JP2003158074A - Semiconductor multilayer substrate and method of manufacturing semiconductor multilayer film - Google Patents

Abstract

[PROBLEMS] To provide a semiconductor multi-layer substrate having good lattice constant or different polarity with few dislocations by forming minute unevenness on a substrate or forming a growth region elongated in a tilt direction. SOLUTION: A mountain-shaped convex portion 32 is formed on a surface of a Si substrate 31 having a surface in a <001> direction so as to have steps in all directions. Then, a GaAs crystal thin film 33 having a thickness of 2 nm and a Si crystal thin film 34 having a thickness of 100 nm are grown on the semiconductor substrate on which the convex portions are formed to obtain a semiconductor multilayer substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor crystal structure in which a plurality of semiconductor crystals having different lattice constants or polarities are grown on the same substrate and a method for manufacturing the same, and a semiconductor laser, a light emitting diode, etc. using the semiconductor crystal structure. The present invention relates to a light emitting element, a light receiving element, an optical waveguide element, an electronic element, and a method for manufacturing the same.

[0002]

2. Description of the Related Art When a semiconductor crystal thin film having a lattice constant different from that of a semiconductor crystal substrate is grown, the atoms constituting the substrate and the atoms constituting the thin film are continuously arranged with the same regularity. The arrangement of atoms forming the crystal thin film is transformed from a cube to a rectangular parallelepiped.

This deformation causes stress in the semiconductor crystal thin film. When the two crystals have different lattice constants, that is, when the stress generated by the lattice mismatch becomes larger than the binding energy of the atoms constituting the crystal, dislocations are generated in the crystals and the stress is relaxed. A dislocation is a region in which no atom exists, and the number of atoms existing in the plane of the crystal surface is adjusted by introducing dislocation, and ((lattice constant of substrate * number of atoms in plane) = ( Lattice constant of thin film * number of atoms in plane ") Therefore, 2 with different lattice constants
When the types of crystals are continuously grown, when the grown film thickness becomes thicker and the internal stress in the thin film becomes equal to or higher than the dislocation generation energy, dislocations are generated to relax the stress. However, dislocations in the thin film act as traps, reducing electron mobility, and becoming photon annihilation centers. Therefore, it is necessary to reduce dislocation density in the active region of the device.

On the other hand, FIG. 1 shows the case where the substrate 21 and the crystal grown crystal 22 have different polarities. For example, Si constitutes a non-polar molecule because it is composed of one kind of atom, whereas GaAs constitutes a polar molecule because it is composed of positive Ga and negative As. When a polar molecular thin film is grown on a non-polar molecule, a large amount of energy is required for bonding between polar and non-polar molecules due to polarity incompatibility, so that there is a problem that a continuous thin film cannot be formed. That is, the polar molecule grows in an island shape because it has smaller energy when it is present on the polar molecule than when it is a non-polar molecule. As a result, growth progresses and each island grows, creating boundaries where they meet. This boundary is called APD23 (antiphased domain). At the boundary, the atoms are not continuous and contain many dislocations.
As in the case of growing a crystal with a different lattice constant, it becomes a big problem. In this case as well, deterioration of device characteristics due to dislocations has been a problem.

As described above, near the crystal interface between the substrate and
Dislocations are generated due to lattice mismatch and polar nonpolarity, but dislocation density is reduced by continuing to grow the buffer layer crystal, and the propagation of dislocations to the active layer region of the device to be grown thereafter is suppressed. be able to. As an effective method, it is possible to stop dislocations at the interface of the thin films by laminating two or more kinds of film films having different compositions and one of which is a critical film thickness or less in which lattice strain is introduced . Thereby, the dislocation density can be reduced according to the growth of the thin film. Then, this crystal is annealed at a high temperature to obtain a stable low-dislocation multi-layer crystal substrate.

In the case of growing a semiconductor crystal having different lattice constants or polarities on the semiconductor substrate as described above, the internal stress generated by the lattice mismatch or polar / nonpolar is caused by dislocation by growing a crystal having a large film thickness. Although studies have been conducted to obtain a good-quality semiconductor multilayer film by absorption, FIG. 2 shows an example of a conventional semiconductor multilayer film.

First GaAs at 200 ° on Si substrate 1
After the crystal 2 is grown to 50 nm, it is annealed at 580 ° C. for 10 minutes, and the second GaAs crystal 4 is annealed at 580 ° C.
It is possible to generate dislocations in the first GaAs2 crystal and relax the stress by growing the third GaAs5 1 μm at 330 degrees after the growth of μm and prevent the dislocation from propagating in the third GaAs5 crystal. Has become. Here, in order to obtain a crystal with a high degree of perfection, a Si substrate tilted by 6 degrees in the <011> direction from the (001) plane is used, or a Si epitaxial substrate is used.
Decreasing dislocations in crystals [Hirofumi Shimomura, Yoshitaka Okata, Mitsuo Kawabe, International Conference on Solid State Devices
And Materia Reals, 1992, S-II-8 (H. Shimomura, Yoshita
ka. Okada, Mitsuo Kawabe, International conference
on Solid State Device and Materials, 1992, S-II-
8].

As a semiconductor light emitting element and an electronic element, S
After growing a GaAs crystal on the entire surface of the i substrate, an active region is formed on the stripe.

As described above, it is possible to obtain a crystal with a low dislocation density by growing and annealing a strained multilayer thin film crystal, but a thick crystal is required to obtain a good crystal,
Not only long-term crystal growth is required, but stress is not completely relaxed even when dislocations occur, so that the multilayer crystal substrate is easily damaged during device fabrication, and process constraints due to substrate bending, etc. It becomes a big problem.

By the way, the problem of polar non-polarity is being solved considerably, and it has been shown that it is possible to suppress the island-like growth by inclining the substrate and increasing the number of points at which crystal growth starts. . However, the inclination of the substrate causes problems such as deterioration of cleavage and deterioration of isotropicity of the device shape.

The above-mentioned low dislocation approach involves a big problem in that a thick film is required. In other words, it is possible to reduce dislocations by increasing the film thickness, but it cannot be considered applicable to mass-produced devices due to problems such as breakage and bending of the substrate. That is, it is necessary to obtain a stable low dislocation crystal without forming a thick film.

Further, since the Si substrate is composed of non-polar atoms, the growing crystal GaAs is a polar molecule, so that the anti-phase domain (AP
D) occurs, but as a method of suppressing this APD,
By growing a crystal on a substrate having a (001) surface having an inclination of about 2 degrees in the <110> direction, A
Generation of PD is suppressed. In addition, there is a report that dislocation due to APD on the crystal surface is extremely reduced by forming a thick film and annealing (NTT).

Further, as a method for forming a stripe using an oxide film on a Si substrate and selectively growing a GaAs crystal (Japanese Patent Laid-Open Nos. 3-171617 and 3-24).
7597). A stripe is formed on a substrate inclined by 2 degrees, and a semiconductor crystal is selectively grown in the opening of the stripe.

However, no mention is made of the extremely important relationship between the stripe direction and the tilt angle of the substrate. Moreover, since the inclination angle of the substrate is as small as 2 degrees,
The effect of suppressing APD is small, and even when the inclination angle of the substrate is the same as that of the stripe, when a thin film crystal is formed, dislocation occurs due to APD, and a low dislocation thin film crystal cannot be realized. It is considered that dislocations could be suppressed by annealing the semiconductor crystal as a thick film.

In other words, in this case, it is necessary to form a thick film crystal of GaAs crystal as thick as the width of the stripe, and the purpose is to grow a compound crystal on the entire surface of the crystal. It cannot be realized.

[0016]

In order to prevent the above dislocation from occurring, it is necessary to grow a thin crystal having a critical film thickness or less. However, since Si is a non-polar crystal and GaAs is a polar crystal, it has been confirmed that dislocations occur even below the critical film thickness.

In view of the above problems, the present invention grows a semiconductor crystal on the surface of a concave-convex crystal substrate in order to eliminate the occurrence of dislocations due to non-polarity, or forms a stripe on a tilted substrate to form a tilt direction. A semiconductor multilayer film in which a plurality of crystals having different lattice constants or polarities are grown by suppressing the generation of dislocations due to polar nonpolarity in the vertical direction, and a method for manufacturing the same are provided, and the semiconductor multilayer film is manufactured using this semiconductor multilayer film. A structure of a light emitting element, a light receiving element, an electronic element, and a method for manufacturing the same are provided.

[0018]

In order to achieve the above object, the semiconductor multilayer film substrate of the present invention has irregularities on the surface of the crystal substrate or has elongated crystal growth regions in the tilt direction of the crystal substrate. , Composed of crystals with different lattice constants or different polarities grown on them. Further, by growing a crystal having a polarity on a semiconductor substrate without steps, the quantum dots are formed uniformly.

Further, the method for manufacturing a semiconductor multilayer film substrate of the present invention comprises a step of forming irregularities on the semiconductor substrate, or a step of forming elongated crystal growth regions in a tilt direction,
The structure has a step of growing crystals having different lattice constants or polarities.

[0020]

In the present invention, all of the above problems can be solved by growing a crystal having a critical film thickness or less for dislocation generation due to lattice mismatch in a minute region. The small area has the following advantages. First, the lateral stress generated in the crystalline thin film is reduced and the critical film thickness is increased. Second, since the stress applied to the substrate is significantly reduced, problems such as damage and bending due to the internal stress existing in the substrate are eliminated. Third, a small amount of raw material is needed,
The crystal growth time is also shortened. Fourthly, since it becomes possible to manufacture a device shape by crystal growth, it becomes possible to simplify the process at the time of manufacturing the device. Fifth, island growth is suppressed because the area where the crystal grows is small.

On the other hand, the following advantages can be obtained by making the film thickness less than the critical film thickness. First, the stress generated in the crystalline thin film is small and dislocations do not occur. Second, since the stress applied to the substrate is significantly reduced, problems such as damage and bending due to the internal stress existing in the substrate are eliminated. Thirdly, since it is not necessary to grow the buffer layer, a small amount of raw material is required and the crystal growth time is shortened. Fourthly, since the active region can be directly formed on the substrate, it becomes possible to fabricate a device utilizing the energy state of the substrate.

Further, by making the shape of the minute region elongated in the tilt direction of the substrate, the influence of polar nonpolarity can be alleviated. For example, when the substrate is inclined in the <110> direction from the (001) plane, the APD suppression in the <-110> direction does not work because there are no steps in the <-110> direction. By forming the elongated region in the <110> direction, the <−110> direction is shortened, so that APD can be suppressed.

By the way, when a multilayer film crystal is required over a wide area, it is impossible to form a minute area. In this case, the inclined surface of the crystal is, for example, <111>.
Steps in the atomic order can be formed over the entire surface of the crystal substrate by forming the direction or by forming minute unevenness on the surface of the substrate and forming the surface by an inclined surface. As a result, the polar and non-polar problem is solved. However, when the lattice constants are different, it is necessary to make the film thickness extremely thin.

As described above, thinning and miniaturization are extremely effective in growing a multilayer film. The present invention provides a device exhibiting unprecedented good characteristics by realizing the growth of crystals having different lattice constants or polarities.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor polycrystalline film according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 3 is a structural diagram of a semiconductor multilayer film in an embodiment of the present invention.

In FIG. 3A, 31 is a Si substrate having a surface in the <001> direction, 32 is a surface of a Si substrate having irregularities, 33 is a 2 nm thick GaAs crystal thin film, and 34 is a 100 nm Si crystalline thin film. .

In this embodiment, the surface of the Si substrate 32 is formed with irregularities made of a grid-shaped resist,
As shown in FIG. 3, the uneven side surface is formed of a (111) plane or the like. The pitch is approximately 100 nm. Since the side surface is composed of the (111) plane, as shown in FIG. 3, the surface of the substrate 31 is composed of atomic level contour-shaped steps. Therefore, Si and G
The lattice mismatch ratio of aAs is about 3%, and the GaAs crystal has a thickness of about 4 nm or less, which is below the critical thickness and can exist stably without generating dislocations.
By growing a Si crystal thin film 34 on the crystal 33, G
The critical film thickness of aAs is increasing. If Si crystal 34
In the case where no is present, the critical film thickness is about 2 nm.

As shown in FIG. 3, since the semiconductor multilayer film of this embodiment has atomic-order steps on all directions in the substrate surface, GaAs is formed at each step.
The crystals 33 nucleate and fuse with each other, thus preventing generation of APD due to polar nonpolarity. Also,
Since the GaAs crystal film 33 has a thickness of 2 nm, which is less than the critical film thickness, dislocation does not occur. Further, since the GaAs crystal 33 has lattice strain, the degeneracy is resolved, and the GaAs crystal 33 exhibits better characteristics than the case where it has no strain as the active region of various devices.

Although the unevenness is formed by etching by a multiple exposure method, a drawing method using an electron beam or the like may be used, or the crystal surface may be roughened by etching.

As described above, the surface of the Si substrate 31 of the present embodiment has irregularities and has atomic steps.
Since a Si crystal thin film is grown on it, GaAs
Even if the crystal 33 is extremely thin, the substrate as a whole can be balanced in terms of stress and dislocations and the like can be suppressed in the GaAs crystal 33.

(Embodiment 2) FIG. 4 is a structural diagram of a semiconductor polycrystalline film in a second embodiment of the present invention.

In FIG. 4, 41 is a Si substrate and 42 is <
Si substrate surface inclined by 10 degrees in the 110> direction, 43 is an insulating film, 44 is a window region for growing crystals, and 45 is a thickness of 2 nm.
Is a GaAs crystal thin film, and 46 is a 100 nm Si crystal thin film.

In this embodiment, the surface of the Si substrate is <110>.
Since the surface is formed by a terrace of 10 atoms and a step of 1 atom in the <10> direction because it is inclined by 10 degrees in the direction, APD due to polar nonpolarity does not occur in that direction.

Here, since there are no steps in the <-110> direction, it is conceivable that surface tension that promotes polar and non-polar island-like growth is generated in the <-110> direction.
In this embodiment, the width in the <-110> direction is 2 μm and the length is 1 m.
Since a window region narrower than the region where m and islands grow is formed and the GaAs crystal 45 is selectively grown therein, the island growth can be suppressed. That is, by making the width of the window region smaller than the size of the island-like crystals formed by polar nonpolarity, the generation of APD in the <-110> direction can be prevented.

Si crystal thin film 46 on GaAs crystal 45
Growth of GaAs increases the critical thickness of GaAs.
The As crystal 45 is below the critical film thickness.

As shown in FIG. 4B, since the semiconductor multilayer film of this embodiment has atomic-order steps on the surface of the substrate 41, APD due to non-polarity does not occur, and the thickness is less than the critical film thickness. Therefore, dislocation does not occur. Furthermore, since the GaAs crystal 45 has lattice distortion,
The degeneracy is resolved, and better characteristics can be obtained as compared with the case where the active region of various devices has no strain.

Also in this embodiment, as in the first embodiment, according to the present invention, since the GaAs crystal 45 is extremely thin and the Si crystal thin film 46 is grown on the GaAs crystal 45, the entire substrate is stress-balanced. That the match is good, and G
The point is that dislocations and the like do not occur in the aAs45 crystal, and it is very different from the growth of thick film crystals even if the growth is performed using insulating film stripes as in the past. I am trying.

(Embodiment 3) FIG. 5 is a structural diagram of a semiconductor laser according to a third embodiment of the present invention.

In FIG. 5, 51 is an n-Si substrate, and 52 is
Is an interference exposure method, and after forming a resist grating in a <110> direction and a <−110> direction at a pitch of 100 nm, the surface of a Si substrate having irregularities by etching 5
3 is an insulating film having a film thickness of 500 nm, 54 is a window region for growing a GaAs crystal, 55 is an epitaxially grown thickness 2n.
m is a GaAs crystal thin film, 56 is an epitaxially grown 200 nm p-Si single crystal thin film, 57 is a p-side electrode, 5
Reference numeral 8 is an n-side electrode. The light emitting light end face was formed by dry etching and separated into elements by scribing. The resonator length is 500 μm. In this embodiment, MBE
Method is used to grow GaAs and Si thin films.

The semiconductor laser of the present embodiment has a Si substrate 51.
GaAs 55 is formed on top, but Ga is used for Si
Since the refractive index of As is large, the light intensity is maximized near the GaAs thin film 55, and the thickness of the GaAs crystal 55, which is the active layer of the laser, is modulated by the unevenness of the grating formed on the Si substrate 51, so that the distributed gain type It oscillates as a DFB laser. At this time, the thickness of the GaAs crystal thin film 55 is 2
APD does not occur in the Si 56 crystal-grown on the GaAs thin film 55 because it is extremely thin as nm. The emission wavelength is about 1.15 μm and the DFB oscillation wavelength is 1.1 μm, which can be used as a fiber amplifier excitation light source for 1.3 μm. The oscillation threshold is 20 mA and the slope efficiency is 5.
It becomes 0%.

(Embodiment 4) FIG. 6 is a structural diagram of a semiconductor laser according to a fourth embodiment of the present invention.

In FIG. 6, 61 is an n-Si substrate and 62
Is an interference exposure method, and a Si substrate surface is formed by forming a resist grating in a <110> direction and a <−110> direction at a pitch of 100 nm and then making unevenness by etching.
Is an epitaxially grown InGaAs crystal thin film having a thickness of 2 nm, and 64 is an epitaxially grown 200 nm p film.
-Si single crystal thin film, 65 is an epitaxially grown n-Si single crystal thin film with a film thickness of 1 [mu] m, and 66 is an electrode. The outer shape of the device was produced in the same manner as in the third embodiment.

The semiconductor laser of this embodiment is different from the semiconductor laser of the third embodiment in that the InGaAs active layer 63 is
The side surface of is covered with p-Si64 instead of an insulating film.

In the semiconductor laser of this embodiment, the injected current is narrowed by the p-Si layer 64 and then injected into the active layer 63. The emission wavelength is about 1.8 μm and the DFB oscillation wavelength is 1.7 μm. The oscillation threshold is 10 mA and the slope efficiency is 50%. The reason why the crystal defects are prevented from propagating to the active layer and the threshold value is lowered as described above is based on the fact that the side surface of the active layer 63 is covered with Si crystal.

(Embodiment 5) FIG. 7 is a structural diagram of a semiconductor light receiving element in a fifth embodiment of the present invention.

In FIG. 7, 71 is 1 in the <110> direction.
N-Si substrate inclined at 0 degree, 72 an insulating film, and 73 Ga
A window region for growing As crystals, 74 is an epitaxially grown InGaAs crystal thin film with a thickness of 2 nm, 75 is an epitaxially grown 100 nm p-Si single crystal thin film, 7
6 is a p-side electrode, and 77 is an n-side electrode. Window area is 50μ
10 pieces are formed in parallel at an m pitch, and one end is gathered by a p-side electrode. The length of the window region is 500 μm. In this embodiment, the InGaAs and Si thin films are grown by using the MBE method.

Since InGaAs has a larger lattice constant than Si, compressive strain is considered to be introduced. However, in the semiconductor laser of this embodiment, the Si substrate 71 is
The light absorption layer I is tilted by 10 degrees in the 110> direction and is I.
The nGaAs thin film 74 is 2.6 μ when there is no strain.
The composition is close to InAs, which is about m.

As a result, the light receiving wavelength can be up to about 2 μm, and a light receiving element having a uniform conversion efficiency in a wide wavelength range can be realized. The conversion efficiency was 98%. In particular, even though it is an MSM photodiode, the light absorption layer has a pin structure, so that the leak current is small and the noise characteristic is good.

Further, the receivable wavelength of the Si light receiving element is 1.
Since the thickness is up to about 4 μm, it can be integrated with a Si IC as a light receiving element having a wavelength longer than that, and a low noise, high gain and high speed light receiving element can be obtained.

(Embodiment 6) FIG. 8 is a structural diagram of a semiconductor optical waveguide according to a sixth embodiment of the present invention.

In FIG. 8, 81 is 1 in the <110> direction.
N-Si substrate inclined by 0 degree, 82 an insulating film, and 83 Ga
Window region for growing As crystal, 84 is epitaxially grown 2 nm thick InGaAs crystal thin film, 85 is epitaxially grown 5 nm Si single crystal thin film, and 86 is Ga.
A waveguide layer having a number of pairs of 50 consisting of an As crystal thin film and a Si single crystal thin film, 87 is an insulating film, 88 is a p-side electrode, 89 is an n-side electrode, and 90 is a refractive index modulator. In this example,
The MBE method is used to grow GaAs and Si thin films.

In the semiconductor optical waveguide of this embodiment, Ga
Since As has a large refractive index with respect to Si, light is confined inside, but when a voltage is applied to the electrodes, the refractive index in the waveguide layer path 86 changes, the phase of the light changes, and the light is combined. Intensity modulation can be applied to the later emitted light. Also, S
An optical IC can be formed in a large area by using a semiconductor crystal, which is inexpensive and has high strength, such as i, as a substrate. Especially Figure 8
In the case of the optical modulator as shown in FIG. 1, a length of about 1 mm is required in the waveguide layer path region and about 200 μm in the refractive index modulator region, so that it is extremely expensive when the element is formed on the GaAs substrate. Will be things.

(Embodiment 7) FIG. 9 is a structural diagram of a semiconductor electronic device according to a seventh embodiment of the present invention.

In FIG. 9, 91 is 1 in the <110> direction.
N-Si substrate tilted by 0 degree, 92 is an insulating film, 93 is a window region for growing a crystal thin film, 94 is an epitaxially grown GaAs crystal thin film having a thickness of 2 nm, and 95 is InG having a thickness of 2 nm.
aAs crystal thin film, 96 is epitaxially grown 10n
m is a Si single crystal thin film, 97 is a source electrode, 98 is a gate electrode, and 99 is a drain electrode. The length of the window area is 30
It is 0 μm. In this embodiment, the GaAs, InGaAs and Si thin films are grown by using the MBE method.

In the semiconductor electronic device of this embodiment, In
GaAs95 functions as an active layer and has a mobility of 100000 cm2 /
sec is obtained, and by applying a voltage to the gate electrode, In
A depletion layer is formed in the GaAs layer 95 to control the current flowing between the source 97 and drain 99 electrodes.
Further, since the InGaAs layer 95 is not doped, the mobility of electrons is large, and since the strain is introduced into the InGaAs layer 95, the mobility is further increased, and a mutual conductance of gm = 250 A / V is obtained. .

In the third to seventh embodiments, even if the semiconductor substrate having the convex portion on the surface is used, the crystal growth region is formed in a stripe shape having a surface different from the (001) surface. The same effect can be obtained by using a semiconductor substrate.

(Embodiment 8) In the above-mentioned first to seventh embodiments, the semiconductor multilayer film and the semiconductor laser in the embodiments of the present invention have been described. However, the semiconductor crystal thin film substrate, the semiconductor laser and the like will be described below. The manufacturing method of will be described.

FIG. 10 shows a method for manufacturing a semiconductor crystal thin film substrate in the eighth embodiment of the present invention.

In FIG. 10, a Si growth step (a) in which Si 102 is epitaxially grown to a thickness of 3 μm on a Si substrate 101 having a (001) surface, and a diffraction grating 10 made of resist in the <110> direction and the <−110> direction on the substrate.
3b, and then a diffraction grating manufacturing step (b) in which the diffraction grating is transferred onto the Si substrate with hydrofluoric acid, and after removing the resist, a GaAs thin film crystal 104 having a thickness of 2 nm is formed on the entire surface of the Si substrate.
Then, a semiconductor thin film crystal substrate is obtained by the step (c) of growing the Si crystal thin film 105 having a thickness of 100 nm by MBE.

In this embodiment, the growth temperature is set to a low temperature of 650 ° C. to suppress the diffusion between Si and GaAs atoms. At this time, the pitch of the diffraction grating 103 is about 100 nm and the etching depth is about 20 nm. . This diffraction grating 10
Since step 3 at the atomic level is generated on the entire surface of substrate 3, polar nonpolar molecules can be grown without limiting the crystal growth region of the thin film to be long and thin. The critical film thickness of the GaAs layer 104 is about 3.5 nm. Although the surface of the substrate was a mirror surface, slight bending of the substrate due to the difference in lattice constant was confirmed.

In the method of manufacturing the semiconductor crystal thin film substrate in this example, the resist mask was manufactured by the diffraction grating by the interference exposure method, but the exposure was performed using the photomask having the line and space of about 1 μm width and about 2 μm pitch. It is also possible to form irregularities on the substrate surface. Of course, the resist mask using the diffraction grating is effective because the pitch can be reduced to 100 nm or less and the uniform slope width is realized because the slope of the uneven surface is small.

Further, in the case of producing irregularities, by setting the direction of the mask line to be the <210> or <120> direction, uniform irregularities can be formed on the substrate surface by one exposure. It cannot be used as a laser diffraction grating. Therefore, when used as a diffraction grating of a DFB laser by cleaving, the cleaving direction must also be oriented in the <110> or <-110> direction in the direction of the line. In this case, after exposure in the <110> direction with a photomask or a diffraction grating, <-11
By overlapping and exposing in the 0> direction, unevenness can be uniformly formed in the surface of the substrate.

(Embodiment 9) FIG. 11 shows a method for manufacturing a semiconductor crystal thin film substrate in a ninth embodiment of the present invention.

In FIG. 11, <11 from the (001) plane
Si substrate 111 having a surface inclined by 10 degrees in the 0> direction
After epitaxially growing Si112 of 3 μm, S
iO ₂Si growth step (a) for depositing 113 to 500 nm
After applying the resist on the front surface of the substrate, <11
Exposed region 1 in the 0> direction, and exposed region 1
Stripes that remove the insulating film at 14 with hydrofluoric acid
Fabrication step (b) and stripes after removing the resist
Si buffer crystal 115, GaAs crystal 116 and
And the thin film growth step (c) for growing the Si crystal 117
A semiconductor thin film crystal substrate is obtained.

In this example, the crystal growth was carried out by the MBE method. In the stripe forming process (b), <-1
The width in the 10> direction is 2 μm, and the length in the <110> direction is 30 μm.
The insulating film is etched away with a resist so as to obtain a window region of 0 μm.
Wet etching is performed to remove the insulating film in the window region so that the substrate is not damaged.

In the thin film forming step (c), good Ga
After epitaxially growing a Si crystal 112 on a Si substrate 111 to obtain an As / substrate interface, a GaAs thin film 116 having a film thickness of 2 nm and a Si crystal 117 having a film thickness of 200 nm are formed.
However, at this time, the semiconductor crystal does not grow on the SiO ₂ 113 but selectively grows on the window region without the Si 02113. As a result, the grown crystal has a shape similar to that of the window region.

Also in the present embodiment, as in the eighth embodiment, the growth temperature is set to a low temperature of 650 ° C. to suppress the diffusion between Si and GaAs atoms. <110 from the (001) plane
By tilting 10 degrees in the> direction, there is a terrace of about 10 atoms for each step of 1 atom. In the case of a terrace having a small size of about 10 atoms, generation of APD due to non-polarity is not observed.

Further, since the surface of the Si substrate is tilted in the <110> direction, there is no step in the <-110> direction, and it is conceivable that APD is generated due to polar nonpolarity.
The width is as small as 2 μm, so it is covered with one crystal grain, and AP
D does not occur. The Si crystal thin film 117 is provided to protect the surface of the GaAs crystal thin film and stabilize the lattice strain.

The surface of the crystal thin film grown by the above method is in a mirror state, and strong photoluminescence emission is observed. From this, it can be seen that there are almost no dislocations in the crystal. In this example, since the crystal is grown on a part of the substrate, a slight deformation due to lattice strain occurs only in a part of the crystal, but since the crystal does not exist in most of the substrate, the whole substrate is As a result, the stress was extremely small and no deformation of the substrate was observed. Further, since stress is not generated in the substrate, there is no cracking of crystals due to residual stress and the yield is improved. Furthermore, since there is no deformation of the substrate, there is no blurring of the image due to photolithography etc.
Uniform exposure conditions are obtained on the front surface of the substrate, and the yield is improved.

(Embodiment 10) FIG. 12 shows a method for manufacturing a semiconductor laser according to a tenth embodiment of the present invention.

In FIG. 12, a Si epitaxial growth step (a) in which a Si crystal 122 is epitaxially grown on an n-Si substrate 121, and a resist 123 is applied on the front surface of the substrate, and then interference exposure is performed at a pitch of 100 nm by <110 nm.
An etching step (b) of forming unevenness 124 by etching after forming a diffraction grating of a resist in the <> and <-110> directions, and an InGaAs crystal thin film 1 having a thickness of 2 nm.
25, a thin film growth step (c) of epitaxially growing a 200 nm p-Si single crystal thin film 126, and the insulating film 12.
Width 2μm, length 3 by etching using 7 as a mask
A stripe process (d) in which a thin film crystal is etched to form a stripe 128 of 00 μm to form an active region, and an insulating film is removed after selectively growing an n-Si single crystal thin film 129 having a film thickness of 1 μm, and electrodes are formed on both surfaces of the substrate. A semiconductor laser structure is obtained by a selective growth step (e) of depositing 130.

In this embodiment, the diffraction grating 12 by the interference exposure method is used.
4, the thickness of the InGaAs active layer 125 fluctuates in the same cycle due to the unevenness of the diffraction grating 124. As a result, a gain-coupled DFB laser is realized.

The end face of the laser is formed by vertical etching by dry etching, and element isolation is performed by sawing. This is because the cleaving property of the Si substrate 121 is poor, and in the case of growing an InP substrate on a GaAs substrate, an end face of a cleavage laser can be formed. In the present embodiment, the stripes may be provided by applying the ninth embodiment, and the laser active layer may be formed there.

(Embodiment 11) FIG. 13 shows a method for manufacturing a semiconductor electronic device according to an eleventh embodiment of the present invention.

In FIG. 13, a Si crystal growth step (a) of depositing an SiO ₂ 132 insulating film to a thickness of 500 nm on an n-Si substrate 131 tilted by 10 degrees in the <110> direction, and a resist 133 was applied to the front surface of the substrate. After that, an etching step (b) of forming a window region 134 having a width of 1 μm and a length of 300 μm for growing the crystal thin film by wet etching, and after removing the resist, the Si crystal thin film 13 having a thickness of 100 nm
5, GaAs crystal thin film 136 having a thickness of 2 nm, I having a thickness of 2 nm
After the nGaAs crystal thin film 137, the GaAs crystal thin film 136 having a thickness of 2 nm, and the Si single crystal thin film 138 having a thickness of 100 nm are epitaxially grown, the SiO ₂ insulating film 139 is formed to 5
A semiconductor electronic device structure is obtained by a thin film growth step (c) of 0 nm deposition and a step (d) of vapor deposition of the source, gate and drain electrodes 140. In this example, GaAs, InGaAs and Si thin films were grown using the MBE method.

In the semiconductor electronic device of this example, the active layer has a thickness of 6 nm in the GaAs and InGaAs layers, but strained crystals can be obtained stably because both sides are made of Si. When a device structure is realized by using, the strain introduced into the active layer can be compressed or pulled. That is, when InGaAs is grown on Si, tensile strain is always generated, but when an InGaAs active layer is grown on Si using GaAs as a buffer layer, the strain introduced into the InGaAs layer is GaAs and InG.
Since it depends on the mutual lattice constant of the aAs crystal, either compressive strain or tensile strain can be introduced.

In the present embodiment, after the crystal is grown on the front surface of the substrate by applying the unevenness shown in the eighth embodiment, only the active region may be formed by etching or ion implantation.

(Embodiment 12) A semiconductor polycrystalline film and a semiconductor laser using the quantum dots of the present invention will be described below.

FIG. 14 is a structural diagram of a semiconductor polycrystalline film in the twelfth embodiment of the present invention.

In FIG. 14, 141 is a Si substrate having a surface in the <001> direction, 142 is a Si crystal thin film with a thickness of 3 μm, 143 is a GaAs dot with a thickness of 2 nm, and 1
Reference numeral 44 is a 100 nm Si crystal thin film.

In this embodiment, the surface of the Si substrate 141 has a step-free (001) plane. Since there are no steps, the crystal grows randomly on the crystal plane and a uniform Ga
Nucleation of As crystals is realized. Also, Si and GaAs
Since GaAs and GaAs have different polarities, three-dimensional growth of GaAs occurs and dot-like growth is realized.

Crystal growth is carried out by MBE at 750 ° C. Since the growth temperature is relatively high, the moving speed of atoms on the substrate surface is high, and uniform dots 143 are formed. Further, by forming the uniform quantum dots 143 described above, the PL is 50 times as large as that in the case where the quantum wells are formed.
The emission intensity can be obtained. On the other hand, the higher the crystal growth temperature, the smaller the number of dots, but the size of one dot becomes larger. Dots should not be fused and the dots must be separated by 5 nm or more. Moreover, the growth temperature had to be relatively high at 750 degrees.

Further, the Si crystal thin film 142 is laminated by about 3 μm in order to suppress the step existing on the substrate. When dislocations exist in the substrate, they are affected by the dislocation and GaA
There is a problem that s cannot grow uniformly. In this embodiment, crystals grow on the front surface of the substrate, but since the space between the crystals is large, problems such as warpage of the substrate do not occur.

(Embodiment 13) FIG. 15 shows the structure of a semiconductor laser according to a thirteenth embodiment of the present invention.

In FIG. 15, 151 is a (001) n-Si epitaxial substrate having no step on the surface, and 152 is a thickness of 10.
nm Si buffer layer, 153 is a 2 nm thick epitaxially grown GaAs dot crystal, and 154 is a thickness of 10
nm Si single crystal thin film, 155 is GaAs crystal thin film 15
3 and a Si single crystal thin film 154, a multi-quantum dot layer having a number of pairs of 10; 156, a p-Si layer; 157, an insulating film;
Reference numeral 58 is a p-side electrode, and 159 is an n-side electrode.

In this example, the quantum dots shown in the twelfth example were applied to a semiconductor laser, and GaAs dots and Si thin films were grown using the MBE method. One layer of GaAs dots is not enough to obtain a gain as a semiconductor laser, and therefore, the GaAs dot 153 is set to 1
A semiconductor laser is realized by stacking 0 layers.

(Embodiment 14) FIG. 16 is a diagram showing a method of manufacturing a semiconductor laser according to a fourteenth embodiment of the present invention.

In FIG. 16, a (001) n-Si epitaxial substrate 161 having no step on the surface, and an S layer having a thickness of 10 nm.
Si crystal growth step (a) for growing i buffer layer 162
A 2 nm thick epitaxially grown GaAs dot crystal 163 and a 10 nm thick Si single crystal thin film 164.
And the active layer growth step (b) of growing the multi-quantum dot layer 165 and the p-Si clad layer 166 having the number of pairs of 10 obtained by alternately growing the film and the insulating film 167 as a mask, the width is 2 μm, and the length is 2 μm. A stripe process (c) in which a thin film crystal is etched into a stripe shape of 300 μm to form an active region, and an n-Si single crystal thin film 16 having a thickness of 1 μm
A semiconductor laser structure is obtained by a selective growth step (d) in which electrodes 169 are vapor-deposited on both surfaces of the substrate after selectively growing 8.

This embodiment is a manufacturing method for realizing the quantum dot semiconductor laser shown in the thirteenth embodiment.
The GaAs dot 163 and the Si thin film are grown by using the method. After growing GaAs dots 163, Si crystal 1
A flat surface is obtained by growing 64 of 10 nm. This is because the height of the GaAs dot 163 is as low as about 2 nm, and the Si crystal is hard to grow on the GaAs dot 163, so that the GaAs dot is buried flat. It is due to the fact.

Although the crystal growth method is the MBE method in the above embodiments, the MOVPE method and the gas source MB method are used.
Not only the E and MOMBE methods, but also other growth methods such as the hydride VPE method may be used. Further, although a semiconductor laser is representatively shown in the examples, a light receiving element, an optical waveguide, and an electronic element can be manufactured by the same method.

Furthermore, although the n-type substrate is used as the conductivity of the crystal substrate, a p-type substrate may be used.

[0093]

As described above, according to the present invention, by (1) forming minute irregularities on a semiconductor substrate, (2) forming a long and narrow crystal growth region in the tilt direction of the semiconductor substrate, Realizes good crystallinity growth for crystals with different constants or polarities.

Also, (3) uniform quantum dots are formed by using a flat semiconductor substrate. Furthermore, these crystals are used as a semiconductor light emitting device, a light receiving device, an optical waveguide device,
By applying it to electronic devices, device characteristics can be dramatically improved. In particular, by forming these elements made of a compound semiconductor in the form of a Si substrate, it is possible to improve the yield, improve the strength, reduce the price, increase the integration, and increase the speed.

[Brief description of drawings]

FIG. 1 is a structural diagram of a conventional GaAs crystal growth substrate on a Si substrate.

FIG. 2 is a schematic sectional view of a crystal surface during growth of a polar crystal on a nonpolar crystal.

FIG. 3 is a structural cross-sectional view of a semiconductor multilayer film according to the first embodiment of the present invention.

FIG. 4 is a structural sectional view and a perspective view of a semiconductor multilayer film according to a second embodiment of the present invention.

FIG. 5 is a structural sectional view of a semiconductor laser according to a third embodiment of the present invention.

FIG. 6 is a structural sectional view of a semiconductor laser according to a fourth embodiment of the present invention.

FIG. 7 is a structural cross-sectional view and perspective view of a light receiving element according to a fifth embodiment of the present invention.

FIG. 8 is a structural sectional view and a plan view of an optical waveguide according to a sixth embodiment of the present invention.

FIG. 9 is a structural cross-sectional view of an electronic device according to a seventh embodiment of the present invention.

FIG. 10 is a manufacturing process diagram of a semiconductor multilayer film according to an eighth embodiment of the present invention.

FIG. 11 is a manufacturing process diagram of a semiconductor multilayer film according to a ninth embodiment of the present invention.

FIG. 12 is a sectional view of a manufacturing process of a semiconductor laser according to a tenth embodiment of the present invention.

FIG. 13 is a manufacturing process drawing of an electronic device according to an eleventh embodiment of the present invention.

FIG. 14 is a structural perspective view of a semiconductor multilayer film according to a twelfth embodiment of the present invention.

FIG. 15 is a structural sectional view of a semiconductor laser according to a thirteenth embodiment of the present invention.

FIG. 16 is a sectional view showing the steps of manufacturing a semiconductor laser according to the fourteenth embodiment of the present invention.

[Explanation of symbols]

1 Si Substrate 2 First GaAs Crystal 3 Second GaAs Crystal 4 Third GaAs Crystal 21 Substrate 22 Grown Crystal 23 APD 31 Si Substrate 32 Uneven Substrate Surface 33 GaAs Crystal Thin Film 34 Si Crystal Thin Film 35 Step 41 Si Substrate 42 Inclined substrate surface 43 Insulating film 44 Window region 45 GaAs crystal thin film 46 Si crystal thin film 47 Step 51 Si substrate 52 Concavo-convex substrate surface 53 Insulating film 54 Window region 55 GaAs crystal thin film 56 p-Si crystal thin film 57 p-side electrode 58 n-side electrode 61 Si substrate 62 Concavo-convex substrate surface 63 InGaAs crystal thin film 64 p-Si crystal thin film 65 n-Si crystal thin film 66 electrode 71 Si substrate 72 insulating film 73 window region 74 InGaAs crystal thin film 75 p-Si crystal thin film 76 p-side electrode 77 n Side electrode 81 Si substrate 82 Insulating film 83 Window region 84 InGaAs Crystal thin film 85 p-Si crystal thin film 86 waveguide layer 87 insulating film 88 p-side electrode 89 n-side electrode 91 Si substrate 92 insulating film 93 window region 94 GaAs crystal thin film 95 InGaAs crystal thin film 96 p-Si crystal thin film 97 source electrode 98 Gate electrode 99 Drain electrode 101 Si substrate 102 Si crystal thin film 103 Diffraction grating 104 GaAs crystal thin film 105 Si crystal thin film 111 Si substrate 112 Si crystal thin film 113 SiO ₂ insulating film 114 Exposure region 115 Si buffer crystal 116 GaAs crystal thin film 117 Si crystal thin film 121 Si substrate 122 Si crystal thin film 123 Resist 124 Concavo-convex substrate surface 125 InGaAs crystal thin film 126 p-Si crystal thin film 127 insulating film 128 stripe mesa 129 n-Si crystal thin film 130 electrode 131 Si substrate 132 insulating film 133 resist 134 window region 135 Si crystal thin film 136 GaAs crystal thin film 137 InGaAs crystal thin film 138 Si crystal thin film 139 insulating film 140 electrode 141 Si substrate 142 Si crystal thin film 143 GaAs dot 144 Si crystal thin film 151 Si substrate 152 Si crystal thin film 153 GaAs dot 154 Si crystal thin film 155 multiple quantum dot layer 156 p-Si 157 insulating film 158 p-side electrode 159 n-side electrode 161 Si substrate 162 Si buffer layer 163 GaAs dot 164 Si crystal thin film 165 multiple quantum dot layer 166 p-Si 167 insulating film 168 n-Si 169 electrode

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[Procedure amendment]

[Submission date] July 30, 2002 (2002.7.3)
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[0018]

In order to achieve the above object, a semiconductor multilayer film substrate of the present invention comprises a semiconductor substrate having a flat surface, and a quantum dot shape formed on the semiconductor substrate and having a polarity different from that of the semiconductor substrate. It has a semiconductor crystal.
Further, the semiconductor laser of the present invention, a semiconductor substrate having a flat surface, a buffer layer formed on the semiconductor substrate,
The semiconductor device has an active layer formed on the buffer layer and made of a quantum dot semiconductor crystal having a polarity different from that of the semiconductor substrate, and a clad layer formed on the semiconductor crystal.

[Procedure 3]

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Further, in the method for manufacturing a semiconductor laser of the present invention, a buffer layer forming step of forming a buffer layer on a semiconductor substrate having a flat surface, and a quantum dot-like shape having a polarity different from that of the semiconductor substrate on the buffer layer. The method includes an active layer forming step of forming an active layer made of a semiconductor crystal and a clad layer forming step of forming a clad layer on the active layer.

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─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 31/10 ZNM H01L 31/10 ZNMA 5F102 33/00 29/80 B H01S 5/02 (72) Inventor Masato Ishino 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Yasushi Matsui 1006 Kadoma, Kadoma City, Osaka Pref. 5F041 AA40 CA04 CA05 CA08 CA33 CA35 CA66 5F045 AA04 AB10 AB17 AF03 BB12 CA09 CA12 CA13 5F049 MA04 MB03 MB07 NA10 NA13 QA02 RA02 SS03 SS08 SS09 WA01 5F052 DA01 DA05 DB06 JA07 JA10 KA01 5F073 AA22 AA64 AA75 AA75 AA CA2 CA07 CA24 CB04 GR01 G01 GR01 G01 G01 G01 EA02

Claims (20)

[Claims] 1. A semiconductor multilayer substrate having a semiconductor substrate having a mountain-shaped convex portion and a semiconductor crystal formed on the semiconductor substrate and having a lattice constant or a polarity different from that of the semiconductor substrate. 2. A semiconductor substrate having a surface different from the (001) plane, an insulating film formed in stripes on the semiconductor substrate, and a window region between the insulating films in stripes on the semiconductor substrate. And a semiconductor multilayer substrate having the semiconductor substrate and a semiconductor crystal having a different lattice constant or polarity. 3. The semiconductor multi-layer substrate according to claim 2, wherein the surface of the semiconductor substrate is constituted by a plane inclined from the (001) plane. 4. The semiconductor multilayer substrate according to claim 2, wherein the window region is formed in a direction inclined from the (001) plane. 5. The semiconductor multi-layer substrate according to claim 1, wherein the semiconductor crystal having a lattice constant or polarity different from that of the semiconductor substrate has a film thickness of 50 nm or less. 6. A semiconductor comprising: a convex forming step of forming a mountain-shaped convex portion on a semiconductor substrate surface; and a semiconductor crystal growing step of growing a semiconductor crystal having a lattice constant or a polarity different from that of the semiconductor substrate on the semiconductor substrate surface. Method for producing multilayer film. 7. A method of forming a protrusion on a semiconductor substrate in the step of forming a protrusion.
7. The method for manufacturing a semiconductor multilayer film according to claim 6, wherein a resist is formed in a stripe shape in a direction different from the 110> direction and a convex portion is formed on the surface of the semiconductor substrate by etching. 8. A method of forming a protrusion on a semiconductor substrate in the step of forming a protrusion.
7. The method for manufacturing a semiconductor multilayer film according to claim 6, wherein resists are formed in stripes in the <110> direction and the <−110> direction, and convex portions are formed on the surface of the semiconductor substrate by etching. 9. A step of forming a buffer layer on a semiconductor substrate, wherein a buffer layer forming step of crystal-growing a semiconductor film having a lattice constant and a polarity equal to or close to that of the semiconductor is added after forming the convex portion. The method for manufacturing a semiconductor multilayer film according to claim 6. 10. An insulating film deposition step of depositing an insulating film on a semiconductor substrate having a surface different from a (001) plane, a stripe window forming step of etching and removing the insulating film into a stripe window shape, and inside the stripe window. And a semiconductor crystal growing step of growing a semiconductor crystal having a lattice constant or polarity different from that of the semiconductor substrate. 11. A step of forming a convex portion on a surface of a semiconductor substrate having a (001) plane, a step of depositing an insulating film on the surface of the semiconductor substrate, and a stripe of the insulating film. A method of manufacturing a semiconductor multilayer film, comprising: a stripe window forming step of removing by etching in a window shape; and a semiconductor crystal growing step of growing a semiconductor crystal having a lattice constant or a polarity different from that of the semiconductor substrate in the stripe window. 12. A buffer layer forming step of growing a semiconductor crystal having a lattice constant or a polarity equal to or close to that of the semiconductor substrate as a buffer layer in the stripe window on the semiconductor substrate after forming the stripe window. The method for manufacturing a semiconductor multilayer film according to claim 10 or 11. 13. An electron having a semiconductor substrate having a mountain-shaped convex portion or a surface different from a (001) plane, and an active layer of a semiconductor crystal formed on the semiconductor substrate and having a lattice constant or a polarity different from that of the semiconductor substrate. element. 14. A protrusion forming step of forming a mountain-shaped protrusion on a semiconductor substrate surface; a semiconductor crystal growing step of growing a semiconductor crystal having a lattice constant or a polarity different from that of the semiconductor substrate on the semiconductor substrate surface; An electrode forming step of forming electrodes on the entire surface of a semiconductor crystal and the back surface of the semiconductor substrate. 15. A first insulating film deposition step of depositing a first insulating film on a semiconductor substrate having a surface different from the (001) plane, and a stripe window forming step of etching and removing the insulating film into a stripe window shape. A semiconductor crystal growing step of growing a semiconductor crystal having a lattice constant or a polarity different from that of the semiconductor substrate in the stripe window, and a second insulating step of depositing a second insulating film on the entire surface of the first insulating film and the semiconductor crystal. A method of manufacturing an electronic device, comprising: a film deposition step; an electrode window formation step of forming an electrode window in the second insulating film; and an electrode formation step of depositing an electrode metal in the electrode window. 16. A semiconductor multilayer substrate having a semiconductor substrate having a flat surface and a quantum dot semiconductor crystal formed on the semiconductor substrate and having a polarity different from that of the semiconductor substrate. 17. A semiconductor substrate having a mountain-shaped convex portion, an active layer formed on the semiconductor substrate and made of a semiconductor crystal having a polarity different from that of the semiconductor substrate, and the semiconductor substrate formed on the entire surface of the semiconductor crystal. A semiconductor laser having crystals of the same polarity. 18. A step of forming a convex portion on a surface of a semiconductor substrate, and a step of forming an active layer made of a semiconductor crystal having a polarity different from that of the semiconductor substrate on the semiconductor substrate. Forming a crystal having the same polarity as that of the semiconductor substrate on the entire surface of the semiconductor crystal. 19. A semiconductor substrate having a flat surface, a buffer layer formed on the semiconductor substrate, and an active layer formed on the buffer layer and made of a quantum dot semiconductor crystal having a polarity different from that of the semiconductor substrate. A semiconductor laser having a cladding layer formed on the semiconductor crystal. 20. A buffer layer forming step of forming a buffer layer on a semiconductor substrate having a flat surface, and an activity of forming an active layer made of quantum dot semiconductor crystals having a polarity different from that of the semiconductor substrate on the buffer layer. A method of manufacturing a semiconductor laser, comprising: a layer forming step; and a clad layer forming step of forming a clad layer on the active layer.