silicon and the silicon needle crystal is removed by BHF. As a result, the silicon needle crystals are exposed. As conditions, BHF is at a temperature of 20 ° C., and the etching time is 5 minutes (corresponding to the etching of a 250 nm thermal oxide film).

In steps (9) and (10), a double ring-shaped sharp crown-shaped edge surrounding the needle-like crystal is formed in the silicon needle-like crystal. In the etching, the top of the polycrystalline silicon is removed so as to be cut off. The etching progresses around the central thermal oxide film. As a result, two crowned edges are formed along the outer and inner perimeters of the etched area as shown. That is, an outer crown-shaped edge is formed at a portion where the outer periphery of the polycrystalline silicon contacts the resist on the outer side. Similarly, an inner crown-shaped edge is formed at a portion where the polycrystalline silicon contacts the thermal oxide film on the inner side.

FIG. 7 is a TEM photograph of the semiconductor device manufactured by the above method, and the semiconductor device having the desired structure shown in FIG. 2 is realized.

As described above, according to the manufacturing method of the present embodiment, after forming the mountain-shaped structure that covers the periphery of the silicon needle with the conductive film, the conductive film portion on the top of the mountain-shaped structure is removed. . As a result, the central needle-like emitter electrode is exposed, and an annular edge is formed in the peripheral emitter electrode. Therefore, the semiconductor device of the present embodiment can be easily obtained with a small number of steps.

In the present embodiment, in particular, the resist is applied by utilizing the structural characteristics of the silicon needle crystal. Paying attention to the difficulty in forming a resist film on the top of the thin and high mountain-shaped structure, the resist is not applied to the top portion, and this portion is selectively etched away. Edges are automatically formed by characteristic resist coating. Fine edge shapes that cannot be obtained by ordinary photolithography can be easily created.

This embodiment can of course be arbitrarily modified within the scope of the present invention. For example, the surrounding emitter electrode 9 in FIG. 2 may be replaced by a material having conductivity other than polycrystalline silicon, for example, amorphous silicon. In this embodiment, the insulating film 7 is provided between the needle-like emitter electrode 5 and the surrounding emitter electrode 9. The film in this portion may be a silicon nitride, and may not be an insulating film. However, in this embodiment, an insulating thermal oxide film is provided as a result of applying the above manufacturing method.

In this embodiment, one layer of the surrounding emitter electrode 9 is provided. However, a plurality of surrounding emitter electrodes 9 may be provided. Preferably, in the manufacturing process of FIGS. 4 to 6, at the stage where polycrystalline silicon is deposited, a thermal oxide film and polycrystalline silicon are further deposited. Here, a desired number of polycrystalline silicon layers are formed.
Then, a multi-ring electron emission surface (three or more layers) is formed by processing the tip of the chevron structure covered with polycrystalline silicon. Thereby, the electron emission area can be further increased, and the electron emission amount can be increased.

It is also preferable to coat a material which easily emits electrons, such as carbon, on the polycrystalline silicon and the needle-like emitter electrode of the electron-emitting device manufactured in the present embodiment, so as to further improve the characteristics. it can.
The same applies to other embodiments described below.

<Embodiment 2. FIG. 8 shows a semiconductor device of the present embodiment. This semiconductor device has basically the same structure as the above embodiment shown in FIG. The manufacturing method is also basically the same as the above-described embodiment described with reference to FIGS. However, as a difference from the above-described embodiment, the polycrystalline silicon layer around the needle-like emitter electrode 5 functions not as an emitter electrode but as an electron extraction electrode (gate electrode) 21. Along with this, wiring (not shown) required as the electron extraction electrode 21 is formed by patterning. Further, the gate electrode on the substrate as in the first embodiment is not required, and the silicon substrate does not need to be provided with the concave portion.

According to this embodiment, the needle-like emitter electrode 5
And the electron extraction electrode 21 can be brought close to each other.
By controlling the thickness of the insulating film 7, the distance between the electrodes (electron extraction electrode and the tip of the emitter) can be easily adjusted, and a desired distance between the electrodes can be obtained. For example, when a thermal oxide film is applied, the film thickness can generally be controlled with a nano-order accuracy in the film forming process. By reducing the distance between the electrodes, the driving voltage (applied voltage) for emitting electrons can be reduced.

This embodiment can of course be arbitrarily modified within the scope of the present invention, similarly to the above-described embodiment. For example, the electron extraction electrode 21 may be replaced with a conductive material other than polycrystalline silicon, and may be, for example, amorphous silicon. However, in the above embodiment, the insulating film 7 may be replaced with a conductive material. However, in the present embodiment, insulation is required.

In another modification, the surrounding emitter electrode may be formed around the needle-like emitter electrode, and the electron extracting electrode may be formed so as to cover the outside. This is a configuration in which an electron extraction electrode is placed outside the emission device of FIG. Multiple layers of surrounding emitter electrodes may be provided. As a manufacturing method, a plurality of conductive layers are formed around the needle-like emitter electrode. The inner conductive layer (or two or more) may be used as the surrounding emitter electrode, and the conductive layer outside the surrounding emitter electrode may be used as the electron extraction electrode.

<Embodiment 3> FIG. 9 is a cross-sectional view showing the electron-emitting semiconductor device of the present embodiment. In the present embodiment, the semiconductor device of the above embodiment is further improved.
Here, an electron extraction electrode is provided around the needle-like emitter electrode, and an electron focusing electrode is further provided outside.

Referring to FIG. 9, a needle-like emitter electrode 35 made of a silicon needle-like body protrudes from a silicon substrate 31 into a vacuum.

The periphery of the needle-shaped emitter electrode 35 is covered with an electron extraction electrode (gate electrode) 39 as a first conductive film via a first insulating film 37. For example, insulating film 3
Reference numeral 7 denotes a thermal oxide film, and the electrode 39 for extracting electrons is polycrystalline silicon doped with phosphorus. The point that the periphery of the emitter is covered with the electron extraction electrode 39 is the same as that of the above-described embodiment of FIG.

The upper end of the first insulating film 37 is at an appropriate position lower than the tip of the needle-shaped emitter electrode 35, and the lower end reaches the root of the needle-shaped emitter electrode 35. A portion near the tip of the electron extraction electrode 39 is provided with a gap 41 between the electron extraction electrode 39 and the needle-like emitter electrode 35. This gap 41
Can be formed by removing a part of the insulating film 37 as described later.

In this embodiment, the outside of the electron extraction electrode 39 is covered with the electron focusing electrode 45 as a second conductive film via the second insulating film 43. For example, the second insulating film 43 is silicon nitride, and the electron focusing electrode 45 is phosphorus-doped polycrystalline silicon. The second insulating film 43 prevents a current flow between the electron extraction electrode 39 and the electron focusing electrode 45.

A ring-shaped sharp crowned edge 47 is formed at the upper end of the electron focusing electrode 45. The crown-shaped edge 47 is provided along the outer periphery of the electron focusing electrode 45. A small crown-shaped edge 49 is also formed along the inner periphery of the upper end of the above-mentioned electron extraction electrode 39. The coronal edge 47 (outside) of the electron focusing electrode 45 is larger and higher than the coronal edge 49 (inside) of the electron extraction electrode 39. The top surface of the electron focusing electrode 45 is located above the top surface of the electron extraction electrode 39.

In the electron-emitting device described above, the electron extracting electrode 39 as the first conductive film causes the needle-shaped emitter electrode 35 to emit electrons. That is, when a driving voltage is applied to the electron extraction electrode 39, electrons are emitted from the needle-like emitter electrode 35 into a vacuum due to electric field concentration. Further, an electron focusing electrode 45 serving as a second conductive film is located on the electron extracting electrode 39, and focuses electrons emitted from the needle-like emitter electrode 35.

According to the present embodiment, as in the above-described embodiment, the drive voltage can be reduced because the electron extraction electrode 39 is close to the needle-like emitter electrode 35. In addition, since the electron focusing electrode 45 is provided separately from the electron extracting electrode 39, emitted electrons can be focused. Therefore, it is possible to provide a suitable semiconductor device having a low driving voltage and capable of appropriately focusing emitted electrons.

The electron-emitting device of this embodiment can be incorporated in a flat panel display as illustrated in FIG. 3 and used as a field emitter array, as in the above-described embodiment. In this case, by improving the convergence, it is possible to effectively prevent another fluorescent material adjacent to the fluorescent material to be emitted from emitting light. Therefore, a field emitter array excellent in pixel control can be provided. The present invention can also contribute to the reduction of the pixel interval.

Next, an example of a method for manufacturing the semiconductor device of the present embodiment will be described with reference to FIGS. Descriptions of items common to the manufacturing method described with reference to FIGS. Also, various conditions, numerical values, and the like in each step are examples.

Step (1) in FIG. 10 to step (4) in FIG.
Then, a silicon needle crystal is formed by the above-described characteristic method. In the step (1), nitrogen is ion-implanted into the n-type Si substrate, and in the step (2), heat treatment is performed. Thus, it is considered that a nano-order SiN compound is formed in the substrate. In step (3), the oxide film is wet-etched with BHF (buffered hydrofluoric acid). In step (4), Si
Using N as a mask, dry etching with a high selectivity at which silicon is more easily etched than SiN is performed. Thereafter, wet etching is performed with BHF to remove deposits at the time of etching. As described above, very thin needle-like crystals are formed as in the above-described embodiment.

Next, in steps (5) to (10), a plurality of conductive films are formed around the above-mentioned needle-like crystals to manufacture the semiconductor device of this embodiment.

In step (5), a thermal oxide film (first insulating film) is formed on the silicon needle crystal. Thickness is about 100nm
It is. In step (6), a polycrystalline silicon film (first conductive film) is formed. Here, polycrystalline silicon is deposited by a low pressure CVD method. The thickness is 150 nm. After that, the polycrystalline silicon is doped with phosphorus. The concentration of phosphorus is about 10 ²¹ cm ⁻³ . This polycrystalline silicon will later become an electrode (gate electrode) for extracting electrons.

In step (7), a silicon nitride film (second insulating film) is deposited by a low pressure CVD method. The film thickness is 100
nm. Thereafter, polycrystalline silicon (second conductive film) is deposited again by the low pressure CVD method. The film thickness is 150n
m. The polycrystalline silicon is doped with phosphorus to provide conductivity. The processing conditions are set so that the density of phosphorus is about 10 ²¹ cm ⁻³ .

Turning to FIG. 12, in the step (8), a resist is spin-coated under such a condition that the resist is applied thinner than the height of the convex structure formed up to the step (7). The resist is of standard specification with a viscosity of 11 cp and the spin speed is 5350 rpm.

Here, as described in the above embodiment, the formation of the resist film on the top of the chevron portion is suppressed by utilizing the structural characteristics of the acicular crystals and the characteristics of the resist. That is, in the present embodiment, a very thin needle-like crystal can be provided. Therefore, when the needle-like crystal is covered with the silicon film, a high peak having a narrow top is formed. When a resist is spin-coated on such a chevron structure, as shown in the figure, the resist film becomes thinner at the upper part of the step, and the resist film is not applied on the top. Therefore, a resist can be applied to portions other than the top of the chevron structure.

In the step (9), the "polycrystalline silicon and silicon nitride" are dry-etched under conditions that are more easily etched than the "thermal oxide film and resist". The dry etching is performed until the thermal oxide film formed on the silicon needle crystal is exposed. As a result, the two-layer polycrystalline silicon film and the silicon nitride film between them are processed and removed near the top of the needle crystal.

Next, in step (10), the resist is removed, and the thermal oxide film is wet-etched with hydrofluoric acid. The etching amount is several 100 nm. This allows
The needle-like silicon crystal is exposed. The removal of the oxide film creates a gap between the needle-like silicon crystal and the surrounding polycrystalline silicon. Further, the silicon nitride film is also slightly etched, and a slight gap is formed between the two layers of polycrystalline silicon films, but this is within a range in which there is no problem.

In steps (9) and (10), the top portion of the chevron structure of polycrystalline silicon is removed so as to be cut off. The periphery of the top (arrow, where the resist is thin), which is a portion close to the resist, is hard to be etched, and the etching proceeds in the center of the top without the resist. A crown edge is formed in the outer polycrystalline silicon. As a result of such etching, the upper end of the outer polycrystalline silicon (second conductive film) is positioned above the inner polycrystalline silicon (first conductive film). It can function as a focusing electrode.

The method for fabricating the semiconductor device according to the present embodiment has been described above. In the present embodiment, a plurality of conductive films are formed around a silicon needle crystal to form a mountain structure, and a top portion of the mountain structure is processed. As a result, an electron extraction electrode and a focusing electrode are simultaneously manufactured. More specifically, a first insulating film, a first conductive film, a second insulating film, and a second conductive film are sequentially formed. Then, the first conductive film, the second insulating film, and the second conductive film are etched until the top of the first insulating film is exposed, and only the first insulating film is etched. As a result, the electrode for extracting electrons and the electrode for focusing are simultaneously formed.

As can be seen from this embodiment, according to the present invention, the electron extraction electrode and the focusing electrode can be formed around the needle-shaped emitter electrode by a simple manufacturing method, and the driving voltage can be reduced. A field emitter array with low pixel control and excellent control can be realized. Of course, the semiconductor device of the present invention may be applied other than the field emitter array.

The present embodiment is advantageous in that the distance between the emitter electrode, the electron extraction electrode, and the focusing electrode can be easily adjusted by controlling the thickness of each insulating film.

Further, in the present embodiment, as described in the above embodiment, the resist is applied by utilizing the structural characteristics of the silicon needle crystal. That is, a mountain-shaped structure having a silicon needle-shaped crystal at its core is thin and high. It is difficult to form a resist film on the top of such a chevron structure. Focusing on this point, resist application to the top portion is suppressed, and this portion is selectively removed by etching. Due to the characteristic resist coating, a sharp coronal edge at the tip of the electrode shape, particularly the focusing electrode, is automatically formed. Fine edge shapes that cannot be obtained by ordinary photolithography can be easily formed.

It is needless to say that this embodiment can be arbitrarily modified within the scope of the present invention, similarly to the other embodiments described above. For example, one or both of the electron extraction electrode and the focusing electrode may be replaced with a conductive material other than polycrystalline silicon (for example, amorphous silicon).

As described in connection with the above-described embodiment, the surrounding emitter electrode may be provided around the needle-like emitter electrode, and the electron extraction electrode and the electron focusing electrode may be provided therearound. The surrounding emitter electrode may have a plurality of layers.

[Brief description of the drawings]

FIG. 1 is a view showing a conventional typical electron-emitting semiconductor device.

FIG. 2 is a cross-sectional view showing an electron emission semiconductor device according to Embodiment 1 of the present invention.

FIG. 3 is a diagram illustrating a configuration example of a flat panel display including the semiconductor device of FIG. 2;

FIG. 4 is a first diagram illustrating the method for manufacturing the semiconductor device of FIG. 2;

FIG. 5 is a second diagram illustrating the method for manufacturing the semiconductor device in FIG. 2;

FIG. 6 is a third diagram illustrating the method for manufacturing the semiconductor device in FIG. 2;

FIG. 7 is a photomicrograph of the semiconductor device produced by the method of FIGS.

FIG. 8 is a sectional view showing an electron emission semiconductor device according to a second embodiment of the present invention.

FIG. 9 is a cross-sectional view illustrating an electron emission semiconductor device according to a third embodiment of the present invention.

FIG. 10 is a first diagram illustrating the method for manufacturing the semiconductor device in FIG. 9;

FIG. 11 is a second diagram illustrating the method for manufacturing the semiconductor device in FIG. 9;

FIG. 12 is a third diagram illustrating the method for manufacturing the semiconductor device in FIG. 9;

[Explanation of symbols]

1,31 silicon substrate, 5,35 needle-shaped emitter electrode, 7 insulating film, 9 surrounding emitter electrode, 13,15
Coronal edge, 19,21,39 Electrode for electron extraction, 3
7 First insulating film, 43 Second insulating film, 45 Electron focusing electrode, 47, 49 Coronal edge.

Claims (13)

[Claims] 1. A needle-shaped emitter electrode made of a silicon needle-shaped body, and at least a single conductive film covering the periphery of the needle-shaped emitter electrode, and a tip of the silicon needle-shaped body on the conductive film. And a surrounding emitter electrode having a crown-shaped edge surrounding the part. 2. A needle-shaped emitter electrode formed of a silicon needle-shaped body, and an electron extraction electrode formed of a conductive film that covers the periphery of the needle-shaped emitter electrode via an insulating film. Semiconductor device for electron emission. 3. The electron-emitting semiconductor device according to claim 2, further comprising a conductive film which covers the periphery of said electron extraction electrode via an insulating film, and focuses electrons emitted from said emitter electrode. A semiconductor device for emitting electrons, comprising an electrode for focusing electrons. 4. The electron emission semiconductor device according to claim 1, further comprising an electron extraction electrode formed of a conductive film that covers the periphery of the surrounding emitter electrode with an insulating film interposed therebetween. Semiconductor device for electron emission. 5. The electron-emitting semiconductor device according to claim 4, further comprising a conductive film that covers the periphery of said electron extraction electrode via an insulating film, and focuses electrons emitted from said emitter electrode. A semiconductor device for emitting electrons, comprising an electrode for focusing electrons. 6. A method of manufacturing a semiconductor device for electron emission, comprising: forming a silicon needle as a needle emitter electrode; and forming at least a single needle surrounding conductive film covering the periphery of the silicon needle. A semiconductor device for electron emission, comprising: removing a conductive film portion on the top of the chevron structure covering the silicon needle-shaped body with the conductive film surrounding the needle to expose the needle-shaped emitter electrode. Manufacturing method. 7. The method for manufacturing an electron-emitting semiconductor device according to claim 6, wherein an etching process is performed in the step of removing the conductive film portion on the top, and a resist film thickness is formed on the top of the chevron structure. A method of manufacturing a semiconductor device for electron emission, characterized in that the conductive film portion on the top is selectively removed by utilizing the difficulty. 8. The method of manufacturing an electron-emitting semiconductor device according to claim 7, wherein the resist film is formed by spin coating. 9. The method of manufacturing a semiconductor device for electron emission according to claim 6, wherein the conductive film around the needle is formed as a surrounding emitter electrode surrounding the needle-like emitter electrode, When removing the film part by etching,
A method of manufacturing a semiconductor device for electron emission, characterized in that a crown-shaped edge surrounding a tip portion of the silicon needle-like body is formed in a portion removed by etching. 10. The method for manufacturing an electron-emitting semiconductor device according to claim 9, wherein a double crowned edge is formed on an inner peripheral side and an outer peripheral side of the portion removed by etching. Manufacturing method. 11. The method according to claim 6, wherein the conductive film around the needle is formed as an electrode for extracting electrons. Manufacturing method. 12. The method of manufacturing an electron emission semiconductor device according to claim 11, wherein another needle surrounding conductive film covering the electron extraction electrode via an insulating film is emitted from the needle emitter electrode. A method for manufacturing an electron emission semiconductor device, wherein the method is formed as an electron focusing electrode for focusing electrons. 13. The method of manufacturing an electron-emitting semiconductor device according to claim 12, wherein a mountain-shaped structure is formed to cover the periphery of the silicon needle-shaped body with a double-needle conductive film, and then around the outer needle. A method of manufacturing a semiconductor device for electron emission, wherein the electron extraction electrode and the electron focusing electrode are simultaneously formed by removing the needle surrounding conductive film inside the conductive film to a deep position.