JP3024648B2 - Field electron emission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field electron emission device which can control the direction of an electron emission distribution axis and can suppress abnormal emission of electrons emitted from a cathode electrode into an adjacent gate electrode.

[0002]

2. Description of the Related Art As a conventional field electron emission device, CA Spindt et al.
Vol. 5248-5263 (1976) "and HF Gray et al.
776-779 (1986). FIG. 7 shows a schematic perspective view of an example of this type of conventional field electron emission device. In the conventional field electron emission device, a gate electrode 33 is provided on a substrate 31 with an insulating film 32 interposed therebetween, and a conical cathode electrode 35 is provided in a gate hole 34 formed in the gate electrode 33. Things. In this field electron emission device, when a positive voltage is applied to the gate electrode 33 with respect to the conical cathode electrode 35, electrons are emitted from near the tip of the conical cathode electrode 35. Conditions under which electrons are emitted from the field electron emission device depend on the shape of the cathode electrode 35 and the distance between the gate electrode 33 and the cathode electrode 35.

[0003]

By the way, in the field electron emission device including the gate electrode 33 and the cathode electrode 35 as shown in FIG. The direction in which electrons emitted from the vicinity of the front end of the cathode electrode 35 (emitted electrons) are determined by the surface state (work function and electron distribution density) near the front end and the surface shape (fine projections). If the cathode electrode 35 has a precise conical shape and the surface state, the surface shape, and the distance relationship to the end of the gate hole 34 are rotationally symmetric, the spread distribution of the emitted electrons spreads around the rotationally symmetric axis direction. , And the spread angle is recognized to be about 20 ° in half angle.

[0004] However, if any of the symmetry such as the surface state is broken, the center of the distribution of the emitted electrons changes in a direction deviating from the axial direction. When the emitted electrons are stopped down by the electron lens, there is a problem that aberration occurs due to axis deviation. Alternatively, even when an electron lens is not provided, a problem often arises when the intended electron emission direction is different from the actual emission direction. Further, when the distribution of the emitted electrons is deviated from the axial direction, there has been a problem that the emitted electrons jump into the gate electrode 33. If the electrons emitted from the cathode electrode 35 jump into the gate electrode 33, extra power is consumed by the amount of the current due to the jumping electrons, and the periphery of the gate electrode 33 is heated by this power consumption, and the electric field generated by gas release is increased. In some cases, discharge breakdown of the electron-emitting device may occur. Some of the jumping electrons jump into the insulating film 32 below the gate electrode 33, and the deterioration of the element insulating characteristics due to the jump of the emitted electrons into the insulating film 32 has been a practical problem.

One of the phenomena of the discharge breakdown is a short-circuit defect. This short-circuit defect is a phenomenon in which the cathode electrode 35 and the gate electrode 33 are electrically short-circuited. As a countermeasure against such a short-circuit defect, a field electron emission device disclosed in Japanese Patent Application Laid-Open No. 4-284324 is known. In Japanese Patent Application Laid-Open No. 4-284324, in FIG. 1 of the drawings and the related article of FIG. 1 described in the specification, a gate electrode including a plurality of cathode electrodes is divided into a plurality of gate electrode elements, and each gate electrode is divided into a plurality of gate electrode elements. A field electron emission device in which a gate branch line made of a soluble resistor is inserted between an electrode element and a gate main electrode has been proposed. However, in the field electron emission device having such a structure, the axial deviation of the emission electron distribution cannot be solved.

The present invention has been made in view of the above circumstances, and is an electric field electron emission device capable of controlling the direction of an electron emission distribution axis and suppressing abnormal emission of electrons emitted from a cathode electrode into an adjacent gate electrode. Is to provide.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a field emission device including a gate electrode and a cathode electrode disposed in a hole formed in the gate electrode. A gate electrode slit concentrically surrounding the gate electrode; and a gate main electrode electrode located outside the gate electrode slit and electrically connected to the gate electrode near the hole by a plurality of gate branch lines. .

Further, the present invention provides the above-described near-hole gate electrode 7.
An electric field control slit 20 is provided on the periphery of the gate main line electrode 8 facing the above. The electric field control slit 20 refers to the spread of the gate electrode slit 10 on both sides of the gate branch line 9. Further, in the present invention, the distance between the inner peripheral edge of the gate electrode 7 near the hole located on the line connecting the gate branch line 9 and the cathode electrode 1 and the cathode electrode 1 is different from the line connecting the gate branch line 9 and the cathode electrode 1. It is characterized in that it is larger than the distance between the inner peripheral edge of the located gate electrode 7 near the hole and the cathode electrode 1.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, one embodiment of the field electron emission device of the present invention will be described. FIG. 1 is a plan view of a field electron emission device according to an embodiment of the present invention (hereinafter, referred to as a field emission device of the first embodiment) viewed from the cathode electrode side, with a gate electrode equivalent circuit superimposed thereon. FIG. The field electron emission device includes a gate electrode and a cathode electrode 1 disposed in a hole formed in the gate electrode. The gate electrode in the first embodiment includes:
A gate electrode 7 near the hole, a gate electrode slit 10 concentrically surrounding the gate electrode 7 near the hole, and an outer side of the gate electrode slit 10 are electrically connected to the gate electrode 7 near the hole and a plurality of gate branch lines 9. The gate main electrode electrode 8 is connected to the gate main line electrode 8. In FIG. 1, a circuit drawn as a gate equivalent circuit 11 is a gate electrode equivalent circuit.

The gate electrode 7 near the hole has a disk shape in this example, and has a diameter of 0.2 μm to 1 μm at the center thereof.
One hole 7a in the range of about one degree is formed. It is preferable that the outer diameter of the gate electrode 7 near the hole be sufficiently small so that the resistance value of the gate electrode 7 near the hole connecting the gate branch lines 9 is larger than the resistance value of the gate branch line 9. In the hole 7a surrounded by the gate electrode 7 near the hole,
A cathode electrode 1 is provided. A gate voltage is applied to the gate main electrode 8 from outside the field electron emission device.

Next, the operation of the field electron emission device of the first embodiment having the above-described structure will be described. In the field electron emission device having this structure, since the potential of the gate electrode 7 near the hole is lowered at the position where the gate descent current is generated, the field electron emission in the direction where the gate descent current is generated is controlled at that stage. Becomes That is, when an axis shift in the electron emission direction occurs, the axis shift is corrected.

Next, an embodiment of the second field emission device of the present invention will be described. FIG. 2 is a plan view of one embodiment of the field electron emission device of the present invention (hereinafter, referred to as a field electron emission device of the second embodiment) as viewed from the cathode electrode side. FIG. 3 is a cross-sectional view of the field electron emission device of FIG. 2 along the line AA. This field electron emission device includes a substrate 4
An insulating film 5 is deposited thereon, and a gate electrode 7 near the hole surrounding the cathode electrode 1 on the insulating film 5 and a gate electrode slit 1 surrounding the gate electrode 7 near the hole concentrically.
And a gate trunk electrode 8 located outside the gate electrode slit 10 and electrically connected to the gate electrode 7 near the hole by a plurality of gate branch lines 9. In the insulating film 5, a hole 5a connected to the hole 7a of the gate electrode 7 near the hole is formed. On both sides of the gate branch line 9, electric field control slits 20 are provided on the inner peripheral edge 21 of the gate main line electrode 8 facing the hole neighboring gate electrode 7.

The cathode electrode 1 is a substantially conical electrode made of a metal such as molybdenum. The cathode electrode 1 is disposed at the bottom of the hole 5a and is electrically connected to the substrate 4. The gate main line electrode 8 is a metal thin film made of a low-resistance metal such as tungsten.
The gate branch line 9 and the gate electrode 7 near the hole are high-resistance polysilicon electrodes. The width of the gate branch line 9 in the second embodiment is about 1 μm or less, and the length of the gate branch line 9 is
It is preferable that the width is at least about 1 times the width.

The gate electrode slit 10 is a region where the gate metal electrode (including the polysilicon electrode) is removed and the underlying insulating film 5 is exposed. Is present. The gate electrode slit 10 is characterized in that it is wide open in the vicinity of the gate branch line 9 on the inner peripheral side of the gate main line electrode 8 facing the near-hole gate electrode 7, but not at other positions. is there. In this embodiment, the spread is called an electric field control slit 20. Also,
The distance between the gate branch lines 9 is preferably equal to or greater than the width of the gate branch line 9. The components of the field electron emission device of the second embodiment that are the same as those of the field electron emission device of the first embodiment of FIG. 1 are the same as those of the device of FIG. Is the same as

In the field electron emission device according to the second embodiment, the influence of the exposure of the insulating film potential by the gate electrode slit 10 is caused by the influence of the equipotential surface 25 drawn on the upper surface of the field electron emission device of FIG. Has occurred. When the gate electrode slit 10 is largely open, the intensity of the electric field actually applied to the cathode electrode 1 tends to be weakened due to the influence of the cathode potential exposure due to the opening.

Next, the effect of the gate electrode slit 10 shown in FIGS. 2 and 3 will be described with reference to FIG. FIG.
3 is a two-dimensional electric field intensity distribution chart of the field electron emission device having the structure shown in FIG. Reference numeral 26 in FIG.
Is the electric field intensity distribution. In FIG. 4, a hatched pattern centered on the position of the cathode electrode 1 is drawn in three layers, and the density of the hatched pattern schematically represents the strength of the electric field intensity.

The direction of the line AA in FIG. 4 (the direction without the electric field control slit 20) extends greatly from the thin and large hatching pattern to the dark and small pattern near the center. Is strong. If the surface state and shape of the cathode electrode 1 are axially symmetric with respect to the center, more electrons are emitted in the direction of a stronger electric field intensity. More electrons are emitted in one diagonal direction (a-a line direction).

On the other hand, the hatching pattern in the direction of the line BB (the direction along the direction in which the opening of the electric field control slit 20 is large) is small, and the electric field intensity distribution is small. This is because the electric field was weakly affected by the influence of the underlying cathode potential because the opening of the electric field control slit 20 was large. Electron emission in this direction (in FIG. 4, there are three other directions showing the same electric field intensity distribution as the direction of the BB line) is reduced. The direction of the line CC (gate branch line 9)
The electric field intensity distribution in the direction along the length direction is a slightly complicated distribution, and the electric field intensity represented by a large and thin hatching pattern shows the same spread as the A-A direction. However, in a small and dark pattern, the distribution is smaller than the direction of AA. The cause of this tendency is a thin gate branch pattern. From the viewpoint of matching of boundary conditions, the electric field originally formed in the direction of CC is not sufficiently formed by the electric field formed in the direction of BB. The electric field intensity distribution becomes smaller nearer the cathode electrode 1 closer to the axis, and electron emission in this direction is smaller. The same applies to the other gate branch line 9 directions.

FIG. 5 is a diagram in which a gate electrode equivalent circuit is superimposed on a plan view seen from the cathode electrode side of the field emission device of the second embodiment. This is the same as the equivalent circuit of the field electron emission device of the first embodiment shown in FIG. In FIG. 5, a circuit drawn as a gate equivalent circuit 27 is a gate electrode equivalent circuit. The operation of the field electron emission device according to the second embodiment will be described with reference to FIGS. Summarizing the electron emission distribution tendency shown in FIG. 4 means that there are many electron emissions in the diagonal direction in FIG. That is, many electrons are emitted in a direction away from the gate branch line 9 in the gate equivalent circuit 27. If the symmetry of the surface state or shape of the cathode is impaired during the manufacturing process, many electrons are emitted in directions depending on the asymmetry. In an actual field electron emission device, the emission distribution is determined as the product of the emission tendency in the diagonal direction described above and the emission tendency due to asymmetry described later. In the field electron emission device of this embodiment, it may be considered that the arrival position of the jumping electrons to the gate other than the normal electron emission concentrates in the diagonal direction. In the case where a diagonal electron jumps into the gate, the equivalent circuit shown in FIG. 5 can sufficiently exhibit the self-suppression function. The arrangement of the gate branch line 9 and the electric field control slit 20 takes into account the symmetry of the emission electron distribution with respect to the axis. As shown in FIG. 2, there is a case where the gate branch line 9 is arranged four times symmetrically, but it is not always necessary to arrange the gate branch line 9 axially symmetrically by adjusting the opening shape of the electric field control slit.

FIG. 6 shows an embodiment of the field electron emission device of the present invention (hereinafter, referred to as a field electron emission device of the third embodiment). In this field electron emission device, as shown in FIG. 6, the shape of the gate electrode 28 near the hole is such that the inner end (inner edge of the gate electrode near the hole) 29 located near the gate branch line 9 is apart from the cathode electrode 1. Has the same structure as the field electron emission device of the first embodiment in FIG. That is, in the field electron emission device of the third embodiment, the distance between the inner peripheral edge 29 of the gate electrode 28 near the hole located on the line connecting the gate branch line 9 and the cathode electrode 1 and the cathode electrode 1 is equal to the gate branch line. The distance between the cathode electrode 1 and the inner peripheral edge 29 of the gate electrode 28 near the hole located other than on the line connecting the cathode electrode 9 and the cathode electrode 1 is larger.

As described above, when the distance between the cathode electrode 1 and the gate electrode is large, the electron emission distribution in that direction decreases. In FIG. 6, electron emission in the direction of the gate branch line 9 is small due to the configuration of the gate electrode 28 near the hole and the arrangement of the gate branch line 9. The effects of the field electron emission device having such electron emission distribution characteristics are as described above.

(Effect of the Present Invention) The field electron emission device of the present invention has a structure in which the direction of the electron emission distribution axis can be controlled by a gate electrode near the hole, a gate main electrode provided apart from the gate electrode near the hole, and Having a gate branch line for electrically connecting the gate electrode near the hole and the gate main electrode, on the side where a large amount of electrons are emitted due to misalignment of electron emission,
The electric field is suppressed because the gate current increases, and as a result,
The self-control that the electron emission on the side where a large amount of electrons are emitted is suppressed is caused to function. Further, since the gate electrode slit is formed between the gate electrode near the hole and the gate main electrode, the electron emission distribution in the direction of the gate branch line is reduced by partially exposing the base cathode potential, and the gate branch line is exposed. Insufficient self-control in directions can be eliminated. In the direction in which the cathode potential is exposed, the electric field distribution is controlled without adding a special electrode by utilizing the effect that the electron emission electric field is weakened by the gate potential.

[0023]

As described above, according to the field electron emission device of the present invention, in a field electron emission device including a gate electrode and a cathode electrode provided in a hole formed in the gate electrode, A near-hole gate electrode, a gate electrode slit concentrically surrounding the near-hole gate electrode, and a gate trunk line located outside the gate electrode slit and electrically connected to the near-hole gate electrode by a plurality of gate branch lines. The use of the electrodes has an advantage that the electron emission distribution axis direction can be self-controlled in a direction perpendicular to the holes. Further, by providing an electric field control slit for electric field control at the periphery of the gate main electrode facing the gate electrode near the hole, the electron emission distribution in the direction of the gate branch line is reduced, thereby eliminating the lack of self-control. can do. Further, the distance between the inner peripheral edge of the hole near gate electrode located on the line connecting the gate branch line and the cathode electrode and the cathode electrode, the inner peripheral edge of the hole near gate electrode located other than on the line connecting the gate branch line and the cathode electrode, Even if the distance is larger than the distance from the cathode electrode, electron emission in the direction of the gate branch line is small, and the shortage of self-control can be solved.

[Brief description of the drawings]

FIG. 1 is a diagram in which a gate electrode equivalent circuit is superimposed on a plan view of a field electron emission device according to a first embodiment of the present invention as viewed from a cathode electrode side.

FIG. 2 is a plan view of the field electron emission device according to the first embodiment of the present invention as viewed from a cathode electrode side.

FIG. 3 is a cross-sectional view of the field electron emission device of FIG. 2 taken along line AA.

FIG. 4 is a two-dimensional distribution chart of electric field intensity of the field electron emission device of FIG. 2;

5 is a diagram showing a gate electrode equivalent circuit superimposed on a plan view of the field electron emission device of FIG. 2 as viewed from the cathode electrode side.

FIG. 6 is a plan view of a third embodiment of the field electron emission device of the present invention as viewed from the cathode electrode side.

FIG. 7 is a perspective view showing an example of a conventional field electron emission device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cathode electrode, 4 ... Substrate, 5 ... Insulating film, 5a ...
Hole, 7: gate electrode near the hole, 7a: hole, 8: gate main electrode, 9: gate branch line, 10: gate electrode slit, 11: gate equivalent circuit, 20 · ..Electric field control slits, 21: inner peripheral edge of gate main electrode, 25: equipotential surface, 26: electric field intensity distribution, 27: gate equivalent circuit, 2
8 ... gate electrode near the hole, 29 ... inner peripheral edge (inner end) of the gate electrode near the hole.

Claims (3)

(57) [Claims] 1. A field electron emission device comprising a gate electrode and a cathode electrode disposed in a hole formed in the gate electrode, wherein a gate electrode near the hole and a gate concentrically surrounding the gate electrode near the hole. A field electron emission device comprising: an electrode slit; and a gate main electrode located outside the gate electrode slit and electrically connected to the gate electrode near the hole by a plurality of gate branches. 2. The field electron emission device according to claim 1, wherein an electric field control slit is provided on a peripheral edge of the gate main electrode facing the gate electrode near the hole. 3. The field electron emission device according to claim 1, wherein a distance between an inner peripheral edge of the gate electrode near the hole located on a line connecting the gate branch line and the cathode electrode and the cathode electrode is equal to the distance between the gate branch line and the cathode electrode. A field electron emission device characterized in that the distance is larger than the distance between the inner peripheral edge of the gate electrode near the hole located other than on the connecting line and the cathode electrode.