JP2933328B2 - Quantum wire device fabrication method and quantum wire device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a quantum wire device having an ultrafine structure and a quantum wire device.

(Prior art) Conventionally, as a method of manufacturing a quantum wire to achieve high performance of a semiconductor device, a method using a fine pattern technology using an electron beam resist or a fine conductivity using a focused ion beam has been used. There was a way to make it. FIG.
It is a schematic diagram which shows the example which produced the thin wire using the pattern technique by the conventional electron beam resist. On a substrate 71 such as GaAs,
An ultra-thin layer of a desired semiconductor material is formed on one of the layers 73 while thin layers 72, 73, and 74 made of various semiconductor materials are stacked in several stages using an epitaxial method. To determine the quality of a semiconductor device, it is important to move electrons in the ultrathin film layer 73 at high speed, and it is necessary to make this thin film layer as thin as possible. Therefore, in the conventional method shown in FIG. 7, thinning is performed by a method using masking or a method of removing unnecessary portions by etching, sputtering or the like after forming a thin film layer. FIG. 8 shows a case where a focused ion beam 75 is irradiated to form a conductive thin wire 76 in a semi-insulating substrate 71 '.

(Problems to be Solved by the Invention) However, in the above-described method, there is a limit in thinning at the quantum level. For example, in the method using an electron beam resist, there is a limit due to a removal action by etching, or damage to a side surface after etching. In the method using the focused ion beam, the beam diameter focusing limit and the control of the beam intensity, that is, the precision of the fine line is greatly influenced by the beam diameter of the pattern to be drawn, the exposure or implantation conditions, etc. There was a problem. Therefore, in the conventional method, a fine wire is produced using a sophisticated apparatus and through a complicated process, so that much work is required, and there is a problem in reproducibility and accuracy.

An object of the present invention is to provide a semiconductor device in which the accuracy of a conductive wire can be accurately defined by the etching depth and the thickness of an epitaxially grown film, that is, the control accuracy of the order of an atomic layer, and an object of the present invention is to easily manufacture a fine wire. .

(Means for Solving the Problems) The above object is to form a layer by obliquely applying a molecular beam of a semiconductor raw material and a dopant raw material to a surface of a substrate having a step, and growing crystals on the surface of the substrate and the step. The method of the present invention is characterized in that the steps described above can be solved by using a vertical step, a forward mesa step, and an inverse mesa step.

In addition, a quantum wire device can be manufactured by embedding the thin wire structure manufactured by the method described above in a laser structure, and further, in the thin wire manufacturing process described above, silicon of an n-type dopant is added to the thin wire region. By doping the vicinity with a high concentration, a high electron mobility transistor type quantum wire device can be manufactured.

Note that as a manufacturing method of the step substrate, a conventional masking method and an etching method can be used.

(Operation) A laminated structure with a very thin film thickness can be easily produced on the order of a single atomic layer by the current molecular beam epitaxy method or metal organic chemical vapor deposition method. As for etching, etching on the order of a single atomic layer has become possible. Therefore, quantum wires can be formed on the stepped substrate with very good width and precision. In addition, this method also eliminates the problem of etching damage and the interface state of the etching surface because quantum wires are formed on the stepped substrate during growth.
An ideal thin line is formed.

(Effects of the Invention) According to the present invention, it is possible to form a high-precision and high-quality fine wire on a substrate in a quantum order. Therefore,
Since the number of non-emission centers can be reduced and the thin line is not exposed to the interface, there is no interface order and the luminous efficiency is good. Further, the present invention has a structure that can be immediately applied to a device such as a quantum wire laser, and the performance of the device can be further improved from each of the above advantages.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a conceptual diagram of a molecular beam epitaxy apparatus for carrying out the present invention. In the figure, the vacuum chamber
Al cell 11, Ga cell 12, As cell containing crystal material in 10
13 are installed. A substrate holder 14 that can be inclined at a predetermined angle θ with respect to the cell is arranged, and a substrate 15 that has been subjected to a step process by etching is attached to the holder. Shutters 16, 17, and 18 for starting or stopping the crystal growth are provided between the substrate holder and each raw material cell. Each raw material cell is wound with a heater 19 for gasifying the solid raw material,
In addition, the substrate holder is provided with a heater 20 for favorably progressing crystal growth. The actual crystal growth conditions are ionization vacuum, 4 × 10 ⁷ Torr for Ga and 1 × 10 ^{7 for} Al.
Torr, the case of As 6 × suit approximately 10 ⁵ Torr, a substrate temperature of 5
By maintaining the temperature at 80 ° C and opening the shutters 17 and 18 of Ga and As simultaneously, GaAs can be grown at 1 μm / hour.
By simultaneously opening the shutters 17, 16, and 18 of Ga, Al, and As, Al _0.3 Ga _0.7 As can be grown at 1.43 μm / hour. The Ga, Al, and As molecular beams of the semiconductor material travel without colliding with each other. Therefore, the substrate is set at θ = 11 with respect to the molecular beam.
When tilted, the crystal growth rate is reduced by 20% compared to the case where the crystal is set in the vertical direction. However, when the step substrate 15 as shown in FIG. 1 is used, the crystal grows thin on the flat portion 21 and grows thick on the step portion 22. I do.

In the present embodiment, the molecular beam is obliquely applied by tilting the substrate by θ = 11 °, but it is possible to appropriately adjust the tilt angle of the substrate within a range of 5 to 30 ° in correspondence with the fine wire structure. desirable.

FIG. 2A to FIG. 2G are schematic views showing work procedures for implementing the present invention.

FIG. 2A is a schematic diagram in which a resist for a mask is applied on a substrate. A resist 24 is applied on the GaAs substrate 23.

FIG. 2B is a schematic view of exposing the resist-coated substrate of FIG. 2A. The exposure method is electron beam exposure, ultraviolet exposure, X
Line exposure can be used.

FIG. 2C is a schematic view of a substrate having a resist to which a pattern has been transferred by exposure and development.

FIG. 2D shows a step substrate 25 formed by etching.

 FIG. 2E shows the step substrate 25 from which the resist has been removed.

FIG. 2F is a schematic view of a GaAs epitaxial layer formed on a step substrate. The epitaxial layer 26 is formed thin in the flat portion 27 and thick in the vicinity of the step 28.

FIG. 2G is a schematic diagram of a structure obtained by repeating alternately using GaAs and AlGaAs raw materials. In the figure, electrons are bound at a location indicated by 29, and one-dimensional (linear) confinement can be performed.
In a typical configuration, a substrate having a step of 20 nm is used, and a molecular beam of a semiconductor raw material is grown at an incident angle of 11 ° so that each layer has a thickness of 5 nm on a flat substrate.
A thin line 29 of nm × 25 nm was formed. In this configuration, both the electron level and the hole level in the thin line region are lower than the electron level and the hole level in the thin film region having a thickness of 5 nm, and both the electron and the hole are energetically stable.

FIG. 3 is a schematic diagram showing a method similar to that of FIG. 2G performed on a normal mesa stepped substrate.

FIG. 4 is a schematic diagram showing the same method as that of FIG. 2G performed on an inverted mesa stepped substrate. In the crystal substrate, a vertical step is formed as shown in FIG. 2G depending on the type of crystal plane and the direction of the step, a step of a forward mesa is formed as shown in FIG. 3, and a step of an inverted mesa is formed as shown in FIG. However, this method can be used for 2G
Thin lines 29, 29 'and 29 "are formed as shown in FIGS. 3, 3 and 4.

FIG. 5 is a schematic view showing a tomographic plane in which a fine wire is embedded in a laser structure by the present method. A pin structure can be easily formed by sandwiching the fine wire structures 52 to 58 formed by the present method between the n-AlGaAs layer 50 and the p-AlGaAs layer 60, and the method can be easily applied to a laser structure. This is an excellent method because the structure can be formed without being exposed to the air during the growth in an ultra-high vacuum and without going through a process that causes other defects.

In addition, a one-dimensional high electron mobility transistor can be realized by supplying an n-type dopant or a p-type dopant obliquely on the step substrate.

FIG. 6 is a schematic view showing a tomographic plane of a one-dimensional high electron transfer transistor. n-type dopant silicon (Si)
Is obliquely incident, so that high concentration doping can be performed near the thin line region, and a one-dimensional thin line high electron mobility transistor is completed. At this time, the growth of the AlGaAs layer is not performed at oblique incidence.

As described above, by growing the molecular beam of the semiconductor raw material and the molecular beam of the dopant on the stepped substrate at oblique incidence, various devices can be produced.

[Brief description of the drawings]

FIG. 1 is a conceptual view of a molecular beam epitaxy apparatus, FIGS. 2A to 2G are schematic views showing work procedures for implementing the present invention, and FIG. 3 is an embodiment of the present invention on a normal mesa stepped substrate. FIG. 4 is a schematic diagram showing the present invention implemented on an inverted mesa stepped substrate, FIG. 5 is a schematic diagram showing a tomographic plane in which the fine wire structure of the present invention is embedded in a laser structure, FIG. Fig. 7 is a schematic view showing a tomographic plane of a one-dimensional high electron transfer transistor, Fig. 7 is a schematic view showing an example of a conventional thin wire creation by an electron beam resistist, and Fig. 8 is an example of a thin wire creation by a focused ion beam. FIG. (Explanation of reference numerals) 10 ... vacuum chamber, 11 ... Al cell, 12 ... Ga cell, 13 ... As cell, 14 ... substrate holder, 15, 25, 25 ', 25 "... stepped substrate, 16 , 17, 18 ... shutter, 19, 20 ... heater, 21, 27 ... flat part, 22 ... step part, 28 ... near step, 23 ... GaAs substrate, 24 ... resist, 26, 26 ', 26 "... GaAs epitaxial layer, 29, 29', 29" ... 1-dimensional fine wire, 30, 30 ', 30 ", 32, 32', 32", 53, 55, 57, 62 ...
AlGaAs layer, 31, 31 ', 31 ", 52, 54, 56, 58, 63 ... GaAs layer, 50 ... n-GaAs step substrate, 51 ... n-AlGaAs layer, 59 ... p-AlGaAs layer, 60 ... p-GaAs stepped substrate, 61 ... GaAS stepped substrate, 62 ... n-AlGaAs layer, 65 ... high concentration n-AlGaAs, 66 ... GaAs fine wire region, 71, 71 '... substrate, 72, 74: Thin film layer, 73: Quantum wire portion, 75: Focused ion beam, 76: Conductive wire portion.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsunobu Aoyagi, Inventor 2-1 Hirosawa, Wako-shi, Saitama Pref. (72) Inventor Susumu Namba 2-1 Hirosawa, Wako-shi, Saitama Pref. Document JP-A-63-175489 (JP, A) JP-A-63-90187 (JP, A)

Claims (9)

(57) [Claims] 1. A quantum wire is formed on a stepped portion by forming a thin crystal layer on a flat portion of the substrate and a thick crystal on the stepped portion by obliquely applying a molecular beam of a semiconductor raw material to the surface of the substrate having the stepped portion. A method for producing a thin wire device. 2. The method according to claim 1, wherein the steps are a vertical step, a forward mesa step, and a reverse mesa step. 3. The method according to claim 1, wherein the semiconductor material is Al, Ga, As. 4. A method in which molecular beams of a semiconductor material and a dopant material are obliquely applied to the surface of a substrate having a step to form a thin crystal growth layer on a flat portion of the substrate and a thick crystal on the step portion, thereby forming a quantum wire on the surface of the substrate. A method for manufacturing a thin wire device, wherein the thin wire device is formed in a portion. 5. The method according to claim 4, wherein the steps are a vertical step, a forward mesa step, and a reverse mesa step. 6. The method according to claim 4, wherein the semiconductor material is Al, Ga, As and the dopant material is Si. 7. An electrode for injecting electrons, a first layer on the electrode having a step and confining light, a thin portion on a flat portion of the first layer, and a step portion thereof. At least one quantum wire of a layer formed by crystal growth of a semiconductor material and a dopant material formed to be thicker, a second layer overlying the quantum wire and confining light, and a second layer overlying the second layer. And an electrode for injecting holes. 8. An electrode for injecting electrons is an n-GaAs step substrate, a first layer is an n-AlGaAs layer, and a thin layer is formed on a flat portion of the first layer and a thick layer is formed on the step portion thereof. 8. The thin wire device according to claim 7, wherein the semiconductor material of the formed layer is GaAs, the second layer is a p-AlGaAs layer, and the electrode for injecting holes is a p-GaAs layer. 9. A one-dimensional fine-wire high electron mobility transistor comprising a semiconductor material layer and a high-concentration dopant material layer formed by thin crystal growth on a flat portion of a substrate having a step and thick crystal growth on the step portion. Make up the fine line device.