WO2004008548A1 - Semiconductor light source device - Google Patents

Abstract

A semiconductor light source device (10) comprising a semiconductor laser diode (12) and a photodiode (18). Since a pn junction is formed up to the end face, out of a plurality of end faces of the photodiode (18), in the vicinity of a region where a monitor laser light (16) emitted from at least the monitor laser light emitting face (15) of the semiconductor laser diode (12) enters, light receiving sensitivity characteristics stabilized against temperature variation are attained. Consequently, a stabilized laser output can be obtained from the semiconductor laser diode (12).

Description

 Statement

Semiconductor light source device

Technical field

 The present invention relates to a semiconductor light source device, and more particularly to a semiconductor light source device, including a semiconductor light emitting element such as a semiconductor laser diode, and a photodiode for receiving monitor light emitted from the semiconductor light emitting element, based on a monitor output of the photodiode. The present invention relates to a semiconductor light source device that controls the intensity of output light emitted from a semiconductor light emitting element.

 Landscape

 Conventionally, as a technique in such a field, there is Japanese Patent Application Laid-Open No. 4-147690. The semiconductor light source device described in this publication receives a monitoring laser beam emitted downward from a monitoring laser beam emitting surface of a semiconductor laser diode to a photodiode fixed on a stem. Then, based on the monitor output by the photodiode, the output of the laser light emitted upward from the laser light emission surface opposite to the monitor laser light emission surface is controlled. Also, in this semiconductor light source device, the monitor laser light reflected from the photodiode surface is fixed by fixing the photodiode on the stem so that the optical axis of the monitor laser light does not cross the surface of the photodiode. The laser light emitted from the light emitting surface is prevented from overlapping.

Disclosure of the invention

 However, the photodiode provided in the conventional semiconductor light source device has a problem that the light receiving sensitivity fluctuates greatly with a change in temperature. As a result, the output control of the semiconductor laser diode becomes difficult. It was difficult.

 [0104] The present invention has been made to solve the above problems, and provides a semiconductor light source device including a photodiode capable of obtaining a stable light receiving sensitivity even with a temperature change.

[0105] The inventors of the present invention have disclosed that a conventional semiconductor light source device has a photo die. We have discovered that the reason why the light receiving sensitivity of the photodiode fluctuates greatly due to temperature changes is that the monitoring laser beam is incident on the fluctuation region around the photosensitive region of the photodiode. Here, the photosensitive region is a region having a first conductive type semiconductor layer and a second conductive type semiconductor layer in a planar structure, and the variable region is a region where the second conductive type semiconductor layer is not formed. Say.

 [0106] Therefore, in order to solve the above problem based on such knowledge, a semiconductor light source device of the present invention includes a semiconductor light emitting element and a photodiode that receives monitor light of the semiconductor light emitting element. In a semiconductor light source device for controlling the intensity of output light emitted from the semiconductor light emitting element based on a monitor output of the photodiode, the semiconductor light emitting element is arranged in a region deviated from a center of a light receiving surface of the photodiode. The photodiode is characterized in that 11 junctions are formed at least up to the end face near the area where the monitor light is incident among the plurality of end faces.

 [0107] According to the present invention, of the plurality of end faces of the photodiode provided in the semiconductor light source device, at least up to the end face near the region where the monitor light is incident!) An n-junction is formed. That is, the light-sensitive region is formed up to the end face where the pn junction is formed, and the above-mentioned fluctuation region can be eliminated in the region where the monitor light enters. As a result, the light receiving sensitivity of the photodiode can be stabilized against a temperature change.

[0108] Further, in order to solve the above problem, a semiconductor light source device of the present invention includes a semiconductor light emitting element, and a photodiode that receives monitor light of the semiconductor light emitting element, and a monitor output of the photodiode is provided. In the semiconductor light source device for controlling the intensity of output light emitted from the semiconductor light emitting element, the semiconductor light emitting element is arranged such that an emission optical axis of the monitor light is located in a region deviated from a center of a light receiving surface of the photodiode. In the photodiode, a separation groove is formed in the semiconductor substrate deeper than the first conductivity type layer and the second conductivity type layer, and a diode is formed from the bottom of the separation groove. An end formed by cutting the semiconductor substrate by ising is provided at least near a region where the monitor light is incident.

 [0109] According to the present invention, in the photodiode provided in the semiconductor light source device, the separation groove is formed in the semiconductor substrate deeper than the first conductivity type layer and the second conductivity type layer, and the bottom of the separation groove is formed. An end formed by cutting the semiconductor substrate by dicing is provided at least near a region where monitor light emitted from the semiconductor light emitting element is incident. In other words, since the pn junction is formed up to this end, the above-mentioned fluctuation region can be eliminated in the region where the monitor light is incident. As a result, the light receiving sensitivity of the photodiode can be stabilized against temperature changes. Also, since the semiconductor substrate is cut by dicing from the bottom of the separation groove, damage to the pn junction formed up to the end can be prevented as compared with the case where the pn junction is exposed by dicing. .

 [0100] In the semiconductor light source device of the present invention, it is preferable that a light-blocking member is embedded in the separation groove.

 According to the present invention, since the light shielding member is embedded in the separation groove, it is possible to prevent the monitor light from entering the inner surface of the separation groove, that is, the pn junction formed at the end of the photodiode. be able to.

 In the semiconductor light source device of the present invention, it is preferable that a thermal oxide film is further provided on the inner surface of the separation groove.

 According to the present invention, the pn junction formed at the end of the photodiode can be covered with the thermal oxide film by forming the separation groove as described above. Joints can be protected.

Further, in order to solve the above problem, a semiconductor light source device of the present invention includes a semiconductor light emitting element and a photodiode for receiving monitor light of the semiconductor light emitting element, and a monitor output of the photodiode is provided. A semiconductor light source device that controls the intensity of output light emitted by the semiconductor light emitting element based on the The photodiode is arranged so that the emission optical axis of the monitor light is located in a region deviated from the center of the light receiving surface of the photodiode, and the photodiode surrounds the photosensitive region and has a first conductivity type layer and a first conductive type layer of the photodiode. The semiconductor device is characterized in that a trench is formed in the semiconductor substrate deeper than the two-conductivity-type layer, and is cut out from the trench at an outer periphery of a predetermined width.

 According to the present invention, since the trench is formed around the photosensitive region of the photodiode, the pn junction is formed up to the inner surface of the trench existing around the photosensitive region. It is possible to eliminate the above-mentioned fluctuation region. Further, by cutting the outer periphery of a predetermined width from the trench groove, a block composed of the first conductivity type layer and the second conductivity type layer can be left on the outer periphery of the trench groove, so that the block is surrounded by the trench groove. The photosensitive area can be protected.

 In the semiconductor light source device of the present invention, it is preferable that a light shielding member is embedded in the trench.

 According to the present invention, since the light shielding member is embedded in the trench, it is possible to prevent the monitor light from entering the pn junction formed on the inner surface of the trench.

 In the semiconductor light source device of the present invention, it is preferable that a thermal oxide film is further provided on the inner surface of the trench.

 By forming the trench as described above, the pn junction formed on the inner surface of the trench can be covered with the thermal oxide film, so that the pn junction can be protected. it can.

Further, in the semiconductor light emitting device of the present invention, the semiconductor light emitting element emits the monitor light to a region deviated from the center of the light receiving surface of the photodiode fixed to the upper surface of the stem. An emission axis is positioned, and the emission axis is fixed to a side surface of a support fixed to the upper surface of the stem such that the emission optical axis and a normal to the surface of the photodiode are inclined at a predetermined angle. According to the present invention, the position of the semiconductor light emitting element and the photodiode is fixed by fixing the semiconductor light emitting element to the side surface of the support fixed on the stem and fixing the photodiode on the stem. Relationships can be kept stable.

 In the semiconductor light source device of the present invention, it is preferable that the semiconductor light emitting element emits light having a wavelength of 550 nm or less.

The inventors of the present invention have found that, in a photodiode provided in a conventional semiconductor light source device, particularly when light having a wavelength of 550 nm or less is used, the light receiving sensitivity greatly varies due to a temperature change. I discovered that. Therefore, the semiconductor light source device using the photodiode having the above-described configuration is particularly effective for light in this wavelength band.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side view of a semiconductor light source device according to an embodiment.

FIG. 2 is a plan view of a photodiode provided in the semiconductor light source device according to the first embodiment.

FIG. 3 is a sectional view of a photodiode provided in the semiconductor light source device according to the first embodiment.

4A to 4H are cross-sectional views illustrating a method for manufacturing a photodiode provided in the semiconductor light source device according to the first embodiment.

FIG. 5 is a diagram illustrating a light receiving sensitivity characteristic with respect to a temperature change of a photodiode provided in the semiconductor light source device according to the embodiment.

FIG. 6 is a plan view of a photodiode provided in the semiconductor light source device according to the second embodiment.

FIG. 7 is a sectional view of a photodiode provided in the semiconductor light source device according to the second embodiment.

8A to 8H show a photodiode provided in the semiconductor light source device according to the second embodiment. FIG. 5 is a cross-sectional view for explaining the method of manufacturing the gate.

FIG. 9 is a plan view of a photodiode provided in the semiconductor optical device according to the third embodiment.

FIG. 10 is a sectional view of a photodiode provided in a semiconductor light source device according to the third embodiment.

11A to 11H are cross-sectional views illustrating a method for manufacturing a photodiode provided in a semiconductor light source device according to the third embodiment.

FIG. 12 is a diagram showing the light receiving sensitivity characteristics of a conventional photodiode with respect to a temperature change.

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, a semiconductor light source device according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the embodiments, in order to facilitate understanding of the description, the same components are denoted by the same reference numerals as much as possible in each drawing, and redundant description will be omitted. Also, the dimensional ratios in the drawings do not always match those described.

 First, a semiconductor light source device 10 according to the first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a side view of the semiconductor light source device 10. The semiconductor light source device 10 according to the present embodiment includes a stem 11 on a disk, a support 20 on a pillar fixed on the stem 11, and a semiconductor laser supported on a side surface of the support 20. The semiconductor laser diode 12 includes a photodiode 18 for receiving the monitor laser light 16 emitted from the monitor laser light emission surface 15 of the semiconductor laser diode 12. The photodiode 18 is provided such that the optical axis 17 of the laser beam 16 for the motor enters a region deviated from the center thereof. The semiconductor laser diode 12 is made of a nitride-based material and emits laser light having a wavelength of 409 nm.

[0 0 26] The photodiode 18 has a normal 19 to its surface and a semiconductor laser. The diode 12 is provided so as to be inclined at a predetermined angle with respect to the optical axis 17 of the monitoring laser light 16 emitted from the monitoring laser light emitting surface 15 of the diode 12. With this configuration, it is possible to prevent the monitor laser beam 16 reflected on the surface of the photodiode 18 from being incident on the monitor laser beam exit surface 15 as return light, and at the same time, to prevent the monitor laser beam from returning. The laser light 14 emitted from the laser light emission end face 13 facing the emission face 15 is prevented from overlapping. The laser beam 14 emitted from the semiconductor laser diode 12 is controlled based on the monitor output from the monitoring laser beam 16 incident on the photodiode 18.

 Next, the photodiode 18 will be described with reference to FIGS. Here, FIG. 2 is a plan view of the photodiode 18 and FIG. 3 is a photodiode.

FIG. 3 is a cross-sectional view of FIG. 18 (a cross-sectional view taken along the line III-III in FIG. 2).

 As shown in FIGS. 2 and 3, the substantially cubic photodiode 18 has a lower impurity concentration than the semiconductor substrate 18 s formed on the n-type semiconductor substrate 18 s. Type semiconductor layer 18 n. Further, after forming a mask pattern on the n-type semiconductor layer 18 n using photolithography technology, the photodiode 18 is formed on the surface of the n-type semiconductor layer (first conductivity type semiconductor layer) 18 n; It has a p-type semiconductor layer (second conductivity type semiconductor layer) 18 p in which the p-type impurity (boron) is added by diffusion and the conductivity type of the surface layer is inverted. A boundary between the n-type semiconductor layer 18n and the p-type semiconductor layer 18p forms a pn junction.

[0229] The photodiode 18 has an insulating layer ILT formed on the surface layer and the inner surface of the isolation groove GRV. Further, the photodiode 18 includes an upper surface electrode eu formed after etching a predetermined position of the insulating layer ILT on the p-type semiconductor layer 18 p and an aluminum layer 18 formed on the lower surface of the semiconductor substrate 18 s. c, and has a lower electrode e1. Here, the upper surface electrode eu is located at a predetermined position in the photodiode 18 outside a region where the monitoring laser beam 16 is incident, for example, the center of the photodiode 18 is irradiated with the monitoring laser beam 16. Opposite to the area where optical axis 17 It is formed at a position near the peripheral part (corner) on the side. The photodiode 18 is formed by cutting the semiconductor substrate 18 s from the bottom of the separation groove GRV. Therefore, the photodiode 18 has a pn junction exposed at the end face of the photodiode 18 via the insulating layer ILT. That is, a photosensitive region is formed up to the end face of the photodiode 18 in the vicinity of the region where the monitoring laser beam 16 is incident, and the region where the monitoring laser beam 16 is incident like a photodiode provided in a conventional semiconductor light source device. Since there is no fluctuation region, the photodiode 18 can obtain a stable light receiving sensitivity to a temperature change.

 Next, a method for manufacturing the photodiode 18 will be described. 4A to 4H are cross-sectional views illustrating a method for manufacturing the photodiode 18. First, as shown in FIG. 4A, a semiconductor substrate 18 s having a thickness of 240 μπι is prepared. Next, as shown in FIG. 4B, an n-type semiconductor layer 18 n having a thickness of 30 / xm is formed on the semiconductor substrate 18 s by using an epitaxy method.

 Next, a mask pattern is formed on the n-type semiconductor layer 18 n using a photolithography technique, and p-type impurities (from the opening of the mask pattern to the surface layer of the n-type semiconductor layer 18 n). Boron) is added by diffusion to invert the conductivity type of the surface layer to form a p-type semiconductor layer 18ρ having a thickness of 0.35 μπι as shown in FIG. 4C. Next, as shown in FIG. 4D, an insulating layer ILT is deposited on the surface of the η-type semiconductor layer 18 η and the ρ-type semiconductor layer 18 ρ exposed on the surface. As this deposition method, a CVD (chemical vapor deposition) method 成長 sputtering method or the like can be used.

Next, a mask pattern is formed using a normal photolithography technique, and the opening of the mask is subjected to ICP (inductively coupled plasma) etching. The region of the opening is formed as shown in FIG. 4E. Then, a separation groove GRV having a U-shaped cross section with a depth of 40 / im and a width of 5 m is formed. The separation groove GRV extends from the boundary between the n-type semiconductor layer 18n and the semiconductor substrate 18s to a deeper position.

Next, the device is heated in an oxygen atmosphere, and the separation groove GRV By thermally oxidizing the inner surface of the trench, an insulating layer ILT is also formed on the inner surface of the separation groove GRV as shown in FIG. 4F. In this way, the pη junction exposed in the separation groove GRV is protected. The temperature of this thermal oxidation is as high as 900 ° C.

 Next, as shown in FIG. 4G, an upper electrode eu of A1 and an aluminum layer 18c are formed by a sputtering method or a vapor deposition method, and further, the lower surface is formed by an electroless plating method. An electrode e 1 (N i -A u) is formed. Then, finally, the semiconductor substrate 18 s is cut from the bottom of the separation groove G RV by dicing to obtain a photodiode 18 as shown in FIG. 4H. As described above, since dicing is performed at the bottom of the separation groove G RV, it is possible to prevent the pn junction from being damaged by dicing.

 Here, FIG. 5 shows a graph showing the characteristics of the light receiving sensitivity with respect to a temperature change when the photodiode 18 is irradiated with laser light having a wavelength of 409 nm. For reference, FIG. 12 shows the same characteristics of a photodiode used in a conventional semiconductor light source device. In FIGS. 5 and 12, the horizontal axis represents temperature, and the vertical axis represents the photocurrent ratio, that is, the variation ratio [%] of the photocurrent at another temperature with respect to the photocurrent at a temperature of 25 ° C. . In FIG. 5 and FIG. 12, the line connecting the plotted black square marks indicates the light receiving sensitivity to a temperature change when only the upper surface of the pn junction, that is, the photosensitive region, is irradiated with laser light. In addition, the line connecting the plots of the black circle marks shows similar characteristics when the chip end of the photodiode 18 is irradiated with laser light in FIG. 5 and in the vicinity of the photosensitive region in FIG. The same characteristics are obtained when laser light is irradiated to the fluctuation region of.

As shown in FIG. 12, the photodiode used in the conventional semiconductor light source device has a laser in the fluctuation region as compared with a case where the laser light is irradiated only in the light-sensitive region. It can be seen that when light is irradiated, the photocurrent ratio, that is, the light-receiving sensitivity, fluctuates greatly with a change in temperature. As described above, in the photodiode used in the conventional semiconductor light source device, the temperature in the case where the laser beam is irradiated to the fluctuation region is also high. The degree coefficient, that is, the amount of change in the photocurrent ratio with a temperature change of 1 ° C is as large as 0.35 [% Z ° C]. On the other hand, as shown in Fig. 5, the photodiode 18 had a temperature coefficient of 1.08 [% / ° C] and was stable against temperature changes even when laser light was irradiated to the chip end. It can be confirmed that light receiving sensitivity can be obtained.

 [0390] The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the present embodiment, the semiconductor laser diode 12 that emits laser light of a wavelength of 409 nm (purple) is used, but a semiconductor laser diode that emits laser light of another wavelength band such as red may be used. good. The photodiode 18 according to the present embodiment is a power having a particularly excellent light receiving sensitivity characteristic with respect to a short-wavelength laser beam having a wavelength of 550 nm or less. Show.

 In the present embodiment, the pn junction is formed up to one end face of the photodiode 18; however, the pn junction is formed up to three end faces depending on the region where the monitoring laser light is incident. Even if it is formed, the same effect can be obtained.

 In the photodiode 18 of the present embodiment, the η-type semiconductor layer 18 η functions as a light absorbing layer, but the ρ-type semiconductor layer 18 ρ and the η-type semiconductor layer 18 η The conductivity type may be changed. In this case, the ρ-type semiconductor layer 18 ρ functions as a light absorption layer.

 In the present embodiment, an example in which the semiconductor laser diode 12 is mounted as the most suitable light source has been described, but a light emitting diode (LED) can be applied as the light source.

Next, a semiconductor light source device 10 according to a second embodiment of the present invention will be described. The semiconductor light source device 10 according to the present embodiment differs from the semiconductor light source device 10 shown in the first embodiment only in the configuration of the photodiode 18. Only the photodiode 18 prepared for 0 will be described, and other description will be omitted. FIGS. 6 and 7 are a plan view and a cross-sectional view (cross-sectional view taken along the line VII-VII in FIG. 6) of the photodiode 18 according to the present embodiment, respectively. As shown in FIGS. 6 and 7, a substantially cubic photodiode 18 is formed on an n-type semiconductor substrate 18 S by forming an n-type semiconductor layer 18 n having a lower concentration than the semiconductor substrate 18 s and a _P- type semiconductor layer 18 n. Semiconductor layers 18 p are sequentially formed, and the boundary between the η-type semiconductor layer 18 η and the ρ-type semiconductor layer 18 ρ forms a pri junction.

 Then, the semiconductor substrate 18s is cut by dicing at the bottom of the separation groove GRV formed to a depth deeper than the boundary between the n-type semiconductor layer 18n and the semiconductor substrate 18s. As a result, a photodiode having the structure shown in FIG. 7 has been obtained. In addition, the surface layer portion and the separation groove GRV of the p-type semiconductor layer 18p are covered with an insulating layer ILT, an upper surface electrode eu is formed at a predetermined position of the P-type semiconductor layer 18p, and Has a lower surface electrode e1. Here, the upper surface electrode eu is located at a predetermined position in the photodiode 18 except for the region where the monitoring laser beam 16 is incident, for example, the center of the photodiode 18 is irradiated with the monitoring laser beam 16 It is formed at a position close to the periphery (corner) on the opposite side of the area where the optical axis 17 is located.

 [0405] Unlike the photodiode included in the conventional semiconductor light source device, the photodiode 18 having such a configuration does not have the above-described fluctuation region, and thus can obtain a stable light receiving sensitivity with respect to a temperature change. . As a result, the semiconductor light source and device 10 according to the present embodiment can obtain a stable laser output.

 Next, a method for manufacturing the photodiode 18 will be described. 8A to 8H are cross-sectional views illustrating a method for manufacturing photodiode 18.

In order to manufacture the photodiode 18, first, as shown in FIG. 8A, an n-type semiconductor substrate 18 s having a thickness of 240 πι is prepared. Next, an n-type semiconductor layer 18n having a thickness of 30 μππ is formed on the semiconductor substrate 18s by an epitaxy method as shown in FIG. 8B. Next, from the surface of the n-type semiconductor layer 18 n! ) Type impurity (boron) is added by diffusion, and the conductivity type of this surface layer is inverted to form a 0.35 m-thick; type semiconductor layer 18 p as shown in FIG. 8C.

 Next, as shown in FIG. 8D, an insulating layer ILT is deposited on the surface of the p-type semiconductor layer 18p. As this deposition method, a CVD (chemical vapor deposition) method 成長 a sputter method can be used.

 [0050] Next, a mask pattern is formed using a normal photolithography technique, and ICP (inductively coupled plasma) etching is performed on the opening of the mask. As shown in FIG. A separation groove GRV having a U-shaped cross section with a depth of 40111 and a width of 5 m is formed.

 Next, by heating the device in an oxygen atmosphere and thermally oxidizing the separation groove GRV, the separation groove GRV is also covered with the insulating layer I LT as shown in FIG. 8F. In this way, the pn junction exposed in the separation groove GRV is protected. The temperature of this thermal oxidation is as high as 900 ° C.

 Next, as shown in FIG. 8G, an upper electrode eu and an aluminum layer 18c made of A 1 are formed by a sputtering method or a vapor deposition method, and the lower electrode e 1 is formed by an electroless plating method. (N i -Au). Finally, the semiconductor substrate 18s is cut from the bottom of the separation groove GRV by dicing to obtain the photodiode 18 shown in FIG. 8H. As described above, since dicing is performed at the bottom of the separation groove GfeV, damage to the pn junction due to dicing can be prevented. The photodiode 18 thus formed does not have the above-mentioned fluctuation region unlike the photodiode provided in the conventional semiconductor light source device, and therefore has the same characteristics as the temperature characteristics shown in FIG. 5 described in the first embodiment. In addition, stable light receiving sensitivity to temperature changes can be obtained. As a result, the semiconductor light source device 10 including the photodiode 18 can obtain a stable laser output.

[0054] The present invention is not limited to the above-described embodiment, but may be variously modified. Modifications can be configured. For example, as described in the first embodiment, even if a semiconductor laser diode that emits laser light in another wavelength band such as red is used as the semiconductor laser diode 12, the photo diode 18 is excellent. Shows the photosensitivity characteristics.

 Also, as in the first embodiment, the same function can be obtained by changing the conductivity types of the p-type semiconductor layer 18p and the n-type semiconductor layer 18n.

 [0556] As described in the first embodiment, a light emitting diode (LED) can be applied as a light source instead of the semiconductor laser diode 12. Next, a semiconductor light source device 10 according to a third embodiment of the present invention will be described. The semiconductor light source device 10 according to the present embodiment also differs from the semiconductor light source device 10 according to the first embodiment in that only the photodiode 18 is different from the semiconductor light source device 10 according to the first embodiment. Only the photo diode 18 prepared for will be described, and other description will be omitted.

 FIGS. 9 and 10 are a plan view and a cross-sectional view (cross-sectional view taken along the line XX in FIG. 9) of the photodiode 18 according to the present embodiment, respectively. As shown in FIGS. 9 and 10, in the approximately cubic photodiode 18, the η-type semiconductor layer 18 η, ρ, Semiconductor layers 18 ρ are sequentially formed, and these η-type semiconductor layers 18 η and! ) Type semiconductor layer 18 Ρ forms a ρη junction. .

Further, the photodiode 18 has a trench groove GRV having a U-shaped cross section formed to a depth from the boundary between the η-type semiconductor layer 18 η and the semiconductor substrate 18 s, In the trench GRV, a light shielding member 18r made of black photoresist or polyimide mixed with a pigment such as black dye or insulated carbon black is embedded. Then, a photodiode 18 is cut out by dicing on the outer periphery of the trench GRV. The photodiode 18 has an insulating layer ILT on the surface of the p-type semiconductor layer 18p and on the inner surface of the trench GRV. And e The photodiode 18 has an upper surface electrode eu formed by exfoliating the insulating layer 1LT by etching at a predetermined position on the p-type semiconductor layer 18p, and a lower surface electrode e on the bottom surface of the semiconductor substrate 18s. With one. Here, the upper surface electrode e U is applied to a predetermined position of the photodiode 18 excluding the region where the monitoring laser beam 16 is incident, that is, the center of the photodiode 18, which is irradiated with the monitoring laser beam 1. It is formed at a position near the periphery (corner) on the opposite side of the area where the optical axis 17 of 6 falls.

 [0606] Unlike the photodiode provided in the conventional semiconductor light source device, the photodiode 18 having such a configuration has no sensitivity at all even when light enters the outside of the trench groove GRV, so that it does not respond to temperature change. On the other hand, stable light receiving sensitivity can be obtained. As a result, the semiconductor light source device 10 according to the present embodiment can obtain a stable laser output.

 [0601] Also, the block formed by the p-type semiconductor layer 18p, the n-type semiconductor layer 18n, and the semiconductor substrate 18s outside the trench groove GRV is surrounded by the trench groove GRV. The protected light detection area can be protected. Further, by embedding the light shielding member 18r in the trench groove GRV, it is possible to prevent the monitoring laser beam from being incident on the pn junction exposed on the trench groove GRV side.

 Next, a method for manufacturing the photodiode 18 will be described. FIG. 11A to FIG. 11I are cross-sectional views for describing a method of manufacturing the photodiode 18.

In order to manufacture the photodiode 18, first, as shown in FIG. 11A, an n-type semiconductor substrate 18 s having a thickness of 240 Aim is prepared. Next, an n-type semiconductor layer 18n having a thickness of 30 / zm is formed on the semiconductor substrate 18s by an epitaxy method as shown in FIG. 11B.

 Next, from the surface portion of the n-type semiconductor layer 18 n, a type impurity (boron) is added by diffusion to reverse the conductivity type of this surface portion, as shown in FIG. 11C. Then, a p-type semiconductor layer 18 p having a thickness of 0.35 μΐη is formed.

Next, as shown in FIG. 11D, the surface layer of the ρ-type semiconductor layer 18 ρ Deposit the edge layer ILT. As this deposition method, a CVD (Chemical Vapor Deposition) method, a sputtering method, or the like can be used.

 [0066] Next, a mask pattern is formed using a normal photolithography technique, and ICP (inductively coupled plasma) etching is performed on the opening of the mask. As shown in FIG. Then, a trench GRV having a depth of 40 μπι and a width of 5 m is formed.

 Next, by heating the device in an oxygen atmosphere and thermally oxidizing the trench G RV, the trench GRV is also covered with the insulating layer I LT as shown in FIG. 11F. In this way, the trench is exposed to the GRV; the n-junction is protected. The temperature of this thermal oxidation is as high as 900 ° C.

 Next, as shown in FIG. 11G, a light shielding member 18r is embedded in the trench GRV. This light shielding member 18r can be embedded in the trench groove G RV by spin coating or the like.

 Next, as shown in FIG. 11H, an upper electrode eu made of A1 and an aluminum layer 18c are formed by a sputtering method or a vapor deposition method, and a lower electrode e is formed by an electroless plating method. 1 (N i -Au). Finally, the lower surface electrode e1 is cut from the insulating layer ILT by dicing in the middle of the two adjacent trench grooves GRV, thereby obtaining the photodiode 18 as shown in FIG. 11I.

[0070] Unlike the photodiode provided in the conventional semiconductor light source device, the photodiode 18 formed in this manner has no fluctuation region around the photosensitive region, and thus has the temperature characteristic shown in FIG. 5 described in the first embodiment. As in the case of, stable light receiving sensitivity to temperature changes can be obtained. As a result, the semiconductor light source device 10 including the photodiode 18 can obtain a stable laser output. [0071] The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, a light shielding member 18r to be embedded in the trench GRV For example, non-doped silica can be used. Also in this case, it is possible to prevent the monitoring laser beam from being incident on the pn junction exposed on the trench GRV side.

 [0722] Further, the light shielding member 18r may not be embedded in the trench groove G R V. In this case, since the monitoring laser light is incident on the pn junction exposed on the trench GRV side, the characteristics of the photodiode 18 are slightly reduced, but the photodiode 18 is stable against temperature change. The effect of having photosensitivity still remains. .

 As described in the first embodiment, even if a semiconductor laser diode that emits laser light of another wavelength such as red is used as the semiconductor laser diode 12, It shows good light receiving sensitivity characteristics.

 Also, as in the first embodiment, the same function can be obtained by changing the conductivity types of the p-type semiconductor layer 18p and the n-type semiconductor layer 18n.

 Also, as described in the first embodiment, a light emitting diode (LED) can be used as a light source instead of the semiconductor laser diode 12. Industrial Available Individuals

 According to the present invention, the pn junction of the photodiode is formed at least up to the end near the region where the monitor light is incident. Can be obtained. As a result, a semiconductor light source device capable of emitting stable output light from a semiconductor light emitting element such as a semiconductor laser diode is provided.

Claims

Scope of Word  1. A semiconductor light source device comprising: a semiconductor light emitting element; and a photodiode for receiving monitor light of the semiconductor light emitting element, wherein the intensity of output light emitted from the semiconductor light emitting element is controlled based on a monitor output of the photodiode. ,  The semiconductor light emitting element is disposed such that an emission optical axis of the monitor light is located in a region deviated from a center of a light receiving surface of the photodiode,  The semiconductor light emitting device according to claim 1, wherein the photodiode has a Pn junction formed at least up to the end face near an area where the monitor light is incident among the plurality of end faces. 2. A semiconductor light source device comprising: a semiconductor light emitting element; and a photodiode that receives monitor light of the semiconductor light emitting element, and controls an intensity of output light emitted by the semiconductor light emitting element based on a monitor output of the photodiode. ,  The semiconductor light emitting element is disposed such that an emission optical axis of the monitor light is located in a region deviated from a center of a light receiving surface of the photodiode,  In the photodiode, an isolation groove is formed to the inside of the semiconductor substrate deeper than the first conductivity type layer and the second conductivity type layer, and an end formed by cutting the semiconductor substrate by dicing from the bottom of the isolation groove. Provided at least in the vicinity of the region where the monitor light is incident. A semiconductor light source device characterized by the above-mentioned.  3. The semiconductor light source device according to claim 2, wherein a light shielding member is embedded in the separation groove.  4. The semiconductor light source device according to claim 2, wherein a thermal oxide film is further provided on an inner surface of the separation groove. 5. A semiconductor light source device comprising: a semiconductor light emitting element; and a photodiode that receives monitor light of the semiconductor light emitting element, and controls an intensity of output light emitted from the semiconductor light emitting element based on a monitor output of the photodiode. , The semiconductor salient light element is arranged such that an emission optical axis of the monitor light is located in a region deviated from a center of a light receiving surface of the photodiode,  In the photodiode, a trench groove is formed to surround a photosensitive region of the photodiode and deeper than a first conductivity type layer and a second conductivity type layer of the photodiode in a semiconductor substrate, and is cut out from the trench groove at an outer periphery of a predetermined width. Was A semiconductor light source device characterized by the above-mentioned.  6. The semiconductor light source device according to claim 5, wherein a light shielding member is embedded in the trench.  7. The semiconductor light source device according to claim 5, wherein a thermal oxide film is further provided on an inner surface of the trench groove.  8. In the semiconductor light emitting device, an emission optical axis of the monitor light is located in a region deviated from a center of the light receiving surface of the photodiode fixed to an upper surface of a stem, and a method for measuring the emission optical axis and the surface of the photodiode is used. 8. The semiconductor light source device according to claim 1, wherein the semiconductor light source device is fixed to a side surface of a support fixed to an upper surface of the stem such that a line is inclined by a predetermined angle.  9. The semiconductor light source device according to claim 1, wherein the semiconductor light emitting element emits light having a wavelength of 550 nm or less.