JPH11112105A - Fabrication of semiconductor laser, optical module and optical application system fabricated by that method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reproducibility and high volume productivity of phase shift type element excellent in single mode selectivity by employing a resist functioning positively in the development with first developer but functioning negatively in the development with second developer in a semiconductor region for forming diffraction grating. SOLUTION: An n-type InP substrate 1 is spin coated with a polyxycarbonyl- styrene(PBOCST) based resist 2 by 100 nm. It is then subjected to interference exposure by means of an He-Cd laser 3 to obtain an exposure pattern where an exposed part and an unexposed part 5 are arranged periodically at a period of 200 nm. A part of an exposed resist is then coated with the shadow mask 6 of a silicon substrate and subjected to spray development with alkaline aqueous solution 7. Subsequently, the exposed part 4 is dissolved to leave an unexposed part and the developed part is protected by the shadow mask 6 before spray development is performed with an anisole 8. According to the method, a resist pattern having inverted positive and negative phases can be transferred onto the surface of an InP substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor laser device having a region where a diffraction grating is formed,
The present invention relates to a method for manufacturing a semiconductor device having a shape in which the period of irregularities forming the diffraction grating is inverted inside the diffraction grating, and an optical module and an optical application system using the semiconductor laser device.

[0002]

2. Description of the Related Art In order to obtain a distributed feedback semiconductor laser operating in a single longitudinal mode with good reproducibility, it is effective to form a diffraction grating whose phase is inverted at the center of a resonator. For a conventional method of forming a phase-shifting diffraction grating, see Journal of Applied Physics, Vol. 75, No. 1 (199).
4 years) Systematically summarized in Makoto Okai et al.'S commentary on pages 1 to 29. As described in the above literature, there are several methods for forming a phase shift type diffraction grating, such as a double resist method, an electron beam exposure method, a phase modulation mask method, a phase modulation layer method, and a diffraction grating mask adhesion method. Is being considered. In addition to the methods described in the above-mentioned documents, an image reversal resist method disclosed in JP-A-3-61901 and JP-A-8-5812 has been studied.

[0003]

The above-mentioned prior art method for forming a phase shift type diffraction grating has the following problems.

In the double resist method, there is a problem that a step of 200 to 400 angstroms (Å) is formed between the negative portion and the positive portion of the substrate. In addition, when transferring the resist pattern to the crystal surface, since it is performed separately for the positive portion and the negative portion, it is difficult to make the diffraction efficiency of both portions uniform with good reproducibility.
In the electron beam exposure method, drawing with an electron beam requires a long time, and there is a problem in mass productivity. The phase modulation mask method and the phase modulation layer method have not been able to accurately obtain the phase shift amount with good reproducibility. In the diffraction grating mask contact method, it is difficult to manufacture a highly accurate diffraction grating mask, and there is a problem in reproducibility and mass productivity. In the image reversal resist method, a resist that inverts a positive / negative image by heating and whole-surface exposure is used. However, since an appropriate exposure amount when functioning as a positive type and an appropriate exposure amount when functioning as a negative type are different, a plurality of times are used. In this case, a phase shift pattern cannot be formed with good reproducibility because the region selection exposure is required and the manufacturing process becomes extremely complicated. As described above, none of the conventional methods of forming a phase shift type diffraction grating is satisfactory in terms of reproducibility, mass productivity, and single-mode selectivity.

A first object of the present invention is to provide a method for manufacturing a semiconductor laser device having a phase shift type diffraction grating having excellent reproducibility, mass productivity and single mode selectivity. A second object of the present invention is to provide an optical module equipped with this semiconductor laser. A third object of the present invention is to provide an optical application system such as an optical transmission system or an optical information processing system equipped with the semiconductor laser.

[0006]

In order to achieve the first object, a semiconductor laser device having a semiconductor region on which a diffraction grating is formed (a so-called distributed feedback type or distributed Bragg reflection type resonator structure). The present invention provides a diffraction grating forming step by the following two types of processes. In either process,
A resist that is applied to a semiconductor region where a diffraction grating is to be formed functions as a positive type for development with a first developer and functions as a negative type for development with a second developer, The resist having one function and two functions is desirably used as a single resist in the semiconductor region (for example,
(Semiconductor substrate).

In a first process, the resist is applied to a semiconductor region on which the diffraction grating is to be formed (first step), and the resist is periodically exposed by an interference exposure method using a laser beam (second step). Process). Specifically, the periodic exposure means that an exposed region and a non-exposed region adjacent thereto are periodically formed in the resist. Next, after developing a part of the resist, particularly a part of the exposed area (hereinafter, referred to as a first part), with one of the first and second developers, a part different from the first part is developed. By developing the undeveloped portion (hereinafter, referred to as a second portion) with another developing solution (a developing solution not used for developing the first portion), the resist has a continuous periodicity having different phases. A pattern is formed (third step). Next, using the periodic unevenness (or periodic notch) pattern of the resist as a mask, continuous unevenness having a different phase is formed in the semiconductor region to form the diffraction grating in the semiconductor region (fourth). Process).

The second process is common to the first process and the first, second and fourth steps, but differs in the third step relating to the development and patterning of the resist. That is,
In the second step, a silylation treatment is performed on the resist, particularly a part (first part) of the exposed area, and dry development is performed with oxygen plasma, and then a part different from the first part (undeveloped part: first part) 2) is developed with the first developer to form a periodic pattern having a different phase and continuity on the resist.

In any of the above processes, a polar solvent may be combined with the first developer and a non-polar solvent may be combined with the second developer, and a chemically amplified resist may be used as the resist.

Further, a second object of the present invention is to manufacture an optical module by incorporating a semiconductor laser device manufactured by using the above-described manufacturing method. This is achieved by incorporating the optical application system.

In the above-described interference exposure method, interference is generated by dividing a laser beam into two light beams and then combining the laser beams, and the interference light is formed on an object surface, for example, on a semiconductor substrate using the interference light. A method of exposing a photoresist film, the method comprising forming a striped exposure pattern that is periodically arranged on an object surface using a photochemical reaction whose speed or property changes according to interference. It is. Specifically, when two light beams having a wavelength λ that are correlated with each other are incident on the sample surface, the angle between the two light beams is 2θ, and the middle direction of the angle and the normal line of the sample surface are formed. Angular σ
Then, a striped pattern having the following period Λ is formed on the sample surface.

[0012]

１ = λ / (2 sin θ · cos σ) If a photoresist film is applied on the sample surface, a stripe-shaped resist pattern that is periodically arranged is formed by exposing with a stripe-shaped interference light. You can.

The above-described chemically amplified resist is a general term for a high-sensitivity resist utilizing a catalytic action of an acid generated by exposure. The acid generated by the exposure acts as a catalyst that causes a number of chemical reactions. The quantum efficiency of the acid generated by exposure is less than 1, but the thermal reaction after exposure that causes solubility proceeds catalytically, so the quantum efficiency of the effective reaction is much higher than 1. This is the mechanism for increasing the sensitivity of the chemically amplified resist.

The operation of the present invention will be described below with reference to FIGS.

A feature of the present invention resides in that a positive pattern and a negative pattern are obtained in a single-layer resist surface by employing a resist which can function as a positive type or a negative type by a processing method after exposure. . As a resist having such properties, a chemically amplified resist capable of functioning as both a positive type and a negative type depending on a developing solution used, and the function changes from a positive type to a negative type by heating after exposure and overall exposure processing. There are two types of resists (hereinafter, referred to as image reversal resists). The operation of each resist will be described below.

As an example of a chemically amplified resist, a polymer (poly (4-tert-butoxycarbonyl)) in which the hydroxyl group of polyvinyl phenol is protected by a tert-butoxycarbonyl group
A system composed of styrene (hereinafter abbreviated as PBOCST) and a sulfonium salt is exemplified. Figure 9 shows the reaction of the chemically amplified resist in this system.
Shown in As shown in FIG. 9, the proton acid generated by the photolysis of the sulfonium salt by the exposure serves as a catalyst, and the PBOCST is thermally decomposed into polyvinylphenol in the post-exposure bake. Polyvinyl phenol is soluble in alkali and insoluble in non-polar organic solvents, and PBOCST shows the opposite solubility. Therefore, this system functions as a positive resist when developed with an aqueous alkali solution or alcohol, and functions as a negative resist when developed with a nonpolar solvent such as anisole. In addition, an ester polymer such as polyvinyl benzoate, for example, functions as a positive type or a negative type by changing the polarity of the solvent similarly to the PBOCST-based resist. After applying such a resist to the substrate and exposing the periodic pattern by laser interference exposure, partially masking, developing with one solvent, and developing the remaining part with a solvent with a different polarity As a result, a periodic resist pattern whose phase is inverted on the way can be obtained.

Next, the image reversal resist will be described. The reaction of this type of resist is shown in FIG. As shown in FIG. 10, the resist of this type is a positive type resist, and the alkali-soluble indene carboxylic acid generated from the diazoquinone photosensitive agent which is a dissolution inhibitor at the time of exposure causes a decarboxylation reaction by heating to form an alkali-insoluble indene. It uses a changing property. Therefore, it functions as a positive type after exposure, but functions as a negative type when it is heated and the whole surface is exposed.

Substrate (or semiconductor layer) of image reversal resist
Positive / negative reversal of the pattern related to processing is performed by applying this resist to a substrate, exposing a periodic pattern by laser interference exposure, partially masking and developing, and irradiating this part with deep UV irradiation etc. After suppressing the solubility in a developing solution by heating, the remaining portion is converted to a negative type by heating and exposing the entire surface, and the development can be realized in a series of steps of development. Further, it can also be realized by a series of steps in which a periodic pattern is formed on a resist applied to a substrate by interference exposure using a laser, and partial heating and exposure are performed to perform positive / negative reversal and development.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to Embodiments 1 to 8 showing preferred embodiments of the present invention and FIGS.

<Embodiment 1> First, a first embodiment will be described in detail with reference to FIG. A poly (4-tert-butoxycarbonyl) styrene (hereinafter abbreviated as PBOCST) -based resist 2 is spin-coated on the n-type InP substrate 1 to a thickness of 100 nm (FIG. 1 (a)). next
Perform interference exposure using He-Cd laser 3 (wavelength 325 nm), 200
An exposure pattern in which the exposed portions 4 and the unexposed portions 5 are periodically arranged at a nm cycle is obtained (FIG. 1 (b)). Next, a part of this periodically exposed resist is covered with a shadow mask 6 made of a silicon substrate, and spray development is performed using an alkaline aqueous solution 7. Since the PBOCST-based resist functions as a positive type with respect to an alkaline aqueous solution, the exposed portion 4 dissolves and the unexposed portion 5 remains (FIG. 1 (c)). Next, the developed portion is protected by a shadow mask 6, and the undeveloped portion is spray-developed using anisole 8. Since the PBOCST-based resist functions as a negative type with respect to the non-polar solvent, the unexposed portion 4 dissolves and the exposed portion remains. As a result, a resist pattern in which the phase was inverted between the positive portion and the negative portion was formed (FIG. 1 (d)).
Further, using an etching solution (HBr: H ₂ O ₂ : H ₂ O = 75: 1: 750, volume ratio), the resist diffraction grating pattern was formed on the InP substrate 1
(FIG. 1 (e)), it was possible to obtain a diffraction grating with a phase inversion of 200 nm on the surface of the InP substrate on the InP substrate surface (FIG. 1 (f)).

<Embodiment 2> Next, a second embodiment will be described in detail with reference to FIG. Normal thermal C is applied to a part of the n-type InP substrate 1
An SiO ₂ film having a thickness of 50 nm is formed using a VD method and a lithography technique (FIG. 2A). Next, a polyvinyl benzoate-based resist 10 is spinner-coated to a thickness of 120 nm (FIG.
(b)). Next, interference exposure is performed using a He-Cd laser 3 (wavelength 350 nm) to obtain an exposure pattern in which the exposed portions 4 and the unexposed portions 5 are periodically arranged at a cycle of 240 nm (FIG. 2C).

Next, the resist that has been periodically exposed
A portion of the SiO ₂ film is covered with a shadow mask 6 made of a silicon substrate, and a polyvinyl benzoate-based resist 10
Is spray applied (FIG. 2 (d)). Next, development is performed using an alkaline aqueous solution. Since the polyvinyl benzoate-based resist functions as a positive type with respect to an alkaline aqueous solution, the exposed portion 4 on the SiO ₂ film dissolves and the unexposed portion 5 on the SiO ₂ film remains (FIG. 2 (e)). .

[0023] Next transferring a periodic pattern consisting of the unexposed portion 5 on the SiO ₂ film on the SiO ₂ film using a buffered hydrofluoric acid
(FIG. 2 (f)). Next, development is performed using cyclohexanone.
Since the polyvinyl benzoate-based resist functions as a negative type with respect to a non-polar solvent, the unexposed portions 5 are dissolved, and the exposed portions 4 remain. As a result, a periodic pattern of the SiO ₂ film formed by using the positive function and a pattern whose phase was inverted at the negative portion were formed. Further, an etching solution (HBr: H
By transferring this diffraction grating pattern to the surface of the InP substrate 1 using NO ₃ : H ₂ O = 1: 1: 22 (volume ratio) (FIG. 2 (g)),
A diffraction grating with a phase inversion of 240 nm on the P substrate surface was obtained (FIG. 2 (h)).

Embodiment 3 Next, a third embodiment will be described in detail with reference to FIG. PBOCST resist 2 on n-type InP substrate 1
Is spinner-coated to a thickness of 110 nm (FIG. 3 (a)). Next, He-
Perform interference exposure using Cd laser 3 (wavelength 325 nm), 200 nm
An exposure pattern in which the exposed portions 4 and the unexposed portions 5 are periodically arranged is obtained periodically (FIG. 3B). Next, a part of this periodically exposed resist is covered with a shadow mask 6 made of a silicon substrate, and an Au film 11 is deposited by a resistance heating method (FIG. 3).
(c)).

Next, a silylation treatment is performed. Unexposed part 5 PBO
CST does not react with the silylating agent at all, but polyvinylphenol produced by exposure reacts covalently with the silylating agent (FIG. 3 (d)). Thereafter, when oxygen plasma development is performed, silyl ether generated in the exposed portion 4 is converted into SiO _x on the surface, and further prevents oxygen plasma etching. On the other hand, since the organic polymer in the unexposed portion 5 is easily etched by oxygen plasma, a negative pattern is obtained in a portion not protected by the Au film 11 (FIG. 3 (e)). Next, deepUV
Irradiation with light 12 suppresses the solubility of the obtained negative pattern in an aqueous alkaline solution (FIG. 3 (f)). Thereafter, the Au film 11 is dissolved and removed with an aqueous ammonium iodide solution (FIG. 3 (g)). Subsequently, development is performed using an alkaline aqueous solution. Since the tert-butoxycarbonyl-based resist functions as a positive type with respect to an alkaline aqueous solution, the exposed portion 4 dissolves and the unexposed portion 5 remains. As a result, a resist pattern in which the phase was inverted between the positive portion and the negative portion was formed (FIG. 3 (h)).

Further, this resist diffraction grating pattern was transferred to the surface of the InP substrate 1 by reactive ion etching using a mixed gas of methane and hydrogen (FIG. 3 (i)). By removing the resist pattern, a diffraction grating with a phase inversion of 200 nm on the surface of the InP substrate could be obtained (FIG. 3 (j)).

<Embodiment 4> Next, a fourth embodiment will be described in detail with reference to FIG. Image reversal resist 1 on n-type InP substrate 1
3 is applied with a spinner to a thickness of 120 nm (FIG. 4 (a)). Then H
Perform interference exposure using e-Cd laser 3 (wavelength 325 nm), 240n
An exposure pattern in which the exposed portions 4 and the unexposed portions 5 are periodically arranged at m periods is obtained (FIG. 4B). Next, a shadow mask 6 made of a silicon substrate is put on a part of the resist that has been periodically exposed, and an Au film 11 is deposited by a resistance heating method (FIG. 4C).

Next, development is performed using an AZ developer. Since the image reversal resist functions as a positive type after exposure, the pattern of the unexposed portion 5 remains (FIG. 4D). Then d
Irradiation with eep UV light 12 suppresses the solubility of the obtained positive pattern in a developer (FIG. 4 (e)). Thereafter, the Au film 11 is dissolved and removed with an aqueous solution of ammonium iodide (FIG. 4 (f)). Following this, baking and overall exposure at 120 ° C,
Convert undeveloped parts to negative type. This utilizes the property that an alkali-soluble indene carboxylic acid generated from a diazoquinone photosensitive agent, which is a dissolution inhibitor at the time of interference exposure, undergoes a decarboxylation reaction by heating to change to an alkali-insoluble indene. Next, development is performed using an alkaline aqueous solution. Since the resist functions as a negative type, the exposed portion 4 dissolves and the unexposed portion 5 remains. As a result, a resist pattern in which the phase was inverted between the positive portion and the negative portion was formed (FIG. 4 (g)). Next, an etching solution (HBr: H ₂ O ₂ : H ₂ O
= 75: 1: 750, volume ratio), the diffraction grating pattern made of the resist was transferred to the main surface of the InP substrate 1 (FIG. 4 (h)).

Finally, by removing the resist pattern by oxygen plasma ashing, it was possible to obtain a diffraction grating (period 240 nm) whose phase was inverted on the surface of the InP substrate (FIG. 4 (j)).

<Embodiment 5> Next, a fifth embodiment will be described in detail with reference to FIG. Image reversal resist 1 on n-type InP substrate 1
3 is spin-coated to a thickness of 100 nm (FIG. 5 (a)). Then H
Perform interference exposure using e-Cd laser 3 (wavelength 350 nm), 200n
An exposure pattern in which the exposed portions 4 and the unexposed portions 5 are periodically arranged at m periods is obtained (FIG. 5B). Next, a part of the resist that has been periodically exposed is covered with a shadow mask 6 made of a silicon substrate and irradiated with an infrared laser 14 to heat only the opening of the shadow mask 6. As a result, in the resist at the opening, the alkali-soluble indene carboxylic acid generated from the diazoquinone photosensitizer, which is a dissolution inhibitor during interference exposure, undergoes a decarboxylation reaction by heating and changes to alkali-insoluble indene.

Further, by irradiating the opening of the shadow mask 6 with ultraviolet light, this portion functions as a negative type. Thereafter, the shadow mask is removed, and development is performed using an alkaline aqueous solution. At this time, the portion protected by the shadow mask 6 functions as a positive type, and the portion corresponding to the opening of the shadow mask 6 functions as a negative type, so that a resist pattern having a phase inverted on the way could be formed (FIG. 5 (d)). )). Next, an etchant (HBr: H ₂ O ₂ : H ₂ O = 75:
This resist pattern was transferred onto the main surface of the InP substrate 1 using a ratio of 1: 750 (volume ratio) (FIG. 5 (e)).

Finally, by removing the resist pattern by oxygen plasma ashing, a diffraction grating (period: 200 nm) whose phase was inverted on the surface of the InP substrate could be obtained (FIG. 5 (f)).

<Embodiment 6> Next, a sixth embodiment will be described in detail with reference to FIG. FIG. 6 shows a wavelength of 1.3 μm using the present invention.
This is an example of fabricating a band distributed feedback semiconductor laser. FIG.
As shown in (a), an n-type (100) InP buffer layer 1.0 μm15, n-type InGaAs
P lower guide layer (composition wavelength 1.10 μm) 0.05 μm, 5-period multiple quantum well layer (6.0% thick 1% compression strained InGaAsP (composition wavelength 1.37 μm) well layer, 10 nm thick InGaAsP (composition wavelength 1.10 μm)
μm) barrier layer), InGaAsP (composition wavelength 1.10 μm), active layer 16 composed of upper light guide layer 0.05 μm, first p-type InP cladding layer 0.1 μm17, undoped InGaAsP (composition wavelength 1.15 μm)
m) Diffraction grating supply layer 0.05 μm 18, p-type InP cap layer 0.01
μm 19 is sequentially formed. The emission wavelength of the multiple quantum well active layer 16 is about 1.31 μm.

Next, as shown in FIG. 6B, a diffraction grating 20 having a period of 241 nm and a phase inverted at the center of the device is formed on the entire surface of the substrate by using the method described in detail in the first embodiment. The depth of the diffraction grating is set to about 80 nm so that the diffraction grating penetrates the diffraction grating supply layer 18 and reaches the first p-type InP clad layer 17. Subsequently, the second p-type InP cladding layer was 1.7 μm thick by metal organic chemical vapor deposition.
21. A high-concentration p-type InGaAs cap layer 0.2 μm 22 is sequentially formed (FIG. 6C). Subsequently, after processing and forming into a buried laser structure having a width of about 1.5 μm or a ridge waveguide laser structure having a width of about 2.2 μm, an upper electrode 23 and a lower electrode 24 are formed. As shown in FIG. 6D, the device length is 400 μm by the cleavage process.
Approximately 1% reflectance on both ends of the element
Is formed by a known method.

The fabricated distributed feedback semiconductor laser device in the 1.3 μm band has a threshold current of 10 mA at room temperature under continuous conditions.
The oscillation efficiency was 0.45 W / A. Also, reflecting the simple fabrication, even at a high temperature of 85 ° C, the threshold current is 25mA and the oscillation efficiency
Good oscillation characteristics of 0.30W / A were obtained. FIG. 6 shows the spectrum shape when a forward bias is applied below the oscillation threshold.
(e). A typical spectrum in which the oscillation dominant mode appears at the center of the stop band reflecting the phase shift type diffraction grating was obtained. Reflecting the excellent mass productivity, reproducibility, and single-mode selectivity of the phase shift diffraction grating fabrication technology according to the present invention, 95% of stable single-mode operation with a submode suppression ratio of 40 dB or more even at a high temperature of 85 ° C This was achieved with the above high production yield. This structure is 1.55μm as well as 1.3μm band
The present invention can also be applied to a distributed feedback semiconductor laser in a band or another wavelength band.

<Embodiment 7> Next, a seventh embodiment will be described in detail with reference to FIG. FIG. 7 shows an optical lens after mounting the distributed feedback semiconductor laser 26 of Embodiment 6 on a heat sink 27.
28 is a structural diagram of an optical transmission module in which a photodiode 29 for monitoring the light output of the rear end face and an optical fiber 30 are integrated. At room temperature and under continuous conditions, the threshold current was 10 mA and the oscillation efficiency was 0.20 W / A. In addition, reflecting simple fabrication, 85
Threshold current 25mA, oscillation efficiency 0.13W /
A and good oscillation characteristics were obtained. Also, stable single mode operation with a sub mode suppression ratio of 40 dB or more even at a high temperature of 85 ° C
Achieved with a high production yield of over 95%. Since the standardized optical coupling coefficient of this laser can be set as high as 2.5 or more, the degradation of the oscillation characteristics due to the return light from the fiber end, which is the biggest problem in module mounting, did not occur at all.

<Eighth Embodiment> Next, an eighth embodiment will be described in detail with reference to FIG. FIG. 8 illustrates a transmission module according to the seventh embodiment.
This is a trunk optical communication system using No. 31. The transmission device 32 has a transmission module 31 and a drive system 33 for driving the module 31. The optical signal from the module 31 passes through the fiber 34 and is detected by the light receiving unit 36 in the receiving device 35.
According to the optical communication system of this embodiment, repeaterless optical transmission over 100 km can be easily realized. This is based on the fact that the chirping is significantly reduced, so that the signal degradation due to the dispersion of the fiber 34 is also significantly reduced.

[0038]

According to the present invention, a phase shift distributed feedback semiconductor laser having excellent single mode selectivity can be realized by an easy method. The use of the present invention not only dramatically improves the mass productivity and reproducibility of the device, but also has the effect of reducing the cost of an optical module and an optical application system equipped with the device.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

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

FIG. 3 is a diagram for explaining a third embodiment of the present invention.

FIG. 4 is a diagram for explaining a fourth embodiment of the present invention.

FIG. 5 is a diagram for explaining a fifth embodiment of the present invention.

FIG. 6 is a diagram for explaining a sixth embodiment of the present invention.

FIG. 7 shows a seventh embodiment in which the semiconductor laser device of the present invention is mounted.
FIG. 3 is a diagram for explaining the optical module configuration of FIG.

FIG. 8 is an eighth embodiment in which the semiconductor laser device of the present invention is mounted.
FIG. 3 is a diagram for explaining the optical application system of FIG.

FIG. 9 is a diagram for explaining the principle of the process of the present invention when a chemically amplified resist is used.

FIG. 10 is a diagram for explaining the principle of the process of the present invention when an image inversion resist is used.

[Explanation of symbols]

1… n-type InP semiconductor substrate, 2… PBOCST resist film, 3… He
-Cd laser light, 4 ... exposed area, 5 ... unexposed area, 6 ... shadow mask, 7 ... alkaline aqueous solution, 8 ... anisole, 9 ... silicon oxide film, 10 ... polyvinyl benzoate resist film, 11 ... Au film , 12 ... deep UV light, 15 ... n-type InP buffer layer, 16 ... multiple quantum well active layer, 17 ... first p-type InP cladding layer, 18 ... undoped InGaAsP diffraction grating supply layer, 19 ... multiple quantum well active layer, 20 ... p-type InP cap layer, 21 ... second p-type InP cladding layer, 22 ... p-type InGaAs cap layer, 23 ...
Upper electrode, 24: lower electrode, 25: low reflection film, 26: distributed feedback semiconductor laser, 27: heat sink, 28: optical lens,
29 ... photodiode, 30 ... optical fiber, 31 ... transmitting module, 32 ... transmitting device, 33 ... drive system, 34 ... optical fiber,
35 ... receiving device, 36 ... light receiving unit.

Claims (6)

[Claims] In a method of manufacturing a semiconductor laser device including a semiconductor region on which a diffraction grating is formed, the semiconductor region on which the diffraction grating is to be formed functions as a positive type for development with a first developer. And applying a resist functioning as a negative type for development with the second developer.
A step of periodically forming an exposed region and a non-exposed region adjacent to the resist in the resist by an interference exposure method using a laser beam; and After developing with any one of the two developing solutions, a second portion, which is an undeveloped portion of the resist, is developed with the other of the developing solutions to form a periodic pattern having a different phase and continuity in the resist. And a fourth step of forming continuous irregularities having different phases in the semiconductor region using the resist pattern as a mask to obtain the diffraction grating. Production method. 2. A method of manufacturing a semiconductor laser device including a semiconductor region on which a diffraction grating is formed, wherein the semiconductor region on which the diffraction grating is to be formed functions as a positive type for development with a first developer. And applying a resist functioning as a negative type for development with the second developer.
And a second step of periodically forming an exposed region and a non-exposed region adjacent to the exposed region on the resist by an interference exposure method using a laser beam, and performing a silylation process on the first portion of the resist. And after dry development with oxygen plasma, the second part which is an undeveloped part of the resist is developed with the first developer to form a periodic pattern having a different phase and continuity in the resist. A method of manufacturing a semiconductor laser device, comprising: a third step; and a fourth step of forming continuous irregularities having different phases in the semiconductor region using the resist pattern as a mask to obtain the diffraction grating. 3. The semiconductor laser device according to claim 1, wherein the first developer is a polar solvent, and the second developer is a non-polar solvent. Production method. 4. The method for manufacturing a semiconductor laser device according to claim 1, wherein said resist is a chemically amplified resist. 5. An optical module comprising a semiconductor laser device manufactured by the manufacturing method according to claim 1. 6. An optical application system comprising a semiconductor laser device manufactured by the manufacturing method according to claim 1.