JPH04214617A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To manufacture an integrated semiconductor light emitting device in high density by automatically forming many pieces of semiconductor light emitting elements separately on the same substrate without needing the element isolating process to be attached later. CONSTITUTION:By arranging a substrate, which has step-shaped structure, obliquely to the material beam, using the crystal growth technology, where the material beam supplied to the substrate surface has linearity, and a region, which become the shade of a material beam, is made at the substrate, and the structure where many pieces of isolated layer are stacked is automatically formed on the substrate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing integrated semiconductor light emitting devices in which a large number of semiconductor light emitting devices are integrated on the same substrate.

0002

[Prior Art] Semiconductor light-emitting devices such as semiconductor lasers or light-emitting diodes, which have direct transition semiconductors such as AlGaAs as their active layers, have advantages such as small size, light weight, and high efficiency, and are used as light sources for optical communication, optical disks, and displays. It is widely used as a light emitting device. In the future, this type of semiconductor light emitting device is expected to be used as a light source for optical coupling between chips in the field of optical integrated circuits. In such applications, semiconductor light emitting devices are used not individually but in large numbers integrated on the same chip substrate, so a process to separate adjacent light emitting devices that operate independently is essential. . As a method for separating light emitting elements on the same substrate, there is known a method of selectively forming an etching groove shown in FIG. 14 or a high resistance layer by proton irradiation shown in FIG. 15 by photolithography.

0003

In applications such as the above-mentioned light source for optical coupling between chips, it is required to integrate as many light emitting elements as possible on a microscopic substrate at a high density. However, in the method of retrofitting the isolation structure as in the conventional example above, in addition to the area that is actually required by the light emitting element, an area for creating the structure for element isolation, such as etching grooves, is required, resulting in a high density It is disadvantageous for the integration of Furthermore, if an attempt is made to create such an element isolation structure, the number of processes will increase, leading to a decrease in mass productivity. In addition, in order to integrate the above-mentioned light-emitting elements at high density, it is necessary to miniaturize the size of each individual element, which requires high alignment accuracy such as the formation of mesa structures using conventional photolithography. Processes need to be reduced as much as possible.

0004

[Means for Solving the Problems] A method for solving the above problems will be explained using molecular beam crystal growth as an example of the crystal growth method used in the present invention.

Molecular beam crystal growth is a crystal growth technique in which a solid material is heated and evaporated as a raw material in an ultra-high vacuum, and then supplied as molecular beams onto a substrate to form crystal films. A characteristic feature is that the molecular beam supplied to the substrate surface has straight propagation. Therefore, as shown in FIG. 8, if a mask that blocks the molecular beams is placed between the molecular beam source and the substrate, the molecular beams will be cut off in the shadowed areas, and no crystal film will grow in these areas. By arranging a suitable mask in this manner, it becomes possible to form a multilayer structure that is automatically separated during crystal growth.

In the present invention, by arranging a substrate having a step-like structure obliquely to the molecular beam, a region shaded by the molecular beam is created as shown in FIG. Automatically forms separated multilayer structures. By forming this multilayer structure into, for example, a double heterostructure, a large number of separate semiconductor light emitting devices can be easily formed on the same substrate.

FIGS. 10 and 11 show an example of a method for forming a step structure in the present invention. First, a substrate is placed at a certain molecular beam irradiation angle, and a first semiconductor layer is grown. Next, when the substrate is arranged so that the molecular beam irradiation angle becomes shallower with respect to the substrate surface and a second semiconductor layer is grown, the width of the area shadowed by the molecular beam changes depending on the difference in the molecular beam incidence angle. However, a multilayer structure having a step structure as shown in the figure can be formed. The width of the stepped shape formed at this time can be easily controlled by setting the molecular beam incidence angle.

FIGS. 12 and 13 show an example of a method for forming a buried structure in the present invention. First, a substrate is placed at a certain molecular beam irradiation angle, and a first semiconductor layer is grown. Next, contrary to the formation of the step structure, the arrangement of the substrate is changed so that the molecular beam irradiation angle becomes deeper with respect to the substrate surface,
When the second semiconductor layer is grown, a multilayer structure can be formed in which the first semiconductor layer is embedded with the second semiconductor layer.

[0009]

[Operation] According to the present invention, a large number of semiconductor light emitting devices can be automatically separated and formed on the same substrate without the need for a subsequent device separation process, and a high density integrated semiconductor light emitting device can be formed. Manufacture is possible.

0010

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings, using an AlGaAs material as an example.

FIG. 1 is a sectional view of an integrated light emitting diode in which a large number of edge-emitting light emitting diodes are formed on the same substrate as a first embodiment of the present invention. First, n-Ga
A staircase structure is formed on the As substrate 10 by, for example, photolithography, and this is introduced into a molecular beam crystal growth apparatus.

Next, the substrate is arranged so that the molecular beam of the material is irradiated from the direction of the arrow in the figure, and the n-GaAs buffer layer 11 and the n-AlGaAs first cladding layer 12 (for example, Al composition ratio 0. 2), p-AlGaAs active layer 13
(for example, Al composition ratio 0.05), p-AlGaAs second cladding layer 14 (for example, Al composition ratio 0.2), p-AlGaAs second cladding layer 14 (for example, Al composition ratio 0.2),
An As contact layer 15 is grown. The rotation of the substrate, which is carried out to improve the uniformity of the grown film in ordinary molecular beam crystal growth methods, is also performed during the growth of the present invention by keeping the molecular beam irradiation angle with respect to the substrate surface constant, with the direction of molecular beam irradiation as the center of rotation. It is permissible to rotate the board to maintain the same.

Finally, both p-n electrodes 16 and 17 are formed, but when forming the p-electrode 16, the electrode material is also irradiated by vacuum evaporation, for example, so that it is irradiated from the same direction as the molecular beam irradiation direction during the crystal growth. If formed by the method, the p-electrode 16 is automatically formed only on the surface of the p-GaAs contact layer 15 of each separated light emitting diode, without requiring any particular mask process.

The light emitted from this light emitting diode can be extracted from the direction shown in the figure, and a large number of integrated light emitting diodes can be formed on the same substrate through the above manufacturing process. 2, 3, and 4 show manufacturing steps for forming a large number of light emitting diodes having a stepped structure on the same substrate as a second embodiment of the present invention.

As in the first embodiment, an n-GaAs substrate 10 having a stepped structure is first grown in a relatively deep direction (in the figure) with respect to the substrate 10 as shown in FIG. 2 in a molecular beam crystal growth apparatus. An n-GaAs buffer layer 11, an n-AlGaAs first cladding layer 12 (for example, Al composition ratio 0.2), a p-AlG
sAs active layer 13 (for example, Al composition ratio 0.05), p-
A portion 214 of the AlGaAs second cladding layer (e.g. Al
A composition ratio of 0.2) is grown.

After that, the arrangement angle of the substrate was changed, and as shown in FIG.
As shown in the figure, the material molecular beam is irradiated from a shallower angle (arrow in the figure) with respect to the substrate surface, and then p-
An AlGaAs second cladding layer 224 (for example, Al composition ratio 0.2) and a p-GaAs contact layer 15 are grown, and finally, as shown in FIG.
6, and an n electrode (not shown) are formed. In the light emitting diode with this structure, the cladding layer is transparent to the wavelength of light emitted from the active layer 13, so it is possible to extract light from the surface obliquely upward as shown in FIG. An integrated light emitting diode is obtained.

FIGS. 5, 6, and 7 show an example of the manufacturing process when a large number of semiconductor lasers are formed on the same substrate as a third embodiment of the present invention. First, n-
The GaAs substrate 10 is arranged in a molecular beam crystal growth apparatus so that the material molecular beam is irradiated from a direction (arrow in the figure) at a relatively deep angle to the substrate 10 as shown in FIG. -GaAs buffer layer 11 and a part 312 of n-AlGaAs first cladding layer (for example, Al composition ratio 0.5) are grown.

Next, the arrangement angle of the substrate 10 is changed to a shallower angle (arrow in the figure) with respect to the surface of the substrate 10, as shown in FIG.
The material molecular beam is irradiated from n.
-AlGaAs first cladding layer 322 (for example, Al composition ratio 0.5), n-AlGaAs active layer 13 (for example, Al
composition ratio 0.05), n-AlGaAs second cladding layer 1
4 (for example, Al composition ratio 0.5) are sequentially grown.

After that, the arrangement angle of the substrate was changed again, and FIG.
As shown in FIG. 5, the irradiation angle of the material molecular beam becomes deep again, and is arranged so that it is slightly shallower than the direction shown in FIG. Subsequently, a p-AlGaAs buried layer 332 (for example, Al composition ratio 0.5) and a p-GaAs contact layer 15 are formed.
grow. Finally, both p and n electrodes (not shown) are formed in the same manner as in the first embodiment, and, for example, RIBE (Reac
tive Ion Beam Etching)
By forming the resonator end face by cutting or cleavage,
A large number of semiconductor lasers can be integrated on the same substrate.

[0020] The semiconductor laser in this example is individually TJS (Transverse Junction).
It is a type of laser (Stripe) and has a p-AlGaAs buried layer 332 with the lowest diffusion potential and an n-AlGa
Current is selectively injected through the pn junction formed at the interface of the As active layer 13, leading to laser oscillation. Figures 5 and 6 above
, 7, steps occur on the surface of each individual element as shown in FIG. 7. If it is necessary to avoid this, for example, after the steps up to FIG. For example, the insulating film is deposited from the n-
The insulating film is formed on the AlGaAs second cladding layer 14 and then selectively grown in the process shown in FIG. 7 using this as a mask, or after each layer is grown on the insulating film in the process shown in FIG. with n-AlGaA
Planarization is also possible by peeling off only the grown film on the s-layer 14.

The present invention is not limited to the light emitting regions of the semiconductor lasers or light emitting diodes shown in the first to third embodiments above, but can also be applied to structures other than those described above, such as a separate confinement structure or a quantum well structure for the active layer. It can be carried out in the same way even when doing so. Also, other materials such as InGaAs
It can be widely applied to semiconductor light emitting devices using P-based and AlGaInP-based materials. Furthermore, although the explanation and examples have been given using the molecular beam crystal growth method as an example of the crystal growth method, the present invention is not limited to this crystal growth method, and the present invention is not limited to this crystal growth method. It can be similarly applied to all other crystal growth methods in which the substrate surface is irradiated. In addition, although this method has been described here as a method suitable for manufacturing integrated semiconductor devices, it is also possible to use the method of the present invention to automatically create a differential structure during crystal growth, and to Applications such as cutting into individual chips after the completion of the process are also possible.

[0022]

As described above, according to the present invention, an integrated semiconductor light emitting device that can integrate a large number of semiconductor light emitting devices at high density on the same substrate without the need for a subsequent device isolation process is provided. It becomes possible to manufacture the device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of an integrated light emitting diode according to a first embodiment of the present invention.

FIG. 2 is a sectional view for explaining a second embodiment of the present invention.

FIG. 3 is a sectional view for explaining a second embodiment of the present invention.

FIG. 4 is a sectional view for explaining a second embodiment of the present invention.

FIG. 5 is a sectional view for explaining a third embodiment of the present invention.

FIG. 6 is a sectional view for explaining a third embodiment of the present invention.

FIG. 7 is a sectional view for explaining a third embodiment of the present invention.

FIG. 8 is an explanatory diagram showing the properties of the molecular beam crystal growth method.

FIG. 9 is an explanatory diagram showing the principle of the present invention.

FIG. 10 is an explanatory diagram showing the principle of the present invention.

FIG. 11 is an explanatory diagram showing the principle of the present invention.

FIG. 12 is an explanatory diagram showing the principle of the present invention.

FIG. 13 is an explanatory diagram showing the principle of the present invention.

FIG. 14 is an explanatory diagram showing a conventional element isolation method.

FIG. 15 is an explanatory diagram showing a conventional element isolation method.

[Explanation of symbols]

10 n GaAs substrate 11 n GaAs buffer layer 12 n
AlGaAs first cladding layer 13 p AlG
aAs active layer 14p AlGaAs 2nd
Cladding layer 15p GaAs contact layer 1
6 p electrode 17 n electrode

Claims (1)

[Claims] 1. When growing a crystal by irradiating a straight material beam onto a substrate surface, a step-like structure is formed in advance on one main surface of the substrate, and a desired angle is formed with respect to the main surface of the substrate. A method of manufacturing a semiconductor device, characterized in that the material beam is irradiated from a direction having a direction of irradiation.