JP2009194307A - Junction-up type optical semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a junction-up type optical semiconductor element, in which the capacitance can be reduced, while suppressing breakage of an insulating film. <P>SOLUTION: A semiconductor laser element 1 includes a substrate 11; a semiconductor laminate section 12 which is formed on the substrate 11 and has a stripe portion; an insulating film 13 which is formed on the semiconductor laminate section 12 so as to expose the stripe portion 28; a bonding pad 18 which has a p-side electrode 15, electrically connected to the stripe portion 28 which is exposed from the insulating film 13 and multiple bonding portions 16, and 17 formed on the insulating film 13 so as to be spaced from each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a junction-up type optical semiconductor element in which a stripe portion side is wire-bonded.

  2. Description of the Related Art Conventionally, an optical semiconductor device such as a semiconductor laser device having a semiconductor laminated portion in which a stripe portion is formed is known. As one of such optical semiconductor elements, there is a junction-up type in which the stripe portion side is wire-bonded (see Patent Document 1).

  14 and 15 includes a substrate 101, a semiconductor laminated portion 102, an insulating film 103, an n-side electrode 104 die-bonded to a submount, and a wire 110. Bonding pad 105. The semiconductor laminated portion 102 is formed on the substrate 101 and has a stripe portion 106 for confining current. The insulating film 103 is formed on the upper surface of the semiconductor stacked portion 102, and an opening 103a is formed so that the stripe portion 106 is exposed. The n-side electrode 104 is formed so as to cover the back surface of the substrate 101. The bonding pad 105 has a p-side electrode part 105a electrically connected to the stripe part 106, and a bonding part 105b to which the wire 110 is bonded. The p-side electrode portion 105 a is formed over the entire length of the stripe portion 106. The bonding part 105 b is formed so as to cover a part of the insulating film 103.

In the above-described optical semiconductor device 100, when a voltage is applied between the n-side electrode 104 and the bonding pad 105, a current flows only in the stripe portion 106 below the bonding pad 105 and the stacking direction in the vicinity thereof. As a result, the semiconductor laminated portion 102 is in an inversion distribution state, and stimulated emission occurs to emit light.
JP 2001-358404 A

  However, the junction-up type optical semiconductor device 100 shown in FIGS. 14 and 15 has a problem that the entire surface of the bonding pad 105 and the semiconductor laminated portion 102 have a capacitor structure, and unnecessary capacitance is generated. In particular, the bonding pad 105 in a region where the wire 110 is not bonded has a capacitance even though it has no function. Therefore, as shown in FIG. 16, it is conceivable to reduce the plane area of the bonding portion 105 b in accordance with the bottom surface of the wire 110. However, when the bonding portion 105b is reduced in this manner, there is a problem that the insulating film 103 is damaged when the wire 110 is displaced from a desired position. Furthermore, since an electrostatic capacitance is generated in the region of the wire 110 that is in contact with the insulating film 103, the effect of reducing the bonding portion 105b is lost.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a junction-up type optical semiconductor element capable of reducing capacitance while suppressing breakage of an insulating film.

  In order to achieve the above object, the invention according to claim 1 is directed to a substrate, a semiconductor stacked portion formed on the substrate and formed with a stripe portion, and the semiconductor stacked portion so that the stripe portion is exposed. An insulating film formed thereon; an electrode portion electrically connected to the stripe portion exposed from the insulating film; and a plurality of bonding portions formed on the insulating film at intervals. A junction-up type optical semiconductor element comprising a bonding pad.

  According to a second aspect of the present invention, in the junction according to the first aspect, the bonding portion is disposed at a distance from the electrode portion and is electrically insulated from the electrode portion. This is an up-type optical semiconductor element.

  In the invention according to claim 3, the junctions according to claim 1 or 2, wherein the plurality of bonding portions are arranged in a matrix at intervals. This is an up-type optical semiconductor element.

  The invention according to claim 4 is the junction-up type optical semiconductor according to any one of claims 1 to 3, wherein the electrode part and the bonding part are made of the same material. It is an element.

  The invention according to claim 5 is the junction up according to any one of claims 1 to 4, wherein the plurality of bonding portions are arranged on both sides of the electrode portion. Type optical semiconductor element.

  According to the present invention, since the gap is formed between the plurality of bonding portions, the bonded wires are floated from the insulating film between the bonding portions. Therefore, even when a voltage is applied to the wire, there is almost no capacitance in the region where the interval is formed. As a result, the capacitance can be reduced without reducing the area where the bonding pads are formed. In addition, since it is not necessary to reduce the region where the bonding pad is formed, it is possible to suppress the wire from being removed from the bonding pad and bonded onto the insulating film. Thereby, damage to the insulating film can be suppressed. As a result, the capacitance can be reduced while suppressing damage to the insulating film.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a semiconductor laser device will be described with reference to the drawings. The semiconductor laser device according to the first embodiment can be applied to an optical disk device, a laser printer, an optical communication device, and the like.

  FIG. 1 is an overall perspective view of the semiconductor laser device according to the first embodiment. FIG. 2 is a plan view of the semiconductor laser element. FIG. 3 is a sectional view taken along line III-III in FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  As shown in FIG. 1, the semiconductor laser device 1 according to the first embodiment is a junction-up type in which a wire 31 is bonded to a stripe portion 28 described later. As shown in FIGS. 1 to 4, the semiconductor laser device 1 includes a substrate 11, a semiconductor laminated portion 12, an insulating film 13, an n-side electrode 14, a p-side electrode portion 15, and bonding portions 16 and 17. And a bonding pad 18. The p-side electrode portion 15 corresponds to the electrode portion described in claim 1.

  The substrate 11 is made of conductive n-type GaN. In plan view, the substrate 11 has a width on the X direction side of about 200 μm and a length on the Y direction side of about 400 μm.

  As shown in FIG. 4, the semiconductor stacked portion 12 is formed on a surface (hereinafter referred to as a main surface) 11 a on the + Z direction side of the substrate 11. The semiconductor laminated portion 12 includes an n-type cladding layer 21, an n-type guide layer 22, an active layer 23, a p-type electron blocking layer 24, a p-type guide layer 25, a p-type cladding layer 26, and a p-type. A contact layer 27 is laminated in order from the substrate 11 side.

  The n-type cladding layer 21 is for confining the light emitted from the active layer 23. The n-type cladding layer 21 is composed of an n-type AlGaN layer doped with Si as an n-type impurity.

  The n-type guide layer 22 is for guiding the light emitted from the active layer 23. The n-type guide layer 22 is composed of an n-type GaN layer doped with Si as an n-type impurity.

  The active layer 23 is for emitting light by stimulated emission. The active layer 23 has an MQW (multiple quantum wells) structure in which a plurality of non-doped InGaN layers (well layers) and GaN layers (barrier layers) are alternately stacked.

  The p-type electron blocking layer 24 is for suppressing electrons injected from the n-side electrode 14 from reaching the p-type semiconductor side. The p-type electron block layer 24 is composed of a p-type AlGaN layer doped with Mg as a p-type impurity.

  The p-type guide layer 25 is for guiding the light emitted from the active layer 23. The p-type guide layer 25 is composed of a p-type GaN layer doped with Mg as a p-type impurity. A convex portion 25 a is formed at the center of the p-type guide layer 25 in the X direction.

  The p-type cladding layer 26 is for confining light emitted from the active layer 23. The p-type cladding layer 26 is formed on the convex portion 25 a of the p-type guide layer 25. The p-type cladding layer 26 is made of a p-type AlGaN layer doped with Mg as a p-type impurity.

  The p-type contact layer 27 is for reducing the electrical resistance between the p-side electrode portion 15 and the semiconductor stacked portion 12. The p-type contact layer 27 is a p-type GaN layer doped with Mg as a p-type impurity.

  A ridge-shaped stripe portion 28 is formed on the + Z direction side of the semiconductor stacked portion 12. The stripe portion 28 is for narrowing the current. The stripe part 28 is formed in the center part in the X direction. The stripe portion 28 has a width in the X direction of 5 μm or less and a height in the Z direction of several μm. The stripe part 28 is formed so as to extend over the entire length in the Y direction. The stripe portion 28 is constituted by a convex portion 25 a of the p-type guide layer 25, a p-type cladding layer 26, and a p-type contact layer 27.

  A Fabry-Perot resonator having a pair of reflective films (not shown) is provided on both end surfaces in the Y direction of the semiconductor laminated portion 12.

The insulating film 13 is for preventing the bonding pad 18 and the semiconductor laminated portion 12 from being electrically connected in a region other than the stripe portion 28. Insulating film 13 is made of a ZrO _2. The insulating film 13 may be made of an insulating material such as Al ₂ O ₃ or SiO ₂ . The insulating film 13 is formed so as to cover substantially the entire area of the surface on the + Z direction side of the semiconductor stacked portion 12. An opening 13a for exposing the upper surface of the stripe portion 28 is formed at the center of the insulating film 13 in the X direction. The opening 13a is formed over the entire length in the Y direction.

  The n-side electrode 14 is for injecting electrons into the semiconductor stacked portion 12 through the substrate 11. The n-side electrode 14 is connected to the outside through an electrode of a submount (not shown). The n-side electrode 14 is made of Al that is ohmically connected to the substrate 11. The n-side electrode 14 is formed so as to cover the surface (hereinafter referred to as the back surface) 11 b on the −Z direction side of the substrate 11.

  A wire 31 is bonded to the bonding pad 18. Hereinafter, the p-side electrode portion 15 and the bonding portions 16 and 17 of the bonding pad 18 will be described.

  The p-side electrode portion 15 is for injecting holes from the stripe portion 28 into the semiconductor stacked portion 12. The p-side electrode portion 15 has a laminated structure of Au, Pt (or a barrier metal such as Mo or W), and Au. The p-side electrode portion 15 is formed in the stripe portion 28 and its vicinity. The p-side electrode portion 15 has a width in the X direction of about 5 μm and a length in the Y direction of about 400 μm. That is, the p-side electrode portion 15 is formed over the entire length in the Y direction. The p-side electrode portion 15 is ohmically connected to the upper surface of the stripe portion 28 exposed from the insulating film 13.

  The bonding parts 16 and 17 are for suppressing damage of the insulating film 13 due to the wire 31. The bonding parts 16 and 17 have a laminated structure of Au, Pt (or a barrier metal such as Mo and W), and Au, similarly to the p-side electrode part 15. The bonding parts 16 and 17 are formed on the insulating film 13. The bonding portion 16 and the bonding portion 17 are formed in symmetrical shapes at symmetrical positions with the p-side electrode portion 15 in between. Each bonding portion 16 (17) has a length in the X direction of about 62.5 μm and a width in the Y direction of about 18 μm. An interval of about 10 μm is formed in the Y direction between adjacent bonding portions 16 (17). Here, the distance between adjacent bonding portions 16 (17) is not particularly limited, but as shown in FIG. 3, the bonded wire 31 is not in contact with the insulating film 13. Is preferred.

  Next, the operation of the above-described semiconductor laser element 1 will be described.

  First, a voltage is applied to the n-side electrode 14 and the p-side electrode portion 15 through the wire 31 and the submount electrode. As a result, electrons are injected from the n-side electrode 14 into the semiconductor multilayer portion 12, and holes are injected from the p-side electrode portion 15 into the semiconductor multilayer portion 12. The electrons and holes injected into the semiconductor stacked portion 12 recombine in the active layer 23 to emit light. The emitted light is guided through the active layer 23 in the inverted distribution state. The light guided in the Y direction reciprocates between the end faces to cause stimulated emission, and then is emitted as laser light from one end face.

  Next, a method for manufacturing the semiconductor laser device 1 described above will be described. 5 to 10 are views for explaining a manufacturing process of the semiconductor laser device of the first embodiment.

First, as shown in FIG. 5, the substrate 11 is introduced into a chamber of an MOCVD (metal organic chemical vapor deposition) apparatus (not shown), and the semiconductor stacked portions 12 are sequentially stacked on the main surface 11 a of the substrate 11. Specifically, any one of silane gas, TMG (trimethylgallium), TMA (trimethylaluminum), and ammonia gas is supplied to the chamber of the MOCVD apparatus at a desired flow rate to grow the n-type semiconductor layers 21 and 22. Next, any of TMI (trimethylindium), TMG, and ammonia gas is supplied to the chamber at a desired flow rate to grow the active layer 23. Thereafter, any one of Cp ₂ Mg (biscyclopentadienyl magnesium) gas, TMA, TMG, and ammonia gas is supplied to the chamber at a desired flow rate to form p-type semiconductor layers 24-27.

Next, as shown in FIG. 6, a first mask layer 45 made of SiO ₂ is formed by a sol-gel method. Thereafter, a second mask layer 46 made of a SiN layer is formed by sputtering. Here, the etching rate of the first mask layer 45 formed by the sol-gel method is higher than that of the second mask layer 46 formed by the sputtering method. Thereafter, a patterned resist film 47 is formed by photolithography.

  Next, as shown in FIG. 7, the second mask layer 46 and the first mask layer 45 in the region exposed from the resist film 47 are etched. Thereafter, the resist film 47 is removed.

  Next, as shown in FIG. 8, dry etching is performed up to the middle of the p-type contact layer 27, the p-type cladding layer 26, and the p-type guide layer 25 in the regions exposed from the mask layers 45 and 46. Thereby, the stripe part 28 is formed.

Next, as shown in FIG. 9, the side surface of the first mask layer 45 is selectively etched with buffered hydrofluoric acid that is a 1-hydrogen 2-ammonium fluoride solution, so that a part of the upper surface of the p-type contact layer 27 is formed. To expose. Thereafter, an insulating film 13 made of a ZrO ₂ layer is formed by sputtering. Then, the second mask layer 46 and the first mask layer 45 are removed together with the insulating film 13b on the second mask layer 46 by immersing the stripe portion 28 in buffered hydrofluoric acid again.

  Next, a resist film (not shown) is formed by photolithography. Then, as shown in FIG. 10, a bonding pad 18 having a p-side electrode portion 15 having a laminated structure of Au, Pt, and Au and bonding portions 16 and 17 is formed by a sputtering method. Thereafter, the resist film is removed together with the metal layer thereon.

  Next, after the back surface 11b of the substrate 11 is polished, the n-side electrode 14 made of Al is formed on the entire back surface 11b of the substrate 11. Then, it is divided into element units. Thereby, the semiconductor laser device 1 shown in FIG. 1 is completed.

  Thereafter, after the n-side electrode 14 is bonded to the submount, the wire 31 is bonded to the region where the bonding portions 16 and 17 of the bonding pad 18 are formed.

As described above, in the semiconductor laser device 1 according to the first embodiment, an interval is formed between a plurality of adjacent bonding portions 16 (17). Therefore, the wire 31 is bonded so as to straddle between the adjacent bonding portions 16 (17). As a result, the wire 31 floats from the insulating film 13 between the adjacent bonding portions 16 (17). For this reason, even if a voltage is applied to the wire 31, a region where the bonding portion 16 (17) is not formed (62.5 [μm] × 10 [μm] × 8≈5.0 × 10 ³ [μm ² ]) ) Hardly generates a capacitance. As a result, unnecessary capacitance can be reduced.

  Further, in the semiconductor laser element 1, since it is not necessary to reduce the region where the bonding pad 18 is formed, a high degree of positional accuracy is not required when the wire 31 is bonded. For this reason, since it can suppress that the wire 31 remove | deviates from the bonding pad 18 and is bonded on the insulating film 13, damage to the insulating film 13 can be suppressed. Furthermore, since the wire 31 is in a floating state between the adjacent bonding portions 16 (17), it is possible to prevent the insulating film 13 from being damaged.

  As a result, in the semiconductor laser device 1, the capacitance can be reduced while the damage of the insulating film 13 is suppressed.

  Further, in the semiconductor laser element 1, since the bonding portion 16 and the bonding portion 17 are formed symmetrically with the p-side electrode portion 15 in between, the bonding balance can be improved.

  Moreover, in the semiconductor laser element 1, since the p-side electrode part 15 and the bonding parts 16 and 17 are comprised with the same material, they can be formed in the same manufacturing process. Thereby, complication of a manufacturing process can be controlled.

(Second Embodiment)
Next, a second embodiment in which a part of the first embodiment described above is changed will be described with reference to the drawings. FIG. 11 is an overall perspective view of the semiconductor laser device according to the second embodiment. 12 and 13 are plan views of the semiconductor laser element. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIGS. 11 and 12, in the bonding pad 18A of the semiconductor laser device 1A according to the second embodiment, the bonding portions 16A and 17A are formed in a square shape having a side of about 20 μm in plan view. . The bonding portions 16A (17A) are arranged in a matrix of 3 × 10 in the X direction and the Y direction, respectively. Here, an interval of about 5 μm is formed between adjacent bonding portions 16A (17A). An interval of about 5 μm is also formed between the p-side electrode portion 15 and the bonding portion 16A (17A). As a result, the p-side electrode portion 15 and the bonding portion 16A (17A) are electrically insulated.

Here, as shown in FIG. 12, when the wire 31 is bonded so that the center of the wire ball at the tip of the wire 31 is on the p-side electrode portion 15, the bonding portion 16 </ b> A in contact with the wire 31. , 17A (see hatching in FIG. 12), and between the p-side electrode portion 15 and the semiconductor laminated portion 12, a capacitance is generated. However, no electrostatic capacitance is generated between the bonding portions 16 </ b> A and 17 </ b> A that are not in contact with the wire 31 and the semiconductor laminated portion 12. That is, a region where 20 bonding portions 16A and 17A and the p-side electrode portion 15 are formed (20 [μm] × 20 [μm] × 18 + 400 [μm] × 5 [μm] = 9.2 × 10 ³ [ Capacitance occurs only in μm ² ]).

  Further, as shown in FIG. 13, even when the center of the wire 31 is displaced from the p-side electrode portion 15, the capacitance is hardly changed. Furthermore, since it is not necessary to reduce the area in which the bonding portions 16A and 17A are formed, the bonding of the wire 31 onto the insulating film 13 can be suppressed even if the position of the wire 31 is shifted.

  As a result, in the semiconductor laser device 1A according to the second embodiment, it is possible to realize a reduction in capacitance while suppressing damage to the insulating film 13.

  Further, since the bonding portions 16A and 17A that do not contact the wire 31 do not generate capacitance, the bonding portions 16A and 17A can be formed over the entire area on the insulating film 13. As a result, there is a margin in positional accuracy when the wire 31 is bonded.

  As mentioned above, although this invention was demonstrated in detail using embodiment, this invention is not limited to embodiment described in this specification. The scope of the present invention is determined by the description of the claims and the scope equivalent to the description of the claims. Hereinafter, modified embodiments in which the above-described embodiment is partially modified will be described.

  For example, the shape, material, numerical value, and the like of the above-described embodiment are examples and can be changed as appropriate.

  In the above-described embodiments, examples in which the present invention is applied to semiconductor laser elements have been described. However, the present invention may be applied to other optical semiconductor devices. For example, the present invention may be applied to a semiconductor optical amplifier (SOA) in which a pair of antireflection films are formed on the end face instead of the reflection film.

  In the above-described embodiment, the GaN-based semiconductor is taken as an example, but other GaAs-based semiconductors, Si-based semiconductors, InGaP-based semiconductors, and the like may be applied.

  In the above-described embodiments, the optical semiconductor element having a ridge-shaped stripe portion has been described. However, the present invention may be applied to an optical semiconductor element having a buried stripe portion.

1 is an overall perspective view of a semiconductor laser device according to a first embodiment. It is a top view of a semiconductor laser element. It is sectional drawing along the III-III line of FIG. It is sectional drawing along the IV-IV line of FIG. It is a figure explaining the manufacturing process of the semiconductor laser element of 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor laser element of 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor laser element of 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor laser element of 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor laser element of 1st Embodiment. It is a figure explaining the manufacturing process of the semiconductor laser element of 1st Embodiment. It is a whole perspective view of the semiconductor laser element by 2nd Embodiment. It is a top view of a semiconductor laser element. It is a top view of a semiconductor laser element. It is a whole perspective view of the conventional semiconductor laser element. It is a top view of the conventional semiconductor laser element. It is a top view of the conventional semiconductor laser element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A Semiconductor laser element 11 Board | substrate 11a Main surface 11b Back surface 12 Semiconductor laminated part 13 Insulating film 13a Opening part 13b Insulating film 14 N side electrode 15 P side electrode part 16, 16A, 17, 17A Bonding part 18, 18A Bonding pad 21 n-type cladding layer 22 n-type guide layer 23 active layer 24 p-type semiconductor layer 24 p-type electron block layer 25a convex portion 25 p-type guide layer 26 p-type cladding layer 27 p-type contact layer 28 stripe portion 31 wire

Claims (5)

A substrate,
A semiconductor laminated portion formed on the substrate and having a stripe portion formed thereon;
An insulating film formed on the semiconductor stacked portion so that the stripe portion is exposed;
A bonding pad having an electrode portion electrically connected to the stripe portion exposed from the insulating film and a plurality of bonding portions formed on the insulating film at intervals from each other; A junction-up type optical semiconductor device characterized.   The junction-up type optical semiconductor device according to claim 1, wherein the bonding portion is disposed with a gap from the electrode portion and is electrically insulated from the electrode portion.   3. The junction-up type optical semiconductor device according to claim 1, wherein the plurality of bonding portions are arranged in a matrix at intervals. 4.   The junction-up type optical semiconductor device according to any one of claims 1 to 3, wherein the electrode part and the bonding part are made of the same material.   5. The junction-up type optical semiconductor device according to claim 1, wherein the plurality of bonding portions are disposed on both sides of the electrode portion. 6.

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