JP5822688B2 - Light emitting / receiving element - Google Patents

Description

  The present invention relates to a light emitting / receiving element in which a light emitting element and a light receiving element are integrally formed on the same substrate.

  Sensor devices that irradiate light from a light emitting element to a measurement object, detect reflected light from the measurement object by a light receiving element, and measure the optical characteristics of the measurement object are used in a wide range of fields. For example, it is used in various applications such as a photo interrupter, a photo coupler, a remote control unit, an IrDA (Infrared Data Association) communication device, an optical fiber communication device, and a document size sensor.

  In such a sensor device, for example, both regular reflection light and scattered reflection light (diffuse reflection light) of light irradiated from a light emitting element to a measurement object, such as a toner sensor that senses both color and monochrome toner, are received. In the case where it is necessary to do so, two light receiving elements are provided as shown in Patent Document 1.

  On the other hand, in order to receive more accurate specular reflection light or diffuse reflection light, it is preferable that the light emitting element and the light receiving element are arranged closer to each other. A light emitting / receiving element array in which a light emitting element and a light receiving element are formed has been proposed.

JP 2006-349715 A JP-A-8-46236

  However, when two light receiving elements are provided on one substrate in order to accurately receive both regular reflection light and diffuse reflection light, the light receiving elements are generally larger than the light emitting elements. Inviting an increase in size. Therefore, an object of the present invention is to provide a small light emitting / receiving element capable of receiving both regular reflection light and scattered reflection light.

  A light emitting / receiving element according to an embodiment of the present invention is made of a semiconductor material of one conductivity type, and includes a substrate having, on one main surface, a depression portion formed by an inclined surface and a bottom surface following the inclined surface, and the one main surface of the substrate. A light emitting diode provided on a surface; a first photodiode provided on the bottom surface of the recess; and a second photodiode provided on the inclined surface of the recess.

  According to the present invention, a small light emitting / receiving element can be provided.

(A), (b) is sectional drawing which shows schematic structure of the light emitting / receiving element which concerns on one Embodiment of this invention, respectively. It is a top view of the sensor apparatus shown in FIG. It is a principal part expanded sectional view of the light emitting diode of the sensor apparatus shown in FIG. It is sectional drawing which shows schematic structure of the light emitting / receiving element which concerns on other embodiment of this invention.

  Hereinafter, an embodiment of a sensor device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of the light receiving / emitting element 1 of the present invention, FIG. 2 is a top view of the light receiving / emitting element 1, and FIG. FIG. In each figure, the ratio of the size of each component may be different from the actual size for clear illustration of the configuration. Further, in FIG. 2, illustration of components located above the light emitting / receiving element 1 is omitted for clear illustration of the configuration of each part. FIG. 1 is a cross-sectional view taken along the line II in FIG.

  As shown in FIGS. 1 to 3, the light emitting element 1 includes a substrate 2, a light emitting diode 3, a first photodiode 4, and a second photodiode 5. Here, the light emitting / receiving element 1 means that at least one first photodiode (light receiving element) 4, at least one second photodiode (light receiving element) 5, and at least one light emission on the one main surface 2a side of the substrate 2. A diode (light emitting element) 3 is provided.

  The substrate 2 is made of one conductivity type semiconductor material. Although there is no limitation on the impurity concentration of one conductivity type, for example, it is preferable to have an electric resistance of 10Ω or less, more preferably 1 to 5Ω. In this example, an n-type silicon substrate is used. Hereinafter, n-type is defined as one conductivity type and p-type is defined as reverse conductivity type.

  A depression 2b is formed on one main surface 2a of the substrate 2. The recess 2b is composed of an inclined surface 2b1 and a bottom surface 2b2 that follows the inclined surface 2b1. In this example, the hollow portion 2b has a shape having a longitudinal direction (D1 direction). Specifically, it has a rectangular shape and has a bottom surface 2b2 having a shape corresponding to the recess 2b.

  The first photodiode 4 is disposed on the bottom surface 2b2 of the recess 2b of the substrate 2 as described above. In this example, there are a plurality of first photodiodes 4 arranged in a straight line along the longitudinal direction of the bottom surface 2b2.

  A light emitting diode 3 is disposed on the main surface 2 a of the substrate 2. In this example, the plurality of light emitting diodes 3 are linearly arranged in the longitudinal direction (D1 direction) of the recess 2b.

  The second photodiode 5 is disposed on the inclined surface 2b1 of the recess 2b of the substrate 2. In this example, there are a plurality of second photodiodes 5 arranged in a straight line along the longitudinal direction of the inclined surface 2b1. In other words, the first photodiodes 4 are arranged along the arrangement direction. More specifically, the second photodiode 5 is disposed between the first photodiode 4 and the light emitting diode 3 that are closest to each other in plan view. That is, in this example, the individual light emitting diodes 3, the first photodiodes 4, and the second photodiodes 5 are arranged on a straight line in the direction D2. In other words, the second photodiode 5 is located between the closest light emitting diode 3 and the first photodiode 4.

  Here, by providing an optical system (not shown) above the main surface 2a of the substrate 2, the light from the light emitting diode 3 is irradiated onto the measurement object. Then, the regular reflection light from the measurement object is measured by the first photodiode 4 (FIG. 1A). Similarly, at least a part of the scattered reflected light from the measurement object is measured by the second photodiode 5 (FIG. 1B). The optical system can be realized by a general lens. For example, a prism, a condensing lens, etc. are mentioned. Such an optical system is designed by using a ray tracing method, and an optical system having a desired shape can be formed. Such an optical system may be provided for each light emitting diode 3 or may be common to a plurality of light emitting diodes 3.

  With this configuration, it is possible to detect the light from the light emitting diode 3 by the first photodiode 4 and confirm the change in the specular reflection light. That is, when used as a toner sensor for a printer, paying attention to a phenomenon in which specular reflection light (regular reflection light) is greatly reduced by adhesion of black toner, by detecting the amount of specular reflection light of the light emitting diode 3. The presence / absence of black toner adhesion and toner density can be detected. Furthermore, the light from the light emitting diode 3 can be detected by the second photodiode 5 to confirm the change in the scattered reflected light. That is, when used as a toner sensor for a printer, paying attention to the phenomenon that the scattered reflected light greatly increases due to the adhesion of the color toner, the amount of the scattered reflected light of the second light emitting diode 4 is detected to detect the color toner. Presence / absence of adhesion and toner density can be detected. Here, since the second photodiode 5 is disposed on the inclined surface 2b1, it is possible to receive scattered reflected light even if it is not disposed far away from the first photodiode 4. By arranging the light receiving surface on the inclined surface 2b1, the space occupied in the plan view is small even if the light receiving surface is sufficient. Furthermore, by arranging the second photodiode 5 on the light emitting diode 3 side of the inclined surface 2b1 when viewed from the first photodiode 4, it is possible to suppress the mixture of specular reflection light, so that the scattered reflected light is more accurately detected. Can be received.

  In addition, in FIG. 1, the locus | trajectory of regular reflected light and scattered reflected light is shown by the arrow.

  In particular, since one of the light receiving elements is arranged on the slope 2b1, a small sensor can be provided even when two light receiving elements are used. Furthermore, since the light emitting / receiving element 1 is used, the light receiving element and the light emitting element can be remarkably reduced in size as compared with the case where the light receiving element and the light emitting element are configured as separate parts, and a plurality of light emitting diodes 3, photodiodes 4, 5 By arranging them closely, regular reflection light and scattered reflection light can be accurately detected.

  In addition, according to the present embodiment, the light emitting diode 3 and the first and second photodiodes 4 and 5 are formed directly on the semiconductor substrate 2, and the size is significantly reduced as compared with the case where another component is mounted on the substrate. It is possible to form an array with a narrow pitch. In addition, it is possible to average the measurement amount of the received light amount by arraying. Further, since the toner application range can be narrowed, the toner application amount can be reduced.

  Furthermore, by providing the photodiodes 4 and 5 in the recess 2b, the path of the leakage current that travels from the light emitting diode 3 to the surface of the substrate 2 can be long and can pass through different crystal planes. Thereby, transmission of the leakage current from the light emitting diode 3 to the photodiodes 4 and 5 can be suppressed, and the highly accurate light receiving and emitting element 1 can be provided.

  Below, the detailed structure of each site | part is demonstrated.

The substrate 2 is not particularly limited as long as it is made of a semiconductor material. In this example, an n-type Si substrate is used. The Si substrate contains P (phosphorus) as one conductivity type impurity, and its concentration is set to 1 × 10 ¹⁴ to 2 × 10 ¹⁷ atoms / cc. More preferably, the concentration of P is 8 × 10 ^{14 to} 5 × 10 ¹⁵ atoms / cc. With such a concentration range, the resistance of the substrate 2 can be set to 1 to 5 Ω · cm.

  The depression 2b may be appropriately provided by physical / chemical etching or mechanical technique. However, when a Si substrate is used as the substrate 2, if the depression 2b is formed by anisotropic etching, a highly accurate depression 2b is produced. It can be formed with good properties.

The light emitting diode 3 includes a buffer layer 31, an n-type contact layer 32, an n-type cladding layer 33, an active layer 34, a p-type cladding layer 35, a p-type contact layer 36, and a cap layer 37 on the substrate 2.
Are stacked in this order from the substrate 2 side. Under the buffer layer 31, there is an n-type impurity diffusion region 2n formed by diffusing impurities in the substrate 2 as will be described later.

  The buffer layer 31 is made of GaAs not doped with impurities and has a thickness of 2 to 3 μm.

The n-type contact layer 32 is made of GaAs doped with an n-type impurity and has a thickness of 0.8 to 1 μm. An example of the n-type impurity is Si, and the doping concentration of the n-type contact layer 32 is 1 × 10 ¹⁸ to 2 × 10 ¹⁸ atoms / cc. As shown in FIG. 3, a part of the upper surface of the n-type contact layer 32 is exposed from the n-type cladding layer 33, the active layer 34, the p-type cladding layer 35, the p-type contact layer 36, and the cap layer 37. A second electrode 11 described later is connected to the exposed portion.

The n-type cladding layer 33 is made of AlGaAs doped with an n-type impurity, and has a thickness of 0.3 to 0.5 μm. An example of the n-type impurity is Si, and the doping concentration of the n-type cladding layer 33 is 1 × 10 ^{17 to} 5 × 10 ¹⁷ atoms / cc.

  The active layer 34 is made of AlGaAs that is not doped with impurities, and has a thickness of 0.3 to 0.5 μm.

The p-type cladding layer 35 is made of AlGaAs doped with a p-type impurity and has a thickness of 0.3 to 0.5 μm. Examples of the p-type impurity include Mg, and the doping concentration of the p-type cladding layer 35 is set to 1 × 10 ¹⁸ to 2 × 10 ¹⁸ atoms / cc.

The p-type contact layer 36 is made of AlGaAs doped with p-type impurities and has a thickness of 0.3 to 0.5 μm. Examples of the p-type impurity include Mg, and the doping concentration of the p-type contact layer 36 is 1 × 10 ^{19 to} 5 × 10 ²⁰ atoms / cc.

  The cap layer 37 is made of GaAs not doped with impurities, and has a thickness of 0.01 to 0.03 μm.

  Each of the semiconductor layers constituting the light emitting diode 3 is formed by epitaxial growth on the substrate 2 using, for example, MOCVD (Metal-organic Chemical Vapor Deposition).

  The first electrode 6 is connected to a part of the upper surface of the cap layer 37. The first electrode 6 extends on the insulating film 13 and is individually provided for the cap layer 37 of each light emitting diode 3. The first electrode 6 is made of, for example, AuNi, AuCr, AuTi, AlCr alloy, which is a combination of Au, Al, and Ni, Cr, Ti, which are adhesion layers, and has a thickness of 0.5 to 5 μm. Has been.

  The second electrode 11 is connected to a part of the upper surface of the n-type contact layer 32. The second electrode 11 extends on the insulating film 13 and connects the n-type contact layers 32 of the light emitting diodes 3 arranged in a row as shown in FIG. In FIG. 2, the insulating film 13 is not shown for convenience of explanation. Moreover, the 2nd electrode 11 is formed with the thickness of 0.5-5 micrometers, using AuSb alloy, AuGe alloy, Ni type alloy etc., for example.

  The first electrode 6 and the second electrode 11 are connected to an external drive circuit (not shown), and by applying a forward voltage between the two electrodes, the p-type cladding layer 35 and the n-type cladding layer 33 pn A current is supplied to the light emitting diode 3 forming the junction, and the active layers 34 and 44 emit light. At this time, any one of the plurality of first electrodes 6 is selected, and a forward voltage is applied between the selected first electrode 6 and the second electrode 11 to select the selected first electrode 6. The light emitting diode 3 connected to the electrode 6 can emit light.

As shown in FIG. 3, the light emitting diode 3 has translucency except for the contact portion between the second electrode 11 and the n-type contact layer 32 and the contact portion between the first electrode 6 and the cap layer 37. The insulating film 13 is covered with the insulating film 13 to ensure insulation between the first electrode 6 and the second electrode 11. Similarly, an insulating film 13 is formed on the surface of the substrate 2, and insulation between the substrate 2 and the first electrode 6 and the second electrode 11 is ensured. The insulating film 13 is made of, for example, an inorganic insulating film such as SiN _x or SiO ₂ or an organic insulating film such as polyimide and has a thickness of 0.1 to 5 μm.

  Next, the plurality of first and second photodiodes 4 and 5 provided on the substrate 2 will be described. In this example, since the first photodiode 4 and the second photodiode 5 have the same configuration except for the arrangement position, the configuration of the first photodiode 4 will be described as an example. As shown in FIG. 2, the first photodiode 4 is provided to be separated from the light emitting diode 3, and along the arrangement direction of the light emitting diode 3, the first photodiode 4 corresponds to the light emitting diode 3 in the recess 2 b of the semiconductor substrate 2. The bottom surface 2b2 is arranged in a row. As shown in FIG. 3, each first photodiode 4 has a p-type semiconductor region 4p formed on the upper surface (one main surface) 2a of the substrate 2, thereby forming a pn junction with the n-type substrate 2. Formed and configured.

The p-type semiconductor region 4p is formed by diffusing p-type impurities in the semiconductor substrate 2 at a high concentration. Examples of the p-type impurity include Zn, B, Al, Ga, In, and the like. In this embodiment, B is diffused as a p-type impurity so as to have a thickness of 0.5 to 3 μm, and the doping concentration of the p-type semiconductor region 4p is 1 × 10 ¹⁸ to 1 × 10 ²² atoms / cc.

  A third electrode 15 is connected to the p-type semiconductor region 4p. More specifically, the third electrode 15 is joined to the peripheral edge of the p-type semiconductor region 4p. The third electrode 15 is made of, for example, an alloy of Au and Cr, Al and Cr, Pt and Ti, or the like, and has a thickness of 0.5 to 5 μm. The third electrode 15 is connected to an external circuit (not shown). The third electrode 15 is ensured to be insulated from the substrate 2 by the insulating film 13.

  At this time, when light enters the first photodiode 4, a photocurrent is generated, and this photocurrent can be taken out by the third electrode 15.

  Here, in the present embodiment, on one main surface 2a of the substrate 2, a blocking region 2c is formed between the region where the light emitting diode 3 is disposed and the recess 2b. Here, the cut-off region 2c is for suppressing leakage current from the light-emitting diode 3 from reaching the photodiodes 4 and 5 through the surface of the semiconductor substrate 2. , 5 are electrically separated from each other. In addition to suppressing the leakage current by providing the photodiodes 4 and 5 in the recess 2b, the blocking region 2c further suppresses the leakage current. In this example, a reverse conductivity type blocking region 2c is formed.

The blocking region 2c may be provided continuously between the region where the light emitting diode 3 is disposed and the recess 2b where the photodiodes 4 and 5 are disposed. When there are a plurality of light-emitting diodes 3 and photodiodes 4 and 5, the light-emitting diode 3 may be provided between the light-emitting diodes 3 and the photodiodes arranged closest to each other, In this example, the light emitting diodes 3 are continuously provided along the arrangement direction of the plurality of light emitting diodes 3 and the arrangement direction of the plurality of photodiodes 4 and 5.

  Here, the blocking region 2c is a semiconductor region having a conductivity type opposite to that of the substrate 2 (p-type). For this reason, a reverse-conductivity type semiconductor region exists in the middle of the path from the light emitting diode 3 to the photodiodes 4 and 5 on the substrate 2, and the leakage current from the light emitting diode 3 reaches the photodiodes 4 and 5. Can be suppressed.

  More specifically, the blocking region 2 c is for suppressing the current supplied from the external drive circuit to the light emitting diode 3 from flowing into the photodiodes 4 and 5 through the semiconductor substrate 2. By doing so, the leakage current from the light-emitting diode 3 is prevented from being mixed as noise into the current output from the photodiodes 4 and 5, and the light-receiving intensity measurement by the photodiodes 4 and 5 is performed with higher accuracy. Is possible. That is, it is possible to provide the light receiving / emitting element 1 with high sensitivity by such a blocking region 2c.

Specifically, the blocking region 2c is formed by diffusing p-type impurities in the semiconductor substrate 2 at a high concentration. Examples of the p-type impurity include Zn, B, Al, Ga, In, and the like. In this embodiment, B is diffused as a p-type impurity so as to have a thickness of 5 μm, and the doping concentration is set to 1 × 10 ¹⁸ to 1 × 10 ²² atoms / cc.

  The preferred thickness in the depth direction of the blocking region 2c varies depending on the material of the substrate 2, the resistivity, and the like. Since the leakage current from the light emitting diode 3 mainly flows on the surface of the substrate 2, it may be present on the upper surface 2a side of the substrate 2, but more preferably from the depth of the recess 2b as in the present embodiment. Is also preferably large. With such a configuration, in addition to the leakage current transmitted through the surface 2a of the substrate 2, the leakage current that passes through the substrate 2 and reaches the p-type semiconductor regions 4p and 5p can be blocked.

  When there is a concentration distribution of impurity concentration in the thickness direction (depth direction) of the blocking region 2c, the depth position of the region having the highest impurity concentration overlaps the depth range where the p-type semiconductor region 5p exists. It is preferable to do.

  A suitable width (width in the left-right direction in FIG. 2) in the separation direction of the light-emitting diode 3 and the photodiodes 4 and 5 in the blocking region 2c has an npn structure from the light-emitting diode 3 toward the photodiodes 4 and 5. There is no particular limitation as long as it is sufficient. However, when the blocking region 2c is formed by thermal diffusion, it is diffused in the lateral direction as much as the depth direction, and therefore has a width that is at least twice the thickness in the depth direction. For this reason, the lower limit value is at least twice the thickness in the depth direction. The upper limit is less than the distance between the light emitting diode 3 and the closest photodiode 5 and is not particularly limited as long as it has an npn structure from the light emitting diode 3 toward the photodiode 5. Or less than the pitch width of the plurality of photodiodes 4 and 5. Usually, these pitch widths are smaller than the distance between the light emitting diode 3 and the closest photodiodes 4 and 5. The “width in the direction in which the light-emitting diodes 3 and the photodiodes 5 are separated from each other” can also be referred to as the width in the direction perpendicular to the arrangement direction of the plurality of light-emitting diodes 3.

  Next, an embodiment of a method for manufacturing the light emitting / receiving element 1 configured as described above will be described.

First, the substrate 2 having 100 main surfaces 2a is prepared. Next, a photoresist is applied, a desired pattern is exposed and developed by a photolithography method, and then a recess 2b is formed by a wet etching method using KOH. Here, by performing Si anisotropic etching, the 111 plane exposed by the etching can be made into the inclined surface 2b1. Further, the recess 2b can have a desired depth and a desired bottom surface 2b2 by adjusting the etching time.

Next, a diffusion blocking film S made of SiO ₂ is formed on the substrate 2 using a thermal oxidation method.

  Next, a photoresist (not shown) is applied on the diffusion blocking film S, a desired pattern is exposed and developed by a photolithography method, and then a p-type semiconductor region 5p and a blocking region 2c are formed by a wet etching method. An opening Sa is formed in the diffusion barrier film S. Instead of the opening Sa, a thinned portion whose thickness is thinner than the periphery may be formed.

  Then, a polyboron film PBF is applied on the diffusion barrier film S. Subsequently, by using a thermal diffusion method, B contained in the polyboron film PBF is diffused into the substrate 2 through the opening Sa or the thinned portion of the diffusion blocking film S, and the p-type semiconductor regions 4p and 5p are diffused. And a blocking region 2c is formed. At this time, for example, the thickness of the polyboron film PBF is set to 1000 to 1 μm, and is thermally diffused at a temperature of 600 to 1200 degrees in an atmosphere containing nitrogen and oxygen. This thermal diffusion may be performed in one step at a constant atmosphere and temperature, or may be performed in several steps. Specifically, heat treatment may be performed in a temperature region on the low temperature side of the above temperature range in an oxygen atmosphere, and then in a temperature region on the high temperature side of the above temperature range in a nitrogen atmosphere. Thereafter, the diffusion blocking film S is removed.

  Next, the natural oxide film formed on the surface of the substrate 2 is removed by heat-treating the substrate 2 in a reaction furnace of the MOCVD apparatus. This heat treatment is performed, for example, at a temperature of 1000 degrees for 10 minutes.

  Next, each semiconductor layer constituting the light emitting diode 3 is sequentially stacked on the substrate 2 by using MOCVD. Then, a photoresist (not shown) is applied on the stacked semiconductor layer L, a desired pattern is exposed and developed by a photolithography method, and then the light emitting diode 3 is formed by a wet etching method. At this time, etching is performed in two stages so that the upper surface of the n-type contact layer 32 is exposed. Thereafter, the photoresist is removed.

  Next, an insulating film 13 covering these surfaces is formed on the exposed surface of the light emitting diode 3 and the upper surface of the semiconductor substrate 2 by using a thermal oxidation method, a sputtering method, a plasma CVD method, or the like. Subsequently, a photoresist (not shown) is applied on the insulating film 13, a desired pattern is exposed and developed by a photolithography method, and then a first electrode 6, a second electrode 11, and a third electrode to be described later are formed by a wet etching method. A hole for arranging 15 is formed in the insulating film 13. Thereafter, the photoresist is removed.

  Next, after applying a photoresist film (not shown) on the insulating film 13 and exposing and developing a desired pattern by a photolithography method, the first electrode 6 and the third electrode 6 are formed using a resistance heating vapor deposition method, a sputtering method, or the like. An alloy film for forming the electrode 15 is formed. Then, using the lift-off method, the photoresist is removed, and the electrodes 6 and 15 are formed in a desired shape. The second electrode 11 is also formed by the same process.

  The light emitting / receiving element 1 according to the present embodiment is obtained by dicing a plurality of light emitting / receiving elements 1 into a disc-shaped wafer and then dividing it.

Here, in order to increase the thickness of the blocking region 12c as compared with the depth of the recessed portion 2b as in the light emitting / receiving element 1, in the step of forming the p-type semiconductor region 5p and the blocking region 2c, first, After p-type impurities are diffused only in the region where the blocking region 2c is formed, the p-type impurities may be diffused into the regions where the p-type semiconductor regions 4p and 5p and the blocking region 2c are formed next. As described above, the diffusion of the p-type impurity is performed in two stages, whereby the thickness of the blocking region 2c can be increased.

  In addition to performing the diffusion of the p-type impurity in two stages, the thickness may be adjusted by the thickness of the diffusion prevention film. Specifically, the diffusion prevention film is thinned in the region where the p-type semiconductor regions 4p and 5p are formed, and an opening is formed in the region where the blocking region 2c is formed, or the thickness of the diffusion prevention film is changed to the p-type semiconductor region 4p. , 5p may be thinner than the region where the p-type semiconductor regions 4p, 5p are formed.

  According to the light emitting / receiving element 1 according to the present embodiment, the blocking region 2c is formed at a position between the light emitting diode 3 and the photodiodes 4 and 5 on the upper surface (one main surface) 2a of the semiconductor substrate 2. The current supplied when driving the light emitting diode 3 can be prevented from flowing into the photodiodes 4 and 5 through the semiconductor substrate 2.

  Further, according to the light receiving and emitting element 1 according to the present embodiment, the photodiodes 4 and 5 constitute a pn type photodiode. Since a photodiode having such a configuration can measure a minute current as compared with a PIN photodiode, it is important to suppress the mixture of leakage current. In particular, when detecting diffuse reflection light in addition to regular reflection light from the light-emitting diode 3, the blocking region 2c can suppress the introduction of leakage current and measure a slight change in light amount.

  Further, according to the light emitting / receiving element 1 according to the present embodiment, the light emitting diode 3 and the photodiodes 4 and 5 are formed on the semiconductor substrate 2 by the thin film process and the semiconductor process. With such a configuration, the light-emitting diode 3 and the photodiodes 4 and 5 are arranged close to each other, and the apparatus can be downsized. And since the interruption | blocking area | region 2c can be formed between the light emitting diode 3 and the photodiodes 4 and 5 which were arrange | positioned in this way by the same process, the light receiving / emitting element 1 which was small and excellent in the detection accuracy is provided. be able to.

  Furthermore, according to the method for manufacturing the light emitting / receiving element 1 according to the present embodiment, since the blocking region 2c can be formed simultaneously with the manufacturing of the p-type semiconductor regions 4p, 5p, the manufacturing process of the light receiving / emitting element 1 is simplified. And can be highly productive.

  And according to the sensor apparatus using such a light emitting / receiving element 1, it can be made small and highly sensitive.

  Hereinafter, a method of using the sensor device according to the above-described embodiment will be described. In the following, a case where the light emitting / receiving element 1 is applied to a sensor device that detects the position of the toner T (irradiated body) attached on the intermediate transfer belt V in an image forming apparatus such as a copier or a printer is taken as an example. explain.

Optical systems corresponding to the light-emitting diodes 3 and the photodiodes 4 and 5 are arranged at intervals in the direction perpendicular to the main surface of the substrate 2 of the light-receiving / emitting element 1. Examples of the optical system include a prism and a condenser lens. That is, the optical system is disposed above the light emitting / receiving element 1 in FIG. Light emitted from the light emitting diode 3 is irradiated to the intermediate transfer belt V, which is an irradiation body, disposed opposite to the main surface 2a of the substrate 2 of the light emitting / receiving element 1 through this optical system. Reflected light (including regular reflected light and scattered reflected light) from the toner T on the intermediate transfer belt V is received by the photodiodes 4 and 5 through the optical system. A photocurrent is generated in the photodiode 5 according to the intensity of the received light, and the photocurrent is detected by an external detection circuit. Since the intensity of the reflected light corresponds to the density of the toner T, the toner density of each part can be detected according to the magnitude of the generated photocurrent.

  The sensor device according to the present invention has a configuration suitable for arraying. More specifically, the configuration is suitable for arraying from the viewpoint of wiring arrangement when a plurality of light emitting diodes (3) and a plurality of photodiodes (4, 5) are provided.

  Specifically, according to the light receiving and emitting element 1 according to the present invention, the light emitting diode 3 and the photodiodes 4 and 5 can lead out wirings to the outside. Thereby, it can connect with the external circuit not shown by a bonding wire. In this example, the third electrode 15 connected to the photodiodes 4 and 5 is drawn to the outside of the recess 2b on the opposite side to the region where the light emitting diode 3 is disposed. These third electrodes function as an anode. A conductor layer 18 is provided as a cathode common to the photodiodes 4 and 5. The conductor layer 18 has a wide pad disposed outside the recessed portion 2b opposite to the region where the light emitting diode 3 is disposed, and a bottom surface 2b2 of the recessed portion 2b. A wide pad disposed between the photodiode 5 and a narrow line portion for electrically connecting the two pads is provided. Here, by providing a wide pad between the first photodiode 4 and the second photodiode 5 in plan view, the cathode can be disposed close to the second photodiode 5. The photocurrent can be detected with high accuracy. In particular, the second photodiode 5 for detecting the scattered reflected light has a small intensity of the photocurrent to be detected, but can be arrayed even if the pads functioning as the cathode are arranged close to each other in this manner. A small light emitting / receiving element 1 can be provided.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described example, a case where there are a plurality of the light emitting diodes 3, the first photodiodes 4, and the second photodiodes 5 has been described as an example, but each may have one each.

  Moreover, in the above-mentioned example, although the some light emitting diode 3 was arrange | positioned at linear form, a zigzag form may be sufficient. In the above-described example, the individual light emitting diodes 3, the first photodiodes 4, and the second photodiodes 5 are arranged on a straight line. However, they may not be arranged on a straight line.

  In the above example, the blocking region 2c is formed by diffusing reverse conductivity type impurities between the region where the light emitting diode 3 of the substrate 2 is formed and the recess 2b. However, as shown in FIG. Instead of 2c, a groove 2d may be formed. The groove 2d can prevent leakage current from the light emitting diode 3 from being transmitted to the photodiodes 4 and 5 disposed in the recess 2b.

  In the above embodiment, the photodiodes 4 and 5 are pn-type, but are formed on the p-type semiconductor region 5p and the upper surface (the inclined surface 2b1 and the bottom surface 2b2) of the substrate 2 apart from the p-type semiconductor region 5p. And a n-type semiconductor region, thereby forming a PIN-type photodiode. In particular, it is preferable that the first photodiode 4 having a large amount of received light is a PIN type and the second photodiode 5 having a small amount of received light is a pn type.

  Further, the one conductivity type and the reverse conductivity type may be reversed.

  Further, in the above-described embodiment, the description has been given using the example in which the plurality of first photodiodes 4 and the second photodiodes 5 are provided in one recess 2b. However, one first photodiode 4 and one first photodiode are provided. You may form the hollow part 2b separately with respect to 1 set of 2 photodiodes 5. FIG.

DESCRIPTION OF SYMBOLS 1 Light emitting / receiving element 2 Board | substrate 2a One main surface (upper surface)
2b hollow 2b1 inclined surface 2b2 bottom 2c blocking region 2d groove 3 light emitting diode 4 first photodiode 5 second photodiode

Claims (5)

A substrate made of a semiconductor material of one conductivity type, and having a depression formed on an inclined surface and a bottom surface following the inclined surface, on one main surface;
A light emitting diode provided in a region of the one main surface of the substrate excluding the recessed portion ;
A first photodiode provided on the bottom surface of the recess,
A light emitting / receiving element comprising: a second photodiode provided on the inclined surface of the recess.   2. The light receiving and emitting element according to claim 1, wherein the second photodiode is provided between the light emitting diode and the first photodiode in a plan view.   The light receiving and emitting element according to claim 1, wherein the substrate has a groove portion between a region where the light emitting diode on the one main surface side is disposed and the hollow portion.   3. The light receiving and emitting element according to claim 1, wherein the substrate has a reverse conductivity type blocking region provided between a region where the light emitting diode on the one main surface side is disposed and the recess. There are a plurality of the light emitting diodes, the first photodiodes, and the second photodiodes, respectively.
The plurality of light emitting diodes are arranged in a straight line,
The plurality of first photodiodes are arranged along the arrangement direction of the light emitting diodes, and the plurality of second photodiodes are arranged along the arrangement direction of the light emitting diodes. The light emitting / receiving element according to any one of the above.

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