JPH0730195A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To obtain a method for manufacturing a semiconductor element such as a refractive index wave-guide type semiconductor element where each process can be executed easily, working time can be reduced, and yield and controllability can be improved. CONSTITUTION:A mask layer 25 is provided at a region other than the region which becomes a desired refractive index waveguide channel on a semiconductor substrate 21 and the substrate 21 is etched, thus forming a groove part 21a at the region which becomes a desired refractive index waveguide channel by etching the substrate 21. Further, a dielectric film 26 is formed at the groove part 21a of the substrate 21 excluding a bottom surface and waveguide channel structures 22, 23, and 24 are selectively formed on the bottom surface of the groove channel with the dielectric film 26 as a selective mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly to a method of manufacturing a semiconductor device that can be suitably used for forming a ridge type or buried type semiconductor.

[0002]

2. Description of the Related Art Conventionally, a process for forming a lateral optical confinement structure for a ridge type semiconductor laser device has been performed as follows.

FIGS. 6A to 6E are process drawings for explaining a conventional method for manufacturing a ridge type semiconductor laser device.

First, as shown in FIG. 6B, an active layer 10 is formed on a flat semiconductor substrate 101 as shown in FIG.
2. Laminate the clad layer 103 and the cap layer 104,
Form a flat semiconductor laser wafer.

Subsequently, as shown in FIG. 6C, a cap layer 10 is formed by a photolithography process and an etching process such as a reactive ion beam etching (RIBE) method.
4 is etched to a predetermined depth in the clad layer 103, which is the lower layer of 4, to form a lateral optical confinement structure.

Thereafter, as shown in FIGS. 6D and 6E, an insulating film 105 is formed on the semiconductor laser wafer, the insulating film 105 at the top of the ridge is removed, and a current injection window is formed. As described above, in the conventional process of forming the lateral optical confinement structure of the ridge type semiconductor laser device, a step of performing epitaxial growth of a desired structure on the semiconductor substrate 101 and then performing etching is used.

Further, conventionally, a process of forming a lateral optical confinement structure of a buried type semiconductor laser device is performed on a flat semiconductor substrate 2 as shown in FIGS. 7 (a) to 7 (d).
01 to the active layer 202, the cladding layer 203, the cap layer 2
After stacking 04 to form a flat semiconductor laser wafer, the substrate 201 below the active layer 202 is etched by a photolithography process and an etching process such as a reactive ion beam etching method, and further, light confinement and current confinement are performed. A buried layer 205 for performing the above is formed.

In the conventional process of forming the buried type semiconductor laser structure, a step of performing epitaxial growth on the semiconductor substrate 201, etching, and then re-growing is used.

[0009]

However, the conventional process for forming the ridge-type semiconductor laser device has the following problems.

Since the dry etching process is required, the yield is low. Since the active layer of the semiconductor laser is etched close to the active layer by the dry etching process, the active layer is damaged, shortening the life of the semiconductor laser device and adversely affecting the electrical characteristics. -When forming a ridge by a dry etching process,
The required accuracy of depth and width is severe (depth accuracy 2.0 μm ±
0.1 μm, width accuracy of 3 μm or less), process control is difficult, and reproducibility is poor.

Further, the process of forming a buried type semiconductor laser device has the following problems.

First, since the dry etching process is required, there are the above three problems. Furthermore, since the regrowth process is required, the throughput and the yield are very poor.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to make it possible to carry out each process easily, to prevent failures, to shorten the working time, and to prolong the life of the refraction. It is an object of the present invention to provide a method capable of manufacturing a semiconductor device such as a rate-guided semiconductor laser device and the semiconductor device.

[0014]

According to the present invention, there is provided a semiconductor device and a method for manufacturing the same, in which a patterned mask layer is provided on at least a region other than a region to be a desired refractive index waveguide, and the substrate is formed at an arbitrary depth. Then, a groove is formed by etching, a dielectric film is formed on this substrate, only the dielectric film on the bottom surface of the groove is removed, and further, an arbitrary semiconductor layer structure is selectively formed on this substrate by epitaxial growth. It is characterized by

Specifically, in the method for manufacturing a semiconductor device of the present invention, a mask layer is provided on a semiconductor substrate in a region other than a region to be a desired refractive index waveguide, and the substrate is etched to obtain a desired refractive index waveguide. Forming a groove portion in a region to be formed, further forming a dielectric film on the groove portion of the substrate except the bottom surface, and selectively forming a waveguide structure on the bottom surface of the groove portion using the dielectric film as a selection mask. Is characterized by.

Further, in the semiconductor device of the present invention, a mask layer is provided on the semiconductor substrate in a region other than the region where the desired refractive index waveguide is formed, and this substrate is etched to form a region where the desired refractive index waveguide is formed. A groove is formed, a dielectric film is formed on the groove of the substrate except the bottom surface, and a waveguide structure is selectively formed on the bottom of the groove using the dielectric film as a selection mask. And

More specifically, the waveguide structure is formed to include an active layer, the refractive index waveguide is formed by a ridge, and the groove portion is formed sufficiently deep to form the refractive index waveguide. Are buried or the energy gap of the active layer is smaller than the energy gap of the semiconductor substrate.

[0018]

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIG. In this embodiment, the present invention is applied to a ridge type semiconductor laser device.

FIGS. 1A to 1D are process drawings for explaining a typical embodiment of the method for manufacturing a semiconductor device of the present invention.

First, as shown in FIG. 1A, a dielectric film 25 having a stripe-shaped region is provided on an n-type semiconductor substrate 21, and a region other than the region where the dielectric film 25 is formed is provided. The area is etched to an arbitrary depth, and stripe-shaped grooves 2
1a is formed. The dielectric film 25 is made of SiO ₂ , SiN,
A dielectric film such as Al ₂ O ₃ is formed by a film forming method appropriately selected according to the material, such as a plasma CVD method or a sputtering method.

Subsequently, as shown in FIG. 1B, the dielectric film 26 is formed on the substrate 21 and the dielectric 25 in the same manner as described above.

Next, as shown in FIG. 1C, the dielectric film 26 on the bottom surface of the stripe-shaped groove 25a is etched to expose the substrate 21. As an etching method, SF ₆ ,
A reactive ion etching method using a gas atmosphere such as CF ₄ may be used.

Next, as shown in FIG. 1D, an active layer 22, a p-type semiconductor cladding layer 23, and a p-type semiconductor cap layer 24 having a multiple quantum well structure are sequentially formed on this semiconductor wafer along a groove 25a. By selectively stacking in stripes to form a ridge type semiconductor laser wafer.

However, the semiconductor laser wafer is not limited to this, and any semiconductor laser wafer applicable to the ridge type can be used.
There are no particular restrictions on the structure and materials, and they can be used.

For example, the above p and n may be replaced with each other, and the active layer may have a multiple quantum well structure (MQ).
Not only W), but also a single quantum well structure (SQW) structure and a double hetero structure (DH) structure. As a laser wafer, a grating is formed on a processed substrate and each layer of the laser structure is grown. Things can be used.

Further, as a material for the semiconductor laser, GaA is used.
s ・ AlGaAs system, InP ・ InGaAsP system,
AlGaInP type etc. can be used.

In addition to the additional parts such as electrodes attached to the product manufactured by the steps described above, necessary processing such as physical processing (for example, processing for forming a resonance surface, heat treatment, etc.) is performed. However, both the ridge type semiconductor laser device that has undergone such necessary processing and the one that has not undergone such necessary processing are the ridge type semiconductor laser devices described in this embodiment.

The resonance surface may be formed by cleavage, or may be formed by subjecting one or both surfaces of the resonance surface to a wet etching process or a dry etching process.

Further, this embodiment is not limited to the manufacture of the above-mentioned index-guided ridge type semiconductor laser device, but is also applicable to a similar stripe-shaped index-guided waveguide, an optical switch,
It can also be applied to the manufacture of semiconductor devices such as optical modulators. In this case, the semiconductor element means an element that has undergone the same steps and necessary processing as those of the ridge type semiconductor laser element.

The processes shown in FIGS. 1 (a) to 1 (d) may be carried out in a vacuum consistent process using a multi-chamber type vacuum device.

Hereinafter, an embodiment in which the above embodiment is further embodied will be described with reference to FIGS. 1 (a) to 1 (d) and FIG.
This will be described with reference to (a) and (b).

First, a dielectric film 25 made of SiO 2 having a thickness of 1200 Å is formed on the entire surface of the n-type InP substrate 21 by the sputter vapor deposition method, and a striped negative pattern having a width of 3 μm is formed by a photolithography process. Four
Reactive ion etching in SF ₆ atmosphere Pa (RI
By E), the dielectric film 25 is selectively etched in a stripe shape having a width of 3 μm. Then, the remaining dielectric film 25
Using as a mask, the InP substrate 21 was etched to a depth of 0.3 μm by reactive ion beam etching in a chlorine atmosphere to form stripe grooves 25a. (Fig. 1
(See (a)) Subsequently, a dielectric film 26 made of SiO 2 is formed on this wafer with a thickness of 2000 Å by a sputter deposition method (see FIG. 1 (b)), and further reactive ions in an SF ₆ atmosphere of 4 Pa are used. By etching, as shown in FIG. 1C, the dielectric film 26 on the sidewall of the stripe-shaped groove 25a is formed.
The dielectric film 26 other than the dielectric film 25 on the substrate 21 was etched to expose the n-InP substrate 21 at the bottom of the groove.

Furthermore, non-doped InGaAs (40 Å) is formed only in the stripe-shaped groove portion 25a of the n-InP substrate 21 by the chemical beam epitaxial (CBE) method.
Thickness) and InGaAsP (200 Å thickness) are repeatedly laminated four times to form a multi-quantum well structure active layer 22, p-I
nP clad layer 23 (2.0 μm thick), p ⁺ -InGaA
An sP cap layer 24 (0.5 μm thick) was sequentially grown selectively to form a ridge portion to form a stripe structure for confining light in the lateral direction.

Subsequently, an insulating film 27 (thickness 1200) made of SiN is formed on the laser wafer on which the ridge is formed.
Å) was formed by a plasma CVD method, and a resist was spin-coated on the SiN insulating film 27 by about 1.0 μm. Then, only the resist formed on the top of the ridge is removed by RIE (reactive ion etching) in an O ₂ atmosphere of 4 Pa, and the SiN insulating film 2 on the top of the ridge is removed.
7 is exposed, and RI is further applied in a CF ₄ gas atmosphere of ₄ Pa.
By performing the E method, the SiN insulating film 27 exposed at the top of the ridge is selectively etched. After that, the remaining resist was removed by the RIE method in an O ₂ atmosphere of 4 Pa.

Next, the surface oxide film formed on the top of the ridge is wet-etched with hydrochloric acid to form a current injection window, and subsequently an Au-Zn-Au ohmic electrode 28 is formed as an upper electrode by a vacuum evaporation method. , InP substrate 2
1 was lapped to a thickness of 100 μm, and then an Au—Sn—Au electrode was vapor-deposited as an n-type ohmic electrode 29. Then, heat treatment for making ohmic contact with the p-type and n-type electrodes was performed to obtain a ridge-type optical semiconductor element.

Finally, the resonance surface is formed by cleavage, and E
A SiO ₂ -based high-reflection film and a low-reflection film are each coated by B (electron beam) vapor deposition, separated by scribing, and the electrodes 28 and 29 are taken out by wire bonding.

When a semiconductor laser device was formed by repeating the same steps, a device having a long life (capable of laser oscillation for 2000 hours or more at room temperature) was obtained with good reproducibility.

[0038]

[Other Embodiments] FIG. 3 shows an embedded type index-guided type D.
FIG. 4 is a top view showing a second embodiment of the FB semiconductor laser device, and FIGS. 4 and 5 are sectional views taken along the lines AA 'and BB' in FIG.

The process procedure of the second embodiment will be described below. First, a dielectric film 37 (thickness 2000 Å) made of SiN is formed on the entire surface of an n-type In-P substrate 31 by a plasma CVD method, and a photolithography process and R
After a stripe-shaped groove having a width of 3 μm is formed by the IE method, the n-type In-P substrate 31 is made to have a depth of 3.0 by the RIBE method in a chlorine atmosphere using the SiN dielectric 37 as a mask.
μm etching was performed to form stripe-shaped grooves.

Subsequently, a dielectric film 38 (thickness 1200 Å) made of SiO is formed on the entire wafer by a sputter deposition method, and further, by RIE in an SF ₆ atmosphere of 4 Pa.
The SiO dielectric film 38 on the bottom of the groove is etched to expose the underlying n-type InP substrate 31.

Further, a grating g perpendicular to the AA 'direction in FIG. 3 was formed on the groove bottom surface by the two-beam interference exposure method and RIBE.

Then, n-InG is formed by MOCVD.
aAsP optical guide layer 32 (1000 Å thickness), undoped InGaAs (40 Å thickness), InGaAsP (2000
Å) is repeatedly laminated four times to form an active layer 33 and a p-InGaAsP optical guide layer 34.
(1000Å thickness), p-InP clad layer 35 (1.5
.mu.m thick), ^p.sup . ⁺ -InGaAsP cap layer 36 (0.
5 .mu.m thick) was sequentially grown selectively in the stripe-shaped trenches and buried therein to form a buried-type refractive index waveguide structure for laterally confining light.

Subsequently, Au--Zn--Au was used as the upper electrode.
The ohmic electrode 39 was formed by a vacuum vapor deposition method, the InP substrate 31 was lapped to a thickness of 100 μm, and then an AuSnAu electrode was vapor deposited as an n-type ohmic electrode 40. Then, heat treatment for making ohmic contact between the p-type and n-type electrodes 39 and 40 was performed to obtain a buried semiconductor element.

Finally, the resonance surface is formed by cleavage, and E
A high reflection film and a low reflection film such as SiO are coated by B vapor deposition and separated by scribing, and electrodes 39, 4 are formed.
0 was taken out by wire bonding.

Also in this example, by repeating the same steps, a semiconductor laser device having a low threshold value (I _th <15 mA) and a long life was obtained with good reproducibility.

[0046]

As described above, in the method for manufacturing a semiconductor device of the present invention, since highly precise etching control is not required, there is no manufacturing failure, no time is required, and the yield and controllability are improved. .

Further, since the vicinity of the active layer and the active layer are not etched, no damage is caused, so that the life of the semiconductor element can be extended. Furthermore, since it can be performed by a vacuum integrated process, the throughput is significantly improved.

The present invention is extremely effective for manufacturing semiconductor elements used in optical communication and optical information transmission devices.

[Brief description of drawings]

FIG. 1 is a process drawing for explaining a typical embodiment of a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is a top view (a) of the first embodiment of the present invention, and an AA ′ sectional view (b) of FIG. 2 (a) of the first embodiment of the present invention.

FIG. 3 is a top view of the second embodiment of the present invention.

FIG. 4 is a sectional view taken along the line AA ′ in FIG. 3 of the second embodiment of the present invention.

FIG. 5 is a sectional view taken along the line BB ′ of FIG. 3 of the second embodiment of the present invention.

FIG. 6 is a process drawing for explaining a conventional method for manufacturing a ridge-type semiconductor laser device.

7A to 7C are process diagrams for explaining a conventional method for manufacturing a buried semiconductor laser device.

[Explanation of symbols]

 21, 31, 101, 201 Semiconductor substrate 22, 33, 102, 202 Active layer 23, 35, 103, 203 Clad layer 24, 36, 104, 204 Cap layer 25, 26, 37, 38 Dielectric film 28, 29, 39, 40 Electrodes 32, 34 Light guide layer g Grating

Claims (10)

[Claims] 1. A semiconductor substrate is provided with a mask layer in a region other than a region to be a desired refractive index waveguide, and the substrate is etched to form a groove portion in a region to be a desired refractive index waveguide. Dielectric film is formed in the groove of
A method of manufacturing a semiconductor device, wherein a waveguide structure is selectively formed on the bottom surface of the groove using the dielectric film as a selection mask. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the waveguide structure is formed to include an active layer. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the refractive index waveguide is formed of a ridge. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the groove is formed sufficiently deep, and the refractive index waveguide is embedded. 5. The method of manufacturing a semiconductor device according to claim 2, wherein an energy gap of the active layer is formed smaller than an energy gap of the semiconductor substrate. 6. A mask layer is provided on a semiconductor substrate in a region other than a region to be a desired refractive index waveguide, and the substrate is etched to form a groove in a region to be a desired refractive index waveguide. A semiconductor device, wherein a dielectric film is formed in a groove portion of a substrate except a bottom surface, and a waveguide structure is selectively formed on the bottom surface of the groove portion by using the dielectric film as a selection mask. 7. The semiconductor device according to claim 1, wherein the waveguide structure includes an active layer. 8. The semiconductor device according to claim 1, wherein the refractive index waveguide is formed of a ridge. 9. The semiconductor device according to claim 1, wherein the groove is formed sufficiently deep, and the refractive index waveguide is embedded. 10. The energy gap of the active layer is
The semiconductor device according to claim 2, wherein the semiconductor device is formed to have an energy gap smaller than that of the semiconductor substrate.