JP2004260227A - Light receiving element and light receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that carriers generated from other than a P type heavily doped layer contribute, as a photocurrent, to diffusion and thus deteriorate the response. <P>SOLUTION: On the periphery of a first P type heavily doped layer 2 constituting the light receiving surface of a semiconductor substrate, a second P type heavily doped layer 6 is formed separately from the first P type heavily doped layer 2. On the insulation coating 7 formed on the surface of the semiconductor substrate 1, a first electrode 82 connected with the first P type heavily doped layer 2 through a through hole and a second electrode 83 connected with the second P type heavily doped layer 6 are provided so that an independent bias voltage can be applied between the second P type heavily doped layer 6 and an N type heavily doped layer 11. When an independent bias voltage is applied between the second P type heavily doped layer 6 and the N type heavily doped layer 11, undesired carriers generated from other than the light receiving area can be taken out separately from the signal and the effect of undesired carriers can be suppressed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a light receiving device suitable for an optical sensor.

  2. Description of the Related Art Conventionally, a light receiving device used in an infrared remote controller or an optical sensor constituting a receiving unit for short-range optical communication is susceptible to electromagnetic noise, for example, as shown in Patent Document 1. Therefore, a metal mesh or conductive film is placed in front of the light receiving element and connected to ground potential, or the surface of the light receiving element is electromagnetically shielded with a transparent electrode or the like, and is housed in a metal case or resin molded. Was.

On the other hand, when the light receiving element portion and the light receiving signal processing circuit are incorporated as a monolithic element, as described in Patent Document 2, when forming the gate and the source of the light receiving signal processing circuit, the high density In some cases, a layer is formed and this high-concentration layer attempts to shield simultaneously with wiring.
Japanese Utility Model Publication No. 5-36181 Japanese Patent Publication No. 7-120761

  However, in the case where the electromagnetic shield is embedded in the light receiving element assembly, prevention of misalignment of the mesh and the film and wiring are complicated, and the production yield is reduced. If a transparent electrode or the like is provided on the element surface, a capacitor will be formed between the shield electrode and the element surface, increasing the electric capacity, reducing the receiving sensitivity and enabling communication in optical communication. There is an inconvenience that the arrival distance is significantly shortened.

  On the other hand, when the light receiving element portion and the light receiving signal processing circuit are monolithically incorporated, the depth and impurity concentration of the layer corresponding to the photoelectric characteristics required for the light receiving element are different from the dopant and impurity concentration required for the circuit portion. Matching between the element part and the circuit part cannot be obtained. Therefore, it is possible to use the shield layer for wiring or the like, but the optical signal is attenuated and the S / N ratio is reduced. Further, such a monolithic photodetector with a circuit cannot be manufactured at a high speed as a photodetector because a manufacturing process is restricted to a circuit portion. In particular, a PiN photodiode cannot be manufactured.

  The light-receiving element of the present invention, as described in claim 1, a first P-type high-concentration layer formed on the surface of the semiconductor substrate to constitute a light-receiving surface, the first of the surface of the semiconductor substrate A second P-type high-concentration layer formed around the P-type high-concentration layer and separated from the first P-type high-concentration layer; an N-type high-concentration layer formed on the back surface of the semiconductor substrate; An insulating coating formed on the surface of the semiconductor substrate, a first electrode connected to the first P-type high concentration layer through a through hole provided in the insulating coating, and an insulating coating provided on the insulating coating. A second electrode connected to the second P-type high concentration layer through a through hole.

  According to a second aspect of the present invention, there is provided a light receiving device having a light receiving element and a frame on which the light receiving element is mounted, wherein the light receiving element is formed on a surface of a semiconductor substrate so as to constitute a light receiving surface. A first P-type high-concentration layer, and a second P-type high-concentration layer formed around the first P-type high-concentration layer on the surface of the semiconductor substrate and separated from the first P-type high-concentration layer. A high-concentration layer, an N-type high-concentration layer formed on the back surface of the semiconductor substrate, an insulating coating formed on the front surface of the semiconductor substrate, and the first through a hole provided in the insulating coating. A first electrode connected to the P-type high-concentration layer, and a second electrode connected to the second P-type high-concentration layer via a through-hole provided in the insulating film; Between the back surface of the semiconductor substrate and the first P-type high concentration layer, and between the back surface of the semiconductor substrate and the second P-type high concentration layer. To and applying the same voltage.

  According to a third aspect of the present invention, there is provided a light receiving device having a light receiving element and a frame on which the light receiving element is mounted, wherein the light receiving element is formed on a surface of a semiconductor substrate so as to constitute a light receiving surface. A first P-type high-concentration layer, and a second P-type high-concentration layer formed around the first P-type high-concentration layer on the surface of the semiconductor substrate and separated from the first P-type high-concentration layer. A high-concentration layer, an N-type high-concentration layer formed on the back surface of the semiconductor substrate, an insulating coating formed on the front surface of the semiconductor substrate, and the first through a hole provided in the insulating coating. A first electrode connected to the P-type high-concentration layer, and a second electrode connected to the second P-type high-concentration layer via a through-hole provided in the insulating film; A voltage is applied between the back surface of the semiconductor substrate and the first P-type high concentration layer to obtain an optical output, and the back surface of the semiconductor substrate is And applying a separate bias voltage between said second P-type high-concentration layer and.

  Waveform rounding has become extremely small. The relative sensitivity became sharper.

FIG. 1 is a side sectional view a and a plan view b of a light receiving device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a semiconductor substrate, for example, an N-type silicon substrate having a low impurity concentration of 4 × 10 ¹² cm ⁻³ or less so as to form a light absorption layer. In particular, in order to increase the sensitivity to infrared light and obtain a high-speed response, it is preferable that the substrate has a resistance of 500 Ω / cm or more in consideration of the expansion of the depletion layer. In addition, the conductivity type of the semiconductor substrate 1 is limited by the conductivity type on the back surface and the current applying means in order to use the same frame as the integrated circuit that obtains the output of the light receiving element. It is determined by the characteristics and whether it is easy to provide an effective electromagnetic shield layer on the surface.

Reference numeral 2 denotes a P-type high concentration layer (P + layer) provided on the surface of the semiconductor substrate 1 and constitutes a light receiving surface. The P-type high-concentration layer (P + layer) has a sheet resistance of 20Ω / □ by diffusing boron (B) to a depth of 1 to 2 μm, for example. In order to obtain photosensitivity, the surface area of the P-type high-concentration layer is preferably large, and the sheet resistance is preferably 10 kΩ / □ or less. In order to use this P-type high-concentration layer (P + layer) as an electromagnetic shielding layer, it is most preferable that this layer has a resistance of 50 Ω / cm or less. Reference numeral 3 denotes an N-type high-concentration layer (N + layer) provided around the P-type high-concentration layer 2, which is a layer having an electrically high gain. Is provided so as to surround the. Therefore, the N-type high concentration layer 3 has a rectangular shape when viewed from the surface, and is formed by diffusing phosphorus (P) to a depth of 1 to 2 μm to an impurity concentration of about 1 × 10 ²⁰ cm ^−3. ing. The N-type high-concentration layer 3 is provided for reducing sensitivity to undesired light and extracting an n-type electrode.

An insulating film 7 made of silicon dioxide (SiO ₂ ) or the like is provided on the surface of the semiconductor for protecting the surface and preventing reflection. Then, electrodes 81 and 82 made of aluminum are provided on the insulating film 7, and are in ohmic contact with the respective layers via through holes provided in the insulating film 7. The electrode 82 connected to the P-type high-concentration layer 2 is provided in a substantially rectangular shape along the outer periphery of the element surface so as to cover the upper surface of the N-type high-concentration layer 3.

  The above description relates to the light receiving element, and constitutes a PiN photodiode. The light receiving element and the integrated circuit element 90 receiving the signal of the light receiving element are mounted on a frame and wired by wiring means 91 and 92.

  Reference numeral 4 denotes a frame made of copper, iron, aluminum, or an alloy thereof, which is subjected to tin plating or the like as necessary, and has a concave portion 41 in a mounting portion of the light receiving element. In this example, the depth of the concave portion 41 is provided to be substantially the same as the height of the light receiving element so as to have a conductive wall near the mounting portion of the light receiving element so as to face the side surface of the light receiving element. Reference numeral 5 denotes an insulating adhesive for fixing the bottom surface of the light receiving element to the mounting portion of the frame 4. Since the P-type high-concentration layer (P + layer) 2 is used as a shield layer and the light receiving element is covered with a shield, both are connected by a wiring means 92 such as a wire bond line.

  By configuring in this way, metal nets and the like are not required in the manufacture, assembly is easy, and a capacitor having an undesirably large capacity is not formed by the surface electrode, and as a result of measuring the reach distance and the noise generation distance, Good results were obtained. Here, the reach distance is the maximum separation distance at which a television set in which a prepared light receiving device is used as a unit and which receives a signal from the remote control and operates normally using a remote controller having a constant light output. It was measured. In addition, the noise generation distance is a unit that can supply power to the prepared light receiving device and monitor the output.It is placed in close proximity to the TV device and household equipment that generates noise from the inverter fluorescent lamp, and the noise component is included in the output. The distance between the device and the light receiving element unit when it appears.

  The optical characteristics will be specifically described. The light receiving element unit includes a so-called conventional light receiving element unit A in which a metal net is arranged on the light receiving element, and a light receiving element unit B of the above-described embodiment in which the frame 4 has no concave portion and the side of the light receiving element is exposed from the frame. And light receiving element unit C according to the above-described embodiment. The reach distance and the noise generation distance were measured for 5 lots of the light receiving element units of the TV remote control set of 50 lots per lot. The reaching distance of the conventional A was 9 m at the longest and the maximum was the same, B and C were almost the same, and the average of 5 lots was 5.4 m and 5.6 m. On the other hand, the noise generation distance was 0 mm for both the conventional A and the C of the embodiment of the present invention, and B was 4 to 25 mm. Therefore, as compared with the conventional unit B, the assembling process and yield are good and there is no practical problem. The unit C according to the embodiment of the present invention is not only advantageous in manufacturing but also extremely excellent in optical characteristics. It can be said.

  Further, the P-type high-concentration layer 2 forms a light receiving surface. However, carriers generated from portions other than the P-type high-concentration layer contribute as photocurrent due to diffusion, resulting in poor responsiveness. For example, when a rectangular wave optical signal is incident, the photocurrent waveform due to the carrier generated in the light receiving unit follows the optical signal, but the carrier generated in other than the light receiving unit contributes as a photocurrent by diffusion. , The diffusion speed is delayed with respect to the incident light signal. Therefore, although the output of the light receiving element follows the rising of the incident light signal, the waveform is rounded at the falling. Further, a portion that cannot be shielded at the boundary between the light-receiving surface and the light-shielding electrode expands, and a leakage current may occur.

  Therefore, as shown in FIG. 2A, a P-type high-concentration layer 2 is provided on the surface of an N-type semiconductor substrate 1 having the same low impurity concentration as the previous example, and a high-concentration layer 11 of the same conductivity type as the substrate is provided on the back surface. To form Then, another P-type high concentration layer (P + layer) 6 is provided around the P-type high concentration layer (P + layer) 2 separately from the P-type high concentration layer 2. Further, the upper part of the P-type high concentration layer 6 provided therearound is covered with a light-shielding electrode 83. The protective film 7 is the same as in the previous embodiment, but a conductive adhesive 51 is used for the frame 4. Then, a predetermined voltage is applied between the back surface of the semiconductor substrate 1 and the P-type high-concentration layer 2 which is a light receiving portion, and the same voltage is applied between the back surface of the semiconductor substrate 1 and the peripheral P-type high-concentration layer 6. Apply. It is preferable to separately apply a bias to the P-type high-concentration layer 6 because the voltage application to the P-type high-concentration layer 2 as a light receiving unit is for obtaining an optical output.

  By doing so, for example, when a rectangular wave optical signal is incident, the output of the light receiving element follows the rising edge of the incident optical signal, and the rounding of the waveform is extremely reduced even at the falling edge. . In addition, as shown in FIG. 2B, at the surface position of the light receiving element, the sensitivity under the light-shielding electrode becomes sharp, and the relative sensitivity, which has conventionally spread as indicated by the broken line, is sharper in the light receiving region as indicated by the solid line. , And the response characteristics well followed the intensity of the light input. The conductive wall of the frame 4 provided near the mounting portion of the light receiving element so as to face the side surface of the light receiving element may be low.

  As described above, since the light receiving surface is an electromagnetic shield and the side surface is covered with the metal frame, a light receiving element with good productivity, strong noise, high speed and high light sensitivity is obtained.

  It can be used as an infrared remote control or an optical sensor that constitutes a receiving unit for short-range optical communication.

It is side sectional drawing a of the light receiving element of other Example, and top view b. FIG. 3 is a side sectional view a and a characteristic diagram b of the light receiving element of the embodiment of the present invention.

Explanation of reference numerals

1 semiconductor substrate 2 P-type high concentration layer (P + layer)
3 N-type high concentration layer 4 Frame 5 Adhesive

Claims (3)

  A first P-type high concentration layer formed on the surface of the semiconductor substrate so as to constitute a light receiving surface; and a first P-type high concentration layer around the first P-type high concentration layer on the surface of the semiconductor substrate. A second P-type high-concentration layer formed apart from the concentration layer; an N-type high-concentration layer formed on the back surface of the semiconductor substrate; an insulating film formed on the surface of the semiconductor substrate; A first electrode connected to the first P-type high-concentration layer through a through-hole provided in the second P-type high-concentration layer through a through-hole in the insulating film; A light-receiving element having a second electrode connected thereto.   In a light receiving device having a light receiving element and a frame on which the light receiving element is mounted, the light receiving element includes a first P-type high concentration layer formed on a surface of a semiconductor substrate so as to constitute a light receiving surface; A second P-type high-concentration layer formed on the surface of the first P-type high-concentration layer around the first P-type high-concentration layer; and an N-type high-concentration layer formed on the back surface of the semiconductor substrate. A high-concentration layer, an insulating coating formed on the surface of the semiconductor substrate, a first electrode connected to the first P-type high-concentration layer through a hole provided in the insulating coating, A second electrode connected to the second P-type high-concentration layer through a through-hole provided in the insulating film; and a back surface of the semiconductor substrate and the first P-type high-concentration layer. And the same voltage is applied between the back surface of the semiconductor substrate and the second P-type high concentration layer. Location.   In a light receiving device having a light receiving element and a frame on which the light receiving element is mounted, the light receiving element includes a first P-type high concentration layer formed on a surface of a semiconductor substrate so as to constitute a light receiving surface; A second P-type high-concentration layer formed on the surface of the first P-type high-concentration layer around the first P-type high-concentration layer; and an N-type high-concentration layer formed on the back surface of the semiconductor substrate. A high-concentration layer, an insulating coating formed on the surface of the semiconductor substrate, a first electrode connected to the first P-type high-concentration layer through a hole provided in the insulating coating, A second electrode connected to the second P-type high-concentration layer through a through-hole provided in the insulating film; and a back surface of the semiconductor substrate and the first P-type high-concentration layer. A voltage is applied to obtain an optical output between the second P-type high-concentration layer and the back surface of the semiconductor substrate. Receiving apparatus characterized by applying a scan voltage.

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