JPH04105313A - Manufacture of quantum box - Google Patents

Abstract

PURPOSE:To obtain a manufacturing method of a quantum box which has fineness sufficient to make quantum effect explicit and is free from working damage, by a method wherein a semiconductor substrate surface having an atom step is selectively eliminated by maskless etching, a wire pattern is formed, and semiconductors whose compositions are different in the inclination direction are laminated along the wire pattern. CONSTITUTION:At least the following are contained; a process wherein the surfaces of semiconductor substrates 10, 11 having atom steps are selectively eliminated by maskless etching, and a wire pattern 14 having an atom step is formed, and a process wherein semiconductors 15, 16 whose compositions are different in the inclination direction of the above atom step are laminated along the wire pattern 14. For example, an AlAs layer 11 is laminated on a (001) GaAs substrate 10 off by 2 deg. in [-110] direction, and while supplying Cl2 12, a convergent electron beam 13 is so projected on the AlAs layer 11 that the wire pattern 14 is left, thereby performing maskless etching. Next, 1/2 atom layer of a GaAs layer 15 is laminated, and then 1/2 layer of an AlAs layer 16 are laminated. By repeating the lamination, a three-dimensional superlattice of a (GaAs)1/2 (AlAs)1/2 is formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a quantum effect device.

[Conventional technology]

Three-dimensional superlattices (quantum boxes) that confine electrons three-dimensionally are difficult to fabricate, so there are few reports, or metal-organic vapor phase epitaxy (MOVPE), holographic lithography, wet etching, and liquid phase epitaxy. An InGaAs/InP quantum box structure with a pn junction and an optical guide structure was fabricated using regrowth technology (LPE method).
The above example is the Japanese Journal of Applied Physics.
of Applied Physics) Volume 26 No. 4,
1987, L225-227. In this example, 3
It has been reported that a shift in emission wavelength has been observed as a dimensional quantum size effect.

[Problem that the invention seeks to solve]

However, since wet etching is currently used, there are problems with the size of the quantum box, the steepness of the interface, etc., and a perfect quantum box has not been realized.

An object of the present invention is to provide a method for manufacturing a quantum box that has sufficient fineness to make quantum effects apparent and is free from processing damage.

[Means to solve the problem]

A method for manufacturing a quantum box according to the present invention includes a step of selectively removing the atomic steps on the surface of a semiconductor substrate having atomic steps by maskless etching to form a thin line pattern having the atomic steps, and a step of forming a thin line pattern having the atomic steps; The manufacturing method is characterized in that it includes at least the step of: laminating semiconductors having different compositions along the thin line pattern.

[Effect]

In the present invention, a thin line with a width of several hundreds of nanometers having atomic steps is formed by maskless etching, and then step-flow growth using metal organic vapor phase epitaxy or the like is performed on this thin line. 100Å within the thin line of
The following periodic structure, in other words, can produce a three-dimensional superlattice structure. Therefore, according to the present invention, a three-dimensional superlattice (quantum box) structure, which is conventionally difficult to produce, can be obtained by simply performing step-flow growth on a semiconductor substrate having atomic steps.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a process explanatory diagram of a method for manufacturing a quantum box explaining a first embodiment of the present invention. As shown in Figure 1(a),
A (001) GaAs substrate 10 with a 2° off angle in the direction of
There were 11 slAs in total.

At this time, all the laminated AlAslAs 11 have 80 atomic steps corresponding to 2° off, like the base substrate. Next, as shown in Figure 1(b), all 11 AlAslAs
The substrate temperature of the GaAs substrate 10 was set at 65°C, chlorine gas (C12) 12 at a gas pressure of 10-5 Torr was supplied, and a focused electron beam 13 of 5 KeV was applied to the AlAs substrate.
Maskless etching was performed by irradiating lAs so that a fine line pattern 14 having a total width of 110 lines remained. At this time, the G
The dose of the electron beam in the [110] direction on the aAs substrate 10 was varied from O to 2.6X1017C11-2 per 1 μm.
The above-mentioned maskless etching was performed to remove the atomic steps other than the thin line pattern 14. The thin line pattern 14 thus formed is coated with GaAs at a growth rate of 0.5 persons/sec using a metal organic vapor phase growth apparatus.
Layer 15 is 1/2 atomic layer, then 0.5 people/sec
The AlAs layer 16 was laminated to have a thickness of 1/2 atomic layer. By repeating this process, as shown in Figure 1(c), the layer thickness was 200 and the period was 80.
As ) l/2 three-dimensional superlattice was created. At this time, the organometallic vapor phase epitaxy is triethylaluminum (TEA).
) ethyl gallium (TEG), arsine (AsH3
) was used as a raw material, and the substrate temperature was 600'C. Incidentally, a mixed crystal layer 17 was formed in areas other than child steps. A total of 1,800 layers of AlAslAs were deposited on the entire surface of the GaAs substrate 10 using a metal organic vapor phase epitaxy apparatus, and a further 500 layers of GaAs layer 19 were deposited as a cap layer. As a result, a quantum box as shown in FIG. 1(d) was formed.

As a second example, a similar quantum box could be formed by using a Ga focused ion beam instead of the focused electron beam in the maskless etching of the first example.

In this example, the growth periods m and n of AlAs and GaAs are set to 1/2 atomic layer each, but if m+n=1 is satisfied, then
It may be other than an atomic layer.

In this example, GaAs-based AlAs, 3
Although we have created a dimensional superlattice, it can also be applied to other material systems such as InP, and although we have shown an example of organometallic vapor phase epitaxy as a crystal growth method, other crystal growth methods, such as organometallic molecules, can also be applied. It can also be applied to line epitaxial growth methods, atomic layer epitaxial growth methods, etc.

Further, in this embodiment, the (001,) plane is used as the semiconductor substrate, but other plane orientations may be used.

〔Effect of the invention〕

In the method for manufacturing a quantum box according to the present invention, a three-dimensional structure can be created during crystal production, so a three-dimensional superlattice (quantum box) structure without processing damage can be manufactured.

Furthermore, since the present invention does not require wet processing using a developer that accompanies resist mask photolithography, it is possible to perform everything from maskless etching to step-flow selective growth using a vacuum-through process. It is effective in avoiding pollution from the atmosphere.

Fine line pattern, 15...G a As layer by step-tube flow growth, 16 - AlAs layer by step-tube flow growth, 17...Mixed crystal layer, 18-A
IAs layer, 19-GaAs layer.

Claims (1)

[Claims] 1. Selectively removing the atomic steps on the surface of a semiconductor substrate having atomic steps by maskless etching to form a thin line pattern having atomic steps;
A method for manufacturing a quantum box, comprising at least the step of laminating semiconductors having different compositions in the direction of inclination of the atomic steps along the thin line pattern. 2. The method for manufacturing a quantum box according to claim 1, wherein the maskless etching is performed by irradiating the surface of the semiconductor substrate with a focused electron beam in a reactive gas or radical atmosphere. 3. The method for manufacturing a quantum box according to claim 1, wherein the maskless etching is performed by irradiating the surface of the semiconductor substrate with a focused ion beam in a reactive gas or radical atmosphere.