JP2003069149A - Semiconductor light element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light element that shows the reduction effect of an effective reflection factor perfectly and has a window section for preventing turbulence from being generated in the field of signal light, and to provide a method for manufacturing the semiconductor light element. SOLUTION: At a window section B connected to the emission side of a laser section A for oscillating a laser beam, a semiconductor layer 22a is formed. In this case, the semiconductor layer 22a does not have any optical waveguide structure on the extended line of a waveguide comprising an active layer 16 at the laser section A and the like, and has a low refractive index. The upper surface of the semiconductor layer 22a becomes higher than the upper surface of a second upper cladding layer 20 of an uppermost layer at the laser section A. Concretely speaking, the upper surface of the semiconductor layer 22a inclines and becomes higher towards the emission end face side of the window section B from height being equal to the second upper cladding layer 20 in the boundary to the laser section A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor optical device and a method for manufacturing the same, and more particularly to a semiconductor optical device having a window portion at one or both ends of an optical waveguide portion having a stripe-shaped waveguide. The manufacturing method is related.

[0002]

2. Description of the Related Art As a key device for high-speed optical communication, a semiconductor laser device that oscillates and outputs a signal light of a predetermined wavelength band, an optical modulator that modulates the light intensity, a semiconductor laser amplifier that amplifies an input optical signal, etc. Is attracting attention. Among such semiconductor optical devices, a DFB (Distributed Feedba) that uses a diffraction grating as a resonator structure is used.
ck; distributed feedback type) laser element, an optical modulator having an absorption layer, and a traveling wave type semiconductor laser amplifier, the signal light is reflected at the emitting end facet and re-incident on the optical waveguide to cause wavelength fluctuation. Due to the nature of easy occurrence of the edge, the non-reflection technology of the end face is indispensable in order to achieve stable operation and high performance of the device.

As a technique for making the end face non-reflecting in such a semiconductor optical device, an AR (Anti Reflection) coating is not applied to the end face of a laser section for oscillating a laser beam, or there is no optical waveguide structure. The method of providing a window is adopted. However, the AR coating requires a multi-layer film whose film thickness is precisely controlled in order to achieve low reflection, which complicates the process steps. On the other hand, the window portion has an advantage that the process steps thereof are relatively simple and the low reflectance can be easily achieved.

An example of a conventional embedded DFB laser device having a window is shown in a partially cutaway perspective view of FIGS. 24 and 25 and a sectional view taken along the line AXI-AX. This D
The FB laser device includes a laser unit A that oscillates laser light,
The window B provided on the output side is, for example, n
It has a structure formed on the same semiconductor substrate 10 made of -InP. The laser section A is made of, for example, InGa.
A diffraction grating 12 made of As, a buffer layer 14 made of n-InP, a well layer made of InGaAs, and InGaA.
The barrier layers made of sP are alternately laminated to form a wavelength of 1.
It has a laminated structure La in which an active layer 16 having a QW (Quantum Well; quantum well) structure that oscillates light of 55 μm and a first upper clad layer 18 made of p-InP are sequentially laminated. The laminated structure La is processed into a mesa stripe shape extending in the longitudinal direction and functions as a waveguide that oscillates light having a predetermined wavelength.

Further, for example, p-InP layers 34a and n-In are formed on both sides of the mesa-stripe-shaped laminated structure La.
A pn carrier block layer 36 formed by sequentially stacking P layers 34b is buried. The upper surface of these laminated structures La and the upper surfaces of the pn carrier block layers 36 on both sides thereof are flush with each other. Furthermore, these laminated structures La and p
The second upper cladding layer 20 made of, for example, p-InP is formed on the n carrier block layer 36, and serves as the laser section A as a whole.

On the other hand, the window portion B has a pn in the laser portion A.
A pn carrier block layer 36 formed simultaneously with the carrier block layer 36, and a second upper clad layer 2 formed simultaneously with the second upper clad layer 20 in the laser section A as well.
0 is sequentially laminated to form a laminated structure Lb of low refractive index semiconductor layers having no waveguide structure. Further, on the second upper cladding layer 20 in the laser part A, the stripe electrode part 24 corresponding to the stripe shape of the laminated structure La is formed.
An upper electrode such as a is provided, and a lower electrode 26 is provided on the back surface of the common semiconductor substrate 10.

The conventional DFB in which the window portion B thus formed with the laminated structure Lb is provided on the emission side of the laser portion A
In the case of a laser element, the signal light from the laminated structure La of the laser section A of the optical waveguide structure spreads by an angle θ (normally θ = 24 ° to 30 °) when emitted to the laminated structure Lb in the window B, and Since a part of the spread signal light is reflected by the exit end face of the window B, the end face reflected light of the window B has a very large light spot size. It becomes difficult to combine them, and the ratio of the returning light that is re-incident becomes extremely small.

That is, when the ratio of the return light that the signal light from the laser section A is reflected by the emission end face and re-enters the optical waveguide is defined as the effective reflectance R, the window B is provided, and this effective reflectance is defined. The effect of reducing R is exhibited.

[0009]

By the way, in the above-mentioned conventional DFB laser device having the window B, the window B
Therefore, in order to further improve the effect of reducing the effective reflectance R, it is preferable to increase the length of the window portion B (window portion length) Lw. When the relationship between the effective reflectance R by the window B and the window length Lw is obtained, it is known that the effective reflectance R decreases rapidly as the window length Lw increases, as shown in the graph of FIG. ing.

On the other hand, however, when the window length Lw is increased, the mode field of the signal light from the laser portion A is angled at the window portion B as shown by the broken line with an arrow in FIG. When spread by θ, a part of the spread signal light is reflected by the upper surface of the second upper cladding layer 20 in the window portion B. Therefore, for example, considering a case where an optical fiber is arranged on the emission end face side of the DFB laser element via a lens, the signal light from the DFB laser element is transmitted from the upper surface of the second upper cladding layer 20 of the window B. Since reflected light is also added, the field of the signal light is disturbed, and there arises a problem that the coupling efficiency with the optical fiber is reduced.

As a measure for dealing with this problem, when the window length Lw is increased, the thickness of the second upper cladding layer 20 in the window B is simultaneously increased so that the mode field of the signal light from the laser section A is increased. It is considered effective to prevent the spread signal light from colliding with the upper surface of the upper cladding layer 20 in the window portion B even if the spread signal light spreads by the angle θ in the window portion B.

The relationship between the window length Lw and the thickness of the upper cladding layer that prevents the signal light from the optical waveguide from being reflected by the upper surface of the upper cladding layer 20 even if it spreads by the angle θ in the window B is shown in FIG. It came to be shown in the graph. That is, in order to increase the window length Lw without reflecting the signal light on the upper surface of the upper clad layer 20, it is necessary to increase the thickness of the upper clad layer 20 in proportion thereto.

However, when the thickness of the second upper clad layer 20 in the window portion B is increased, the thickness of the second upper clad layer 20 in the laser portion A is naturally increased, so that the thickness of the second upper cladding layer 20 in the laser portion A from the upper electrode 24 is increased. There is also a problem that the resistance to the injection current increases, and therefore the laser characteristics deteriorate, and the growth time of the upper cladding layer 20 becomes long. As a result, as a practical matter, increasing the thickness of the second upper cladding layer 20 is limited. As a result, similarly to the conventional case, the lengthening of the window length Lw is limited, and the effect of sufficiently reducing the effective reflectance R cannot be obtained.

Therefore, in spite of the provision of the window portion B, in order to further reinforce the effect of reducing the effective reflectance R by the window portion B, a complicated AR coating must be additionally performed. There was also a situation where nothing happened. The present invention has been made in consideration of the above circumstances, and is a semiconductor provided with a window portion capable of fully exerting the effect of reducing the effective reflectance without causing the disturbance of the field of the signal light. An object is to provide an optical element and a method for manufacturing the same.

[0015]

The above objects can be achieved by the following semiconductor optical device and method of manufacturing the same according to the present invention. That is, in the semiconductor optical device according to the present invention, an optical waveguide portion having a stripe-shaped waveguide and a window portion made of a semiconductor layer connected to one end or both ends of the optical waveguide portion are formed on the same semiconductor substrate. In the semiconductor optical device described above, the upper surface of the semiconductor layer is higher than the uppermost surface of the optical waveguide portion (claim 1).

In the semiconductor optical device according to the above-mentioned claim 1, the upper surface of the semiconductor layer of the window portion has a shape gradually increasing from the boundary between the window portion and the optical waveguide portion toward the emission end face of the window portion. It may be formed (claim 2) or may be formed in a substantially flat shape as a whole (claim 3). Further, it is preferable that the waveguide of the optical waveguide portion has an active layer that performs laser light oscillation, an absorption layer that performs optical modulation, or an active layer that performs optical amplification (claim 4).

Further, in the method for manufacturing a semiconductor optical device according to the present invention, when a predetermined semiconductor layer is simultaneously formed in the optical waveguide portion forming region and the window portion forming region, the crystal growth rate is locally increased to increase the selective growth. Is used to make the upper surface of the predetermined semiconductor layer in the window forming region higher than the upper surface of the predetermined semiconductor layer in the optical waveguide forming region (claim 5).

Specifically, after stacking a plurality of semiconductor layers on a semiconductor substrate to form a laminated body, a striped mask member and a striped mask member are formed on the laminated body in the optical waveguide portion forming region and the window portion forming region. A pair of mask members sandwiching the extension line of the stripe-shaped mask are provided respectively, and the stacked body is selectively etched using the stripe-shaped mask member and the pair of mask members to form a pair of mesa stripes and a pair for selective growth. The first step of forming each mask body and the local crystal growth at the same time when the first and second carrier block layers are simultaneously embedded and formed in both sides of the mesa stripe and in the region sandwiched by the pair of mask bodies, respectively. The upper surface of the first carrier block layer is made substantially flush with the upper surface of the layered body while the upper surface of the second carrier block layer is formed by using the selective growth that increases the speed. The second step of making the carrier block layer higher than the upper surface of the first carrier block layer, and after removing the stripe-shaped mask member and the pair of mask members, the laminated body in the optical waveguide part formation region, the first carrier block layer, and the window part An upper clad layer is formed on the second carrier block layer in the formation region to form an optical waveguide part and a window part, and
A third step of making the upper surface of the semiconductor layer including the first carrier block layer and the upper cladding layer in the window portion higher than the upper surface of the upper cladding layer in the optical waveguide portion (claim 6).

Alternatively, after a stacked body formed by stacking a plurality of semiconductor layers on a semiconductor substrate is selectively etched to form a mesa stripe in an optical waveguide portion forming region, both sides of the mesa stripe and a window are formed. A first step in which a carrier block layer is embedded and formed in the part formation region so that the upper surface of the carrier block layer is substantially flush with the upper surface of the stacked body; and the extension of the mesa stripe on the carrier block layer in the window part formation region. After providing a pair of mask members for selective growth sandwiching the line, a first layer is formed on the carrier block layer sandwiched between the laminated body and the carrier block layer in the optical waveguide formation region and the pair of mask members in the window formation region. And the second upper clad layer are simultaneously formed, the upper surface of the second upper clad layer is formed on the upper surface of the first upper layer by selective growth that locally increases the crystal growth rate. A second step of making the upper surface of the lad layer higher than the upper surface, a pair of mask members are removed to form an optical waveguide portion and a window portion, and a semiconductor including a carrier block layer and a second upper cladding layer in the window portion A third step of making the upper surface of the layer higher than the upper surface of the first upper cladding layer in the optical waveguide section (claim 7).

In the method for manufacturing a semiconductor optical device according to any one of claims 5 to 7, the width of the pair of mask members provided in the window forming region in the direction orthogonal to the extension line of the mesa stripe is the window portion. It may be gradually widened from the boundary between the formation region and the optical waveguide part formation region toward the end face of the window part formation region (claim 8), or may be substantially constant (claim 9).

Further, the method for manufacturing a semiconductor optical device according to the present invention comprises an optical waveguide section having a stripe-shaped waveguide,
A method for manufacturing a semiconductor optical device, in which a window made of a semiconductor layer connected to one end or both ends of the optical waveguide portion is formed on the same semiconductor substrate, wherein a plurality of semiconductor layers are laminated on the semiconductor substrate. The formed laminate is selectively etched to form a mesa stripe in the optical waveguide portion forming region, and then a carrier block layer is formed by embedding on both sides of the mesa stripe and the window forming region. The first step of making the upper surface substantially flush with the upper surface of the laminated body, and the carrier and the carrier block layer sandwiched between the laminated body and the carrier block layer in the optical waveguide forming region and the pair of mask members in the window forming region. A second step of forming an upper clad layer to form an optical waveguide part, and a supplementary semiconductor layer having a predetermined thickness is selectively laminated on the upper clad layer in the window part formation region to form a window part. To And a third step of making the upper surfaces of the semiconductor layers including the carrier block layer, the upper cladding layer, and the supplementary semiconductor layer in the window portion higher than the upper surfaces of the upper cladding layer in the optical waveguide portion. (Claim 10).

Further, after a stacked body formed by stacking a plurality of semiconductor layers on a semiconductor substrate is selectively etched to form a mesa stripe in an optical waveguide portion forming region, both sides of the mesa stripe and a window portion are formed. A first step of embedding a carrier block layer in the formation region so that the upper surface of the carrier block layer is substantially flush with the upper surface of the laminate, and the laminate, carrier block layer, and window portion in the optical waveguide formation region. The second step of forming an upper clad layer on the carrier block layer sandwiched between the pair of mask members in the formation region to form a window, and the upper clad layer in the optical waveguide part formation region to a predetermined thickness. Selectively etched away,
A third step of forming the optical waveguide part and making the upper surface of the semiconductor layer including the carrier block layer and the upper clad layer in the window part higher than the upper surface of the upper clad layer in the optical waveguide part. (Claim 1
1).

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) FIGS. 1A and 1B show a DFB as an example of a semiconductor optical device according to a first embodiment of the present invention.
A schematic plan view showing a laser device and a cross-sectional view taken along line AI-AI thereof, FIGS. 2 to 8 are process drawings for explaining the first manufacturing method of the DFB laser device of FIG. 1, and FIGS. 9 to 12 are respectively. FIG. 7A is a process diagram for describing a second manufacturing method of the semiconductor optical device in FIG. 1. The same components as those of the DFB laser device of FIGS. 24 and 25 are designated by the same reference numerals and the description thereof will be omitted as appropriate.

The semiconductor optical device according to the present embodiment is a QW structure embedded DFB laser device for outputting a signal light in a long wavelength band for optical communication, as shown in FIGS. 1 (a) and 1 (b). In addition, the laser portion A that oscillates the laser light and the window portion B that is provided so as to be connected to the emission side thereof are the same semiconductor substrate 10.
Formed on. A highly reflective end surface portion C is provided on the end surface of the laser portion A opposite to the emission side.

This laser section A is similar to that shown in FIGS.
In the same manner as in the conventional case already described by using, a mesa stripe-shaped laminated structure La that functions as a waveguide that oscillates light of a predetermined wavelength is provided, and a pn carrier block layer 36 is embedded on both sides thereof. Further, the second upper clad layer 20 is formed on the laminated structure La and the pn carrier block layer 36 which are flush with each other.

On the other hand, the window B is formed of a low refractive index semiconductor layer having no waveguide structure, which is the same as in the conventional case already described with reference to FIGS. 24 and 25. The upper surface of the semiconductor layer 22a is higher than the upper surface of the second upper cladding layer 20 of the laser portion A, and the height is higher while being inclined from the boundary with the laser portion A toward the emission end face side of the window portion B. That is the basic difference from the conventional case.

Then, on the second upper cladding layer 20 in the laser section A, the upper electrode 24 consisting of the stripe electrode section 24a corresponding to the stripe shape of the laminated structure La and the pad electrode section 24b connected to this stripe electrode section 24a. The lower electrode 26 is provided on the back surface of the semiconductor substrate 10 common to the laser section A and the window section B. Further, in the high reflection end face portion C, a high reflection film 28 is coated on the end face of the laser portion A opposite to the emission side.

Although not shown, the second upper cladding layer 20 and the upper electrode 24 of the laser portion A and the semiconductor layer 22a of the window portion B are formed by a passivation film except for the opening on the pad electrode portion 24b. Covered and protected. Next, a first method of manufacturing the semiconductor optical device shown in FIG. 1 will be described. First, for example, as shown in FIG.
OCVD (Metal Organic Chemical Vapor Depositio
n: Inorganic metal vapor phase epitaxy) device is used to epitaxially grow a light absorption layer made of InGaAs, which has a large difference in refractive index from InP, on the semiconductor substrate 10 made of n-InP. A photoresist (not shown) is applied on the layer, and subsequently, a resist diffraction grating pattern of a predetermined cycle is formed using, for example, an EB (Electron Beam) drawing device or an interference exposure device, and this resist diffraction grating pattern is further formed. Using the as a mask, the light absorption layer is selectively etched to form the diffraction grating 12.

Next, as shown in FIG. 3, the buffer layers 14 and I made of n-InP for burying the diffraction grating 12 are formed.
An active layer 16 of a QW structure that oscillates light having a wavelength of 1.55 μm, in which well layers made of nGaAs and barrier layers made of InGaAsP are alternately laminated, and a first layer made of p-InP
The upper clad layer 18 is sequentially laminated to form a laminated structure La, and the intermediate M1 is manufactured.

Next, as shown in FIGS. 4A and 4B, for example, plasma CVD (Chemical Vapor Depositio) is performed.
n) A device is used to deposit a SiN film on the first upper cladding layer 18 of the intermediate M1, and then the SiN film is subjected to photolithography and RIE (Reactive Ion Etchin).
g; reactive ion etching) device is used for patterning, and a stripe-shaped mask member 3 is formed in the laser portion formation region.
0, and a pair of mask members 30a and 30b each forming a right triangle in the window forming region.

Here, the pair of right-angled triangular mask members 30a and 30b are arranged symmetrically with respect to the extension line of the striped mask member 30 with their hypotenuses on the outside, and sandwich the extension line. The opposite sides are parallel at regular intervals. That is, the pair of mask members 30a,
The interval of 30b is constant from the boundary between the laser portion formation region and the window portion formation region to the end of the window portion formation region. The width of the mask members 30a and 30b in the direction orthogonal to the extension line of the mask member 30 gradually increases from the boundary between the laser portion forming region and the window portion forming region toward the end of the window portion forming region.

Next, the mask members 30, 30a, 30b
Using, the laminated structure La is selectively etched and removed until it reaches the semiconductor substrate 10. As a result, as shown in FIG. 5, the mesa stripe 32 in which the upper surface of the mesa stripe-shaped laminated structure La extending in the longitudinal direction in the laser portion forming region on the common semiconductor substrate 10 is covered with the mask member 30 is the laser. A pair of triangular columnar mask bodies 32a and 32b for selective growth, which are formed in the region forming region and have a similar laminated structure, are formed in the window forming region.

Then, p- is formed on the exposed semiconductor substrate 10.
The InP layer and the n-InP layer are selectively grown in order.
As a result, as shown in FIGS. 6A and 6B, both sides of the mesa stripe 32 and the pair of triangular prism-shaped mask bodies 32 are formed.
The periphery of a and 32b is filled with a pn carrier block layer in which a p-InP layer and an n-InP layer are stacked. At this time, the thickness of the pn carrier block layer 36 on both sides of the mesa stripe 32 is controlled so that the upper surface thereof is substantially flush with the upper surface of the first upper cladding layer 18 of the mesa stripe 32.

On the other hand, p in the window forming region at this time
Considering the embedded state of the n carrier block layer, although crystal growth by the transported source atoms (molecules) proceeds on the semiconductor substrate 10 sandwiched by the pair of triangular prism-shaped mask bodies 32a and 32b, the mask member 30a , 30b
The raw material atoms (molecules) supplied to the upper surface are mask members 30.
a and 30b are desorbed from the surface without crystal growth,
It moves to the area sandwiched between the pair of triangular prism-shaped mask bodies 32a and 32b. Moreover, the right triangle mask member 30
As the widths of a and 30b are relatively wide, the amount of migration of the source atoms (molecules) from the region increases, and the concentration of the source atoms (molecules) at the migration destination increases.

Therefore, the pair of triangular prism-shaped mask bodies 32 are provided.
On the semiconductor substrate 10 sandwiched between a and 32b, the concentration of the raw material atoms (molecules) increases from the boundary between the laser portion formation region and the window formation region toward the end of the window formation region, and crystal growth occurs. Speed increases. As a result, the upper surface of the pn carrier block layer 36a in this region is higher than the upper surface of the first upper clad layer 18 in the laser portion formation region, and moreover, from the boundary between the laser portion formation region and the window portion formation region to the window portion formation region. The height gradually increases toward the end, and the upper surface becomes an inclined surface.

Next, the mask members 30, 30a, 30b
Then, the second upper clad layer 20 made of p-InP is laminated on the entire surface. As a result, as shown in FIG. 7, in the window formation region, a semiconductor layer 22a having no waveguide structure, in which the pn carrier block layer 36a and the second upper cladding layer 20 are stacked on the semiconductor substrate 10, is formed. It At this time, the upper surface of the semiconductor layer 22a is p
Reflecting the surface shape of the n carrier block layer 36a, the height is higher than the upper surface of the second upper cladding layer 20 in the laser portion formation region, and the edge of the window portion formation region from the boundary between the laser portion formation region and the window portion formation region. As it goes to the section, it inclines and becomes higher.

Then, as shown in FIG. 8, a laminated structure La is formed on the second upper cladding layer 20 in the laser portion forming region.
The striped electrode portion 24a corresponding to the stripe shape and the pad electrode portion 24b connected to the striped electrode portion 24a are formed to provide the upper electrode 24, and the lower electrode 26 is provided on the back surface of the common semiconductor substrate 10. Next, although illustration is omitted, after forming a passivation film on the entire surface, the passivation film on the pad electrode portion 24b of the upper electrode 24 is selectively removed by etching to form an opening. After that, a wafer-shaped substrate is cleaved in a predetermined direction to form a chip, and a laser section A for oscillating laser light and the laser section A
A continuous window portion B is formed on the emission side of. Further, a high reflection film 28 is coated on the end surface of the laser section A opposite to the emission side to form a high reflection end surface section C. Thus, the semiconductor optical device shown in FIGS. 1A and 1B is manufactured.

Next, a second method of manufacturing the semiconductor optical device shown in FIGS. 1A and 1B will be described. First, FIG. 2 and FIG.
After the intermediate M1 is manufactured in the same manner as in the step shown in FIG. 1, a stripe-shaped mask member 30 is formed on the first upper cladding layer 18 in the laser portion formation region, and the stripe-shaped mask member 30 is used. The laminated structure La is selectively removed by etching until it reaches the semiconductor substrate 10. As a result, as shown in FIG. 9, a mesa stripe 32 in which the upper surface of the mesa stripe-shaped laminated structure La extending in the longitudinal direction is covered with the mask member 30 in the laser portion formation region on the common semiconductor substrate 10 is formed. To be done.

Next, p- is formed on the exposed semiconductor substrate 10.
The InP layer and the n-InP layer are selectively grown in order.
As a result, as shown in FIGS. 10A and 10B, on both sides of the mesa stripe 32 and the window forming region in the laser forming region, the pn carrier in which the p-InP layer and the n-InP layer are laminated is formed. The block layer 36 is embedded. At this time, the film thickness of the pn carrier block layer 36 is controlled so that p
The upper surface of the n carrier block layer 36 is made substantially flush with the upper surface of the first upper cladding layer 18 of the mesa stripe 32. In this way, the intermediate body M2 is produced.

Next, as shown in FIGS. 11A and 11B, a pair of mask members 3 forming a right triangle on the pn carrier block layer 36b in the window forming region of the intermediate M2.
8a and 38b are formed. The mask members 38a, 38
4b has the same material, shape, and arrangement position as the pair of mask members 30a and 30b shown in FIGS. 4 (a) and 4 (b).

Then, as shown in FIGS. 12A and 12B, p-In is formed using a pair of mask members 38a and 38b.
By selectively growing the P layer, the first upper cladding layer 18 and the pn carrier block layer 3 in the laser portion formation region are formed.
The second upper clad layer 20 is laminated on 6 and the second upper clad layer 20a is also laminated on the pn carrier block layer 36 sandwiched between the pair of mask members 38a and 38b in the window forming region.

At this time, as in the case of the step shown in FIG. 6, the mask members 38 forming a pair of right triangles.
In the region sandwiched between a and 38b, the crystal growth rate increases from the boundary between the laser formation region and the window formation region toward the end of the window formation region, so that the second upper cladding layer in this region increases. The upper surface of 20a is higher than the upper surface of the second upper clad layer 20 formed in the laser portion forming region, and further, it is inclined from the boundary between the laser portion forming region and the window portion forming region toward the end of the window portion forming region. Become higher.

Thus, the semiconductor layer 22a having no waveguide structure, in which the pn carrier block layer 36 and the second upper cladding layer 20a are laminated on the semiconductor substrate 10, is formed in the window formation region. At this time, the upper surface of the semiconductor layer 22a is higher than the upper surface of the second upper clad layer 20 in the laser section forming region, inheriting the surface shape of the second upper clad layer 20a, and the laser section forming area and the window section are formed. It becomes higher with an inclination from the boundary with the region toward the end of the window forming region.

Next, although not shown, similarly to the case of the first manufacturing method, the upper electrode 24 and the lower electrode 2 are formed.
The semiconductor optical device shown in FIGS. 1A and 1B is manufactured through the process of forming 6.

(Second Embodiment) FIG. 13 is a schematic sectional view showing a DFB laser device as an example of a semiconductor optical device according to a second embodiment of the present invention. FIGS. 14 to 16 are DFB laser devices shown in FIG. FIG. 17 and FIG. 18 are process diagrams for explaining the first manufacturing method of the laser device, and FIGS.
It is a flowchart for explaining the 2nd manufacturing method of a B laser element. The schematic plan view showing the DFB laser device of the present embodiment is the same as that shown in FIG. 1A of the first embodiment.

The semiconductor optical device according to this embodiment has a window portion B.
The semiconductor optical device has a structure similar to that of the semiconductor optical device according to the first embodiment except for the top surface shape of the low refractive index semiconductor layer having no optical waveguide structure provided in FIG. There is. That is, as shown in FIG. 13, the upper surface of the low refractive index semiconductor layer 22b having no optical waveguide structure provided in the window portion B is the second upper cladding layer 2 of the laser portion A.
0 is higher than the upper surface, is a steep inclined surface in the vicinity of the boundary with the laser portion A, and is substantially flat in other regions.

Next, a first method of manufacturing the semiconductor optical device shown in FIG. 13 will be described. First, FIG. 2 of the first embodiment.
Then, after the intermediate M1 is manufactured in the same manner as the step shown in FIG. 3, as shown in FIGS. 14A and 14B, stripes are formed on the first upper clad layer 18 in the laser section forming region. The mask member 40 is formed, and a pair of rectangular mask members 40a and 40b are formed in the window formation region. Therefore, the pair of rectangular mask members 40
The distance between a and 40b and the width of each of the mask members 40a and 40b are constant from the boundary between the laser portion formation region and the window portion formation region to the end of the window portion formation region.

Then, in the same manner as the steps shown in FIGS. 5 and 6 of the first embodiment, the mask members 40, 40 are formed.
The laminated structure La is selectively etched away using the a and 40b until it reaches the semiconductor substrate 10, and the laminated structure La having a mesa stripe shape is formed in the laser portion formation region and the window portion formation region.
After forming a mesa stripe whose upper surface is covered with a mask member 40 and a pair of rectangular columnar mask bodies having a similar laminated structure, p- is formed on the exposed semiconductor substrate 10.
The InP layer and the n-InP layer are selectively grown in order, and the pn carrier block layer in which the p-InP layer and the n-InP layer are laminated is buried around both sides of the mesa stripe and the pair of rectangular columnar mask bodies.

Also in this case, the pair of rectangular mask members 42a, 4a and 4a are formed in the same manner as in the step shown in FIG.
Since the crystal growth rate is relatively increased in the region sandwiched by 2b, as shown in FIGS. 15A and 15B, the pn carrier block layer formed by embedding on both sides of the mesa stripe in the laser portion formation region is formed. When the film thickness is controlled so that the upper surface of the 36 is substantially flush with the upper surface of the first upper cladding layer 18, a pn carrier block to be embedded and formed in a region sandwiched by a pair of square columnar mask bodies in the window forming region. The upper surface of the layer 36b is higher than the upper surface of the first upper cladding layer 18 in the laser section formation region. In this case, since the pair of mask members 42a and 42b are rectangular rather than right-angled triangles, steep selective growth proceeds at the boundary between the mesa stripe and the pair of quadrangular prism-shaped mask bodies, resulting in the first A steep inclined surface is formed near the boundary with the upper cladding layer 18, and the remaining region is substantially flat.

Next, the mask members 40, 40a, 40b
Then, the second upper clad layer 20 made of p-InP is laminated on the entire surface. As a result, as shown in FIG. 16, in the window portion forming region, the semiconductor substrate 10 is
A semiconductor layer 22b having no waveguide structure, on which the pn carrier block layer 36b and the second upper cladding layer 20 are laminated
Is formed. At this time, the upper surface of the semiconductor layer 22b is
Reflecting the surface shape of the pn carrier block layer 36b,
The height is higher than the upper surface of the second upper cladding layer 20 in the laser portion formation region, and is substantially flat except for the vicinity of the boundary with the laser portion formation region.

Next, although illustration is omitted, in the same manner as in the case of the first or second manufacturing method of the first embodiment,
Through the steps of forming the upper electrode 24 and the lower electrode 26,
The semiconductor optical device shown in FIG. 13 is manufactured. Next, description will be given using a second method for manufacturing the semiconductor optical device shown in FIG.
First, after the intermediate M2 is manufactured and the stripe-shaped mask member 30 is removed in the same manner as in the steps shown in FIGS. 2, 3, 9 and 10 of the first embodiment,
As shown in FIGS. 17A and 17B, a pair of rectangular mask members 42a and 42b is formed again on the pn carrier block layer 36b in the window formation region.

Then, in the same manner as the step shown in FIG. 12 of the first embodiment, a pair of rectangular mask members 4 is formed.
2a and 42b, the p-InP layer is selectively grown, and the first upper clad layer 18 in the laser section formation region is formed.
And the second upper clad layer 20 is laminated on the pn carrier block layer 36, and the second upper clad layer 36 is sandwiched between the pair of rectangular mask members 42a and 42b in the window formation region. The layers 20b are laminated.

Also in this case, the pair of rectangular mask members 4
Since the crystal growth rate is relatively increased in the region sandwiched between 2a and 42b, the upper surface of the second upper cladding layer 20b in this region is formed by the laser portion formation as shown in FIGS. 18 (a) and 18 (b). Second upper cladding layer 20 in the region
The height is higher than the upper surface, and a steep inclined surface is formed near the boundary with the laser portion forming region, and the remaining region is substantially flat.

Thus, in the window portion forming region, the semiconductor layer 22b having no waveguide structure, in which the pn carrier block layer 36 and the second upper cladding layer 20b are laminated on the semiconductor substrate 10, is formed. At this time, the semiconductor layer 22b
The upper surface inherits the surface shape of the second upper clad layer 20b, and the second upper clad layer 20 in the laser section formation region is inherited.
It becomes higher than the upper surface and becomes substantially flat except for the vicinity of the boundary with the laser portion formation region.

Next, although illustration is omitted, the semiconductor optical device shown in FIG. 13 is processed through the steps of forming the upper electrode 24 and the lower electrode 26 in the same manner as in the first manufacturing method of this embodiment. Create.

(Third Embodiment) FIG. 19 is a schematic sectional view showing a DFB laser device as an example of a semiconductor optical device according to a third embodiment of the present invention, and FIGS. 20 and 21 are DFB of FIG. 19, respectively. FIG. 22 and FIG. 23 are process diagrams for explaining the first manufacturing method of the laser element, and FIGS.
It is a flowchart for explaining the 2nd manufacturing method of a FB laser element. The schematic plan view showing the DFB laser device of the present embodiment is the same as that shown in FIG. 1A of the first embodiment.

The semiconductor optical device according to this embodiment has a window portion B.
The semiconductor optical device has a structure similar to that of the semiconductor optical device according to the first embodiment except for the top surface shape of the low refractive index semiconductor layer having no optical waveguide structure provided in FIG. There is. That is, as shown in FIG. 19, the upper surface of the low-refractive-index semiconductor layer 22c having no optical waveguide structure provided in the window portion B is the second upper cladding layer 2 of the laser portion A.
0 is higher than the upper surface and is flat as a whole.

Next, a first method of manufacturing the semiconductor optical device shown in FIG. 19 will be described. First, in the same manner as the steps shown in FIGS. 2, 3, 9, and 10 of the first embodiment, the intermediate M2 is produced, and the stripe-shaped mask member 30 is removed. As shown by 20, a second upper clad layer 20 made of p-InP is laminated on the entire surface.

Then, as shown in FIG. 21, a mask member 44 made of, for example, a SiN film is formed so as to cover the entire surface of the laser portion forming region, and the mask member 44 is used to make a supplementary semiconductor layer made of, for example, InP. 46 is selectively grown. Thus, the semiconductor substrate 1 is provided in the window formation region.
A semiconductor layer 22c having no waveguide structure is formed by stacking the pn carrier block layer 36, the second upper cladding layer 20, and the supplementary semiconductor layer 46 on the substrate 0. At this time, the upper surface of the semiconductor layer 22c is higher than the upper surface of the second upper clad layer 20 in the laser portion formation region by the amount of the supplementary semiconductor layer 46 stacked, and is flat as a whole.

Next, although not shown, the mask member 4
After removing 4, the semiconductor optical device shown in FIG. 19 is subjected to the steps of forming the upper electrode 24 and the lower electrode 26 in the same manner as in the first or second manufacturing method of the first embodiment. To make. Next, the second semiconductor optical device shown in FIG.
The manufacturing method of will be described. First, in the same manner as in the steps shown in FIGS. 2 and 3, 9, and 10 of the first embodiment, the intermediate M2 is manufactured, and the stripe-shaped mask member 30 is removed, and thereafter, FIG. As shown in FIG. 3, the second upper clad layer 20c made of p-InP is laminated on the entire surface. The thickness of the second upper clad layer 20c is the original second upper clad layer in the laser portion forming region. Be thicker than required.

Next, as shown in FIG. 23, after forming a mask member 48 made of, for example, a SiN film for covering the entire surface of the window portion forming region, this mask member 48 is used.
The second upper clad layer 20c in the laser portion formation region is selectively etched to have a predetermined thickness.
Form 0. Thus, in the window formation region, the pn carrier block layer 36 and the second upper clad layer 20c are laminated on the semiconductor substrate 10 and the semiconductor layer 2 having no waveguide structure.
2c is formed. At this time, the upper surface of the semiconductor layer 22c is higher than the upper surface of the second upper clad layer 20 in the laser section formation region by the amount of the second upper clad layer 20c selectively removed by etching, and is flat as a whole.

Next, although not shown, the mask member 4
After removing 8, the semiconductor optical device shown in FIG. 19 is manufactured through the steps of forming the upper electrode 24 and the lower electrode 26, etc., as in the case of the first manufacturing method of the present embodiment. As described above, according to the first to third embodiments, in the window portion B provided so as to be connected to the emission side of the laser portion A that oscillates the laser light, the optical layer including the active layer 16 and the like in the laser portion A is formed. Low refractive index semiconductor layers 22a, 22b, 22c having no optical waveguide structure are formed on the extended line of the waveguide, and the upper surfaces of these semiconductor layers 22a, 22b, 22c are the upper surfaces of the uppermost second upper cladding layer 20 of the laser section A. Since the mode field of the signal light oscillated in the optical waveguide of the laser section A spreads by the angle θ in the window B, the spread signal light is reflected on the upper surface of the window B by being higher than Instead, the window length Lw can be increased.

Therefore, the original effect of the window portion, that is, the return light to the optical waveguide due to the end face reflection can be fully exerted, and the disturbance of the field of the signal light can be prevented. The coupling efficiency when optically coupling can be improved. Moreover, in this case, it is not necessary to make the thickness of the second upper cladding layer 20 in the laser section A thicker than in the usual case, so that the resistance to the injection current does not increase and the laser characteristics are not deteriorated.

According to the trial production by the present inventors, in any of the first to third embodiments, it is possible to fabricate a DFB laser element having a window length Lw = 50 μm, which has been difficult in the past. It was confirmed that the far-field pattern exhibited good unimodal characteristics in both the lateral and vertical directions. Also, from the light output spectrum, a good result that the variation (ripple) of the light output indicating the reflection from the end face is 0.1 dBm or less is obtained, and the influence of the return light due to the end face reflection is effectively suppressed. I was able to confirm that

Further, in the first manufacturing method of each of the semiconductor optical devices according to the first and second embodiments, the pn carrier block layer 36 in the laser portion forming region and the pn carrier block layer 36a in the window forming region are formed. , 36b are simultaneously embedded, selective crystal growth for locally increasing the crystal growth rate is adopted so that the upper surfaces of the pn carrier block layers 36a, 36b are higher than the upper surface of the pn carrier block layer 36. Therefore, it is possible to suppress an increase in the number of steps for making the upper surfaces of the semiconductor layers 22a and 22b including the pn carrier block layers 36a and 36b in the window B higher than the upper surface of the uppermost second upper cladding layer 20 of the laser section A, This can contribute to cost reduction.

Further, in the second manufacturing method of each of the semiconductor optical devices according to the first and second embodiments, the second upper cladding layer 20 in the laser portion forming region and the second upper cladding layer in the window forming region are used. When the layers 20a and 20b are formed at the same time, the second upper cladding layers 20a and 20b are formed by using selective crystal growth that locally increases the crystal growth rate.
Since the upper surface of the second upper clad layer 20 is higher than that of the second upper clad layer 20, the upper surfaces of the semiconductor layers 22a and 22b including the second upper clad layers 20a and 20b in the window B are the uppermost second layers of the laser section A. It is possible to suppress an increase in the number of steps for making the height higher than the upper surface of the upper clad layer 20, and to contribute to cost reduction.

In the above first to third embodiments, the case where the semiconductor layers 22a, 22b, 22c in the window portion B have three surface shapes has been described.
The surface shape is not limited to these three. In short, the upper surface of the semiconductor layer is higher than the upper surface of the uppermost layer of the laser section A, and even if the mode field of the signal light oscillated in the optical waveguide of the laser section A spreads by the angle θ in the window section B, it spreads. It suffices that the generated signal light is not reflected on the upper surface of the semiconductor layer.

Therefore, the pattern shape of the pair of mask members used in the selective crystal growth in the first and second manufacturing methods of the semiconductor optical device according to the first and second embodiments is also a right triangle mask. Members 30a, 30b; 38
a, 38b and rectangular mask members 40a, 40b; 4
Not limited to 2a and 42b, various pattern shapes other than these can be used. Further, the distance between the pair of mask members can be adjusted to be wider or narrower as necessary.

A DFB laser device for high output is exemplified as the semiconductor optical device according to the first to third embodiments, a window B is provided only on the emission side of the laser unit A, and the other end face is made high. Although the case where the reflection end face portion C is used has been described, the installation of the window portion B is not limited to one side of the laser portion A. For example, in the case of a phase shift type DFB laser element, the semiconductor layers 22a, 22b, 22c on both sides of the laser section A are the same as those in the first to third embodiments.
It is preferable to provide the window portion B formed with.

In the first to third embodiments, as the waveguide structure of the laser section A to which the window section B is connected,
The case where the diffraction grating 12 is formed over the entire structure to form an active waveguide that directly contributes to oscillation of light having a predetermined wavelength has been described, but the structure is not limited to such a waveguide structure. is not. For example, a waveguide structure in which a passive waveguide that does not directly contribute to the oscillation of light is provided in a part of the entire waveguide, more specifically, a waveguide structure in a region adjacent to the window B is provided. The present invention can be applied even in the case of a waveguide structure in which the waveguide is a passive waveguide in which no diffraction grating is formed.

Further, the semiconductor optical device according to the present invention is not limited to the DFB laser devices according to the first to third embodiments, and an optical modulator having an absorption layer or a traveling wave type semiconductor can be used. It is naturally possible to apply the present invention to the window portion of a laser amplifier or the like.

[0072]

As is apparent from the above description, the semiconductor optical device and the method of manufacturing the same according to the present invention can bring about the following effects. That is, according to the semiconductor optical device in the first aspect, the upper surface of the semiconductor layer of the window portion formed by connecting to one end or both ends of the optical waveguide portion is higher than the upper surface of the uppermost layer of the optical waveguide portion. Therefore, even if the mode field of the light entering the window portion from the optical waveguide portion spreads by the angle θ in the window portion, the spread signal light can be lengthened without being reflected on the upper surface of the window portion B. become. Therefore, it is possible to fully exert the original effect of the window part, that is, to suppress the return light to the optical waveguide due to the end face reflection, prevent the disturbance of the field of the signal light, and, for example, couple it with the optical fiber arranged outside. It can greatly contribute to improvement of optical characteristics such as improvement of efficiency.

Further, according to the method of manufacturing a semiconductor optical device in accordance with a fifth aspect, when a predetermined semiconductor layer is simultaneously formed in the optical waveguide forming region and the window forming region, the crystal growth rate is locally high. In order to make the upper surface of the predetermined semiconductor layer in the window formation region higher than the upper surface of the predetermined semiconductor layer in the optical waveguide formation region using the selective growth, the upper surface of the semiconductor layer including the predetermined semiconductor layer in the window It is possible to suppress an increase in the number of steps when making the height higher than the uppermost surface in the optical waveguide portion, and to contribute to cost reduction.

According to the method of manufacturing a semiconductor optical device according to the sixth aspect, a mesa stripe and a pair of mask bodies for selective growth are formed in the optical waveguide forming region and the window forming region, and then the mesa stripe is formed. When the first and second carrier block layers are simultaneously embedded and formed on both sides of the first carrier block layer and the region sandwiched by the pair of mask bodies, the second carrier is selectively grown by locally increasing the crystal growth rate. In order to make the upper surface of the block layer higher than the upper surface of the first carrier block layer, the upper surface of the semiconductor layer including the second carrier block layer in the window section is higher than the upper surface of the upper clad layer which is the uppermost layer in the optical waveguide section. It is possible to suppress an increase in the number of steps in the case of increasing the cost and contribute to cost reduction.

Further, according to the method of manufacturing a semiconductor optical device in accordance with the seventh aspect, after providing a pair of mask members for selective growth sandwiching the extension line of the mesa stripe on the carrier block layer in the window forming region, When the first and second upper clad layers are simultaneously formed on the laminated body and the carrier block layer in the optical waveguide formation region and the carrier block layer sandwiched between the pair of mask members in the window formation region, respectively. In order to make the upper surface of the second upper clad layer higher than the upper surface of the first upper clad layer by using selective growth that increases the crystal growth rate, the semiconductor layer including the second upper clad layer in the window part It is possible to suppress an increase in the number of steps in the case where the upper surface of (1) is made higher than the upper surface of the first upper clad layer, which is the uppermost layer in the optical waveguide section, and to contribute to cost reduction.

According to the method of manufacturing a semiconductor optical device in accordance with a tenth aspect, the upper clad layer in the optical waveguide section and the window section are formed so that their upper surfaces have substantially the same height, and then the upper clad layer in the window section is formed. In order to selectively form a supplementary semiconductor layer having a predetermined thickness on the layer, the upper surface of the semiconductor layer including the supplementary semiconductor layer in the window portion should be higher than the upper surface of the upper clad layer which is the uppermost layer in the optical waveguide portion. Can be easily realized.

Further, according to the method of manufacturing a semiconductor optical element in the eleventh aspect, after the upper clad layer in the optical waveguide portion and the window portion are formed so that the upper surfaces thereof have substantially the same height, the upper portion of the optical waveguide portion is formed. Since the clad layer is selectively etched away by a predetermined thickness, it is easy to make the upper surface of the semiconductor layer including the upper clad layer in the window portion higher than the upper surface of the upper clad layer which is the uppermost layer of the optical waveguide section. Can be realized.

[Brief description of drawings]

1A and 1B are a schematic plan view and a sectional view taken along the line AI-AI of a DFB laser device as an example of a semiconductor optical device according to a first embodiment of the present invention.

FIG. 2 is a process diagram (1) for explaining the first manufacturing method of the DFB laser device in FIG. 1, and is a schematic cross-sectional view showing the DFB laser device during the process.

FIG. 3 is a process diagram (No. 2) for explaining the first manufacturing method of the DFB laser device in FIG. 1, and a schematic cross-sectional view showing the DFB laser device in the process.

FIG. 4 is a process diagram (No. 3) for explaining the first manufacturing method of the DFB laser device of FIG. 1, wherein (a) and (b) are schematic plan views showing the DFB laser device during the process, respectively. It is a figure and its AII-AII sectional view taken on the line.

5A and 5B are process diagrams (4) for explaining the first manufacturing method of the DFB laser device in FIG. 1, and are schematic perspective views showing the DFB laser device during the process.

6A and 6B are process diagrams (5) for explaining the first manufacturing method of the DFB laser device in FIG. 1, in which (a) and (b) are schematic plan views showing the DFB laser device during the process, respectively. It is a figure and its AIII-AIII sectional view taken on the line.

FIG. 7 is a process diagram (6) for explaining the first manufacturing method of the DFB laser device in FIG. 1, and a schematic cross-sectional view showing the DFB laser device in the process.

FIG. 8 is a process view (No. 7) for explaining the first manufacturing method of the DFB laser device in FIG. 1, and a schematic cross-sectional view showing the DFB laser device in the process.

FIG. 9 is a process view (8) for explaining the first manufacturing method of the DFB laser device in FIG. 1, and is a schematic perspective view showing the DFB laser device in the process.

FIG. 10 is a process diagram (1) for explaining the second manufacturing method of the DFB laser device of FIG. 1, including (a) and (b);
FIG. 4A is a schematic plan view showing the DFB laser device during the process and a sectional view taken along line AIV-AIV thereof.

FIG. 11 is a process diagram (No. 2) for explaining the second manufacturing method of the DFB laser device of FIG. 1, including (a) and (b).
3A and 3B are a schematic plan view and a sectional view taken along the line AV-AV, respectively, showing the DFB laser device during the process.

FIG. 12 is a process diagram (3) for explaining the second manufacturing method of the DFB laser device of FIG. 1, including (a) and (b);
3A and 3B are a schematic plan view and a cross-sectional view taken along the line AVI-AVI, respectively, showing the DFB laser device during the process.

FIG. 13 is a schematic sectional view showing a DFB laser device as an example of a semiconductor optical device according to a second embodiment of the present invention.

FIG. 14 is a process diagram (1) for explaining the first manufacturing method of the DFB laser device of FIG.
(b) is a schematic plan view showing a DFB laser device in the middle of the process and its cross-sectional view taken along the line AVII-AVII.

FIG. 15 is a process diagram (2) for explaining the first manufacturing method of the DFB laser device of FIG. 13, (a),
FIG. 2B is a schematic plan view showing the DFB laser device in the middle of the process and its cross-sectional view taken along the line AVIII-AVIII.

16 is a process diagram (No. 3) for explaining the first manufacturing method of the DFB laser device in FIG. 13, and is a schematic cross-sectional view showing the DFB laser device in the process.

FIG. 17 is a process chart (1) for explaining the second manufacturing method of the DFB laser device of FIG.
FIG. 2B is a schematic plan view showing a DFB laser device in the middle of the process and a cross-sectional view taken along the line AIX-IX.

FIG. 18 is a process diagram (2) for explaining the second manufacturing method of the DFB laser device of FIG.
FIG. 2B is a schematic plan view showing the DFB laser device during the process and a cross-sectional view taken along the line AX-AX.

FIG. 19 is a schematic sectional view showing a DFB laser device as an example of a semiconductor optical device according to a third embodiment of the present invention.

FIG. 20 is a process diagram (1) for explaining the first manufacturing method of the DFB laser device in FIG. 19, and is a schematic cross-sectional view showing the DFB laser device in the process.

FIG. 21 is a process diagram (part 2) for explaining the first manufacturing method of the DFB laser device in FIG. 19, and is a schematic cross-sectional view showing the DFB laser device in the process.

FIG. 22 is a process diagram (1) for explaining the second manufacturing method of the DFB laser device in FIG. 19, and is a schematic cross-sectional view showing the DFB laser device in the process.

23 is a process diagram (part 2) for explaining the second manufacturing method of the DFB laser device in FIG. 19, and is a schematic cross-sectional view showing the DFB laser device during the process. FIG.

FIG. 24 is a partial cutaway perspective view showing a conventional DFB laser device.

25 is a cross-sectional view of the DFB laser device of FIG. 24 taken along the line AXI-AX.

FIG. 26 shows the relationship between the effective reflectance R due to the window and the window length Lw in the DFB laser device, and the thickness of the upper clad layer that prevents the signal light from the optical waveguide from being reflected on the upper surface of the upper clad layer. It is a graph which shows the relationship between and the window part length Lw.

[Explanation of symbols]

A laser part B window part C high reflection end face part 10 semiconductor substrate 12 diffraction grating 14 buffer layer 16 active layer 18 first upper clad layer 20, 20a, 20b, 20c second upper clad layer 22a, 22b, 22c semiconductor layer 24 upper part Electrode 24a Stripe electrode portion 24b Pad electrode portion 26 Lower electrode 28 Highly reflective film 30, 40 Stripe-shaped mask members 30a, 30b; 38a, 38b Pair of right-angled triangular mask members 32 Mesa stripes 32a, 32b Pair of triangular prism masks Body 34a p-InP layer 34b n-InP layers 36, 36a, 36b pn carrier block layers 40a, 40b; 42a, 42b A pair of rectangular mask members 44, 48 Mask member 46 Replenishment semiconductor layers La, Lb Laminated structure M1, M2 intermediate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01S 5/223 H01S 5/223 (72) Inventor Shuichi Tamura 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Kawasaki Electric Co., Ltd. F term (reference) 5F045 AA04 AB12 CA12 DB05 5F073 AA07 AA64 AA74 AA83 AA87 AB12 BA01 CA02 CB02 CB14 DA05 DA32 DA33 EA03 EA15 EA26

Claims (11)

[Claims] 1. A semiconductor optical device in which an optical waveguide portion having a stripe-shaped waveguide and a window portion made of a semiconductor layer connected to one end or both ends of the optical waveguide portion are formed on the same semiconductor substrate. In the semiconductor optical device, the upper surface of the semiconductor layer of the window portion is higher than the uppermost surface of the optical waveguide portion. 2. The semiconductor optical device according to claim 1, wherein an upper surface of the semiconductor layer of the window portion gradually increases from a boundary between the window portion and the optical waveguide portion toward an emission end face of the window portion. . 3. The upper surface of the semiconductor layer is substantially flat.
The semiconductor optical device according to claim 1. 4. The semiconductor optical device according to claim 1, wherein the waveguide has an active layer that performs laser light oscillation, an absorption layer that performs optical modulation, or an active layer that performs optical amplification. 5. A semiconductor optical device in which an optical waveguide part having a stripe-shaped waveguide and a window part made of a semiconductor layer connected to one end or both ends of the optical waveguide part are formed on the same semiconductor substrate. A method of manufacturing, wherein, when a predetermined semiconductor layer is simultaneously formed in the optical waveguide formation region and the window formation region, the predetermined growth in the window formation region is performed by using selective growth that locally increases the crystal growth rate. 2. A method for manufacturing a semiconductor optical device, comprising the step of making the upper surface of the semiconductor layer higher than the upper surface of the predetermined semiconductor layer in the optical waveguide portion forming region. 6. A semiconductor optical device in which an optical waveguide portion having a stripe-shaped waveguide and a window portion made of a semiconductor layer connected to one end or both ends of the optical waveguide portion are formed on the same semiconductor substrate. A manufacturing method, comprising: stacking a plurality of semiconductor layers on a semiconductor substrate to form a laminated body, and then forming a stripe-shaped mask member and the stripe on the laminated body in the optical waveguide forming region and the window forming region. A pair of mask members sandwiching an extension line of the mask shape, and the laminated body is selectively etched by using the striped mask member and the pair of mask members to form a mesa stripe and a pair for selective growth. And forming a first carrier block layer on both sides of the mesa stripe and a region sandwiched between the pair of mask bodies. When the buried formation is performed simultaneously, the upper surface of the first carrier block layer is made substantially flush with the upper surface of the stacked body by using selective growth that locally increases the crystal growth rate, while the second layer is formed. The upper surface of the carrier block layer of the first
Second step of making the carrier block layer higher than the upper surface of the carrier block layer, and after removing the stripe-shaped mask member and the pair of mask members, the laminated body and the first carrier block layer in the optical waveguide portion forming region. Also, an upper clad layer is formed on the second carrier block layer in the window formation region to form an optical waveguide section and a window section, and the first carrier block layer and the upper section in the window section are formed. And a third step of making the upper surface of the semiconductor layer including the clad layer higher than the upper surface of the upper clad layer in the optical waveguide section. 7. A semiconductor optical device in which an optical waveguide section having a stripe-shaped waveguide and a window section made of a semiconductor layer connected to one end or both ends of the optical waveguide section are formed on the same semiconductor substrate. A manufacturing method, wherein a laminated body formed by laminating a plurality of semiconductor layers on a semiconductor substrate is selectively etched to form a mesa stripe in an optical waveguide portion forming region, and then, both sides of the mesa stripe and a window are formed. A first step of embedding a carrier block layer in the part formation region so that the upper surface of the carrier block layer is substantially flush with the upper surface of the laminate; and the step of forming a carrier block layer on the carrier block layer in the window part formation region. After providing a pair of mask members for selective growth sandwiching the extension line of the mesa stripe, the laminated body and the carrier block layer in the optical waveguide formation region and the pair of mask members in the window formation region are provided. On the carrier block layer sandwiched disk member, the first
When simultaneously forming the second upper clad layer and the second upper clad layer respectively, the upper surface of the second upper clad layer is separated from the upper surface of the first upper clad layer by selective growth that locally increases the crystal growth rate. And a step of removing the pair of mask members to form an optical waveguide portion and a window portion, and a semiconductor layer including the carrier block layer and the second upper clad layer in the window portion. A third step of making the upper surface higher than the upper surface of the first upper cladding layer in the optical waveguide section. 8. A width of the pair of mask members in a direction orthogonal to an extension line of the mesa stripe is gradually increased from a boundary between the window forming region and the optical waveguide forming region toward an end face of the window forming region. 8. The method for manufacturing a semiconductor optical device according to claim 5, wherein 9. The method of manufacturing a semiconductor optical device according to claim 5, wherein a width of the pair of mask members in a direction orthogonal to an extension line of the mesa stripe is substantially constant. 10. A semiconductor optical device in which an optical waveguide section having a stripe-shaped waveguide and a window section made of a semiconductor layer connected to one end or both ends of the optical waveguide section are formed on the same semiconductor substrate. A manufacturing method, wherein a laminated body formed by laminating a plurality of semiconductor layers on a semiconductor substrate is selectively etched to form a mesa stripe in an optical waveguide portion forming region, and then, both sides of the mesa stripe and a window are formed. A first step of embedding a carrier block layer in the part formation region so that the upper surface of the carrier block layer is substantially flush with the upper surface of the laminated body; and the laminated body and the carrier block in the optical waveguide formation region. A second step of forming an upper clad layer on the carrier block layer sandwiched between the pair of mask members in the layer and window forming region to form an optical waveguide section; A supplementary semiconductor layer having a predetermined thickness is selectively laminated on the upper clad layer in the window forming region to form a window, and the carrier block layer in the window, the upper clad layer, and And a third step of making the upper surface of the semiconductor layer including the supplementary semiconductor layer higher than the upper surface of the upper clad layer in the optical waveguide section. 11. A semiconductor optical device in which an optical waveguide section having a stripe-shaped waveguide and a window section made of a semiconductor layer connected to one end or both ends of the optical waveguide section are formed on the same semiconductor substrate. A manufacturing method, wherein a laminated body formed by laminating a plurality of semiconductor layers on a semiconductor substrate is selectively etched to form a mesa stripe in an optical waveguide portion forming region, and then, both sides of the mesa stripe and a window are formed. A first step of embedding a carrier block layer in the part formation region so that the upper surface of the carrier block layer is substantially flush with the upper surface of the laminated body; and the laminated body and the carrier block in the optical waveguide formation region. A second step of forming an upper clad layer on the carrier block layer sandwiched between the pair of mask members in the layer and the window forming region to form a window part; The upper clad layer in the path forming region is selectively removed by etching to a predetermined thickness to form an optical waveguide part, and a semiconductor layer including the carrier block layer and the upper clad layer in the window part is formed. And a third step of making the upper surface higher than the upper surface of the upper clad layer in the optical waveguide portion.