JPS6218709A - Photovolatically growing method - Google Patents

Abstract

PURPOSE:To enable selectively the production of a fine structure by disposing a substrate in a vacuum chamber, and selectively producing a substance to be produced from a raw gas by the heat of the substrate and the emission of an optical interference pattern to the substrate on the substrate. CONSTITUTION:A substrate 11 is disposed in a vacuum chamber 12, and regulated at the prescribed position. Then, the chamber 12 is exhausted, the substrate 11 is heated to remove surface absorption gas, and the entire surface is cleaned by sputtering with Ar ion gas. Then, raw gas 13 is fed to the chamber 12, and the substrate 11 is emitted by an entire surface emitting system. An InP buffer layer 11a produced from the gas 13 without surface contamination is formed on the entire substrate 11 by this operation. Then, the layer 11a is emitted by an interference pattern system. In this case, the pitch of an interference moire 14 is set to the prescribed value. This operation is repeated to form by epitaxially growing the desired corrugated lattice 5a made of InP on the layer 11a. The thus formed lattice 5a has a lattice pitch of the interference moire 14 and a sectional shape of sinusoidal wave shape.

Description

[Detailed description of the invention] [Summary] A substrate is heated in a vacuum, a raw material gas is introduced, and light is irradiated.
In photo-excited growth in which a substance generated from the raw material gas is grown on the substrate, the irradiated light is made into an optical interference pattern, and the growth is selectively grown in a fine structure corresponding to the pattern, such as a corrugated diffraction grating. This enabled the formation of

[Industrial application field]

The present invention relates to improvements in photostimulated growth methods.

In photo-excited growth, a material gas is introduced and irradiated with light while heating the substrate in a vacuum, thereby producing materials such as semiconductors such as gallium arsenide (GaAs) + indium phosphide (InP), etc. silicon dioxide (
This is a new technology that grows insulators such as SiO2 on a substrate.

This technique: (1) Since optical excitation is used to generate the growth material, growth can be performed at a relatively low substrate temperature.

■ It is possible to continuously grow a multilayer structure by switching the raw material gas.

■ Easy to finely control the thickness of the grown layer.

It has the following characteristics, and its utilization is expected.

If selective growth of fine structures becomes possible, the range of use will be further expanded.

[Conventional technology]

FIG. 4 is a process-sequential side sectional view (a) to (dl) showing an example of forming a fine structure by a conventional method.

This fine structure is created by, for example, a DFB laser (Distri-
This is a corrugation diffraction grating that is incorporated into a butted feedback (La5er), etc., and the grating pinch is approximately 4,000 people, and the semiconductor on which the grating is formed is InP.

A so-called photolithography technique is used to form this fine structure.

That is, first, as shown in Figure (a), a photoresist layer 2 is formed on an epitaxially grown InP layer 1, and a laser beam 3 is
．． After exposure and development with the interference fringes of No. 4, as shown in the figure (bl),
The photoresist layer 2 is patterned into lines.

Next, as shown in Figure (C), the InP layer 1 is wet-etched using the patterned photoresist layer 2 as a mask to form a corrugated diffraction grating 5.
As shown in dl, the photoresist layer 2 is removed to complete the formation of the diffraction grating 5.

[Problem that the invention seeks to solve]

A semiconductor is further epitaxially grown on the diffraction grating 5, but the following problems arise in this case.

(2) Since the formation of the diffraction grating 5 is performed in the atmosphere, contamination remains on the surface of the diffraction grating 5.

(2) Since the above-mentioned epitaxial growth is normally carried out at about 600° C., the diffraction grating 5 is damaged and even deformed during the temperature raising process before growth.

[Means for solving problems]

FIG. 1 is an explanatory diagram of the outline of the method of the present invention.

The above problem is solved by moving the substrate 11 into the vacuum chamber 1 as shown in FIG.
2, evacuating the vacuum chamber 12, heating the substrate 11, introducing a raw material gas 13 into the vacuum chamber 12, and irradiating the substrate 11 with an optical interference pattern 14,
This problem can be solved by employing the photoexcitation growth method of the present invention in which a substance generated from the source gas 13 is selectively grown on the substrate 11 by the heating and the irradiation.

[Effect]

Photo-excited growth utilizes light excitation to generate a growth substance, so it has the characteristic that growth is rapid in areas exposed to light and difficult to grow in areas not exposed to light.

The method of the present invention utilizes this feature, and the method of the present invention uses the irradiation light to form an optical interference pattern 14 (for example, interference fringes of laser light).
The pattern 14 is then selectively grown depending on the intensity of the light intensity, and since the corrugated diffraction grating described in the conventional example is formed using laser light interference fringe exposure,
through the formation of such microstructures.

According to this method, the fine structure is directly formed by the selective growth described above, so by subsequently switching to normal photoexcitation growth, the next step can be performed on the fine structure while avoiding the contamination and damage that were problems in the conventional method. growth can be achieved.

〔Example〕

Examples will be described below using the top view +6) and side view of Figure 2 showing an example of an apparatus for carrying out the method of the present invention, and the side sectional view of Figure 3 showing an example of growth using the apparatus. do.

The apparatus shown in FIG. 1 is a growth apparatus capable of forming a corrugated diffraction grating on a substrate 11. The apparatus shown in FIG.

In FIG. 2, 12 is a quartz window 12 that introduces the irradiation light.
15 is a stainless steel vacuum chamber equipped with a structure that allows the substrate 11 to be taken in and taken out;
Molybdenum heat block that holds and heats 16
1 is a holder that supports the heat block 15 and allows fine adjustment of X, Y, Z and rotational directions; 17 is a gas inlet for introducing raw material gas and other necessary gases into the vacuum chamber 12;
8 is a vacuum evacuation system that evacuates the inside of the vacuum chamber 12; 19 is a He-Cd laser 19a with a wavelength of 4416; a mirror 19b;
Beam expander 19c, half mirror 19d.

This is an interference pattern irradiation system that includes mirrors 19e, 19f, etc. and irradiates an interference pattern (interference fringes) 14 onto the substrate 11.

Further, 20 is a full-surface irradiation system that uniformly irradiates the entire surface of the substrate 11, which includes a mercury lamp 20a, a movable mirror 20b, etc.;
Reference numeral 21 denotes a substrate angle monitoring system that includes a He-Ne laser 21a, a mirror 21b, etc., and irradiates the side surface of the substrate 11, and detects the direction of the reflected light to indicate the adjustment position in the rotational direction of the substrate 11.

And these things are attached to one surface plate 22,
It is installed on an independent foundation 23 via an air spring 24 for vibration isolation.

The operating procedure for forming a corrugated diffraction grating according to an example using this apparatus is as follows.

■ The substrate 11 has a size of approximately 20 m square and a thickness of approximately 500 μm.
An InP substrate with a one-plane orientation (100) is used, and it is attached to the heat block 15 with indium solder, and then attached to the holder 16.
or the substrate angle monitor system 21, etc., to adjust to a predetermined position.

■ The pressure inside the vacuum chamber 12 is reduced to 10-9 Torr or less, the temperature of the substrate 11 is raised to about 450°C, and maintained for about 10 minutes to remove the surface adsorbed gas, and then heated with an argon (Ar) ion gun (acceleration voltage of about 250 V). Clean the entire surface by sputtering.

■ Set the temperature of the substrate 11 to 350°C.

■ The pressure in the vacuum chamber 12 is 10-5 to 10''' Tor.
The first raw material gas 13a, trimethyl
Indium (TMIn: In (CH3) 3 )
is introduced and then evacuated to IO-'Torr.

■ The pressure in the vacuum chamber 12 is 10”-5 to 10-’Torr.
The second raw material gas 13b, phosphine (
PFf3) is introduced and then exhausted to 10'''' Torr.

(2) Irradiate the substrate 11 with the entire surface irradiation system 20.

■ Repeat operations from ■ to ■ approximately 100 times. By this operation, an InP buffer layer 11a (see FIG. 3) with no surface contamination is epitaxially grown over the entire surface of the substrate 11.

■ Perform the same operation as ■.

■ Perform the same operation as ■.

[Phase] The buffer layer 11a is irradiated with the interference pattern irradiation system 19. At this time, the pitch of the interference fringes 14 is set to 4000 people.

0 Repeat operations from ■ to [phase] approximately 400 times. By this operation, a desired corrugated diffraction grating 5a (see FIG. 3) made of InP is epitaxially grown on the buffer layer.

When further epitaxially growing a semiconductor on the diffraction grating 5a, if the above operation is followed by the introduction of a predetermined raw material gas and irradiation by the entire surface irradiation system 20, epitaxial growth can be achieved without contaminating or damaging the diffraction grating 5a. It can be done.

The formed diffraction grating 5a has a grating pitch of 4000 people,
The height is approximately 1,000 people, and its cross-sectional shape is sinusoidal. Although the height can be changed by changing the number of repetitions of 0, the sinusoidal waveform is maintained.

Incidentally, in the case of etching as described in the conventional example, the cross-sectional shape changes when the etching depth is changed, so the present method has an excellent feature in this respect as well.

In the above embodiment, the case of a striped interference pattern has been explained, but the interference pattern irradiation system 19 may be replaced by another interference pattern irradiation system, for example, an irradiation system in which a plurality of interference systems are combined or an appropriate slit is interposed in the optical path. Based on the principles of the present invention, it is possible to selectively grow patterns with different symmetries by doing this, and that it is also possible to use other semiconductors or insulators as mentioned above for the symmetrical growth material. It can be easily inferred.

〔Effect of the invention〕

As explained above, according to the configuration of the present invention, in photoexcitation growth in which a substrate is heated in a vacuum, a source gas is introduced, and light is irradiated, a substance generated from the source gas is grown on the substrate. , it is possible to selectively grow a fine structure corresponding to an optical interference pattern, making it possible to form, for example, a corrugation diffraction grating, and also having the effect of reducing troubles related to the diffraction grating when further growth is performed on it.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the outline of the method of the present invention, Figure 2 is a plan view (a) and side view (b) of an example of an apparatus for carrying out the method of the present invention, and Figure 3 is a side cross-section of an example of growth using the apparatus. 4 are side sectional views (a) to (d) in the order of steps showing an example of forming a fine structure by a conventional method. In the figure, 5.5a is a corrugation diffraction grating, 11 is a substrate, 11a is a buffer layer, 12 is a vacuum chamber, 13.13a and 13b are source gases, 14 is an interference pattern (interference fringes), 15 is a heat block, 16 is a holder, 17 is a vacuum evacuation system, 18 is an interference pattern irradiation system, 19 is an entire surface irradiation system, 20 is a substrate angle monitor system, and 12 is a surface plate.

Claims (1)

[Claims] A substrate (11) is placed in a vacuum chamber (12), the vacuum chamber (12) is evacuated, the substrate (11) is heated, and a source gas (13) is introduced into the vacuum chamber (12). and the substrate (1
1) by irradiating the source gas (13) with an optical interference pattern (14).
A photoexcitation growth method characterized by selectively growing a substance produced from a substance on the substrate (11).