JPWO2013065731A1 - Sensor device - Google Patents

Abstract

A sensor device with excellent light detection accuracy is provided. A substrate (2) made of a semiconductor material of one conductivity type and having a first region (2a) and a second region (2b) located in parallel with one main surface (2A), and a first region (2a) ), A first light emitting diode (3) and a second light emitting diode (4) provided in the second region (2b), a first light emitting diode (3) and a substrate (2). ) Is disposed between the measurement object positioned above one main surface (2A), irradiates the measurement object with light from the first light-emitting diode (3), and a part of the regular reflection light is applied to the photodiode. The first optical system (8) guided to (5), the second light emitting diode (4), and the measurement object are arranged, and the measurement object is irradiated with light from the second light emitting diode (4), The specularly reflected light is guided to the area excluding the photodiode (5) and a part of the scattered reflected light is blocked. A second optical system for guiding the bets diode (5) and (9).

Description

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

  2. Description of the Related Art A sensor device that irradiates a measurement target with light from a light emitting element, detects reflected light from the measurement target with a light receiving element, and measures optical characteristics of the measurement target is used in a wide field. 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. When it is necessary to do this, two light receiving elements are provided as disclosed in JP-A-2006-349715.

  However, since the light receiving element is generally larger than the light emitting element, the provision of two light receiving elements has led to an increase in the size of the sensor device. Therefore, there has been a demand for a small sensor device that can receive both regular reflection light and scattered reflection light.

  A sensor device according to an embodiment of the present invention is made of a semiconductor material of one conductivity type, and is provided in the first region, the substrate having a first region and a second region located in parallel with one main surface, Lamination of a photodiode including a reverse conductivity type semiconductor portion formed by doping impurities on the one principal surface of the substrate, and a semiconductor layer laminated on the one principal surface of the substrate provided in the second region A first light-emitting diode and a second light-emitting diode configured by a body, and between the first light-emitting diode and a measurement object located above the one main surface of the substrate, and from the first light-emitting diode Is disposed between the second light emitting diode and the measurement object, and irradiates the measurement object to the measurement object and directs a part of the specularly reflected light to the photodiode. From the diode And a second optical system for guiding specularly reflected light to a region excluding the photodiode and guiding a part of the scattered reflected light to the photodiode, and from the first light emitting diode. The output current from the photodiode is detected by a part of the regular reflected light of the light and a part of the scattered reflected light of the light from the second light emitting diode.

  According to the present invention, a small sensor device can be provided.

(A), (b) is sectional drawing which shows schematic structure of the sensor apparatus 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 the schematic which shows incidence | injection and reflection of the light in one point P of a measuring object. It is the schematic explaining the positional relationship of each component in the sensor apparatus shown in FIG. It is a principal part top view which shows the modification of the sensor apparatus shown in FIG. It is the schematic which shows the modification of the sensor apparatus shown in FIG.

  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 sensor device 10 of the present invention, FIG. 2 is a top view of the sensor device 10, and FIG. 3 is an enlarged cross-sectional view of a main part of the first light-emitting diode 3 of the sensor device 10. is there. 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 sensor device 10 includes a light emitting / receiving element 1, a first optical system 8, and a second optical system 9. The light emitting / receiving element 1 includes a substrate 2, a plurality of first light emitting diodes 3 disposed on one main surface 2 </ b> A of the substrate 2, a plurality of second light emitting diodes 4, and a plurality of photodiodes 5. Hereinafter, the light emitting diode is referred to as LED and the photodiode is referred to as PD. Here, the light emitting / receiving element 1 is an element in which at least one light receiving element (PD), at least one first light emitting element (LED), and a second light emitting element are provided on one main surface of the substrate 2. In other words, one light receiving element has a plurality of combinations of two light emitting elements.

  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, the n-type is a single conductivity type, and the p-type is a reverse conductivity type.

  A first region 2a and a second region 2b are positioned in parallel on one main surface of the substrate 2. Each of the first region 2a and the second region 2b has a shape having a longitudinal direction (D1 direction), and is located in parallel in a direction orthogonal to the longitudinal direction. In this example, it has a rectangular shape, and is arranged side by side in the short side direction (D2 direction) constituting the rectangle.

  PD5 is arrange | positioned in the 1st area | region 2a of such a board | substrate 2. FIG. In this example, the plurality of PDs 5 are linearly arranged along the longitudinal direction of the first region 2a.

  In the second region 2 b of the substrate 2, the first LED 3 and the second LED 4 are located. In this example, the plurality of first LEDs 3 are arranged linearly in the longitudinal direction (D1 direction) of the second region 2b. Similarly, a plurality of second LEDs 4 are linearly arranged in the longitudinal direction (D1 direction) of the second region 2b. That is, two rows of LEDs are arranged. And the row | line | column of 1st LED3 is located in the 1st area | region 2a side rather than the row | line | column of 2nd LED4. In this example, the individual PD5, the first LED3, and the second LED are arranged on a straight line in the direction D2. In other words, the first LED 3 is positioned between the closest second LED 4 and the PD 5.

  The first optical system 8 and the second optical system 9 change the optical path by refracting the light of the LEDs 3 and 4 emitted in the normal direction of one main surface of the substrate 2 and irradiate one point P of the measurement object. The reflected light from one point P is received by the PD 5.

  The first optical system 8 irradiates the measurement object V with light from the first LED 3 and guides the specularly reflected light to the PD 5. The second optical system 9 irradiates the measurement object V with the light from the second LED 4, guides the specularly reflected light to the outside of the PD5, and guides at least a part of the scattered reflected light to the PD5. In other words, the second optical system 9 guides the specularly reflected light to a region where the PD 5 is not disposed, and guides at least a part of the scattered reflected light to the photodiode 5. Here, it is preferable that the second optical system 9 guides specularly reflected light to the side where the first LED 3 is not disposed in the D2 direction with the PD 5 as the center.

  Such optical systems 8 and 9 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 a first optical system 8 may be provided for each first LED 3 or may be common to a plurality of first LEDs 3. Similarly, the second optical system 9 may be provided for each of the second LEDs 4 or may be common to the plurality of second LEDs 4.

  Here, the specularly reflected light has an incident angle equal to a reflection angle. As shown in FIG. 4, the incident light at the point P and the reflected light from the point P are actually broad. In other words, the incident angle of incident light and the reflection angle of reflected light have an angular spread. In this case, when the incident angle at the peak position with the strongest intensity in the distribution of incident light is equal to the emission angle at the peak position with the strongest intensity in the distribution of emitted light, it is regarded as regular reflection. In the case of specularly reflected light, the distribution of the spread of incident light and the spread of outgoing light has a similar relationship. In the case of scattered reflected light, there is no similarity in the distribution of the incident light spread and the outgoing light spread, the incident angle at the peak position of the incident light distribution and the peak position of the outgoing light distribution. The emission angle does not match. In the case of scattered reflected light, there may be a case where there are a plurality of peaks in the distribution of emitted light, or the distribution is broad and a clear peak cannot be confirmed.

  A specific positional relationship that satisfies the above relationship will be described with reference to FIG.

  In the example shown in FIG. 1, the LEDs 3 and 4 emit light in the normal direction of the first main surface of the substrate 2. For this reason, the first optical system 8 and the second optical system 9 are provided directly above the LEDs 3 and 4, respectively. In this example, the first optical system 8 and the second optical system 9 are further provided at the same height position. Specifically, the substrate 2 is disposed at a height a with respect to one main surface 2A of the substrate 2.

  The distance to the center of the first LED 3 is x1, the distance to the center of the second LED 4 is x2, and the distance to the center of the PD 5 is x3 on the basis of the point Pa on the substrate 2 facing the point P on the measurement object. And

  The first optical system 8 changes the light from the first LED 3 emitted in the normal direction of one principal surface of the substrate 2 at an angle θ1 and guides the light to one point P of the measurement object at an incident angle θ1, and at a reflection angle θ1. The regularly reflected light is guided to PD5.

  When such an optical system is used, the positions of the first LED 3 and the PD 5 are adjusted so that the distance x3 becomes (sin θ1 / cos θ1) a + x1.

  The second optical system 9 changes the light from the second LED 4 emitted in the normal direction of one principal surface of the substrate 2 at an angle θ2 and guides the light to one point P of the measurement object at an incident angle θ2, and at a reflection angle θ2. The regularly reflected light is guided to an area other than PD5.

  When such an optical system is used, the position of the second LED 4 is adjusted so that the distance x2 becomes (cos θ1 / sin θ1) (sin θ2 / cos θ2) x1, and x3 becomes smaller than (sin θ2 / cos θ2) a + x2.

  By setting it as such a structure, the light from 1st LED3 can be detected and the change of specular reflected light can be confirmed. That is, when used as a toner sensor for a printer, paying attention to the phenomenon that specular reflection light (regular reflection light) is greatly reduced by adhesion of black toner, black light is detected by detecting the amount of specular reflection light of the first LED 3. The presence / absence of toner adhesion and the toner density can be detected. Furthermore, the light from the second LED 4 can be detected 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 is greatly increased by the adhesion of the color toner, the presence or absence of the adhesion of the color toner by detecting the amount of the scattered reflected light of the second LED 4 The toner density can be detected. As described above, when detecting black toner, only the first LED 3 can emit light, and when detecting color toner, only the second LED 4 can emit light. In FIG. 1, (a) shows the locus of specularly reflected light from the first LED 3 and the second LED 4, and (b) shows the locus of scattered reflected light from the second LED 4. In this figure, the locus of light from the first LED 3 is indicated by a broken line, and the locus of light from the second LED 4 is indicated by a long chain line. As described above, by using two light emitting elements (LEDs 3 and 4), even if one light receiving element (PD5), the state of change of two reflected lights (regular reflected light and scattered reflected light) can be confirmed. Can do.

  In particular, since a plurality of light receiving elements are not required, a sensor that is smaller than the conventional configuration can be provided. In addition, since the light receiving / emitting 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 LEDs 3, 4, PD5 are arranged close to each other. Thus, the scattered reflected light can be accurately detected.

  In addition, according to the present embodiment, the first and second LEDs 3 and 4 and the PD 5 are directly formed on the semiconductor substrate 2 and can be significantly reduced in size as compared with those in which separate components are mounted on the substrate. An array can be formed at a narrow pitch. Moreover, the precision of the arrangement position of 1st LED3, 2nd LED4, and PD5 can be improved compared with what mounts another components via a bonding agent. 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.

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

The substrate 2 is made of a semiconductor material and is not particularly limited as long as the PD 5 that can be detected with respect to the emission wavelength from the LEDs 3 and 4 can be formed. For example, Si, InP, or the like can be used. In this example, an n-type Si substrate is used. The Si substrate contains P (phosphorus) as an impurity of one conductivity type, and its concentration is set to 1 × 10 ¹⁴ to 2 × 10 ¹⁷ atoms / cm ³ .

  The first and second LEDs 3 and 4 are formed on the substrate 2 with buffer layers 31 and 41, n-type contact layers 32 and 42, n-type cladding layers 33 and 43, active layers 34 and 44, p-type cladding layers 35 and 45, P-type contact layers 36 and 46 and cap layers 37 and 47 are formed in this order from the substrate 2 side. Under the buffer layers 31 and 41, there is an n-type impurity diffusion region 2n formed by diffusing impurities in the substrate 2 as will be described later.

  The buffer layers 31 and 41 are made of GaAs not doped with impurities and have a thickness of 2 to 3 μm.

The n-type contact layers 32 and 42 are made of GaAs doped with n-type impurities, and have a thickness of 0.8 to 1 μm. Examples of the n-type impurity include Si, and the doping concentration of the n-type contact layers 32 and 42 is set to 1 × 10 ¹⁸ to 2 × 10 ¹⁸ atoms / cm ³ . As shown in FIG. 3, a part of the upper surface of the n-type contact layers 32 and 42 includes n-type cladding layers 33 and 43, active layers 34 and 44, p-type cladding layers 35 and 45, p-type contact layers 36 and 46, The cap layers 37 and 47 are exposed, and the second electrode 11 described later is connected to the exposed portions.

The n-type cladding layers 33 and 43 are made of AlGaAs doped with n-type impurities and have a thickness of 0.3 to 0.5 μm. Examples of the n-type impurity include Si, and the doping concentration of the n-type cladding layers 33 and 43 is set to 1 × 10 ^{17 to} 5 × 10 ¹⁷ atoms / cm ³ .

  The active layers 34 and 44 are made of AlGaAs not doped with impurities and have a thickness of 0.3 to 0.5 μm.

The p-type cladding layers 35 and 45 are made of AlGaAs doped with a p-type impurity and have a thickness of 0.3 to 0.5 μm. An example of the p-type impurity is Zn, and the doping concentration of the p-type cladding layers 35 and 45 is 1 × 10 ¹⁸ to 2 × 10 ¹⁸ atoms / cm ³ .

The p-type contact layers 36 and 46 are made of AlGaAs doped with a p-type impurity, and have 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 layers 36 and 46 is set to 1 × 10 ^{19 to} 5 × 10 ²⁰ atoms / cm ³ .

  The cap layers 37 and 47 are made of GaAs that is not doped with impurities, and have a thickness of 0.01 to 0.03 μm.

  Each of the semiconductor layers constituting the first and second LEDs 3 and 4 is formed by epitaxial growth on the substrate 3 using, for example, MOCVD (Metal-organic Chemical Vapor Deposition) method. .

  The first electrode 6 is connected to a part of the upper surface of the cap layers 37 and 47. The first electrode 6 extends on the insulating film 13 and is individually provided for the cap layers 37 and 47 of the LEDs 3 and 4. 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 layers 32 and 42. The second electrode 11 extends on the insulating film 13 and connects between the n-type contact layers 32 and 42 of the LEDs 3 and 4 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 constant current drive circuit (not shown), and by applying a forward voltage between both electrodes, the p-type cladding layers 35 and 45 and the n-type cladding layer A current is supplied to the LEDs 3 and 4 that form a pn junction with the active layers 34 and 44 so that 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 LEDs 3 and 4 connected to the electrode 6 can emit light.

As shown in FIG. 3, the LEDs 3 and 4 have a contact portion between the second electrode 11 and the n-type contact layers 32 and 42 and a contact portion between the first electrode 6 and the cap layers 37 and 47. It is covered with a light-transmitting insulating film 13 to ensure insulation from 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, a plurality of PDs 5 provided on the substrate 2 will be described. As shown in FIG. 2, the PDs 5 are provided apart from the LEDs 3 and 4, and are arranged in a row on the semiconductor substrate 2 so as to correspond to the LEDs 3 and 4 along the arrangement direction of the LEDs 3 and 4. Yes. As shown in FIG. 3, each PD 5 is formed by forming a pn junction with the n-type substrate 2 by providing a p-type semiconductor region 5p formed on the upper surface (one main surface) 2A of the substrate 2. Is done.

The p-type semiconductor region 5p is formed by diffusing p-type impurities in the semiconductor substrate 2 at a high concentration. Examples of the p-type impurity include Zn, Mg, C, 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 7p is set to 1 × 10 ¹⁸ to 1 × 10 ²² atoms / cm ³ .

  A third electrode 15 is connected to the p-type semiconductor region 5p. More specifically, the third electrode 15 is joined to the peripheral edge of the p-type semiconductor region 5p. 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 PD 5, a photocurrent is generated, and this photocurrent can be taken out by the third electrode 15.

  Here, in this embodiment, a reverse conductivity type blocking region 2c is formed between the first region 2a and the second region 2b on one main surface of the substrate 2.

  The blocking region 2c may be provided continuously in a portion where the second region 2b in which the LEDs 3 and 4 are disposed and the first region 2a in which the PD 5 is disposed are opposed to each other. In the case where there are a plurality of LEDs 3 and 4 and PD5, the LEDs 3 and 4 may be provided between the LEDs 3 and 4 and the PD 5 that is disposed closest to each other. In this example, a plurality of LEDs 3 and 4 are provided. Are arranged continuously along the arrangement direction, the plurality of PDs 5 and the arrangement direction.

  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, the semiconductor region of the reverse conductivity type exists in the middle of the path connecting the LEDs 3 and 4 to the PD 5 on the substrate 2, and the leakage current from the LEDs 3 and 4 can be prevented from reaching the PD 5. .

  More specifically, the blocking region 2 c is for suppressing the current supplied from the external drive circuit to the LEDs 3 and 4 from flowing into the PD 5 through the semiconductor substrate 2. By doing so, it is possible to suppress the leakage current from the LEDs 3 and 4 from being mixed into the current output from the PD 5 as noise, and to accurately measure the received light intensity by the PD 5. 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, Mg, C, 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 / cm ³ .

  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 leakage current from the LEDs 3 and 4 mainly flows on the surface of the substrate 2, it may be present on the upper surface 2 </ b> A side of the substrate 2, but more preferably in the p-type semiconductor region 5 p as in this embodiment. The thickness is preferably larger than the thickness in the depth direction. 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 region 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.

  The preferred width of the blocking region 2c in the direction in which the LEDs 3, 4 and the PD 5 are separated (the width in the left-right direction in FIG. 2) is particularly limited as long as it has an npn structure from the LEDs 3, 4 to the PD 5. Not. 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 LED 3 and the closest PD 5 and is not particularly limited as long as it has an npn structure from the LED 3 to the PD 5, but for example, it is less than the pitch width of the plurality of LEDs 3 or the plurality of PD 5. That's fine. Usually, these pitch widths are smaller than the distance between the LED 3 and the closest PD 5. The “width in the direction in which the LED 3 and the PD 5 are separated” can be rephrased as the width in the direction orthogonal to the arrangement direction of the plurality of LEDs 3.

  In particular, when the upper surface of the blocking region 2c is flush with the upper surface 2A of the substrate 2 as in this embodiment, the leakage current passing through the upper surface 2A of the substrate 2 can be reliably blocked.

  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 is prepared. Then, 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 barrier 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 region 5p is blocked. Region 2c is formed. At this time, for example, the thickness of the polyboron film PBF is set to 1000 to 1 μm and thermally diffused at a temperature of 700 to 1200 ° C. in an atmosphere containing nitrogen and oxygen. 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 H ₂ gas atmosphere in a reactor 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 LEDs 3 and 4 is sequentially laminated on the substrate 2 by using the MOCVD method. Then, a photoresist (not shown) is applied onto the laminated semiconductor layer L, and a desired pattern is exposed and developed by a photolithography method, and then LEDs 3 and 4 are formed by a wet etching method. At this time, etching is performed in two stages so that the upper surfaces of the n-type contact layers 32 and 42 are exposed. Thereafter, the photoresist is removed.

  Next, an insulating film 13 that covers these surfaces is formed on the exposed surfaces of the LEDs 3 and 4 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, which will 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 3 are formed by using a resistance heating vapor deposition method or a sputtering method. 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 p-type semiconductor region 5p 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 the p-type impurity is diffused only in the region where the blocking region 2c is formed, the p-type impurity may be diffused in the region where the p-type semiconductor region 5p and the blocking region 2c are formed next. By thus performing the diffusion of the p-type impurity in two stages, the thickness of the blocking region 2c can be made larger than the thickness of the p-type semiconductor region 5p.

  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 region 5p is 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 5p. The region to be formed may be thinner than the region for forming the p-type semiconductor region 5p.

  According to the light emitting / receiving element 1 according to the present embodiment, since the blocking region 2c is formed at a position between the LEDs 3 and 4 and the PD 5 on the upper surface (one main surface) 2A of the semiconductor substrate 2, the LEDs 3 and 4 It is possible to suppress the current supplied at the time of driving from flowing into the PD 5 through the semiconductor substrate 2.

  Moreover, according to the light emitting / receiving element 1 according to the present embodiment, the PD 5 constitutes a pn-type PD. Since a PD having such a configuration can measure a minute current compared to a PIN-type PD, it is important to suppress mixing of leakage current. In particular, when detecting diffuse reflection light in addition to regular reflection light from the LEDs 3 and 4, the blocking region 2c can prevent the leakage current from being mixed and measure a slight change in light amount.

  Further, according to the light emitting / receiving element 1 according to the present embodiment, the LEDs 3 and 4 and the PD 5 are formed on the substrate 2 made of a semiconductor by a thin film process and a semiconductor process. With such a configuration, the LEDs 3 and 4 and the PD 5 can be arranged close to each other, and the apparatus can be downsized. And since the interruption | blocking area | region 2c can be formed between LED3 and 4 and PD5 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 can be provided.

  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 region 5p, the manufacturing process of the light receiving / emitting element 1 can be simplified. And can be highly productive.

  And according to the sensor apparatus 10 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 description, 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 that is a measurement target in an image forming apparatus such as a copier or a printer. An example of this will be described.

  First and second optical systems 8 and 9 corresponding to the LEDs 3, 4, and PD 5 are disposed at a distance in a direction perpendicular to the main surface of the substrate 2 of the light receiving and emitting element 1. Examples of the optical system include a prism and a condenser lens. That is, the optical systems 8 and 9 are disposed above the light emitting / receiving element 1 in FIG. Light emitted from the LEDs 3 and 4 is applied 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 receiving and emitting 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 PD 5 via the optical systems 8 and 9. A photocurrent is generated in the PD 5 according to the intensity of 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 LEDs (3, 4) and a plurality of PDs (5) are provided.

  Specifically, according to the sensor device of the present invention, the wiring of the LEDs 3 and 4 is opposite to the first region 2a where the PD 5 is disposed, and the wiring of the PD 5 is the second region 2b where the LEDs 3 and 4 are disposed. Can be pulled out on the opposite side. Thereby, it can connect with the external circuit not shown by a bonding wire. Moreover, the 1st electrode 6 of LED3, 4 can be extended to the outer side of both LED3, 4 with respect to the interruption | blocking area | region 2c, for example by carrying out solid wiring through an insulating film. This facilitates connection to an external circuit when the array is further formed.

  Moreover, according to the sensor apparatus which concerns on this invention, the pad for connecting LED3,4, PD5 to an external circuit can be reduced.

  PD5 needs to confirm the output individually. For this reason, two pads (electrical wiring) are required for one PD5. For this reason, in the case of the structure which uses two light receiving elements with respect to one light emitting element like the past, a pad was not able to be reduced. On the other hand, the first and second LEDs 3 and 4 can be individually operated by so-called matrix wiring. That is, the wiring can be time-division driven. In this case, although the two LEDs 3 and 4 are used for one PF 5, the number of pads can be reduced.

  FIG. 6 shows a wiring diagram specifically realized for the above configuration. In FIG. 6, only a part of the second region 2b characteristic of the wiring is shown. In addition, each of the first LED 3 and the second LED 4 is assumed to be eight.

  First, the first LED 3 and the second LED 4 have a symmetrical structure. Specifically, it arrange | positions so that the taking-out direction of the 2nd electrode 11 may be on the opposite side to between 1st LED3 and 2nd LED4. That is, it arrange | positions so that the mutual 2nd electrode 11 may be located outside and the 1st electrode 6 may be located inside.

  Next, the plurality of first LEDs 3 and the second LEDs 4 are divided into a plurality of groups along the arrangement direction. Each group includes N first LEDs 3 and N second LEDs 4. Here, N is a natural number of 2 or more. The optimum number varies depending on the total number of LEDs 3 and 4 and the like, but about 4 to 10 is preferable. In this example, four first LEDs 3 and four second LEDs 4 form one group.

  And in the same group, 2nd electrode 11 which is one electrode of four 1st LED3 is electrically connected, and it connects to common pad K11, K12 .... Similarly, in the same group, the 2nd electrodes 11 which are one electrode of four 2nd LED4 are electrically connected, and it connects to common pad K21, K22 .... That is, a pad K1 to which one electrode of the first LED 3 is commonly connected and a pad K2 to which one electrode of the second LED 4 is commonly connected are provided for each group.

  Next, the first electrode 6 that is the other electrode of one first LED 3 and the first electrode 6 that is the other electrode of one second LED 4 are electrically connected. Thereby, the combination of 1st LED3 and 2nd LED4 by which N sets of other electrodes were connected in one group is made.

  Each of the combinations of the first LED 3 and the second LED 4 to which the N other electrodes are connected is connected between different groups and connected to N pads A.

  In this example, between the plurality of groups, the first electrodes 6 of the first LED 3 and the second LED 4 positioned first in the arrangement direction in the group are electrically connected to each other and connected to the common pad A1. Similarly, the first electrodes 6 of the LEDs 3 and 4 positioned second in the arrangement direction are connected to a common pad A2. Hereinafter, the same applies to the third and fourth arrangement directions.

  Originally, in order to individually drive the 16 LEDs together with the first LED 3 and the second LED 4, two pads are used for one LED, so 32 pads are necessary. Even if one electrode of the LED is a common electrode as shown in FIG. 2, 18 pads are required. On the other hand, in the example shown in FIG. 6, the number of pads necessary for individually driving the 16 LEDs together with the first LED 3 and the second LED 4 can be eight. For this reason, a pad can be arranged without difficulty.

  As described above, by electrically connecting in this way, the individual LEDs 3 and 4 can be individually controlled, and all the pads K11, K12..., K21, K22. .. Can be arranged outside the second region on the opposite side of the first region. With such a configuration, even if bonding wires are connected to these pads, light emission from the first LED 3 and the second LED 4 is not blocked.

(Modification)
Next, a modification of the sensor device shown in FIG. 1 will be described with reference to FIG.

  The sensor device shown in FIG. 7 further includes a third optical system 21 that is disposed at the same height as the first and second optical systems 8 and 9 when the main surface 1A of the substrate 2 is used as a reference. The third optical system 21 guides light incident on the position where the third optical system 21 is disposed to the PD 5. In this example, the third optical system 21 is located immediately above the PD 5. The third optical system 21 can use a prism, a condenser lens, or the like.

  Such first to third optical systems 8, 9, 21 are held by a package 22 disposed on one main surface 1 a of the substrate 2. The package 22 has a cap shape, and has a lid portion 22a that is arranged to be opposed to the one main surface 1a at a predetermined interval. Three holes are formed in the lid portion 22a, and the first to third optical systems 8, 9, and 21 are held in the holes, respectively. These holes are formed at positions overlapping the positions at which the first LEDs 3, the second LEDs 4, and the PD 5 are arranged in plan view.

  Although PD5 is larger than the hole, it may be arranged so that the center of gravity of PD5 matches the center of the hole.

  By using such a package, all the constituent elements (first and second LEDs 3, 4, PD 5, first to third optical systems 8, 9, 21) are arranged with reference to the main surface 1 a of the substrate 2. Therefore, a sensor device with high position accuracy can be obtained.

  A specific positional relationship for realizing the case of the configuration as described above will be described.

  Here, as in FIG. 5, the height at which the first to third optical systems 8, 9, and 21 are arranged with reference to one main surface 2 </ b> A of the substrate 2 is a, and the point P on the measurement object is With reference to the point Pa on the opposing substrate 2, the distance to the first LED 3 is x1, the distance to the second LED 4 is x2, the distance to the PD 5 is x3, and the first optical system 8 is set to one point P of the measurement object. The incident angle of the guided light is θ1, and the incident angle of the light guided by the second optical system 9 to one point P of the measurement object is θ2.

  In the example shown in FIG. 7, the distance x1 and the distance x3 are equal. That is, an intermediate point between the center of gravity of PD5 (in this example, PD5 is synonymous with the center because it is circular) and the first LED 3 is a point Pa. Then, in the arrangement direction (short side direction, D2 direction) of the PD 5, the first LED 3, and the second LED 4, adjustment is performed so that the PD 5 is not arranged at a position separated by a distance x 3 in the direction away from the second LED 4 around the point Pa. In other words, in the arrangement direction of PD5, first LED3, and second LED4, PD5 is formed in front of a position separated by distance x3 in the direction away from second LED4 with point Pa as the center. In other words, the PD 5 is arranged on the inner side (point Pa side) than the position symmetrical to the second LED 4 across the point Pa. More preferably, it is preferable that the end portion of the substrate 2 is designed so as to be inward of the position separated by the distance x3 in the direction away from the second LED 4 around the point Pa.

  By setting it as such a structure, it can suppress that the regular reflection light from 2nd LED4 injects into PD5.

  Table 1 shows combinations of actual arrangement examples that satisfy the above positional relationship when the height a from the substrate 2 to the lid portion 22a of the package 22 is 1 mm.

  In Table 1, the distance in the height direction from the package 22 to the measurement object is z1, the diameter of the PD 5 is d1, and the length of one side (short side) of the chip size of the sensor device 1 is d2.

  From Table 1, it can be confirmed that the sensor device of the present invention can be realized by adjusting the arrangement of the first LED 3, the second LED 4, PD 5, and the first to third optical systems 8, 9, and 21.

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

  For example, in the above-described example, the case where there are a plurality of first LEDs 3, second LEDs 4, and PDs 5 has been described as an example, but it is also possible to have one each.

  Moreover, in the above-mentioned example, although several 1st LED3 and several 2nd LED4 were each arrange | positioned at linear form, what is called zigzag form may be sufficient. In the above-described example, the first LED 3 and the second LED 4 are arranged in two rows. However, the first LED 3 and the second LED 4 may be arranged in a straight line alternately. Furthermore, in the above-described example, the individual first LEDs 3, the second LEDs 4, and the PD5 are arranged on a straight line, but may not be arranged on a straight line. For example, a plurality of first diodes 3 and a plurality of second diodes may be alternately arranged in a staggered manner.

  In the above example, the blocking region 2c is formed between the first region 2a and the second region 2b of the substrate 2. However, as shown in FIG. 5, a groove 2d may be formed instead of the blocking region 2c. Good. The groove 2d can prevent leakage current from the LEDs 3 and 4 disposed in the second region 2b from reaching the PD 5 disposed in the first region 2a.

  In the above embodiment, the PD 5 is a pn type, but has a p type semiconductor region 5p and an n type semiconductor region formed on the upper surface 2A of the substrate 2 apart from the p type semiconductor region 5p. This may constitute a PIN type PD.

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

DESCRIPTION OF SYMBOLS 1 Light emitting / receiving element 2 Semiconductor substrate 2A One main surface (upper surface)
2a 1st area | region 2b 2nd area | region 2c interruption | blocking area | region 2d groove | channel 3 1st light emitting diode 4 2nd light emitting diode 5 photodiode 5p p-type semiconductor area 8 1st optical system 9 2nd optical system 10 Sensor apparatus

Claims (7)

A substrate made of a semiconductor material of one conductivity type and having a first region and a second region located in parallel with one main surface;
A photodiode including a reverse conductivity type semiconductor portion formed by doping impurities on the one main surface of the substrate provided in the first region;
A first light emitting diode and a second light emitting diode, each of which is formed of a stack of semiconductor layers stacked on the one main surface of the substrate, provided in the second region;
It is disposed between the first light emitting diode and a measurement object located above the one main surface of the substrate, and irradiates the measurement object with light from the first light emitting diode to provide one of regular reflection light. A first optical system for guiding a portion to the photodiode;
It is arranged between the second light emitting diode and the measurement object, irradiates the measurement object with light from the second light emitting diode, guides specular reflection light to a region excluding the photodiode, and scattered reflected light. A second optical system for guiding a part of the first to the photodiode,
A sensor device that detects an output current from the photodiode due to a part of specularly reflected light from the first light emitting diode and a part of scattered reflected light from the second light emitting diode.   The sensor device according to claim 1, wherein the first light emitting diode is disposed between the second light emitting diode and the photodiode. A third optical system that is located immediately above the photodiode and guides incident light to the photodiode;
The first optical system and the second optical system are arranged at the same height as the third optical system directly above the first light emitting diode and the second optical system, respectively.
In the arrangement direction of the photodiode, the first light emitting diode, and the second light emitting diode, the intermediate point is sandwiched when the intermediate point between the center of the photodiode and the center of the first light emitting diode is used as a reference. The sensor device according to claim 2, wherein the photodiode is located closer to the intermediate point than a position symmetrical to the second light emitting diode.   In the arrangement direction of the photodiode, the first light emitting diode, and the second light emitting diode, when the intermediate point is used as a reference, the intermediate point is more than the position symmetrical to the second light emitting diode across the intermediate point. The sensor device according to claim 3, wherein an end portion of the substrate is located on a side.   The first region and the second region each have a longitudinal direction and are arranged in parallel in a direction orthogonal to the longitudinal direction, and the photodiode, the first light emitting diode, and the second light emitting diode are The sensor device according to claim 1, wherein a plurality of each of the sensor devices are linearly arranged in the longitudinal direction.   6. The wiring according to claim 1, wherein wiring for connecting the first light emitting diode and the second light emitting diode to an external circuit is led out to the opposite side of the second region to the first region side. A sensor device according to claim 1. When the first light-emitting diode and the second light-emitting diode are divided into groups each including N (N is a natural number of 2 or more) along the longitudinal array,
A pad K1 to which one electrodes of the first light emitting diodes in the same group are connected in common;
A pad K2 to which one electrodes of the second light emitting diodes in the same group are connected in common;
N pads A to which the other electrode is connected in common between different groups for each of N combinations of the first light emitting diode and the second light emitting diode in the same group, The sensor device according to claim 5, wherein the pad K1, the pad K2, and the pad A are disposed on the opposite side of the second region to the first region side.

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