JP3074704B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to a semiconductor device utilizing an electron interference effect, and is suitably applied to various quantum interference devices.

[Summary of the Invention] The present invention realizes an AB effect transistor and other quantum interference devices that can operate even at room temperature in a semiconductor device using an electron interference effect by configuring the electron to travel in a vacuum. It is something that can be done.

[Conventional technology]

With recent advances in ultrafine structure fabrication technology, research on quantum interference devices using interference of electron waves has been actively conducted. For example, Aharonov-Bohm
m) The quantum interference transistor utilizing the effect (hereinafter, “AB
Effect transistor) using an AlGaAs / GaAs double heterojunction has been proposed (for example,
Technical Digest of IEDM 86, pp.76-79).

On the other hand, in recent years, research on vacuum microelectronics has become active. One of the achievements is a micro vacuum tube using a semiconductor.

[Problems to be solved by the invention]

The above-mentioned conventional AB effect transistors and other quantum interference devices must be cooled to cryogenic temperatures below liquid helium temperature (4.2K) in order to maintain the coherence of electrons. For this reason, simple use is difficult and it is disadvantageous in terms of cost.

On the other hand, in the conventional micro vacuum tube, the arrival of electrons generated from the cathode to the anode is merely controlled by changing the path of the electrons by a gate voltage applied to the gate, and the interference effect of electrons is utilized. Not something.

Accordingly, an object of the present invention is to provide a semiconductor device capable of realizing an AB effect transistor and other quantum interference devices that can operate even at room temperature.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a semiconductor device using an electron interference effect, comprising a cathode, an anode, a gate, and a blocker in a vacuum chamber, wherein the blocker is provided on a line connecting the cathode and the anode, The gate is provided outside the line connecting the cathode and the anode.Electron waves generated from the cathode are separated by a blocker, then merged at the anode, and the phase of the electron wave is changed by the gate voltage applied to the gate. I have to.

According to the present invention, in a semiconductor device using an electron interference effect, an electron is configured to travel in a vacuum, and a field emission electron source is used as an electron source for generating electrons.

The present invention is further configured in a semiconductor device using an interference effect of electrons, wherein the electrons travel in a vacuum,
In addition, a field emission electron source formed by a non-equilibrium crystal growth method is used as an electron source for generating electrons.

[Action]

According to the semiconductor device of the present invention configured as described above, since the electrons travel in a vacuum, unlike the case of traveling in a solid, the electrons are coherent regardless of the temperature. It is possible to run ballistic while holding the ball. Therefore, this semiconductor device can operate at a temperature much higher than the liquid helium temperature,
Operation at room temperature is also possible. As a result, an AB effect transistor and other quantum interference devices that can operate at room temperature can be realized. In addition, by using a field emission electron source as an electron source for generating electrons, electrons with high coherence can be generated. Furthermore, by using a field emission electron source formed by a non-equilibrium crystal growth method as an electron source for generating electrons, the radius of curvature at the tip can be made extremely small.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. This embodiment shows an embodiment in which the present invention is applied to an AB effect transistor. In FIGS. 1, 2, and 3A to 3D, the same portions are denoted by the same reference numerals.

FIG. 1 shows an AB effect transistor according to one embodiment of the present invention.

As shown in FIG. 1, in the AB effect transistor according to this embodiment, a cathode K, an anode A, a gate G and a blocker B are provided in a vacuum chamber V at a pressure of, for example, about 10 ⁻⁵ Torr or less. I have. Here, the potential of the anode A is set to a positive potential with respect to the cathode K. The blocker B is set at a negative potential with respect to the cathode K.

Next, the operation of the AB effect transistor according to this embodiment configured as described above will be described.

In FIG. 1, highly coherent electrons are generated from the pointed tip of the cathode K by electric field radiation. The electrons generated from the cathode K travel toward the anode A as an electron wave. On the way, an electron wave passing through one side of the blocker B (for example, the left side of the blocker B in FIG. After being separated into an electron wave passing through the other side (for example, an electron wave passing through the right side of the blocker B in FIG. 1), they merge at the anode A. Then, by changing the phase of the electron wave passing on the right side of the blocker B in FIG. 1 by the gate voltage applied to the gate G, the interference between the electron waves merging at the anode A is controlled to perform the transistor operation.

Note that the phase change θ of the electron wave due to the gate voltage applied to the gate G is It is represented by Here, e is the absolute value (unit charge) of the electron charge, Is a value obtained by dividing Planck's constant h by 2π (Dirac's h), V is a gate voltage, and t is time.

FIG. 2 shows a specific example of the structure of the AB effect transistor according to this embodiment.

As shown in FIG. 2, in this structure example, a pointed cathode K made of, for example, n ⁺⁺ type GaAs is formed on an n-type GaAs substrate 1, for example. Reference numeral 2 denotes an n ⁺⁺ type GaAs layer. Reference numeral 3 indicates, for example, a semi-insulating GaAs layer. A pair of gate electrodes G ₁ and G ₂ are formed on the semi-insulating GaAs layer 3 so as to face each other. These gate electrodes G ₁ , G
₂ , different gate voltages can be applied to each other. In actual use, _one of the gate electrodes G ₁ and G ₂ , for example, the gate electrode G ₂ is grounded, and the gate voltage applied to the gate electrode G ₁ is changed.

Above the cathode K, a blocker B is formed. Here, the blocker B is supported by the semi-insulating GaAs layer 3 at one end or both ends. Reference numeral 4 denotes an insulating film. An opening 4a is formed in a portion of the insulating film 4 above the cathode K. An anode A is formed so as to cover the opening 4a.

Note that a back contact electrode 5 is formed on the back surface of the n-type GaAs substrate 1.

Next, a method of manufacturing the AB effect transistor shown in FIG. 2 will be described.

As shown in FIG. 3A, first, n ⁺⁺
A type GaAs layer 2, a semi-insulating GaAs layer 3, and a metal film 6 for forming a gate electrode are sequentially formed.

Next, the metal film 6 for forming a gate electrode is patterned by etching to form gate electrodes G ₁ and G ₂ as shown in FIG. 3B. Thereafter, a mask 7 is formed on a portion of the semi-insulating GaAs layer 3 where the blocker B is to be formed.

Next, etching is performed, for example, halfway in the thickness direction of the semi-insulating GaAs layer 3 under the condition of anisotropic etching by reactive ion etching (RIE), and then RI
Etching is performed by the E method under isotropic etching conditions until the upper surface of the n-type GaAs substrate 1 is reached. Thereby, as shown in FIG. 3C, a cathode K made of n ⁺⁺ type GaAs is formed, and a blocker B is formed.

Next, the insides of the openings formed in the n ⁺⁺ type GaAs layer 2 and the semi-insulating GaAs layer 3 by the above-described etching are filled with a substance such as an insulator or a resist to planarize the surface. Next, as shown in FIG. 3D, after an insulating film 4 is formed on the entire surface by, for example, a CVD method, a predetermined portion of the insulating film 4 is removed by etching to form an opening 4a. After this, this opening 4a
Through the above, the above-mentioned material for surface flattening is removed.

Next, a metal film is formed on the insulating film 4 by oblique deposition in a vacuum so that the opening 4a is filled. At the same time, vacuum sealing is performed, and a vacuum chamber V is formed. Next, this metal film is patterned by etching to form an anode A as shown in FIG. Thereafter, the n-type GaAs substrate 1
A back contact electrode 5 is formed on the back surface of the substrate by, for example, an evaporation method.

As described above, according to the AB effect transistor of this embodiment, the cathode K, the anode A, the gate G, and the blocker B are formed in the vacuum chamber V, and the electrons generated from the cathode K are generated in the vacuum regardless of the temperature. Proceed ballistic while maintaining coherence. Therefore, AB according to this embodiment
The effect transistor can operate at a much higher temperature than before, and can also operate at room temperature.

Further, the AB effect transistor according to this embodiment only needs to change the phase of the electron wave by the gate G.
The change in the gate voltage applied to the gate G may be very small, so that the AB effect transistor can operate at high speed. Furthermore, AB-effect transistor according to this embodiment, by selecting a gate voltage appropriate, it can be set to any of the transconductance g _m of positive or negative. That is, the AB effect transistor according to this embodiment has a performance far exceeding that of a simply reduced-sized vacuum tube.

Incidentally, an electron source used in conventional vacuum microelectronics is formed by vapor deposition of metal or wet etching. However, the radius of curvature of the tip of the electron source formed by these methods is about 500 °, and cannot be said to be sufficiently sharp. Field E _c required for electron field emission, the voltage applied to the electron source V, when the curvature radius of the electron source and the x Therefore, when δx is large, δV also becomes large. For example, if E _c 1010 ⁸ V / cm and δx〜500Å, then δV = E _c δx = 10 ⁸ (V / cm) × 500 (Å) = 500V.

Therefore, a method of forming a field emission electron source having an extremely small radius of curvature at the tip by utilizing crystal growth will be described below.

FIG. 4 shows a case where a linear field emission electron source is formed. As shown in FIG. 4, in this example, a linear pattern is formed on a semi-insulating GaAs substrate 11 having, for example, a (100) plane orientation by etching.
For example, GaAs is epitaxially grown thereon by a non-equilibrium crystal growth method such as a metal organic chemical vapor deposition (MOCVD) method. In this epitaxial growth, GaAs is grown on the above-mentioned linear pattern by selecting a growth material or the like.
The growth can be stopped when a vertex is formed at the top. Thus, a triangular prism-shaped linear field emission electron source 12 is formed on the above-described linear pattern. In this case, the plane orientations of the two slopes of the triangular prism-shaped field emission electron source 12 are (110) and (10), respectively, and the angle between the two slopes is 90 °. In the growth of GaAs by the MOCVD method, a sharp end point is formed when the ratio of As to Ga in the growth material is small. More generally, II
In the case of growing an IV group compound semiconductor, I
Sharp endpoints are formed when the ratio of group V element to group II element is small.

Thus, according to this example, a linear field emission electron source
The shape of the tip of 12 has a sharp shape defined by the crystal plane, and the radius of curvature of the tip can be reduced by about one digit as compared with the related art. For this reason, the voltage applied to the field emission electron source 12 for performing the field emission can be reduced by about one digit as compared with the related art, and the power consumption can be reduced.

FIG. 5 shows a case where a point-shaped field emission electron source is formed.

As shown in FIG. 5, in this example, for example, a rectangular parallelepiped protrusion whose side surface is a (001) plane, a (010) plane, or the like is formed on a (100) plane semi-insulating GaAs substrate, not shown. The portion 21 is formed by etching, and, for example, GaAs is epitaxially grown on the protrusion 21 by, for example, the MOCVD method. As a result, a point-shaped field emission electron source 22 having a pyramid shape is formed on the protrusion 21. In this case, the angle formed by the pair of opposed slopes of the field emission electron source 22 having the pyramid shape is 90 degrees.
゜.

Thus, according to this example, the point-shaped field emission electron source 22 having a very small radius of curvature at the tip can be easily formed by crystal growth. As a result, the voltage applied to the field emission electron source 22 for causing the field emission of electrons can be reduced.

In the above two examples, the non-equilibrium crystal growth method
The MOCVD method is used. For example, molecular beam epitaxy (M
It is also possible to use the BE) method.

JP-A-1-294336 proposes a method for forming a field emission electron source having a pointed tip by growing a crystal using a seed single crystal controlled to a specific orientation by heat treatment. However, it is disadvantageous in that it is difficult to control the growth location of the seed single crystal.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible.

For example, in the above-described embodiment, the phase of the electron wave is changed by the gate G.
In the drawing, a magnetic field may be applied in a direction perpendicular to the plane of the drawing, and the phase of the electron wave may be changed by the magnetic field. In the above-described embodiment, the electron wave generated from the cathode K is divided into two electron waves by the blocker B to make the electron path doubly connected. However, this electron path is multiplexed more than triple connection. It is also possible to link them.

Furthermore, although GaAs is used in the structure example of the AB effect transistor of the above embodiment, for example, Si can be used instead of GaAs.

Further, a cold cathode can be used as an electron source of the AB effect transistor of the above-described embodiment.

〔The invention's effect〕

Since the present invention is configured as described above,
The following effects are obtained.

That is, since the electron is configured to travel in a vacuum, an AB effect transistor and other quantum interference devices that can operate even at room temperature can be realized.

Further, by using a field emission electron source as an electron source for generating electrons, the coherence of the electrons can be increased.

Further, since the electron source is a field emission electron source formed by a non-equilibrium crystal growth method, a field emission electron source having an extremely small radius of curvature at the tip can be realized. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of an AB effect transistor according to one embodiment of the present invention, and FIG. 2 is an AB effect transistor according to one embodiment of the present invention.
3A to 3D are cross-sectional views for explaining a method of manufacturing the AB effect transistor shown in FIG. 2 in the order of steps, and FIG. 4 is a linear electric field emission. FIG. 5 is a perspective view for explaining a method for forming an electron source, and FIG. 5 is a perspective view for explaining a method for forming a point-shaped field emission electron source. Explanation of main symbols in the drawings K: cathode, A: anode, G, G ₁ , G ₂ : gate, B: blocker.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 29/66 H01J 19/38 H01J 21/10 H01J 21/20 H01L 29/80

Claims (3)

(57) [Claims] 1. A semiconductor device using an electron interference effect, comprising: a cathode, an anode, a gate, and a blocker in a vacuum chamber, wherein the blocker is provided on a line connecting the cathode and the anode; It is provided outside the line connecting the cathode and the anode, and after the electron wave generated from the cathode is divided by the blocker, it is merged at the anode and the phase of the electron wave is adjusted by the gate voltage applied to the gate. A semiconductor device characterized by being changed. 2. A semiconductor device utilizing the interference effect of electrons, wherein the electrons are configured to travel in a vacuum, and a field emission electron source is used as an electron source for generating the electrons. Semiconductor device. 3. A semiconductor device utilizing the interference effect of electrons, wherein said electrons are configured to travel in a vacuum, and are formed by a non-equilibrium crystal growth method as an electron source for generating said electrons. A semiconductor device using a field emission electron source.