JP2008091769A - Method of manufacturing semiconductor laser element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor laser element, by which an etching removal of unnecessary current inhibition layer formed on a ridge stripe can be easily and certainly carried out and the semiconductor laser element can be designed with a degree of freedom. <P>SOLUTION: A ridge stripe 150 is constituted by: a p-type GaAs top cap layer 111 of a ridge stripe shape; a p-type Al<SB>y</SB>Ga<SB>1-y</SB>As cap etching stop layer 110; a p-type GaAs bottom cap layer 109; and a p-type Al<SB>x</SB>Ga<SB>1-x</SB>As second cladding layer 108. By selectively carrying out the etching removal of unnecessary n-type GaAs current inhibition layer 1160 on the ridge stripe 150 and the p-type GaAs top cap layer 111 with ammonia/hydrogen peroxide based etchant, the etching removal of the p-type Al<SB>y</SB>Ga<SB>1-y</SB>As cap etching stop layer 110 is selectively carried out with hydrofluoric acid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  In recent years, the demand for semiconductor laser devices used as pickups for DVD (digital multipurpose disc) and CD (compact disc) as compound semiconductor devices has been increasing, and semiconductor lasers with less variation in characteristics and excellent reliability. Is required. Furthermore, since the demand for cost reduction is increasing year by year, it is indispensable to improve the yield rate not only in semiconductor lasers but also in the manufacture of semiconductor devices. For this purpose, it is necessary to develop a simple and stable wafer process having a large process margin, excellent reproducibility, and the like.

  3A to 3D are process diagrams of a method for manufacturing a loss guide buried ridge type semiconductor laser device.

When manufacturing the semiconductor laser device, first, as shown in FIG. 3A, an n-type GaAs buffer layer 302 is formed on an n-type GaAs substrate 301 by metal organic chemical vapor deposition (MOCVD). N-type Al _x Ga _1-x As first cladding layer 303, n-type Al _x Ga _1-x As second cladding layer 304, non-doped Al _x Ga _1-x As quantum well active layer 305, p-type Al _x Ga _{The 1-x} As first cladding layer 306, the p-type GaAs etching stop layer 307, the p-type Al _x Ga _1-x As second cladding layer 308, and the p-type GaAs cap layer 309 are grown in this order.

Next, as shown in FIG. 3B, after a resist 310 having a mask pattern covering the predetermined region is formed by photolithography or the like, the p-type GaAs cap layer 309 and the p-type Al _{x on} both sides of the predetermined region are etched. The Ga _1-x As second cladding layer 308 is removed, and a ridge stripe 350 is formed.

  Next, after removing the resist 310, as shown in FIG. 3C, an n-type GaAs current blocking layer 311 is laminated so that no current flows outside the ridge stripe 350.

  Next, in order to remove the unnecessary n-type GaAs current blocking layer 311 on the ridge stripe 350 formed when the n-type GaAs current blocking layer 311 is stacked, a resist is applied to a portion other than the ridge stripe 350 by photolithography. (Not shown) is formed, and the p-type GaAs cap layer 309 including the unnecessary current blocking layer 311 is removed by etching halfway.

  Next, after removing the resist, as shown in FIG. 3D, a p-side electrode 312 is formed on the p-type GaAs cap layer 309 and the n-type GaAs current blocking layer 311, while n is formed under the n-type GaAs substrate 301. Side electrodes 313 are formed.

  In a semiconductor laser device in which such a ridge stripe structure is embedded with a current blocking layer or the like, an originally unnecessary current blocking layer is stacked on the ridge stripe, and thus it is necessary to remove it.

  If a current blocking layer remains on the ridge stripe, no current flows through the ridge stripe, resulting in oscillation failure. If not only the current blocking layer on the ridge stripe but also the p-type cap layer under the current blocking layer is removed, problems such as failure to contact the electrode occur.

  The removal of the unnecessary current blocking layer on the ridge stripe is ideally stopped in the middle of the p-type GaAs cap layer including the current blocking layer. As a method for removing the unnecessary current blocking layer by etching, there are a dry etching method and a wet etching method.

  When the unnecessary current blocking layer is removed by the dry etching, there is a problem in the influence of damage to the crystal and the shape after etching. In addition, when the current blocking layer on both sides of the ridge stripe is thick, the unnecessary current blocking layer on the ridge stripe has a mountain shape, and when the dry etching isotropically progresses, the mountain shape remains as it is. Since the shape is reflected, both sides of the p-type GaAs cap layer are greatly depressed. Due to this depression, when the p-side electrode is interrupted or a laser chip is formed as an element, there is a possibility that distortion is applied to the active layer due to the depression and the reliability is affected.

  On the other hand, when the unnecessary current blocking layer is removed by the wet etching, there is no damage to the crystal unlike dry etching, and isotropic and anisotropic etching is relatively easy if the type of etchant is selected. In addition, the wet etching is easy to handle because it can be selectively etched with respect to the etching material.

  However, when the thickness of the current blocking layer on both sides of the ridge stripe is large, the etching amount of unnecessary portions also increases, so it is not easy to stop wet etching in the middle of the p-type GaAs cap layer. In the wet etching, overetching of the p-type GaAs cap layer and underetching, which is an unnecessary layer remaining, may occur due to the etching rate variation of the etchant, which is not always a stable process.

In addition, in Japanese Patent Application Laid-Open No. 2004-303897, the current blocking layer on the ridge stripe is specified by defining the range of the thickness of the current blocking layer in order to easily remove the current blocking layer on the ridge stripe. However, since the thickness is defined, the degree of freedom in design is lost.
JP 2004-303897 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a semiconductor laser device that can easily and reliably etch away an unnecessary current blocking layer formed on a ridge stripe and has a degree of freedom in designing the semiconductor laser device. There is.

In order to solve the above problems, a method for manufacturing a semiconductor laser device of the present invention includes:
Forming a semiconductor layer group on the substrate;
A step of sequentially forming a lower cap layer, a cap etching stop layer and an upper cap layer on the semiconductor layer group;
Processing the lower cap layer, the cap etching stop layer and the upper cap layer into a ridge stripe shape to form a ridge stripe;
Forming a current blocking layer on both sides of the ridge stripe-shaped lower cap layer, cap etching stop layer and upper cap layer;
Removing the ridge stripe-shaped upper cap layer with a first etchant and then removing the ridge stripe-shaped cap etching stop layer with a second etchant;
The material composition of the cap etching stop layer is different from the material composition of the upper cap layer and the lower cap layer,
The cap etching stop layer and the upper cap layer have a material composition that can be selectively removed by wet etching,
The cap etching stop layer and the lower cap layer have a material composition that can be selectively removed by wet etching.

  According to the method of manufacturing a semiconductor laser device having the above configuration, since the cap etching stop layer and the upper cap layer can be selectively removed by wet etching, the ridge stripe-shaped cap etching stop layer is removed. Without this, the upper cap layer of the ridge stripe shape can be removed with the first etchant.

  In addition, since the cap etching stop layer and the lower cap layer have a material composition that can be selectively removed by wet etching, the ridge stripe-shaped cap etching stop layer can be obtained without removing the ridge stripe-shaped lower cap layer. Can be removed with a second etchant.

  Therefore, the wet etching for the ridge stripe can be easily and reliably stopped by the lower cap layer.

  Therefore, the unnecessary current blocking layer on the ridge stripe can be easily and reliably removed without over-etching or under-etching.

  Further, since it is not necessary to define the thickness of the current blocking layer, there is a degree of freedom in designing the semiconductor laser element.

In the manufacturing method of the semiconductor laser device of one embodiment,
The cap etching stop layer is configured with a material composition in which the etching rate of the cap etching stop layer with respect to the second etchant is higher than the etching rate of the current blocking layer with respect to the second etchant.

  According to the method of manufacturing the semiconductor laser device of the above embodiment, the cap etching stop layer has a material composition ratio that is higher than that of the current blocking layer, so that the cap etching stop layer is etched with the second etchant. In this case, the influence on the current blocking layer due to the penetration of the second etchant can be reduced.

In the manufacturing method of the semiconductor laser device of one embodiment,
The semiconductor layer group includes a cladding layer,
The cap etching stop layer is configured with a material composition in which the etching rate of the cap etching stop layer with respect to the second etchant is higher than the etching rate of the cladding layer with respect to the second etchant.

  According to the method of manufacturing a semiconductor laser device of the above embodiment, since the cap etching stop layer has a material composition ratio that is higher in etching rate than the cladding layer, the cap etching stop layer is etched with the second etchant. In addition, the influence on the cladding layer due to the penetration of the second etchant can be reduced.

In the manufacturing method of the semiconductor laser device of one embodiment,
The current blocking layer is made of Al _x Ga _1-x As (x = 0 to 0.7), and the cap etching stop layer is made of Al _y Ga _1-y As (x <y).

According to the method for manufacturing the semiconductor laser device of the above embodiment, the current blocking layer is made of Al _x Ga _1-x As (x = 0 to 0.7), and the cap etching stop layer is made of Al _y Ga _1. Since it is configured by _−y As (x <y), when the cap etching stop layer is etched with the second etchant, the influence on the current blocking layer due to the penetration of the second etchant can be reduced.

In the manufacturing method of the semiconductor laser device of one embodiment,
The cladding layer is made of Al _x Ga _1-x As (x = 0.4 to 0.6), and the cap etching stop layer is made of Al _y Ga _1-y As (x <y).

According to the method for manufacturing the semiconductor laser device of the above embodiment, the cladding layer is made of Al _x Ga _1-x As (x = 0.4 to 0.6), and the cap etching stop layer is made of Al _y Ga. Since it is composed of _1-y As (x <y), when the cap etching stop layer is etched with the second etchant, the influence on the cladding layer due to the penetration of the second etchant can be reduced.

In the manufacturing method of the semiconductor laser device of one embodiment,
The current blocking layer is composed of (Al _x Ga _1-x ) _0.5 In _0.5 P (x <1), and the cap etching stop layer is (Al _y Ga _1-y ) _0.5 In It is composed of _0.5 P (x <y).

According to the method for manufacturing the semiconductor laser device of the above embodiment, the current blocking layer is made of (Al _x Ga _1-x ) _0.5 In _0.5 P (x <1), and the cap etching stop layer is formed. Is made of (Al _y Ga _1-y ) _0.5 In _0.5 P (x <y), when the cap etching stop layer is etched with the second etchant, the current due to the penetration of the second etchant The influence on the blocking layer can be reduced.

In the manufacturing method of the semiconductor laser device of one embodiment,
Constitute the current blocking layer in GaAs, and constitute the cap etch stop layer _{(Al y Ga 1-y)} 0.5 In 0.5 P (y <1).

According to the method of manufacturing the semiconductor laser device of the above embodiment, the current blocking layer is made of GaAs, and the cap etching stop layer is (Al _y Ga _1-y ) _0.5 In _0.5 P (y < 1), when the cap etching stop layer is etched with the second etchant, the influence on the current blocking layer due to the penetration of the second etchant can be reduced.

In the manufacturing method of the semiconductor laser device of one embodiment,
The cladding layer is composed of (Al _x Ga _1-x ) _0.5 In _0.5 P (x = 0.5 to 0.8), and the cap etching stop layer is (Al _y Ga _1-y). ) _0.5 In _0.5 P (x <y).

According to the method of manufacturing a semiconductor laser device of the above embodiment, the cladding layer is made of (Al _x Ga _1-x ) _0.5 In _0.5 P (x = 0.5 to 0.8), and Since the cap etching stop layer is composed of (Al _y Ga _1-y ) _0.5 In _0.5 P (x <y), the second etching layer is used when the cap etching stop layer is etched with the second etchant. It is possible to reduce the influence of the etchant soaking on the cladding layer.

In the manufacturing method of the semiconductor laser device of one embodiment,
The cap etching stop layer is made of an Al _x Ga _1-x As material,
The upper cap layer and the lower cap layer are made of GaAs,
Using an ammonia-based etchant as the first etchant,
Hydrofluoric acid is used as the second etchant.

In the manufacturing method of the semiconductor laser device of one embodiment,
The cap etching stop layer is made of (Al _x Ga _1-x ) _0.5 In _0.5 P-based material,
The upper cap layer and the lower cap layer are made of GaAs,
Using an ammonia-based etchant as the first etchant,
Phosphoric acid is used as the second etchant.

  According to the semiconductor laser device manufacturing method of the present invention, the cap etching stop layer and the upper cap layer have a material composition that can be selectively removed by wet etching, and the cap etching stop layer and the lower cap layer are selected from each other. Since the material composition can be removed by wet etching, wet etching on the ridge stripe can be easily and reliably stopped by the lower cap layer.

  Therefore, the unnecessary current blocking layer on the ridge stripe can be easily and reliably removed without over-etching or under-etching.

  In addition, the unnecessary current blocking layer on the ridge stripe can be easily and reliably removed without over-etching or under-etching, so that a semiconductor laser can be manufactured with good reproducibility and stability.

  Further, since it is not necessary to define the thickness of the current blocking layer, there is a degree of freedom in designing the semiconductor laser element.

  Hereinafter, a method for manufacturing a semiconductor laser device of the present invention will be described in detail with reference to illustrated embodiments.

(First embodiment)
1A to 1F show process drawings of a method for manufacturing a semiconductor laser device according to the first embodiment of the present invention. In this manufacturing method, the semiconductor laser element is made of an AlGaAs material.

In the method of manufacturing the semiconductor laser device, first, as shown in FIG. 1A, an n-type GaAs buffer layer 102 (layer thickness 0.5 μm), n, and n are formed on an n-type GaAs substrate 101 by metal organic chemical vapor deposition. Type Al _x Ga _1-x As first cladding layer 103 (x = 0.485, layer thickness 1.5 μm), n-type Al _x Ga _1-x As second cladding layer 104 (x = 0.550, layer thickness) 0.2 μm), non-doped Al _x Ga _1-x As quantum well active layer 105, p-type Al _x Ga _1-x As first cladding layer 106 (x = 0.550, layer thickness 0.1 μm), p-type GaAs Etching stop layer 107 (layer thickness 26 mm), p-type Al _x Ga _1-x As second cladding layer 1108 (x = 0.550, layer thickness 1.0 μm), p-type GaAs lower cap layer 1109 (layer thickness 0. 4μm), p-type A _y Ga _1-y As cap etch stop layer 1110 (y = 0.700, thickness 0.1 [mu] m), is grown p-type GaAs on the cap layer 1111 (thickness 0.4 .mu.m) sequentially. The n-type GaAs buffer layer 102, the n-type Al _x Ga _1-x As first cladding layer 103, the n-type Al _x Ga _1-x As second cladding layer 104, and the p-type Al _x Ga _1-x As second The two cladding layers 1108 constitute an example of a semiconductor layer group.

Next, as shown in FIG. 1B, after a resist 112 having a mask pattern covering a predetermined region is formed by photolithography or the like, p-type GaAs upper cap layer 1111 and p-type Al _y on both sides of the predetermined region are etched. The Ga _1-y As cap etching stop layer 1110, the p-type GaAs lower cap layer 1109, and the p-type Al _x Ga _1-x As second cladding layer 1108 are removed by etching to form a ridge stripe 150.

The ridge stripe 150 includes a ridge stripe-shaped p-type GaAs upper cap layer 111, a p-type Al _y Ga _1-y As cap etching stop layer 110, a p-type GaAs lower cap layer 109, and a p-type Al _x Ga _1-x As. The second clad layer 108 is used.

  Next, after removing the resist 112, as shown in FIG. 1C, an n-type GaAs current blocking layer 1160 (layer thickness: 1.4 μm) is laminated so that no current flows outside the ridge stripe 150.

Next, in order to remove the unnecessary n-type GaAs current blocking layer 1160 on the ridge stripe 150, a resist 113 is formed on the portion other than the ridge stripe 150 by photolithography as shown in FIG. 1D. The unnecessary n-type GaAs current blocking layer 1160 and the p-type GaAs upper cap layer 111 are selectively removed by etching. Thus, the n-type GaAs current blocking layer is formed on both sides of the p-type Al _y Ga _1-y As cap etching stop layer 110, the p-type GaAs lower cap layer 109, and the p-type Al _x Ga _1-x As second cladding layer. 2160 is obtained.

  For the etching removal, an etchant that can selectively etch only GaAs without etching AlGaAs, for example, an ammonia hydrogen peroxide (ammonia water: hydrogen peroxide water: pure water = 1: 30: 50) etchant is used. This ammonia hydrogen peroxide etchant is an example of a first etchant.

Next, as shown in FIG. 1E, an etchant that can selectively etch only AlGaAs without etching GaAs, for example, only p-type Al _y Ga _1-y As cap etching stop layer 110 with hydrofluoric acid is selectively used. Etch away. This hydrofluoric acid is an example of a second etchant.

The p-type Al _y Ga _1-y As cap etching stop layer 110 has an Al mixed crystal ratio y of 0.700, and the p-type Al _x Ga _1-x As second cladding layer 108 has an Al mixed crystal ratio x of 0. .550. As a result, the p-type Al _y Ga _1-y As cap etching stop layer 110 has a higher hydrofluoric acid etching rate than the p-type Al _x Ga _1-x As second cladding layer 108. And can be removed in a short time. Therefore, even if hydrofluoric acid penetrates into the p-type Al _x Ga _1-x As second cladding layer 108 from the gap between the crystals, the influence is reduced.

If the Al mixed crystal ratio of the p _- type Al _y Ga _1-y As cap etching stop layer 110 is lower than the Al mixed crystal ratio of the p-type Al _x Ga _1-x As second cladding layer 108, the p-type The etching time of the Al _y Ga _1-y As cap etching stop layer 110 becomes longer, and the influence of the penetration of hydrofluoric acid into the p-type Al _x Ga _1-x As second cladding layer 108 also increases.

Similarly, since the n-type GaAs current blocking layer 2160 has a negligible etching rate with respect to hydrofluoric acid that etches the p-type Al _y Ga _1-y As cap etching stop layer 110, the p-type Al _y Ga _{1- The} etching of the _y As cap etching stop layer 110 does not affect the n-type GaAs current blocking layer 2160.

  Next, after removing the resist 113, as shown in FIG. 1F, a p-side electrode 114 is formed on the p-type GaAs lower cap layer 109 and the n-type GaAs current blocking layer 160, while under the n-type GaAs substrate 101. An n-side electrode 115 is formed on the substrate.

Finally, the wafer is cleaved in a direction perpendicular to the ridge stripe composed of the p-type GaAs lower cap layer 109 and the p-type Al _x Ga _1-x As second cladding layer 108 to form a plurality of laser bars. An insulating film is coated on both end faces of the laser bar (both end faces perpendicular to the ridge stripe), and each laser bar is divided into a plurality of parts.

Thus, on the p-type Al _x Ga _1-x As second cladding layer 108, a p-type GaAs lower cap layer 109, a p-type Al _y Ga _1-y As cap etching stop layer 110, and a p-type GaAs upper cap. Since the layer 111 is formed, each of the p-type Al _y Ga _1-y As cap etching stop layer 110 and the p-type GaAs upper cap layer 111 can be selectively removed by etching.

Therefore, it is possible to easily and reliably prevent the p-type GaAs lower cap layer 109 from being etched or the p-type Al _y Ga _1-y As cap etching stop layer 110 from remaining on the p-type GaAs lower cap layer 109. Can do.

  Therefore, the unnecessary n-type GaAs current blocking layer 1160 on the ridge stripe 150 can be easily and reliably removed without over-etching or under-etching.

  That is, a more stable wafer process was realized than in FIGS. 3A to 3D and Japanese Patent Application Laid-Open No. 2004-303897.

  In addition, since the thickness of the n-type GaAs current blocking layer 1160 need not be defined, there is a degree of freedom in designing the semiconductor laser device.

  In the first embodiment, the semiconductor laser device including the n-type GaAs current blocking layer 112 is manufactured. However, an actual refractive index confined semiconductor laser device including a current blocking layer made of n-type AlGaAs may be manufactured. .

In the case of the above-described real refractive index confined semiconductor laser device, current blocking against hydrofluoric acid is achieved by setting the Al mixed crystal ratio of n-type Al _z Ga _1-z As in the current blocking layer to, for example, z = 0.65. The etching rate of the layer becomes slower than the etching rate of the p-type Al _y Ga _1-y As cap etching stop layer 110 with respect to hydrofluoric acid.

Therefore, even in the case of the real refractive index confined semiconductor laser element, the current blocking layer is etched during the etching of the p-type Al _y Ga _1-y As cap etching stop layer 110 as in the first embodiment. The influence of the penetration of hydrofluoric acid in can be reduced.

(Second Embodiment)
2A to 2F show process diagrams of a method of manufacturing a semiconductor laser device according to the second embodiment of the present invention. In this manufacturing method, the semiconductor laser element is made of an AlGaInP-based material.

In the semiconductor laser device manufacturing method, first, as shown in FIG. 2A, an n-type Al _x Ga _1-x InP clad layer 202 (x = 0.65), a non-doped active layer 203 (multiple quantum well structure with an oscillation wavelength of 650 nm), a p-type Al _x Ga _1-x InP first cladding layer 204 (x = 0.65), a p-type GaInP etching stop layer 205, p-type Al _x Ga _1-x InP second cladding layer 1206 (x = 0.65), p-type GaInP intermediate layer 1207, p-type GaAs lower cap layer 1208, p-type Al _y Ga _1-y InP cap etching stop layer 1209 (y = 0.8) and the p-type GaAs upper cap layer 1210 are grown in order. The n-type Al _x Ga _1-x InP cladding layer 202, the non-doped active layer 203,..., And the p-type GaInP intermediate layer 1207 constitute an example of a semiconductor layer group.

Next, as shown in FIG. 2B, a resist 211 having a mask pattern covering a predetermined region is formed by photolithography or the like, and then p-type Al _x Ga _1-x InP second cladding on both sides of the predetermined region is etched. The ridge stripe 250 is formed by removing the layer 1206, the p-type GaInP intermediate layer 1207, the p-type GaAs lower cap layer 1208, the p-type Al _y Ga _1-y InP cap etching stop layer 1209, and the p-type GaAs upper cap layer 1210. To do.

The ridge stripe 250 includes a ridge stripe-shaped p-type Al _x Ga _1-x InP second cladding layer 206, a p-type GaInP intermediate layer 207, a p-type GaAs lower cap layer 208, and a p-type Al _y Ga _1-y InP cap. An etching stop layer 209 and a p-type GaAs upper cap layer 210 are included.

  Next, after removing the resist 211, an n-type GaAs current blocking layer 1260 is stacked so that no current flows outside the ridge stripe 250, as shown in FIG. 2C.

Next, in order to remove the unnecessary n-type GaAs current blocking layer 1260 on the ridge stripe 250, a resist 212 is formed on the portion other than the ridge stripe 250 by photolithography as shown in FIG. 2D. The unnecessary n-type GaAs current blocking layer 1260 and the p-type GaAs upper cap layer 210 are selectively etched away. Thus, both sides of the p-type Al _x Ga _1-x InP second cladding layer 206, the p-type GaInP intermediate layer 207, the p-type GaAs lower cap layer 208, and the p-type Al _y Ga _1-y InP cap etching stop layer 209. Thus, an n-type GaAs current blocking layer 2260 is obtained.

  For the etching removal, an etchant capable of selectively etching only GaAs without etching AlGaInP, for example, an ammonia hydrogen peroxide (ammonia water: hydrogen peroxide water: pure water = 1: 30: 50) etchant is used. This ammonia hydrogen peroxide system is an example of a first etchant.

Next, as shown in FIG. 2E, an etchant that can selectively etch only AlGaInP without etching GaAs, for example, only p-type Al _y Ga _1-y InP cap etching stop layer 209 is selectively etched away with phosphoric acid. To do. This phosphoric acid is an example of a second etchant.

The Al mixed crystal ratio x of the p-type Al _y Ga _1-y InP cap etching stop layer 209 is 0.8, and the Al mixed crystal ratio x of the p-type Al _x Ga _1-x InP second cladding layer 206 is 0. .65. Thereby, the p-type Al _y Ga _1-y InP cap etching stop layer 209 has a higher etching rate of phosphoric acid than the p-type Al _x Ga _1-x InP second cladding layer 206, Can be removed in a short time. Therefore, even if phosphoric acid penetrates into the p-type Al _x Ga _1-x InP second cladding layer 206 from the gap between the crystals, the influence is reduced.

If the Al mixed crystal ratio of the p _- type Al _y Ga _1-y InP cap etching stop layer 209 is lower than the Al mixed crystal ratio of the p-type Al _x Ga _1-x InP second cladding layer 206, the p-type The etching time of the Al _y Ga _1-y InP cap etching stop layer 209 is increased, and the influence of the penetration of phosphoric acid into the p-type Al _x Ga _1-x InP second cladding layer 206 is also increased.

Similarly, the n-type GaAs current blocking layer 2260 has a negligible etching rate with respect to phosphoric acid that etches the p-type Al _y Ga _1-y InP cap etching stop layer 209, so that the p-type Al _y Ga _{1 -y} The etching of the InP cap etching stop layer 209 does not affect the n-type GaAs current blocking layer 2260.

  Next, after removing the resist 212, as shown in FIG. 2F, a p-side electrode 213 is formed on the p-type GaAs lower cap layer 208 and the n-type GaAs current blocking layer 260, while under the n-type GaAs substrate 201. An n-side electrode 214 is formed on the substrate.

Finally, the wafer is cleaved in a direction perpendicular to the ridge stripe composed of the p-type Al _x Ga _1-x InP second clad layer 206, the p-type GaInP intermediate layer 207, and the p-type GaAs lower cap layer 208, and a plurality of A laser bar is formed, and both end faces (both end faces perpendicular to the ridge stripe) of each laser bar are coated with an insulating film to divide each laser bar into a plurality of parts.

Thus, on the p-type Al _x Ga _1-x InP second cladding layer 206, a p-type GaInP intermediate layer 207, a p-type GaAs lower cap layer 208, and a p-type Al _y Ga _1-y InP cap etching stop layer. Since 209 and the p-type GaAs upper cap layer 210 are formed, the p-type Al _y Ga _1-y InP cap etching stop layer 209 and the p-type GaAs upper cap layer 210 can be selectively removed by etching.

Therefore, it is possible to easily and reliably prevent the p-type GaAs lower cap layer 208 from being etched or the p-type Al _y Ga _1-y InP cap etching stop layer 209 from remaining on the p-type GaAs lower cap layer 208. Can do.

  Therefore, the unnecessary n-type GaAs current blocking layer 1160 on the ridge stripe 250 can be easily and reliably removed without causing over-etching or under-etching.

  That is, a more stable wafer process was realized than in FIGS. 3A to 3D and Japanese Patent Application Laid-Open No. 2004-303897.

  Further, since it is not necessary to define the thickness of the n-type GaAs current blocking layer 1160, there is a degree of freedom in designing the semiconductor laser device.

  In the second embodiment, the semiconductor laser device including the n-type GaAs current blocking layer 260 is manufactured. However, an actual refractive index confined semiconductor laser device including a current blocking layer made of n-type AlGaInP may be manufactured. .

In the case of the above-described real refractive index confined semiconductor laser element, by setting the Al mixed crystal ratio of n-type Al _z Ga _1-z InP in the current blocking layer to, for example, z = 0.75, the current blocking layer against phosphoric acid The etching rate is slower than the etching rate of the p-type Al _y Ga _1-y InP cap etching stop layer 209 with respect to phosphoric acid.

  Therefore, even in the real refractive index confined semiconductor laser element, the influence of the penetration of phosphoric acid in the current blocking layer can be reduced as in the second embodiment.

FIG. 1A is a process diagram of a semiconductor laser device manufacturing method according to a first embodiment of the present invention. FIG. 1B is a process drawing of the method for manufacturing the semiconductor laser element according to the first embodiment of the present invention. FIG. 1C is a process diagram of the method for manufacturing the semiconductor laser element according to the first embodiment of the present invention. FIG. 1D is a process drawing of the method for manufacturing the semiconductor laser element according to the first embodiment of the present invention. FIG. 1E is a process drawing of the semiconductor laser device manufacturing method according to the first embodiment of the present invention. FIG. 1F is a process drawing of the method for manufacturing the semiconductor laser element according to the first embodiment of the present invention. FIG. 2A is a process diagram of a semiconductor laser device manufacturing method according to a second embodiment of the present invention. FIG. 2B is a process drawing of the method for manufacturing the semiconductor laser element according to the second embodiment of the present invention. FIG. 2C is a process drawing of the method for manufacturing the semiconductor laser element according to the second embodiment of the present invention. FIG. 2D is a process drawing of the method for manufacturing a semiconductor laser element according to the second embodiment of the present invention. FIG. 2E is a process drawing of the method for manufacturing a semiconductor laser element according to the second embodiment of the present invention. FIG. 2F is a process drawing of the method for manufacturing a semiconductor laser element according to the second embodiment of the present invention. FIG. 3A is a process diagram of a conventional method for manufacturing a semiconductor laser device. FIG. 3B is a process diagram of a conventional method for manufacturing a semiconductor laser device. FIG. 3C is a process diagram of a conventional method for manufacturing a semiconductor laser device. FIG. 3D is a process diagram of a conventional method of manufacturing a semiconductor laser element.

Explanation of symbols

101 n-type GaAs substrate 102 n-type GaAs buffer layer 103 n-type Al _x Ga _1-x As first cladding layer 104 n-type Al _x Ga _1-x As second cladding layer 105 non-doped Al _x Ga _1-x As quantum well Active layer 106 p-type Al _x Ga _1-x As first cladding layer 107 p-type GaAs etching stop layer 108, 1108 p-type Al _x Ga _1-x As second cladding layer 109, 1109 p-type GaAs lower cap layer 110, 1110 p-type _Al y _{Ga 1-y} As cap etch stop layer 111,1111 p-type GaAs on the cap layer 150 ridge stripe 160,1160,21060 n-type GaAs current blocking layer 201 n-type GaAs substrate 202 n-type _Al x _{Ga 1- x} InP cladding layer 203 an undoped active layer 20 p-type _Al x _{Ga 1-x} InP first cladding layer 205 p-type GaInP etching stop layer 206,1206 p-type _Al x _{Ga 1-x} InP second cladding layer 207,1207 p-type GaInP intermediate layer 208,1208 p-type GaAs Lower cap layer 209, 1209 p-type Al _y Ga _1-y InP cap etching stop layer 210, 1210 p-type GaAs upper cap layer 150 ridge stripe 260, 1260, 2260 n-type GaAs current blocking layer

Claims (10)

Forming a semiconductor layer group on the substrate;
A step of sequentially forming a lower cap layer, a cap etching stop layer and an upper cap layer on the semiconductor layer group;
Processing the lower cap layer, the cap etching stop layer and the upper cap layer into a ridge stripe shape to form a ridge stripe;
Forming a current blocking layer on both sides of the ridge stripe-shaped lower cap layer, cap etching stop layer and upper cap layer;
Removing the ridge stripe-shaped upper cap layer with a first etchant and then removing the ridge stripe-shaped cap etching stop layer with a second etchant;
The material composition of the cap etching stop layer is different from the material composition of the upper cap layer and the lower cap layer,
The cap etching stop layer and the upper cap layer have a material composition that can be selectively removed by wet etching,
The method of manufacturing a semiconductor laser device, wherein the cap etching stop layer and the lower cap layer have material compositions that can be selectively removed by wet etching. In the manufacturing method of the semiconductor laser device according to claim 1,
The cap etching stop layer is configured with a material composition in which an etching rate of the cap etching stop layer with respect to the second etchant is higher than an etching rate of the current blocking layer with respect to the second etchant. Manufacturing method of semiconductor laser device. In the manufacturing method of the semiconductor laser device according to claim 1,
The semiconductor layer group includes a cladding layer,
A semiconductor comprising the cap etching stop layer having a material composition in which an etching rate of the cap etching stop layer with respect to the second etchant is higher than an etching rate of the cladding layer with respect to the second etchant. A method for manufacturing a laser element. In the manufacturing method of the semiconductor laser device according to claim 2,
The current blocking layer is made of Al _x Ga _1-x As (x = 0 to 0.7), and the cap etching stop layer is made of Al _y Ga _1-y As (x <y). A method of manufacturing a semiconductor laser device. In the manufacturing method of the semiconductor laser device according to claim 3,
The cladding layer is made of Al _x Ga _1-x As (x = 0.4 to 0.6), and the cap etching stop layer is made of Al _y Ga _1-y As (x <y). A method for manufacturing a semiconductor laser device, comprising: In the manufacturing method of the semiconductor laser device according to claim 2,
The current blocking layer is composed of (Al _x Ga _1-x ) _0.5 In _0.5 P (x <1), and the cap etching stop layer is (Al _y Ga _1-y ) _0.5 In _A method of manufacturing a semiconductor laser device, characterized by comprising _0.5 P (x <y). In the manufacturing method of the semiconductor laser device according to claim 2,
A semiconductor laser device, wherein the current blocking layer is made of GaAs, and the cap etching stop layer is made of (Al _y Ga _1-y ) _0.5 In _0.5 P (y <1). Manufacturing method. In the manufacturing method of the semiconductor laser device according to claim 3,
The cladding layer is composed of (Al _x Ga _1-x ) _0.5 In _0.5 P (x = 0.5 to 0.8), and the cap etching stop layer is (Al _y Ga _1-y). ) _0.5 In _0.5 P (x <y) In the manufacturing method of the semiconductor laser device according to claim 4 or 5,
The cap etching stop layer is made of an Al _x Ga _1-x As material,
The upper cap layer and the lower cap layer are made of GaAs,
Using an ammonia-based etchant as the first etchant,
A method of manufacturing a semiconductor laser device, wherein hydrofluoric acid is used as the second etchant. In the manufacturing method of the semiconductor laser device according to any one of claims 6 to 8,
The cap etching stop layer is made of (Al _x Ga _1-x ) _0.5 In _0.5 P-based material,
The upper cap layer and the lower cap layer are made of GaAs,
Using an ammonia-based etchant as the first etchant,
A method of manufacturing a semiconductor laser device, wherein phosphoric acid is used as the second etchant.

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