JP2005203814A - Ridge-type semiconductor laser device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ridge-type semiconductor laser device manufacturing method capable of separately controlling a current confining effect and a light-confining effect, and further realizing a low threshold and high efficiency, because the current in a ridge portion can hardly spread out to both sides, so that electrons are efficiently poured into an activity layer, and also the width of a conductive region and the thickness of high resistance regions can be controlled independently, since the high resistance regions are disposed on both sides of the conductive region forming the redge portion. <P>SOLUTION: A ridge-type semiconductor laser device manufacturing method comprises the steps of sequentially growing a cladding layer and an active layer on a substrate; and forming a ridge-shaped layer on the active layer, which consists of a conductive region forming a ridge portion and high-resistance regions, disposed on both sides of the conductive region. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a ridge type semiconductor laser.

FIG. 14 shows a cross-sectional structure of a conventional ridge type long wavelength semiconductor laser and its process flow. In FIG. 14, 1 is a P-InP substrate, 2 is a P-InP clad layer, 3 is an active layer, 5 is a SiO ₂ stripe film, 7 is a SiO ₂ film, and 8 is an n-InP clad layer.

The manufacturing process will be described. First, a P-InP clad layer 2 (P≈1 × 10 ¹⁸ cm ⁻³ , 1.5 μm), an active layer 3 (0.1 μm), an n-InP clad layer on a P-InP substrate 1. 8 (n≈1 × 10 ¹⁸ cm ⁻³ , 2.0 μm) are sequentially grown using the MOCVD method (FIG. 14A). Next, a SiO ₂ film is formed on the wafer surface by sputtering, and a SiO ₂ stripe film 5 (width 2.0 μm) is formed using a photoengraving technique (FIG. 14B).

Then the SiO ₂ stripe film 5 by dry etching as a mask, after the n-InP cladding layer 8 was 1.8μm etching, the SiO ₂ stripe film 5 is removed by using an HF solution. Next, after a SiO ₂ film 7 is formed on the surface by sputtering, the n-InP clad layer 8 is exposed only at the upper portion of the ridge portion by using a photoengraving technique (FIG. 11C). Finally, Cr / Au and Ti / Pt / Au are formed as P-type and n-type electrodes (both not shown), respectively.

  Next, the laser function will be described. Light confinement takes advantage of the fact that less light oozes out of the active layer 3 into the cladding layer on both sides of the ridge than at the bottom of the ridge. Accordingly, the remaining thickness of the n-InP clad layer 8 on both sides of the ridge is important, and the remaining thickness is required to be about 0.2 μm in order to stabilize the mode of light.

  Current confinement is performed by injecting into the active layer 3 a current spreading from the electrode (not shown) formed on the ridge portion to the width of the ridge portion. However, the current spreads in the remaining thickness on both sides of the ridge (see Fig. 2 (a)), the current component that does not contribute to laser oscillation increases, the threshold current increases and the slope efficiency decreases, and the initial laser characteristics are reduced. Deteriorate. FIG. 15 shows a calculation example of the current spread of the semiconductor laser (LD) having the structure of FIG. The horizontal axis represents the distance L from the side surface of the ridge portion, and the vertical axis represents the current density. From this, it can be seen that the current spreads by about 2 μm on the outside (one side) of the ridge.

  In addition, the following Patent Documents 1 to 3 disclose such ridge type semiconductor lasers.

JP 02-203583 A JP 05-327124 A Japanese Unexamined Patent Publication No. 03-053582

  As described above, in the conventional ridge type semiconductor laser, the current spreads in the remaining thickness portions on both sides of the ridge portion, the current component that does not contribute to the laser oscillation increases, the threshold current increases and the slope efficiency decreases, There were problems such as deterioration of the initial laser characteristics.

  The present invention has been made to solve the above problems, and a method of manufacturing a ridge type semiconductor laser capable of separately controlling current confinement and optical confinement, and capable of lowering the threshold and increasing the efficiency. The purpose is to provide.

  In view of the above object, the present invention provides a ridge comprising a step of sequentially growing a cladding layer and an active layer on a substrate, a conductive region forming a ridge portion on the active layer, and a high resistance region on both sides of the conductive region. A method of manufacturing a ridge type semiconductor laser, comprising: forming a mold layer.

  In the present invention, the current of the ridge portion does not spread on both sides, electrons are efficiently injected into the active layer, and the high resistance region is on both sides of the ridge portion, that is, the conductive region. Therefore, the current confinement and the optical confinement can be controlled separately, and a semiconductor laser manufacturing method capable of lowering the threshold and increasing the efficiency can be provided.

Hereinafter, description will be given according to each embodiment.
Embodiment 1 FIG.
FIG. 1 is a diagram showing a cross-sectional structure of a ridge type semiconductor laser and a process flow thereof according to an embodiment of the present invention. In the figure, 1 is a (001) P-InP substrate, 2 is a P-InP cladding layer, 3 is an active layer, 4 is an Fe-InP layer, 5 and 7 are SiO ₂ films, and 6 is an n-InP layer. Note that the Fe-InP layer 4 and the n-InP layer 6 constitute a ridge type layer, the Fe-InP layer 4 becomes a high resistance region, and the n-InP layer 6 becomes a conductive region.

To explain in accordance with the manufacturing process, first, a MOCVD method is used on a (001) P-InP substrate 1 to form a P-InP clad layer 2 (1.5 μm, 1 × 10 ¹⁸ cm ⁻³ ), an active layer 3 (0.1 μm). ) And an Fe—InP layer 4 (2 μm, Fe concentration of 4 × 10 ¹⁶ cm ⁻³ ) are grown sequentially (FIG. 1A). Next, a SiO ₂ film 5 is formed on the surface by sputtering, and a window having a width of 2 μm is opened by using a photolithography technique (FIG. 1B). The direction to open the window may be either (110) or (11 bar 0).

Next, Si is diffused or ion-implanted to make the window region an n-InP layer 6 (1 × 10 ¹⁸ cm ⁻³ ) (FIG. 1C). At this time, the Si profile is controlled so that Si is not taken into the active layer 3. Next, after removing the SiO ₂ film 5, an SiO ₂ film (not shown) is formed again, leaving the SiO ₂ film only on the n-InP layer 6, and dry etching only the Fe—InP layers 4 on both sides. Etching leaves an Fe-InP layer thickness of 0.2 μm.

Next, the SiO ₂ film is removed again, and another SiO ₂ film is formed on the entire surface. This time, only the SiO ₂ film on the n-InP layer 6 is removed by using the photoengraving technique, and FIG. A structure having the SiO ₂ film 7 shown in d) is obtained. Then, an n-type electrode Ti / Pt / Au is formed on the front surface, and a Pn electrode Cr / Au (both not shown) is formed on the back surface.

  Next, the operating principle of this laser will be described. The Fe—InP layer 4 serves as a high resistance layer for electrons. Therefore, the electrons injected from the n-type electrode flow only to the n-InP layer 6 as shown in FIG. 2B, and do not spread as in the conventional FIG. Injected. On the other hand, light confinement can be performed in the same manner as in the conventional example because the Fe—InP layer 4 remains at 0.2 μm on both sides of the ridge.

In more detail about the light confinement, in the ridge waveguide LD, the upper cladding layer (Fe-InP layer 4) of the ridge side portion is made thinner than the ridge portion to provide an effect of low refractive index, and the transverse mode is changed. Confine. Therefore, the effective refractive index difference Δn _eff in the lateral direction is determined by the remaining thickness of the upper cladding of the ridge side portion.

FIG. 3A shows the relationship between the remaining thickness of the upper cladding layer and the effective refractive index difference Δn _{eff in} the lateral direction, and FIG. 3B shows the relationship between the remaining thickness of the upper cladding layer and the ridge width for cutting off the lateral higher-order mode. Indicates.

In the design, the high-order mode cut-off condition of the long wave ridge LD was calculated. In the design, the refractive index guided type, the suppression of spatial hole burning, the increase of the threshold current density due to insufficient light confinement, Due to the requirement to prevent the degradation of differential efficiency, the effective refractive index difference Δn _{eff in} the lateral direction cannot be made very small (Δn _eff > 0.005). Therefore, the remaining upper cladding thickness <0.3 μm and ridge width <3.5 μm are targeted.

  As described above, since the Fe—InP layer 4 is on both sides of the ridge portion, current confinement and light can be controlled by independently controlling the width of the ridge portion (width of the n-InP layer 6) and the thickness of the Fe—InP layer 4. The confinement can be controlled separately, and the threshold value and the efficiency can be reduced, and a ridge type semiconductor laser having excellent characteristics can be obtained.

Embodiment 2. FIG.
In the first embodiment, an example using a P-type substrate has been described. When an n-type substrate is used, it is not necessary to simply invert other layers by P / n. This is because, as described above, the Fe—InP layer does not become a high-resistance layer for holes, and the current spreads as shown in FIG. Therefore, in this embodiment, an example using an n-type substrate is shown. The basic process is the same as in the first embodiment.

FIG. 4 is a view showing a sectional structure of the ridge type semiconductor laser according to this embodiment and a process flow thereof. In the figure, 10 is an n-InP substrate, 11 is an n-InP clad layer, 3 is an active layer, 12 is a Ti-InP layer, 5 is a SiO ₂ film, and 13 is a P-InP layer. The Ti—InP layer 12 and the P—InP layer 13 form a ridge type layer, the Ti—InP layer 12 becomes a high resistance region, and the P—InP layer 13 becomes a conductive region.

To explain according to the manufacturing process, first, an n-InP clad layer 11 (1 × 10 ¹⁸ cm ⁻³ , 1.5 μm), an active layer 3 (0.1 μm), and a Ti—InP layer 12 (2 μm) are formed on an n-InP substrate 10. , Ti concentration 1 × 10 ¹⁷ cm ⁻³ ) is successively grown by using the MOCVD method (FIG. 4A). A SiO ₂ film is formed on the surface, and stripes of the SiO ₂ film 5 as shown in FIG. 4B are formed using photolithography. The Ti—InP layer 12 is partially made into a P—InP layer 13 by ion implantation or diffusion of Zn (FIG. 4C). Next, using the same photoengraving technique and dry etching technique as in the first embodiment, the ridge type semiconductor laser of FIG.

The operation principle will be described. The Ti—InP layer 12 functions as a high resistance layer against holes. Therefore, holes injected from the P-type electrode on the surface are efficiently injected into the active layer 3 as shown in FIG. 2B without spreading on both sides of the ridge portion. Light confinement is performed with the remaining thickness of the Ti-InP layer 12.
As described above, the ridge semiconductor laser shown in FIG. 4D operates with a low threshold and high current efficiency.

Embodiment 3 FIG.
In the first and second embodiments, in order to increase the resistance of InP, a deep trap level formed by doping impurities of Fe and Ti and using impurities is used. For this reason, it is necessary to change the impurities for increasing the resistance depending on the injected carriers (electrons, holes).

  Therefore, in this embodiment, a high resistance layer that can be applied regardless of the substrate to be used is used without depending on the carrier to be injected. As this high resistance layer, an undoped AlInAs layer grown at a low temperature (500 ° C.) using the MOCVD method is used. The principle of high resistance is because the Fermi level is near the center of the band gap because the amounts of donor and acceptor impurities are almost equal. Therefore, it functions as a high resistance layer for both holes and electrons.

FIG. 5 is a view showing a sectional structure of the ridge type semiconductor laser according to this embodiment and a process flow thereof. In the figure, 10 is an n-InP substrate, 20 is an n-AlInAs cladding layer, 3 is an active layer, 21 is an undoped AlInAs layer, 5 is a SiO ₂ film, and 22 is a P-AlInAs layer. The undoped AlInAs layer 21 and the P-AlInAs layer 22 form a ridge type layer, the undoped AlInAs layer 21 becomes a high resistance region, and the P-AlInAs layer 22 becomes a conductive region.

Explaining according to the manufacturing process, first, an n-AlInAs cladding layer 20 (1 × 10 ¹⁸ cm ⁻³ , 1.5 μm) and an active layer 3 (0.1 μm) are grown on the n-InP substrate 10 at a growth temperature of 650 ° C. Then, an undoped AlInAs layer 21 (2.0 μm) is sequentially grown using a MOCVD method at a growth temperature of 500 ° C. (FIG. 5A). After a SiO ₂ film is formed on the surface by sputtering, stripes of the SiO ₂ film 5 as shown in FIG. 5B are formed using photolithography.

Next, Zn is ion-implanted or diffused to the active layer 3 to form a P-AlInAs layer 22 (1 × 10 ¹⁸ cm ⁻³ ) as shown in FIG. The undoped AlInAs layer 21 is etched using a dry etching technique, leaving 0.2 μm of the undoped AlInAs layer 21 as shown in FIG.

  Thereby, since the undoped AlInAs layer 21 functions as a high resistance layer with respect to the holes, a ridge type semiconductor laser with excellent characteristics can be obtained as shown in FIG. In the case of this laser structure, when a P-InP substrate is used, the conductivity types of the layers excluding the undoped AlInAs layer 21 and the active layer 3 may be simply reversed.

Embodiment 4 FIG.
In the first to third embodiments, a conductive region (ridge portion) through which a current flows is formed by diffusion or implantation of impurities about 2 μm from the surface to the active layer. In this case, stopping impurities immediately before the active layer is not stable in terms of controllability. Accordingly, an example in which the reproducibility of the impurity profile is improved by reducing the diffusion or implantation depth will be described below. The following embodiment is a modification of the first embodiment, but the same effect can be obtained for the modifications of the second and third embodiments by using the same technique.

  FIG. 6 is a diagram showing a sectional structure of the ridge type semiconductor laser according to this embodiment and a process flow thereof. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

Explaining in accordance with the manufacturing process, a P-InP layer 2 (1 × 10 ¹⁸ cm ⁻³ , a film thickness of 1.5 μm), an active layer 3 (0.1 μm), an Fe—InP layer 4 (Fe A concentration of 4 × 10 ¹⁶ cm ⁻³ and a film thickness of 0.2 μm) is sequentially grown using the MOCVD method (FIG. 6A). A SiO ₂ film is formed on the surface by sputtering, and stripes of the SiO ₂ film 5 as shown in FIG. 6B are formed by photolithography. Next, Si is ion-implanted or diffused to form an n-InP layer 6 (1 × 10 ¹⁸ cm ⁻³ ) (FIG. 6C).

Next, after removing the SiO ₂ film 5 with an HF solution, an n-InP layer 9 (1 × 10 ¹⁸ cm ⁻³ ) is grown by 1.8 μm (FIG. 6D). In FIG. 6C, a SiO ₂ film (not shown) is formed only on the Si diffused region, and the Fe-InP layer 4 (the remaining thickness of the Fe—InP layer 4) is formed using a dry etching technique. After the etching to 0.2 μm), the SiO ₂ film is removed (FIG. 6E).

Embodiment 5 FIG.
In the first to fourth embodiments, the ridge portion is formed using the dry etching technique. However, in this embodiment, the ridge type is formed using the selective growth technique using the stripe of the diffusion SiO ₂ film 5. A semiconductor laser is formed.

Next, according to the manufacturing process, first, after performing the steps of FIGS. 6A to 6C, the n-InP layer 9 (1 × 10 ¹⁸ cm ⁻³⁾ is removed without removing the stripe of the SiO ₂ film 5. , 1.8 μm). When the direction of the stripe window of the SiO ₂ film 5 is the (11 bar 0) direction, a ridge shape as shown in FIG. 7A is obtained, and when the direction is the (110) direction, a ridge shape as shown in FIG. 7B is obtained. In addition, (1) the stripe direction is inclined by 45 ° from the (110) direction, and (2) the growth conditions are also selected in the (11 bar 0) and (110) directions, whereby the structure of FIG. Can be formed.

In this embodiment, since the dry etching and its mask pattern process can be omitted, the process can be simplified. Further, since the remaining thickness of the Fe—InP layer 4 is automatically determined by the film thickness of the Fe—InP layer 4 during growth in FIG. 6A, a device structure as designed can be achieved.
When an n-InP substrate is used, the Fe—InP layer portion is a Ti—InP layer and the conductivity type of this embodiment is reversed.

Embodiment 6 FIG.
Next, in the case of selective growth according to the fifth embodiment, the case where the substrate is an n-InP substrate will be described with reference to FIG.

First, an n-AlInAs cladding layer 20 (1.5 μm, 1 × 10 ¹⁸ cm ⁻³ ), an active layer 3 and a low temperature growth undoped AlInAs high resistance layer 21 (0.2 μm) are sequentially formed on the n-InP substrate 10 by MOCVD. Grow using the method. A SiO ₂ film is formed on the surface, and stripes of the SiO ₂ film 5 as shown in FIG. 8A are formed using photolithography. Next, a P-AlInAs layer 22 (1 × 10 ¹⁸ cm ⁻³ ) is formed by ion implantation or diffusion of Zn (FIG. 8B). Without removing the SiO ₂ film 5, a P-InP layer 9a (1.8 μm, 1 × 10 ¹⁸ cm ⁻³ ) is grown by MOCVD. When the stripe direction of the SiO ₂ film 5 is the (11 bar 0) direction, the ridge type semiconductor laser is as shown in FIG.

  Further, when the AlInAs layer is exposed to air, the surface is easily oxidized, and it is difficult to grow the InP layer on the surface. Therefore, after the undoped AlInAs layer 21 is formed, an undoped InP film (not specifically shown) is grown to about 100 mm continuously. By forming this undoped InP layer, even if the P-InP layer 9a as shown in FIG. 8C or FIG. 8D is grown, the P-InP layer 9a is grown without deteriorating the crystallinity. be able to.

Embodiment 7 FIG.
In the above fourth to sixth embodiments, in order to control the impurity diffusion into the active layer, the thickness of the diffused layer is reduced. This embodiment is further characterized in that a conductive layer is thinly inserted between the active layer and the high resistance layer in order to suppress impurity diffusion into the active layer.

  FIGS. 9 and 10 are views showing a cross-sectional structure of the ridge type semiconductor laser according to this embodiment and a process flow thereof. In the figure, the parts denoted by the same reference numerals as those in the above embodiment are the same or corresponding parts. Reference numeral 30 denotes an n-InP clad film (conductive film).

To explain in accordance with the manufacturing process, a P-InP clad layer 2 (1 × 10 ¹⁸ cm ⁻³ , 1.5 μm), an active layer 3 (0.1 μm), an n-InP clad film 30 ( 1 × 10 ¹⁸ cm ⁻³ , 500 Å) and an Fe—InP layer 4 (0.2 μm) are sequentially grown by MOCVD (FIG. 9A). After the SiO ₂ film is formed, stripes of the SiO ₂ film 5 are formed in the (110) or (11 bar 0) direction using photolithography (FIG. 9B). Next, an n-InP layer 6 is formed by ion implantation or diffusion of Si (FIG. 9C). The tip of the Si impurity profile at this time may be anywhere in the n-InP clad film 30, and impurity diffusion into the active layer 3 is further suppressed.

Next, after removing the stripes of the SiO ₂ film 5, an n-InP layer 9 (1 × 10 ¹⁸ cm ⁻³ , 1.8 μm) is grown by MOCVD (FIG. 8D), dry etching and photolithography Using the technique, a ridge type semiconductor laser shown in FIG. 10A is formed.
On the other hand, in the case of using selective growth, after the step of FIG. 9C, the n-InP layer 9 is selectively grown using the MOCVD method to obtain the structure of FIG.

  By doing as described above, in this embodiment, impurity diffusion into the active layer is further suppressed, so that a ridge type semiconductor laser with better characteristics can be obtained.

Embodiment 8 FIG.
In each of the above embodiments, a high resistance layer is grown at the time of crystal growth, and a conductive layer (region) is formed by ion implantation or diffusion.In this embodiment, in order to prevent deterioration of the laser characteristics, impurities are added. In order not to enter the active layer as much as possible, the conductive layer is first grown, and then both sides of the ridge are increased in resistance.

  FIG. 11 is a diagram showing a sectional structure of a ridge type semiconductor laser according to this embodiment and a process flow thereof. In the figure, the parts denoted by the same reference numerals as those in the above embodiment are the same or corresponding parts. 31 is a P-AlInAs cladding layer.

When described according to the manufacturing process, an n-AlInAs cladding cladding layer 20 (1 × 10 ¹⁸ cm ⁻³ , 1.5 μm), an active layer 3 (0.1 μm), a P-AlInAs cladding layer 31 ( 5 × 10 ¹⁷ cm ⁻³ , 0.2 μm) and a P-InP cladding layer 9a (1 × 10 ¹⁸ cm ⁻³ , 1.8 μm) are sequentially grown by MOCVD, and then a SiO ₂ film is formed on the surface. Then, a stripe (width 2.0 μm) of the SiO ₂ film 5 as shown in FIG. 11A is formed by using a photoengraving technique.

The dry etching technique is used to etch the P-InP cladding layer 9a on both sides of the stripe of the SiO ₂ film 5 (FIG. 11B). Next, oxygen is ion-implanted, a deep level is formed in the P-AlInAs cladding layer 31, the resistance of the P-AlInAs cladding layer 31 is increased, and an AlInAs high resistance layer 32 (high resistance region) is formed. Finally, the SiO ₂ film 5 is removed (FIG. 11C). When injecting oxygen, as shown in FIG. 11 (c), it is not necessary to stop oxygen immediately before the active layer 3, and the active layer 3 and the n-AlInAs cladding layer 20 may be injected. However, if oxygen is implanted deeper than the film thickness (1.8 μm) of the P-InP cladding layer 9a, the resistance of the P-AlInAs layer 31 below the ridge also increases, so that the depth of oxygen implantation is a maximum of 1.8 μm. .

  Accordingly, the depth control for ion implantation may be more than the thickness of the P-AlInAs cladding layer 31, and the process margin is remarkably improved as compared with the above embodiment. As described above, in this embodiment, after the conductive ridge-type layer is formed, the resistance of both sides thereof is increased to suppress the spread of current, and the laser characteristic with a low threshold (operation) current can be obtained. I did it.

Embodiment 9 FIG.
In the eighth embodiment, the case of the AlInAs system is described, but in this embodiment, the case of the InP system is shown. Doping oxygen into InP does not increase the resistance, and doping with Fe or Ti increases the resistance of InP if the background carrier concentration of InP exceeds 1 × 10 ¹⁷ cm ⁻³ . It is difficult. Therefore, in the case of the InP system, the resistance is increased by proton implantation.

  FIG. 12 is a diagram showing a sectional structure of the ridge type semiconductor laser according to this embodiment and a process flow thereof. In the figure, the parts denoted by the same reference numerals as those in the above embodiment are the same or corresponding parts. Reference numeral 33 denotes a high resistance layer (high resistance region).

To explain in accordance with the manufacturing process, an n-InP clad layer 11 (1 × 10 ¹⁸ cm ⁻³ , 1.5 μm), an active layer 3 (0.1 μm), and a P-InP clad layer 9 a (1 × 10 ¹⁸ cm ⁻³ , 2.0 μm) are sequentially grown using the MOCVD method. A SiO ₂ film is formed, and stripes of the SiO ₂ film 5 are formed using a photoengraving technique (FIG. 12A). Etching is stopped when the P-InP layer 9a on both sides of the SiO ₂ film 5 is etched using dry etching technique and 0.2 μm of the P-InP layer 9a is left (FIG. 12B).

Next, proton implantation is performed to remove the stripes of the SiO ₂ film 5 (FIG. 12C). Proton implantation does not have to be stopped immediately before the active layer 3 and may reach the n-InP cladding layer 11. The proton implanted region 33 becomes a high resistance layer.

  By doing as described above, even in the case of the InP system, the depth control for proton implantation may be more than the thickness of the P-InP cladding layer 9a, the process margin is further improved, and the characteristics are excellent. A ridge type semiconductor laser can be manufactured.

  The AlInAs layer in each of the above embodiments may be an AlGaInAs layer as long as the laser characteristics are not impaired. Moreover, this invention is not limited to said embodiment, The possible combination of the said embodiment is also included.

Further, although the ridge type long wavelength semiconductor laser has been described, a device with excellent characteristics can be obtained by similarly increasing the resistance of both sides of the ridge for the short wavelength band ridge type semiconductor laser.
In addition, the width of the ridge and the width of current flow are the same in the embodiment except for the case where the semiconductor laser is manufactured using selective growth.

Further, as shown in FIG. 13A, even when the high resistance layer 40 is located to the inside of the conductive layer 41, or even when the width of the conductive layer 41 is slightly larger than the ridge width as shown in FIG. The effect is never lost.
Further, Si has been described as the n-type impurity, and Zn as the P-type impurity. However, if there are other impurities exhibiting the respective conductivity types, the same effects as those of the above embodiment can be obtained even if they are used. Is obtained.

  As described above, in the first feature, the method includes a step of sequentially growing a clad layer and an active layer on a substrate, a conductive region constituting a ridge portion on the active layer, and high resistance regions on both sides of the conductive region. Since the ridge type semiconductor laser is manufactured by the process of forming the ridge type layer, the current in the ridge portion does not spread on both sides, electrons are efficiently injected into the active layer, and the high resistance region is on both sides of the ridge portion, that is, the conductive region. Therefore, since the width of the conductive region and the thickness of the high-resistance region can be controlled independently, the current confinement and the optical confinement can be controlled separately, and the semiconductor laser manufacturing method capable of lowering the threshold and increasing the efficiency Can be provided.

  In the second feature, the step of forming the ridge-type layer includes a step of forming a high-resistance layer on the active layer, and performing either impurity diffusion or ion implantation on the high-resistance layer to obtain a desired width. Forming a conductive region and a step of cutting the high resistance regions on both sides of the conductive region to a desired thickness, so that the current in the ridge portion does not spread on both sides, and electrons are efficiently injected into the active layer. Since the high-resistance region is on both sides of the ridge, that is, the conductive region, the width of the conductive region and the thickness of the high-resistance region can be controlled independently, so that current confinement and optical confinement can be controlled separately, resulting in lower thresholds. In addition, it is possible to provide an effect of providing a semiconductor laser manufacturing method capable of increasing efficiency.

  In the third feature, the substrate is a P-InP substrate, an Fe-InP layer is formed as the high resistance layer, and either Si diffusion or ion implantation is performed before the active layer. Since the conductive region is formed, it is possible to obtain an effect such as providing a manufacturing method capable of realizing the second feature with the P-InP substrate.

  In the fourth feature, the substrate is an n-InP substrate, a Ti-InP layer is formed as the high resistance layer, and Zn diffusion or ion implantation before the active layer is performed on the Ti-InP layer. Since the conductive region is formed, it is possible to obtain an effect such as providing a manufacturing method capable of realizing the second feature with the n-InP substrate.

  In the fifth feature, regardless of the conductivity type of the substrate, an undoped AlInAs layer grown at a low temperature is formed as the high-resistance layer, and either impurity diffusion or ion implantation before the active layer is formed on the undoped AlInAs layer. Since the conductive region is formed by applying the second method, it is possible to provide a manufacturing method capable of providing the second feature regardless of the conductivity type of the substrate.

  In the sixth feature, the step of forming the ridge-type layer includes a step of forming a high resistance layer having a desired thickness on the active layer, and performing either impurity diffusion or ion implantation on the high resistance layer. The step of forming a conductive region of a desired width and the step of growing the conductive region are included, so that the impurity profile reproducibility is improved by reducing the depth of impurity diffusion or implantation. Thus, it is possible to provide an effect of providing a manufacturing method capable of manufacturing a semiconductor laser with reduced yield and high manufacturing accuracy.

  In the seventh feature, the substrate is a P-InP substrate, an Fe-InP layer is formed as the high-resistance layer, and Si is diffused or ion-implanted before the active layer. A conductive region is formed, and in the conductive region growth step, an n-InP layer is grown on the high-resistance layer including the conductive region, and then portions of the n-InP layer on both sides of the conductive region are removed. Since it did in this way, effects, such as providing the manufacturing method which can implement | achieve the 6th characteristic with a P-InP board | substrate, are acquired.

  In the eighth feature, in the conductive region growing step, portions other than the conductive region of the high-resistance layer are masked and the conductive region is selectively grown, so that dry etching and a mask pattern process therefor can be omitted. Therefore, the process can be simplified, and the remaining thickness of the high-resistance region is automatically determined by the film thickness at the time of growth, so that the device structure as designed can be achieved, which further simplifies the process and increases the manufacturing accuracy. Effects such as providing a manufacturing method capable of manufacturing a semiconductor laser can be obtained.

  In a ninth feature, the substrate is a P-InP substrate, and an Fe-InP layer is formed as the high-resistance layer, and either Si diffusion or ion implantation before the active layer is performed on the Fe-InP layer. Since the conductive region is formed and the conductive region is selectively grown by masking a portion other than the conductive region in the conductive region growth step, a manufacturing method capable of realizing the eighth feature on the P-InP substrate is provided. The effect that it can provide is acquired.

  In a tenth feature, the substrate is an n-InP substrate, and an undoped AlInAs layer grown at a low temperature as the high-resistance layer and an undoped InP film are continuously formed on the surface thereof, before the active layer. The conductive region is formed by performing either Zn diffusion or ion implantation, and in the conductive region growth step, the conductive region is selectively grown by masking portions other than the conductive region. It is possible to obtain an effect such as providing a manufacturing method whose characteristics can be realized with an n-InP substrate.

  In the eleventh feature, the step of forming the ridge-type layer includes a step of forming a thin conductive film on the active layer, a step of forming a high resistance layer having a desired thickness on the conductive film, Since the conductive layer having a desired width is formed by performing either impurity diffusion or ion implantation on the resistance layer, and the step of growing the conductive region, the conductive layer is applied to the active layer by the conductive film. Since impurity diffusion is further suppressed, effects such as providing a manufacturing method capable of manufacturing a semiconductor laser with better characteristics can be obtained.

  In a twelfth feature, the substrate is a P-InP substrate, an n-InP clad film is formed as the conductive film, an Fe-InP layer is formed as the high-resistance layer, and the high-resistance layer is formed on the high-resistance layer. Since the conductive region is formed by performing either Si diffusion or ion implantation, effects such as providing a manufacturing method capable of realizing the eleventh feature with the P-InP substrate can be obtained.

  In a thirteenth feature, in the conductive region growing step, an n-InP layer is grown on the high-resistance layer including the conductive region, and thereafter, portions on both sides of the conductive region of the n-InP layer are removed. Since it did in this way, effects, such as providing the manufacturing method which can obtain the effect which added the 6th characteristic to the 12th characteristic, are acquired.

  In the fourteenth feature, since the conductive region is selectively grown in the conductive region growing step by masking portions other than the conductive region, an effect obtained by adding the eighth feature to the twelfth feature is obtained. Effects such as providing a manufacturing method can be obtained.

  In the fifteenth feature, the step of forming the ridge-type layer includes a step of forming a conductive layer on the active layer, a step of scraping both sides of the conductive layer so as to form a ridge portion having a desired width, and a desired And a step of forming a high resistance region by ion implantation of impurities into the cut portions on both sides of the conductive layer, and conversely growing the conductive layer first. Since the resistance of both sides of the ridge is increased after the process, impurities are not introduced into the active layer as much as possible, and the laser characteristics are not deteriorated. Therefore, it is possible to provide a manufacturing method capable of manufacturing a semiconductor laser having further excellent characteristics. Etc. are obtained.

  In a sixteenth feature, the substrate is an n-InP substrate, and is formed by laminating a P-AlInAs cladding layer and a P-InP cladding layer having a desired thickness in the conductive layer forming step, and scraping both sides of the ridge portion. Since the portion of the P-InP clad layer is cut in the step and oxygen is ion-implanted into the P-AlInAs clad layer in the high resistance region forming step, the fifteenth feature can be realized by an AlInAs-based device. Effects such as providing a manufacturing method can be obtained.

  In a seventeenth feature, the substrate is an n-InP substrate, a P-InP clad layer is formed in the conductive layer forming step, and the P-InP clad layer is formed to a desired thickness in the step of scraping both sides of the ridge portion. Since the proton is ion-implanted into the P-InP clad layer in the step of forming the high resistance region, effects such as providing a manufacturing method capable of realizing the fifteenth feature with an InP-based device can be obtained. .

It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 1 of this invention, and its process flow. It is sectional drawing which shows the spread of an electric current. It is a figure which shows the relationship between upper cladding layer remaining thickness, an effective refractive index difference, and a ridge width. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 2 of this invention, and its process flow. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 3 of this invention, and its process flow. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 4 and 5 of this invention, and its process flow. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 5 of this invention, and its process flow. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 6 of this invention, and its process flow. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 7 of this invention, and its process flow. FIG. 10 is a diagram showing a cross-sectional structure of a ridge-type semiconductor laser according to a seventh embodiment following FIG. 9 and a process flow thereof. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 8 of this invention, and its process flow. It is a figure which shows the cross-section of the ridge type semiconductor laser by Embodiment 9 of this invention, and its process flow. It is a figure which shows the relationship between the high resistance layer and conductive layer of the ridge type semiconductor laser by this invention. It is a figure which shows the cross-section of the conventional ridge type semiconductor laser, and its process flow. It is a figure which shows the example of calculation of the spread of the electric current of the ridge type semiconductor laser of the structure of FIG.

Explanation of symbols

1 P-InP substrate, 2 P-InP clad layer, 3 active layer, 4 Fe-InP layer, 5 SiO ₂ film, 6 n-InP layer, 7 SiO ₂ film, 9 n-InP layer, 9a P-InP layer 10 n-InP layer, 11 n-InP cladding layer, 12 Ti-InP layer, 13 P-InP layer, 20 n-AlInAs layer, 21 undoped AlInAs layer, 22 P-AlInAs layer, 30 n-InP cladding layer, 31 P-AlInAs cladding layer, 32 AlInAs high resistance layer, 33 high resistance layer, 40 high resistance layer, 41 conductive layer.

Claims (16)

A step of sequentially growing a cladding layer and an active layer on the substrate;
Forming a ridge-type layer comprising a conductive region forming a ridge on the active layer and a high-resistance region on both sides of the conductive region;
A method for manufacturing a ridge type semiconductor laser comprising: The step of forming the ridge type layer includes
Forming a high resistance layer on the active layer;
Subjecting the high resistance layer to either impurity diffusion or ion implantation to form a conductive region of a desired width;
Scraping the high resistance regions on both sides of the conductive region to a desired thickness;
The ridge type semiconductor laser manufacturing method according to claim 1, comprising:   The substrate is a P-InP substrate, an Fe-InP layer is formed as the high-resistance layer, and a conductive region is formed by performing either Si diffusion or ion implantation up to the front of the active layer. A method for manufacturing a ridge type semiconductor laser according to claim 2.   The substrate is an n-InP substrate, a Ti-InP layer is formed as the high-resistance layer, and a conductive region is formed by either Zn diffusion or ion implantation before the active layer. A method for manufacturing a ridge type semiconductor laser according to claim 2.   Regardless of the conductivity type of the substrate, an undoped AlInAs layer grown at a low temperature is formed as the high resistance layer, and a conductive region is formed by either impurity diffusion or ion implantation before the active layer. The method of manufacturing a ridge type semiconductor laser according to claim 2, wherein: The step of forming the ridge type layer includes
Forming a high resistance layer having a desired thickness on the active layer;
Subjecting the high resistance layer to either impurity diffusion or ion implantation to form a conductive region of a desired width;
Growing the conductive region;
The ridge type semiconductor laser manufacturing method according to claim 1, comprising:   The substrate is a P-InP substrate, an Fe-InP layer is formed as the high resistance layer, and a conductive region is formed by performing either Si diffusion or ion implantation up to the front of the active layer. In the conductive region growing step, an n-InP layer is grown on the high resistance layer including the conductive region, and thereafter, portions on both sides of the conductive region of the n-InP layer are removed. Item 7. A method for manufacturing a ridge type semiconductor laser according to Item 6.   7. The method of manufacturing a ridge type semiconductor laser according to claim 6, wherein, in the conductive region growth step, a portion other than the conductive region of the high resistance layer is masked to selectively grow the conductive region.   The substrate is a P-InP substrate, an Fe-InP layer is formed as the high resistance layer, and a conductive region is formed by performing either Si diffusion or ion implantation up to the front of the active layer. 9. The method of manufacturing a ridge type semiconductor laser according to claim 8, wherein, in the conductive region growing step, a conductive region is selectively grown by masking a portion other than the conductive region.   The substrate is an n-InP substrate, and an undoped AlInAs layer grown at a low temperature as the high-resistance layer and an undoped InP film are continuously formed on the surface, and Zn diffusion and ions before the active layer are formed on the undoped AlInAs layer. 9. The ridge type according to claim 8, wherein a conductive region is formed by performing any one of implantations, and the conductive region is selectively grown in the conductive region growth step by masking a portion other than the conductive region. Semiconductor laser manufacturing method. The step of forming the ridge type layer includes
Forming a thin conductive film on the active layer;
Forming a high resistance layer having a desired thickness on the conductive film;
Subjecting the high resistance layer to either impurity diffusion or ion implantation to form a conductive region of a desired width;
Growing the conductive region;
The ridge type semiconductor laser manufacturing method according to claim 1, comprising:   The substrate is a P-InP substrate, an n-InP clad film is formed as the conductive film, an Fe-InP layer is formed as the high resistance layer, and Si is diffused and ion-implanted into the high resistance layer. 12. The method of manufacturing a ridge type semiconductor laser according to claim 11, wherein the conductive region is formed by performing any of the above.   In the conductive region growing step, an n-InP layer is grown on the high resistance layer including the conductive region, and thereafter, portions on both sides of the conductive region of the n-InP layer are removed. Item 13. A method for manufacturing a ridge type semiconductor laser according to Item 12.   13. The method of manufacturing a ridge type semiconductor laser according to claim 12, wherein, in the conductive region growing step, a conductive region is selectively grown by masking a portion other than the conductive region. The step of forming the ridge type layer includes
Forming a conductive layer on the active layer;
Scraping both sides of the conductive layer to form a ridge having a desired width, and cutting to a desired thickness;
Forming a high resistance region by ion implantation of impurities into the shaved portions on both sides of the conductive layer;
The ridge type semiconductor laser manufacturing method according to claim 1, comprising:   The substrate is an n-InP substrate, and is formed by laminating a P-AlInAs cladding layer and a P-InP cladding layer having a desired thickness in the conductive layer forming step, and the P-InP in the step of scraping both sides of the ridge portion. 16. The method of manufacturing a ridge type semiconductor laser according to claim 15, wherein a portion of the clad layer is shaved and oxygen is ion-implanted into the P-AlInAs clad layer in the high resistance region forming step.

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