JP2010251433A - Semiconductor light-receiving element and semiconductor light-receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light-receiving element capable of adding modulation signals to bias to impress to a light-receiving element without using a bias T and achieving a small-sized and low-cost light-receiving device capable of a modulation bias operation or the like. <P>SOLUTION: The semiconductor light-receiving element includes a conductive semiconductor substrate 6, a light-receiving part formed of a semiconductor layer for converting optical signals to electrical signals, electrodes (2, 3) for electrical signal extraction for extracting the electrical signals converted in the light-receiving part to the outside, and an electrode 5 for modulation signal input. The light-receiving part and the electrodes (2, 3) for the electrical signal extraction are formed on the substrate 6, and the electrode 5 for the modulation signal input is formed, at a location different from the light-receiving part and the electrodes (2, 3) for the electrical signal extraction on the substrate 6 in the state of being insulated from the electrodes (2, 3) for the electrical signal extraction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor light receiving element and a semiconductor light receiving device.

  In fields such as optical communication and optical measurement, semiconductor light receiving elements are used as elements that convert optical signals into electrical signals. The semiconductor light-receiving element has a p-type electrode and an n-type electrode as electric signal extraction electrodes for taking out an electric signal generated by the light receiving unit to a semiconductor laminate having a light receiving unit that generates an electric signal from an optical signal. Has the basic structure formed. FIG. 1 shows an example of the basic structure of a semiconductor light receiving element. As shown in the figure, the semiconductor light receiving element has a semiconductor laminate 1 having a light receiving portion, a p-type or n-type electrode 2 as an electric signal extraction electrode, and an electrode 3 different from the above-mentioned electrode. The semiconductor light receiving element is used by applying a reverse bias voltage between the electrode 2 and the electrode 3 in order to enhance the light detection characteristics of the semiconductor light receiving element when an electrical signal is extracted from the optical signal. As prior art documents concerning such a semiconductor light receiving element and the like, there are, for example, Patent Documents 1 to 3.

  The semiconductor light-receiving element described in Patent Document 1 has a wavelength-selective layer with a band gap, has an annular second pn junction surrounding the pn junction, and is adjacent to the p region of the second pn junction. It is a semiconductor light receiving element provided with electrodes so as to straddle the n region.

  The semiconductor light receiving device described in Patent Document 2 includes a semiconductor light receiving device including a substrate, a first semiconductor layer, a light absorbing layer, a second semiconductor layer, a first electrode portion, a second electrode portion, and a third semiconductor layer. Device.

  The semiconductor light receiving element described in Patent Document 3 uses a Si-based material as a crystal substrate, has a transparent electrode above the photosensitive layer on one side of the substrate, and has a light receiving element on the other side of the substrate. This is a semiconductor light-receiving element provided with the electrode on the other side that constitutes.

  In the semiconductor light receiving element as described above, for example, when it is desired to further improve the light detection characteristics of the semiconductor light receiving element, a modulation signal can be added to the bias in accordance with the optical signal. When a modulation signal is added to the bias, for example, a gain can be obtained by device characteristics, and for example, a signal-to-noise ratio (S / N ratio) of a received optical signal can be improved. This effect can be obtained particularly well in a semiconductor light receiving element having an amplifying function such as an avalanche photodiode. In particular, in the light receiving element of an avalanche photodiode, the operating condition of the light receiving element that applies a bias higher than the breakdown using a modulation signal is called a gated Geiger mode and is applied. When a high-speed modulation bias is externally applied to the semiconductor light receiving element, it is necessary to apply the bias by adding a high-speed modulation signal to the bias power source via the bias T. The bias T includes an inductor and a capacitor, and is an electronic circuit element that can superimpose a high-speed modulation signal on a bias from a bias power source, for example. Here, for example, a semiconductor light receiving element having an operating speed of up to about 10 GHz is often mounted in a TO package. When a modulation bias is applied to the semiconductor light receiving element, a bias T is applied to the outside of the semiconductor light receiving element. Need to connect. FIG. 2 shows a circuit configuration example when a modulation bias is applied to the semiconductor light receiving element from the outside. As shown in the figure, in the circuit configuration, a bias T504 is connected to the outside of the semiconductor light receiving element 505, and the bias T504 is interposed between the semiconductor light receiving element 505 and a bias power source 503. The bias T is normally used in a state where it is mounted on a package with a connector, and is connected to a modulation bias power source 501.

JP 2000-036615 A JP 2004-111762 A Japanese Patent Laid-Open No. 2007-123587

  As an example of the normally used bias T, for example, a package (box) of about 15 mm × 32 mm × 8.9 mm is used in a state where the bias T is accommodated together with two K connector terminals and one DC terminal. That is, for example, in the case of configuring a semiconductor light receiving device that applies a modulation bias to a semiconductor light receiving element, the semiconductor light receiving element mounted on the package includes the bias T mounted on the package together with the connector as described above and its connection portion. Therefore, there is a problem that the device is bulky. Even if a smaller package and bias T can be realized, it is necessary to mount the inductor and the capacitor at a position where they do not interfere with each other, so that a considerable area is required for mounting. Furthermore, there are few types of commercially available bias T compared to inductors and capacitors such as solenoids, and it is difficult to select the bias T according to the design of the light receiving device. As described above, when a modulation bias is applied to the semiconductor light receiving element, it is necessary to dispose the bias T or the bias T module outside the light receiving element module, which increases the size of the device, increases the installation area on the circuit, and increases the cost. is there.

  Therefore, the present invention can add a modulation signal to the bias applied to the light receiving element without using the bias T, and realize a small-sized and low-cost light receiving device capable of operating the modulation bias, and the like. An object of the present invention is to provide a semiconductor light receiving device used.

The semiconductor light receiving element of the present invention includes a conductive semiconductor substrate, a light receiving portion formed from a semiconductor layer for converting an optical signal into an electric signal, an electric signal extraction electrode for taking out the electric signal converted by the light receiving portion to the outside, and a modulation signal Having input electrodes,
The light receiving portion and the electrical signal extraction electrode are formed on the conductive semiconductor substrate,
The modulation signal input electrode is formed in an insulated state from the electrical signal extraction electrode at a location different from the light receiving portion and the electrical signal extraction electrode on the substrate.

In the first semiconductor light receiving device of the present invention, the light receiving unit includes a conductive semiconductor layer of the same type as the conductive semiconductor substrate, and a conductive semiconductor layer of a different type from the conductive semiconductor substrate. As the electrode, the semiconductor light receiving element of the present invention including an electrode electrically connected to the conductive semiconductor substrate and an electrode electrically connected to the atypical conductive semiconductor layer;
An inductor connected to an electrode electrically connected to the conductive semiconductor substrate is included.

  According to a second aspect of the present invention, there is provided a semiconductor light receiving device including the semiconductor light receiving element of the present invention and a modulation signal generating device for generating a modulation signal to be input to the modulation signal input electrode.

In the third semiconductor light-receiving device of the present invention, the light-receiving portion includes a conductive semiconductor layer having the same type as the conductive semiconductor substrate, and a conductive semiconductor layer having a different type from the conductive semiconductor substrate. As the electrode, the semiconductor light receiving element of the present invention including an electrode electrically connected to the conductive semiconductor substrate and an electrode electrically connected to the atypical conductive semiconductor layer;
An inductor connected to an electrode electrically connected to the conductive semiconductor substrate;
And a modulation signal generator for generating a modulation signal to be input to the modulation signal input electrode.

  According to the present invention, a modulation signal can be added to the bias applied to the light receiving element without using the bias T, and a small-sized and low-cost semiconductor light receiving element capable of performing a modulation bias can be realized.

FIG. 1 is a cross-sectional view showing a basic structure of a semiconductor light receiving element. FIG. 2 is a diagram illustrating a circuit configuration example when a modulation bias is applied to the semiconductor light receiving element using the bias T. FIG. 3 is a cross-sectional view showing an embodiment of the semiconductor light receiving element of the present invention. FIG. 4 is a cross-sectional view showing an embodiment of the semiconductor light receiving element of the present invention. FIG. 5 is a cross-sectional view showing an embodiment of the semiconductor light receiving element of the present invention. FIG. 6 is a cross-sectional view showing an embodiment of the semiconductor light receiving element of the present invention. FIG. 7 is a circuit diagram showing a configuration example of the semiconductor light receiving device of the present invention. FIG. 8 is a cross-sectional view showing an embodiment of the semiconductor light receiving element of the present invention. FIG. 9 is a rear view showing the back surface of the embodiment shown in FIG. FIG. 10 is a diagram showing an example of a chip carrier on which the embodiment shown in FIGS. 8 and 9 is mounted. FIG. 11A is a diagram showing a mounting example in the stem of the embodiment shown in FIGS. 8 and 9 mounted on the chip carrier shown in FIG. FIG. 11B is a diagram showing an example of a light receiving module including the semiconductor light receiving element of the present invention. FIG. 12 is a diagram showing a circuit configuration example when a modulation bias is applied to the semiconductor light receiving element of the present invention. FIG. 13 is a cross-sectional view showing an embodiment of the semiconductor light receiving element of the present invention. FIG. 14 is a rear view showing the back surface of the embodiment shown in FIG. 13. FIG. 15 is a side view showing the embodiment shown in FIGS. 13 and 14.

  As described above, in the semiconductor light receiving element of the present invention, the light receiving portion and the electric signal extraction electrode are formed on the conductive semiconductor substrate. The modulation signal input electrode is formed in an insulated state from the electrical signal extraction electrode at a location different from the light receiving portion and the electrical signal extraction electrode on the conductive semiconductor substrate. FIG. 3 shows a configuration of an example of the semiconductor light receiving element of the present invention. FIG. 3 shows an example in which signal light is incident from the upper surface (front surface) of the semiconductor light receiving element as indicated by an arrow. As shown in the figure, in the semiconductor light receiving element of the present invention, a light receiving portion and electrodes 2 and 3 which are electric signal extraction electrodes are formed on a conductive semiconductor substrate 6, and the modulation signal input electrode 5 is provided with the light receiving portion. The electrode 2 and the electrode 3 and the electrode 3 are formed in an insulating state in a place different from the electrode and the electrode 2 and the electrode 3. The semiconductor light-receiving element of the present invention shown in the same figure is formed on a conductive semiconductor substrate 6 in order from the conductive semiconductor substrate 6, a semiconductor layer 7 of the same type as the conductive semiconductor substrate 6, a light absorption layer 8, and a conductive layer. It is formed from a semiconductor stacked body 1 in which a semiconductor substrate 6 and a different type semiconductor layer 9 are stacked. The light receiving portion is formed of a semiconductor layer (7, 8, 9) in a mesa-shaped portion at the center of the semiconductor stacked body 1. A modulation signal input electrode 5 is formed on the conductive semiconductor substrate 6 via an insulating film 4. However, the semiconductor light receiving element of the present invention is not limited to the embodiment shown in FIG. For example, in FIG. 3, the light receiving portion is formed of the semiconductor layer 7, the light absorption layer 8, and the semiconductor layer 9, but is not limited to such a structure, and may be formed of a semiconductor layer. In FIG. 3, the modulation signal input electrode 5 is formed on the conductive semiconductor substrate 6 with the insulating film 4 interposed therebetween. However, the present invention is not limited to such a structure, and the electric signal extraction electrode (2, It is only necessary to be formed on the conductive semiconductor substrate 6 in an insulating state with 3). In addition, in the same figure, as described above, a surface incident type semiconductor light receiving element in which signal light enters from the surface of the semiconductor light receiving element is shown, but the semiconductor light receiving element of the present invention is not limited to this. Thus, since the semiconductor light receiving element of the present invention has the modulation signal input electrode 5, it is not necessary to use the bias T for adding the modulation signal to the bias, and the cost for realizing the modulation signal operation is not required. The degree of freedom in mounting design can be increased.

In the semiconductor light receiving element of the present invention, the conductive semiconductor substrate is not particularly limited as long as it is formed of a semiconductor. As the conductive semiconductor substrate, for example, an InP substrate or a GaAs substrate can be used, and for example, an InP substrate can be suitably used. The conductive semiconductor substrate may be formed of a p-type semiconductor or an n-type semiconductor. The light receiving portion is not particularly limited as long as it is formed of a semiconductor layer and can convert an optical signal into an electric signal. The light receiving unit receives, for example, signal light that is incident from the front or back surface of the semiconductor light receiving element of the present invention and reaches the light receiving unit as an optical signal. The light receiving portion is, for example, a portion that generates a photoelectric effect in a stacked body of semiconductor layers. The light receiving portion is formed of, for example, a p-type semiconductor layer formed of a p-type semiconductor and an n-type semiconductor layer formed of an n-type semiconductor. In such a light receiving part, the part that produces the photoelectric effect is, for example, a pn junction or a pin junction. Such a light receiving unit is, for example, a first semiconductor layer having the same type as the conductive semiconductor substrate, a light absorption layer, and a different type from the conductive semiconductor substrate on the conductive semiconductor substrate. The second semiconductor layer can be sequentially stacked. The light receiving unit may include other semiconductor layers. The first and second semiconductor layers are, for example, buffer layers. Each of the first semiconductor layer and the second semiconductor layer may be formed by stacking a plurality of layers via other layers such as an etching layer. The light receiving section may include a conductive contact layer, a multiplication layer, and an electric field relaxation layer as the other semiconductor layer. Such a light receiving portion can be produced, for example, by epitaxially growing the respective layers on the conductive semiconductor substrate. The signal light may enter the light receiving unit from any surface of the light receiving unit. That is, the semiconductor light receiving element may have a region for passing the signal light (referred to as “signal light passing region” in the present invention) on at least one of the front surface and the back surface. The semiconductor light-receiving element can be manufactured, for example, in a square shape of about 500 μm square, and thereby, a large number of semiconductor light-receiving elements of the present invention can be manufactured from one wafer, yield can be improved, and manufacturing cost can be reduced. it can. From the viewpoint of ease of handling in the manufacturing process and the like, the conductive semiconductor substrate is preferably formed in a rectangular shape having a side length of about 200 μm or 200 μm. From the viewpoint of improving yield, the conductive semiconductor substrate desirably has a small planar area, and for example, the planar area is preferably at least 1 mm ² or less. By doing so, for example, when manufacturing using a 2-inch substrate (2025 mm ² size), nearly 2000 conductive semiconductor substrates can be manufactured, thereby reducing costs. However, it is not limited to such a size. On the other hand, from the viewpoint of forming a modulation signal input electrode, it is preferable that the conductive semiconductor substrate has a large planar area because it can cope with a broadband modulation signal. For example, the semiconductor element of the present invention can be manufactured with a good yield and in terms of forming a modulation signal input electrode when it is formed in a square shape with a side of 250 μm to 500 μm, but it is limited to such a range. Any size is acceptable. For example, in order to increase the dynamic range particularly from the viewpoint of the modulation signal input electrode, the conductive semiconductor substrate can be formed in a rectangular shape with a side of 5 mm at maximum.

  The electrical signal extraction electrode includes, for example, an electrode electrically connected to the conductive semiconductor substrate and an electrode electrically connected to a semiconductor layer of a different type from the conductive semiconductor substrate in the light receiving unit. . Such an electrical signal extraction electrode is only required to be electrically connected to the conductive semiconductor substrate or the different type semiconductor layer, and is directly connected to the conductive semiconductor substrate or the different type semiconductor layer. Alternatively, for example, the substrate to be electrically connected or the semiconductor layer of a different type may be connected via another layer. Such electrodes are, for example, a p-type electrode connected to the p-type semiconductor layer and an n-type electrode connected to the n-type semiconductor layer. For example, when the light receiving unit receives an optical signal, the semiconductor light receiving element of the present invention is electrically connected to an electrode electrically connected to the conductive semiconductor substrate and to the different type semiconductor layer. A reverse bias is applied between the electrodes. As a result, the optical signal is converted into an electrical signal by the light receiving unit, and the electrical signal is output from the electrical signal extraction electrode as a current (hereinafter also referred to as “signal current”). Can be taken out.

  In the semiconductor light receiving element of the present invention, as long as the modulation signal input electrode can input a modulation signal to the conductive semiconductor substrate from the outside of the semiconductor light receiving element and is insulated from the electric signal extraction electrode. There is no particular restriction. The modulation signal input electrode is formed at a location different from the light receiving portion and the electrical signal extraction electrode on the conductive semiconductor substrate. The modulation signal input electrode is formed, for example, on the surface of the conductive semiconductor substrate opposite to the light receiving portion and the electric signal extraction electrode, but is not limited thereto. The modulation signal input electrode is not connected to the ground (GND). The modulation signal input electrode can be formed on the conductive semiconductor substrate via an insulating film, for example. It is preferable that the modulation signal input electrode can have a capacitance between the conductive semiconductor substrate and the insulating film. For example, by forming the modulation signal input electrode using a conductor, a capacitance can be provided between the conductive semiconductor substrate and the conductive film via the insulating film. In the semiconductor light receiving element of the present invention, the modulation signal input electrode may be formed on at least a part of the insulating film. That is, if the modulation signal input electrode is formed not on the entire surface of the insulating film but on a part of the insulating film, a modulation signal can be appropriately added to the bias. It is preferable that the modulation signal input electrode is not formed in a portion having a constant width inside from the end of the insulating film. Thereby, for example, an allowable range of misalignment with respect to the insulating film when the modulation signal input electrode is formed on the insulating film can be expanded. However, for example, when using the apparatus capable of performing the alignment with high accuracy, such as when using the alignment with high accuracy, the distance from the end of the insulating film of the modulation signal input electrode is made smaller. can do. The modulation signal can be appropriately selected according to the signal light, and is not particularly limited. For example, the modulation signal is a high-speed signal, for example, a sine wave or a pulse wave. The modulation signal is, for example, a high frequency signal of 2 MHz to 10 GHz, but is not limited thereto.

The insulating film generates a capacitance between the modulation signal input electrode and the conductive semiconductor substrate, and prevents a direct current from flowing between the modulation signal input electrode and the conductive semiconductor substrate. The insulating film may be formed on one surface of the conductive semiconductor substrate with the same size as the one surface. For example, in order not to reduce element isolation work efficiency by scribe, the conductive film It may be formed in a range within a certain distance from the edge of the conductive semiconductor substrate. That is, in order to prevent such a decrease in element isolation work efficiency, it is preferable that the element is not formed in a portion having a constant width inside from the end of the conductive semiconductor substrate. For example, it is preferable that the insulating film is formed in a range that is more than the width of the scribing blade of the scribing device from the end of the conductive semiconductor substrate. For example, when the width of the scribe blade is small, or when the angle of the edge of the scribe blade is small, there is no problem with reducing the constant distance. More specifically, in order to prevent a decrease in the element isolation work efficiency, it is preferable that the insulating film is formed in an inner area of 5 μm or more from the end of the conductive semiconductor substrate. The insulating film can be formed of an insulating material. As the insulating film, either an organic dielectric film or an inorganic dielectric film can be used, and the insulating film may be formed as a laminated body in which the organic dielectric film and the inorganic dielectric film are combined. A capacitor can be formed between the modulation signal input electrode and the conductive semiconductor substrate by using the organic dielectric film, the inorganic dielectric film, or the laminate as the insulating film. For example, a polyimide film or a BCB film can be used as the organic dielectric film, but the organic dielectric film is not limited thereto. For example, SiNx, SiOx, or SiOxNx can be used as the insulator for forming the inorganic dielectric film, but is not limited thereto. In particular, by forming the insulating film of SiNx, a withstand voltage characteristic of about 4 to 6 MV / cm can be secured in the insulating film. The insulating film can be appropriately selected according to the operating voltage of the semiconductor light receiving element of the present invention. For example, it is preferable that the insulating film has a thickness that can suppress at least a leakage current at an operating voltage of the semiconductor light receiving element of the present invention. By forming the insulating film thick, a leak current can be suppressed, and a highly sensitive semiconductor light receiving element of the present invention with a small signal current can be manufactured. On the other hand, when the insulating film is formed thin, the capacitance as a capacitor increases, the frequency of the modulation bias can be lowered, and a pulsed modulation bias can be added to the conductive semiconductor substrate. For example, when the semiconductor light-receiving element of the present invention is a pin photodiode having a low operating voltage, the operating voltage is up to about 5 V, so that the bias voltage applied to the insulating film is equal to or lower than the operating voltage. . Thereby, the leakage current is reduced, and for example, the insulating film can be formed thin. That is, in this case, the thickness of the insulating film is not particularly limited, but for example, 100 to 2000 mm is preferable, and 100 to 500 mm is preferable. In addition, 1、１０ is equal to 10 ⁻¹⁰ m. Further, for example, when the semiconductor light receiving element of the present invention is an avalanche photodiode (APD) having a high operating voltage, it is preferable to use an insulating film having a high withstand voltage. Specifically, an insulating film in which the leakage current of the insulating film is 1 μA or less at a voltage in the operating range of the semiconductor light receiving element of the present invention is preferable. That is, when the semiconductor light receiving element of the present invention is an APD, it is preferable that the film is formed thick according to the operating voltage. Specifically, when the semiconductor light receiving element of the present invention is an APD, the breakdown voltage may be 30 V or higher. In such a semiconductor light receiving element of the present invention, when, for example, SiNx, SiOx, or SiOxNx is used as the insulator, for example, if the insulating film is formed to have a thickness of 500 mm or more, the leakage current is 1 nA even when the operating voltage is high. The following can be suppressed, and the signal current is not affected. In particular, when the insulator is SiNx, for example, an insulating film having a breakdown voltage of about 3 MV / cm can be used. In this case, the insulating film is preferably formed with a thickness of (breakdown voltage Vb × 33) Å or more. As a specific example, in the case of an APD with an operating voltage of 30 V, the insulating film is preferably formed with a thickness of 990 mm or more. Further, in this case, except for the case where the operating voltage is very high, it is preferably formed with a thickness of 2039 mm or less which is the thickness of the antireflection film described later. In the semiconductor light receiving device of the present invention, when the photocurrent used for detecting the signal light is small, the semiconductor light receiving device of the present invention is an avalanche photodiode, and the avalanche photodiode emits weak signal light. In the case of detection, it is preferable that the insulating film can prevent a significant influence on the extracted signal current. Therefore, it is preferable to use an insulating film having a leakage current of about 1 nA or 1 nA or less at the operating voltage of the semiconductor light receiving element of the present invention as the insulating film.

As the insulating film, a dielectric that transmits signal light can be used. According to such a dielectric, an insulating film having both an insulating effect as the insulating film and an antireflection effect as an antireflection film for preventing reflection of signal light can be produced. However, when the antireflection effect is given, the relationship between the refractive index and the thickness of the insulating film is used for antireflection, so that the degree of freedom in design is reduced with respect to the thickness. For example, when the insulating film is formed of a single layer of SiNx, the insulating film has a thickness of about 2000 mm in order to reduce the reflectance of signal light between the conductive semiconductor substrate and air. Good. The thickness of the insulating film that is preferable from the viewpoint of reducing the reflectance varies depending on the refractive index of the insulating film and the wavelength of the signal light. The insulating film preferably has a thickness (d) represented by the following formula (I), where d is the thickness.

(0.9λ / 4n) ≦ d ≦ (1.1λ / 4n) (I)

In the formula (I), λ means the wavelength of the signal light, and n means the refractive index of the insulating film at the signal light wavelength. For example, when the signal light is calculated to be 1.55 μm and the refractive index of the insulator is 1.9, it is 2039 cm × 0.9 or more and 2039 cm × 1.1 or less. By forming in this way, a function as an insulating film can be secured. The semiconductor light receiving element of the present invention can correspond to signal light having any wavelength, but can correspond to signal light having a wavelength of 1.2 μm to 1.6 μm, for example. The semiconductor light receiving element of the present invention can cope with signal light having a wavelength such as 1.3 μm or 1.55 μm, for example. The refractive index (n) of the insulating film is, for example, 1.80 to 2.10 (for example, 1.9) in the case of an insulating film formed of SiN, and for example, an insulating film formed of SiON. In the case of a film, it is 1.5 to 1.9. In addition, as the insulating film having an antireflection effect, a film formed of a material having a refractive index value (n) close to a value calculated by the following formula (II) can be preferably used.

n = SQRT (X) (II)

In the formula (II), n means the refractive index of the insulating film, SQRT (X) means the square root of X, X = n1 × n2, and n1 is the refraction of the conductive semiconductor substrate. N2 means the refractive index of air. For example, when n1 is 3.53, the insulating film has a refractive index value close to n = SQRT (3.53 × 1) ≈1.88, calculated by the above formula (II). What is formed from material can be used conveniently. However, the present invention is not limited to such a range. In the case of forming such an antireflection layer, formation of a conductor required for forming a modulation signal input electrode having the same capacity as the semiconductor light receiving element of the present invention using a thin insulating film as compared with the antireflection layer. The area becomes wider. Here, as the insulating film is as thin as possible, the capacity is increased and a broadband modulation signal can be passed. For this reason, for example, the dielectric film as the antireflection film and the insulating film of the capacitor portion may be formed separately, whereby the characteristics of the modulation signal input electrode can be improved. For example, the antireflection film can be formed in a wider range than the region through which the signal light passes, and the insulating film can be thinly formed on the outer portion of the antireflection film. As described above, in order to manufacture a highly sensitive semiconductor light receiving element with a small signal current while suppressing a leakage current, it is necessary to form the insulating film thick to some extent. On the other hand, in order to increase the capacity of the insulating film and pass a broadband modulation signal, the insulating film needs to be formed to be thin to some extent. From this viewpoint, when the antireflection film and the insulating film are separately formed, the thickness of the insulating film is preferably 50 to 1000 mm, and more preferably 100 to 500 mm. In the case where the dielectric film as the antireflection film and the insulating film of the capacitor portion are separately formed, for example, after the dielectric is formed as the antireflection film, only the insulating film portion is thinly formed by etching or the like. In this way, an insulating film can be formed. In addition, after forming the dielectric as the antireflection film, the dielectric may be removed only at a location where the insulating film is to be formed, and a new insulating film may be formed. In addition, after forming the dielectric as the insulating film, the dielectric may be removed only at a portion where the antireflection film is to be formed, and then the antireflection film may be newly formed.

  In the semiconductor light receiving element of the present invention, when the surface on which the modulation signal input electrode is formed and the incident surface of the signal light are the same, the modulation signal input electrode is formed on the incident surface of the conductive semiconductor substrate. It is preferably formed in a portion excluding the signal light passage region through which signal light passes. That is, in this case, it is preferable that the modulation signal input electrode is formed on a portion outside the signal light passage region on the one surface of the conductive semiconductor substrate. Thereby, the influence of the modulation signal input electrode on the signal light detection capability of the semiconductor light receiving element of the present invention can be suppressed. For example, when the modulation signal input electrode includes a conductor, 10% or more of the signal light may be absorbed depending on the conductor. In such a case, forming the modulation signal input electrode outside the region can suppress the influence on the signal light detection capability of the light receiving element due to the absorption of the signal light by the conductor, and is particularly effective. is there. The signal light passage region is preferably formed in a shape having an area larger than the area of the signal light receiving spot on the incident surface of the conductive semiconductor substrate. The size of the signal light passage region can be appropriately determined depending on the diameter of the light receiving spot of the signal light. For example, the signal light passage region can be formed in a circular shape having a diameter longer than the diameter of the signal light receiving spot on the incident surface of the conductive semiconductor substrate. Thus, by forming the modulation signal input electrode outside the signal light passage region, it is possible to prevent interference between the modulation signal input electrode and the signal light passing through the signal light passage region. For example, when the light receiving spot of the signal light is circular and the diameter of the light receiving spot is smaller than the thickness of the conductive semiconductor substrate, the signal light passing region has a diameter greater than or equal to the thickness of the conductive semiconductor substrate. It is preferable that it has a circular shape. For example, when the light receiving spot of the signal light has a circular shape and the diameter of the light receiving spot is larger than the thickness of the conductive semiconductor substrate, the signal light passing region has a diameter equal to or larger than the diameter of the light receiving spot. It is preferably a circular shape having Specifically, when the semiconductor light receiving element of the present invention includes a conductive semiconductor substrate having a thickness of 100 μm and the diameter of the light receiving spot is shorter than 100 μm, the signal light passing region is formed in a circular shape having a diameter of about 100 μm. Thus, interference between the modulation signal input electrode and the signal light can be prevented. Further, for example, when the diameter of the light receiving spot is longer than 100 μm, the signal light passing region is formed in a circular shape having a diameter approximately the same as the diameter of the light receiving spot, so that the modulation signal input electrode and The interference of the signal light can be prevented. Furthermore, for example, when the light receiving spot of the signal light has an elliptical shape or an oval shape, and the long diameter of the light receiving spot is smaller than the thickness of the conductive semiconductor substrate, the signal light passing region is the conductive semiconductor. A circular shape having a diameter equal to or larger than the thickness of the substrate is preferable. Further, for example, when the light receiving spot of the signal light has an elliptical shape or an oval shape, and the long diameter of the light receiving spot of the signal light is larger than the thickness of the conductive semiconductor substrate, the signal light passing region is A circular shape having a diameter equal to or larger than the major axis of the light receiving spot is preferable. For example, when the light receiving spot is not circular or elliptical, the signal light passing region may be formed in a larger shape (area) than the light receiving spot.

  The modulation signal input electrode preferably includes a conductor portion and a pad electrode. As a result, the modulation signal input electrode can function as an electrode plate for generating a capacitance. In particular, it is preferable that the modulation signal input electrode is formed on the conductive semiconductor substrate via the insulating film, and the conductor portion is disposed between the insulating film and the pad electrode. Thereby, the conductor part can transmit the modulation signal from the external modulation signal generator to the conductive semiconductor substrate. Moreover, the said conductor part can be functioned as an electrode plate which generate | occur | produces a capacity | capacitance through the said insulating film between the said conductive semiconductor substrates, for example by expanding the area. That is, by increasing the element capacity in order to function as a DC block, the characteristics of the semiconductor light receiving element of the present invention can be improved. Specifically, in the semiconductor light receiving element of the present invention, the frequency range that can be passed with low loss can be expanded.

  The conductor may be formed of a single metal, may be formed of a plurality of metals, so-called alloys, or may have a laminated structure in which a plurality of metal layers are combined. By forming the conductor with a metal, the conductor can be thinned. As the metal, for example, any one of Ti, Pt, Au, Ni, Cr, Mo, and Al can be used. However, the metal is not limited thereto, and for example, a metal in the same group as the metal may be used. it can. The metal is preferably a metal having a melting point of 330 ° C. or higher. As such a metal, either a simple substance or an alloy can be used. It is preferable that the conductor has a thickness required to function as a capacitor electrode plate. From this viewpoint, the conductor preferably has a thickness of, for example, 100 mm or more, but is not particularly limited. For example, a conductor having a thickness of 600 to 3500 mm can be suitably used as the conductor, but the conductor is not limited thereto, and a conductor having a thickness of 5000 mm can be used. In order to ensure adhesion with the conductive semiconductor substrate, for example, the conductor can be a Ti layer of about 300 mm and an Au layer of about 1000 mm, respectively. It can be formed stably. When the conductor includes a Ti layer and an Au layer, the Ti layer preferably has a thickness of 100 to 500 mm. The Au layer preferably has a thickness of 500 to 3000 mm. However, when the thickness of the conductor is increased, the formation time (electrode preparation time) becomes longer, and the manufacturing cost including working time and raw material cost increases. Therefore, considering the cost, the conductor is 3000 mm or less. It is preferable to have a thickness. As described above, it is preferable that the modulation signal input electrode is not formed in a portion inside the fixed film by a certain width from the end of the insulating film. That is, when the modulation signal input electrode includes the conductor, it is preferable that the conductor is formed within a certain distance inner side from the end of the insulating film. This also prevents a short circuit between the modulation signal input electrode and the conductive semiconductor substrate, and ensures an insulation state of the modulation signal input electrode from the electrical signal extraction electrode. In order to prevent the short circuit, it is preferable that the conductor is not formed in a range of 3 μm or more from the end of the insulating film. In addition, when the portion where the conductor is not formed is a portion which is 10 μm or more inside from the end of the insulating film, it is possible to tolerate a shift in the production of the semiconductor light receiving element of the present invention, a crack of the insulating film, etc. Does not affect.

For example, in the case where the modulation signal input electrode includes the flat plate-like conductor portion, the planar area of the conductor portion is 1.64 × 10 ⁶ μm ² or less so that it can be mounted on a TO-56 package. The semiconductor light receiving element of the present invention can be produced. Further, when the modulation signal input electrode includes the flat plate-like conductor portion, the planar area of the conductor portion is 3.03 × 10 ⁷ μm ² or less, so that the mounting on a TO-8 package is possible. The semiconductor light receiving element of the present invention can be produced.

  The pad electrode is an electrode for connecting to an external device such as a modulation signal generator using a material such as a bonding wire, a conductive paste, solder, or a eutectic alloy. Thereby, the modulation signal from an external modulation signal generator can be supplied to the conductor portion by wire bonding to the pad electrode. The pad electrode can be formed of metal, for example, can be formed on the conductor using aluminum or gold. By forming the pad electrode with metal, the connectivity of the pad electrode with an external device can be improved. In particular, the adhesiveness with the wiring wire is improved by forming the pad electrode with aluminum or gold. For example, the pad electrode may be formed in a rectangular shape having a side of about 80 μm or 80 μm or less, but is not limited thereto. That is, when the pad electrode is produced in such a rectangular shape, there is an advantage that the manufacturing work with the naked eye is facilitated. For example, when using a device capable of realizing high-precision mounting, a smaller pad is used. An electrode can be formed. The pad electrode made of aluminum or gold has, for example, excellent wire bond characteristics. The pad electrode preferably has a thickness of about 2000 mm or more than 2000 mm, so that, for example, it can be stably thermally bonded to a wiring wire. The pad electrode can be formed to a thickness of about 2 to 3 μm using, for example, gold plating, and can be more stably adhered to, for example, a wiring wire.

  The semiconductor light-receiving element of the present invention can be produced using semiconductor processing techniques such as lithography, etching, diffusion, CVD, vapor deposition, and polishing. That is, in the semiconductor light-receiving element of the present invention, for example, the semiconductor signal is epitaxially grown on the conductive semiconductor substrate, and the electrical signal extraction electrode and the modulation signal input electrode are formed on the stacked body in which the light-receiving portion is formed. It can produce by doing. The semiconductor light receiving element of the present invention can be mounted on a chip carrier on which the semiconductor light receiving element of the present invention can be mounted, for example. The chip carrier is formed of, for example, an insulator, and includes conductors on one surface for wiring with the electrical signal extraction electrode and the modulation signal input electrode, such as the semiconductor light receiving element of the present invention. It has an electrode pattern and has a metal portion for connecting to the stem on the other surface. The electrical signal extraction electrode and the modulation signal input electrode of the semiconductor light receiving element or the like of the present invention are connected to the corresponding electrode patterns. In this way, the semiconductor light receiving element of the present invention mounted on the chip carrier is mounted on a stem and wired to three independent terminals other than GND. For example, the package can be completed like a normal CAN module (pigtail module) by sealing the lid and welding the fiber module.

  The semiconductor light receiving element of the present invention can output a signal current from the electrical signal extraction electrode by applying a reverse bias to the electrical signal extraction electrode. At this time, the modulation signal can be added to the bias by inputting the modulation signal to the modulation signal input electrode. The modulation signal can be input to the modulation signal input electrode using, for example, any modulation signal generator capable of generating the modulation signal. Such a modulated signal generator is not particularly limited as long as it can generate the modulated signal. The modulation signal generator is, for example, a modulation bias power supply, a combination of a pulse source and an amplifier, an oscillator, a combination of an oscillator and a wideband amplifier, a pulse pattern generator, a combination of a pulse pattern generator and a wideband amplifier, etc. It is not limited. Here, the semiconductor light receiving element of the present invention can be used, for example, by connecting an inductor to the electrical signal extraction electrode that is electrically connected to the conductive semiconductor substrate. The inductor is a circuit element having an inductance such as a coil, for example. In the present invention, for example, a bias voltage and a current can be passed through the inductor. As a result, the modulation signal can be input to the semiconductor laminate without missing the modulation signal from the electrical signal extraction electrode electrically connected to the conductive semiconductor substrate. The inductor includes, for example, a solenoid. As described above, according to the semiconductor light receiving element of the present invention, for example, in the photodetector circuit for adding the modulation signal to the DC bias, the modulation bias operation can be performed using the inductor, for example, without using the bias T. A possible photodetection device can be designed, and the device size can be reduced and the manufacturing cost can be reduced. In addition, since the inductors are generally more abundant and less expensive than the bias T, according to the semiconductor light receiving element of the present invention, the degree of freedom in designing the device such as the photodetection device can be increased.

  The aspect of the semiconductor light receiving element of the present invention is not particularly limited as long as the effects of the present invention are exhibited. The semiconductor light receiving element of the present invention is, for example, a pin photodiode or an avalanche photodiode, but is not limited thereto. For example, when the semiconductor light receiving element of the present invention is an avalanche photodiode, the semiconductor light receiving element of the present invention can take an operation mode called a gated Geiger mode. That is, the operating point of the semiconductor light receiving element is set near the breakdown using, for example, a DC bias, the DC bias applied to the conductive semiconductor substrate, and the amplitude of the modulation signal applied from the modulation signal input electrode A voltage pulse having the same sign as that of the DC bias can be applied as the modulation signal so that the sum of the above becomes equal to or greater than the breakdown. In this aspect, since a bias exceeding the breakdown is instantaneously applied, a highly sensitive signal light detection effect can be obtained to the extent that one photon is received. The amplitude of the modulation signal required in such an operation mode of the gated Geiger mode is 1 V or more, and the larger the amplitude, the higher the signal-to-noise ratio (S / N ratio) for detecting signal light. . The amplitude of the modulation signal in such a gated Geiger mode operation mode is preferably, for example, 10% to 20% of the breakdown voltage, but is not limited to this range. Specifically, when the breakdown voltage of the APD is 20V to 80V, the amplitude of the modulation signal is preferably 2V to 16V. The amplitude of the modulation signal is preferably 1 V or more so as to exceed the breakdown voltage. In the semiconductor light receiving element of the present invention of the above aspect, a photodetection circuit can be formed using, for example, a commercially available amplifier. The commercially available amplifier can generate a high-voltage gate pulse of, for example, about 13 V and apply it to other devices, and the pulse width of the gate pulse is, for example, 0.1 ns to 100 ns. The range is not limited. The semiconductor light receiving element of the present invention can cope with a wide range of gate pulse widths, and can be operated with a pulse width of 0.5 to 2 ns, for example. In the photodetection circuit configured as described above, it is not necessary to use the bias T, and the modulation bias operation can be performed only by connecting an inductor such as a solenoid to the semiconductor light receiving element of the present invention. For this reason, the photodetector circuit capable of the modulation bias operation has a simple structure and can be realized at low cost. That is, according to the semiconductor light receiving element of the present invention, a compact and low cost semiconductor light receiving device can be manufactured.

  As described above, in the first semiconductor light-receiving device of the present invention, the light-receiving unit includes a conductive semiconductor layer that is the same type as the conductive semiconductor substrate, and a conductive semiconductor layer that is different from the conductive semiconductor substrate, As the electrical signal extraction electrode, the semiconductor light receiving element of the present invention including an electrode electrically connected to the conductive semiconductor substrate and an electrode electrically connected to the atypical conductive semiconductor layer, An inductor connected to an electrode electrically connected to the conductive semiconductor substrate is included. FIG. 7 is a circuit diagram showing a configuration of an example of the semiconductor light receiving device of the present invention. In the figure, a portion 500 surrounded by a dotted line is a portion of the semiconductor light receiving device of the present invention including the semiconductor light receiving element of the present invention and the inductor. In the figure, an electrode 2 is an electrode electrically connected to the conductive semiconductor substrate in the semiconductor light receiving element 508. As shown in the figure, the semiconductor light receiving device 500 of the present invention includes the semiconductor light receiving element 508 of the present invention and an inductor 507 connected to the electrode 2. In the semiconductor light receiving device of the present invention, the configuration and function of the inductor are as described for the semiconductor light receiving element of the present invention. Such a semiconductor light receiving device of the present invention can add a modulation signal to the bias without using the bias T. That is, a bias can be applied from the external bias power source 503 to the electrode extraction electrodes (2 and 3) via a solenoid. At this time, the modulation signal from the modulation bias power source 501 can be input to the modulation signal input electrode 5. In this manner, the modulation bias operation can be realized in the semiconductor light receiving device of the present invention. Such a semiconductor light-receiving device of the present invention can be formed with a smaller circuit area of the photodetection circuit and can be manufactured at a lower cost than a semiconductor light-receiving device using a bias T.

  As described above, the second semiconductor light receiving device of the present invention includes the semiconductor light receiving element of the present invention and a modulation signal generating device for generating a modulation signal to be input to the modulation signal input electrode. FIG. 7 is a circuit diagram showing a configuration of an example of the semiconductor light receiving device of the present invention. In the figure, a portion 500 'surrounded by a dotted line is a portion of the semiconductor light receiving device of the present invention including the semiconductor light receiving element of the present invention and the modulation signal generating device. As shown, the semiconductor light receiving device 500 ′ of the present invention includes the semiconductor light receiving element 508 of the present invention and a modulation signal generating device 501 that generates a modulation signal to be input to the modulation signal input electrode 5. The configuration and function of the modulation signal generator are as described for the semiconductor light receiving element of the present invention. The semiconductor light-receiving device of the present invention having such a configuration can add a modulation signal to the bias without using the bias T. That is, in such a semiconductor light receiving device of the present invention, for example, the inductor 507 is connected to the electrical signal extraction electrode 2 electrically connected to the conductive semiconductor substrate, so that the electrical signal extraction electrode is connected. The modulation signal can be input to the conductive semiconductor substrate 6 without losing the modulation signal from 2. That is, a bias can be applied from the external bias power source 503 to the electrode extraction electrodes (2 and 3) via a solenoid. At this time, the modulation signal from the modulation bias power source 501 can be input to the modulation signal input electrode 5. In this manner, the modulation bias operation can be realized in the semiconductor light receiving device of the present invention. According to such a semiconductor light receiving device of the present invention, a photodetection circuit for adding a modulation signal to the bias can be formed with a small circuit area and at a low cost as compared with a semiconductor light receiving device using a bias T.

  In the third semiconductor light-receiving device according to the present invention, as described above, the light-receiving portion includes a conductive semiconductor layer having the same type as the conductive semiconductor substrate, and a conductive semiconductor layer having a different type from the conductive semiconductor substrate. The semiconductor light receiving element of the present invention including an electrode electrically connected to the conductive semiconductor substrate and an electrode electrically connected to the atypical conductive semiconductor layer as the electrical signal extraction electrode And an inductor connected to an electrode electrically connected to the conductive semiconductor substrate, and a modulation signal generator for generating a modulation signal to be input to the modulation signal input electrode. FIG. 7 is a circuit diagram showing a configuration of an example of the semiconductor light receiving device of the present invention. In the drawing, a portion 500 "surrounded by a dotted line is a portion of the semiconductor light receiving device of the present invention including the semiconductor light receiving element of the present invention, the inductor, and the modulation signal generating device. In the drawing, the electrode 2 is the semiconductor. The electrode is electrically connected to the conductive semiconductor substrate in the light receiving element 508. As shown in the drawing, the semiconductor light receiving device 500 ″ of the present invention is connected to the semiconductor light receiving element 508 of the present invention and the electrode 2. And a modulation signal generator 501 for generating a modulation signal to be input to the modulation signal input electrode 5. The inductor and the modulation signal generator are as described above. Such a semiconductor light receiving device of the present invention can add a modulation signal to the bias without using the bias T. That is, a bias can be applied from the external bias power source 503 to the electrode extraction electrodes (2 and 3) via the inductor 507. At this time, the modulation signal from the modulation bias power source 501 can be input to the modulation signal input electrode 5. In this manner, the modulation bias operation can be realized in the semiconductor light receiving device of the present invention. Such a semiconductor light-receiving device of the present invention can be formed with a smaller circuit area of the photodetection circuit and can be manufactured at a lower cost than a semiconductor light-receiving device using a bias T.

  Next, the semiconductor light receiving element of the present invention will be described with reference to the drawings. However, the following embodiment is an exemplification, and the present invention is not limited or limited by the following embodiment.

[Embodiment 1]
In this embodiment, an example of the semiconductor light receiving element of the present invention is shown. In the present embodiment, an example of the semiconductor light receiving element of the present invention in which signal light enters from the upper surface (surface) of the semiconductor light receiving element is shown. FIG. 3 shows the configuration of the semiconductor light receiving element of this embodiment. As shown in the figure, the semiconductor light receiving element of the present embodiment includes a conductive semiconductor substrate 6, a light receiving portion described later, the electric signal extraction electrodes (2 and 3), and a modulation signal input electrode 5. The light receiving portion and the electric signal extraction electrode (2 and 3) are formed on the substrate 6, and the modulation signal input electrode 5 is different from the light receiving portion and the electric signal extraction electrode on the substrate 6. It is formed in a place in an insulated state from the electrical signal extraction electrode. In the present embodiment, a first conductive semiconductor layer 7 having the same type as that of the conductive semiconductor substrate 6, a light absorption layer 8, and the conductive semiconductor substrate 6 are formed on the conductive semiconductor substrate 6 in order from the conductive semiconductor substrate 6. The second type semiconductor conductive layer 9 different from the above is laminated to form the semiconductor light receiving element of this embodiment. In the present embodiment, the light receiving portion is formed of a mesa-shaped semiconductor layer stack including the light absorption layer 8 in the center on the conductive semiconductor substrate 6. Such a light receiving portion can be produced by, for example, epitaxially growing the first conductive semiconductor layer 7, the light absorption layer 8, and the second conductive semiconductor layer 9 on the conductive semiconductor substrate 6. . The light receiving portion may be formed of a stacked body of semiconductor layers including layers other than these layers. As described above, the conductive semiconductor substrate 6 is connected to the first conductive semiconductor layer 7, and is connected to the electrode 2 electrically connected to the conductive semiconductor substrate 6 and the second conductive semiconductor layer 9. The electrode 3 and the modulation signal input electrode 5 are formed. In this embodiment, the modulation signal input electrode 5 is formed on the conductive semiconductor substrate 6 via the insulating film 4. That is, in this embodiment, the insulating film 4 is formed on the back surface of the conductive semiconductor substrate 6, and the modulation signal input electrode 5 is formed on a part of the insulating film 4. The electrode 2 and the electrode 3 can be connected to an external DC bias power source, for example. The modulation signal input power source 5 can be connected to an external modulation signal generator, for example.

  In the present embodiment, for example, a reverse bias is applied between the electrode 2 and the electrode 3 when the light receiving unit receives an optical signal. Accordingly, the light signal is converted into an electric signal by the light receiving unit, and the electric signal is output from the electrode 2 and the electrode 3 as a signal current, so that the electric signal can be extracted to the outside. Here, in the present embodiment, for example, when the reverse bias is applied, a modulation signal can be input to the modulation signal input electrode 5 from an external modulation signal generator. Thereby, a modulation signal can be added to the bias, a gain can be obtained by the element characteristics of the semiconductor light receiving element of this embodiment, and the S / N ratio of the optical signal can be improved.

[Embodiment 2]
In this embodiment, another example of the semiconductor light receiving element of the present invention is shown. The semiconductor light receiving element of the present embodiment has the same configuration as that of the first embodiment except that the modulation signal input terminal 5 in the first embodiment includes the conductor portion 10 and the pad electrode 11. FIG. 4 shows the configuration of the semiconductor light receiving element of this embodiment. As shown in the drawing, the semiconductor light receiving element of this embodiment is the same as the semiconductor light receiving element of FIG. 3 except that the modulation signal input electrode 5 includes a conductor portion 10 and a pad electrode 11. In FIG. 4, the same components as those in FIG. 3 are denoted by the same reference numerals. The modulation signal input electrode 5 is configured by forming a conductor portion 10 on an insulating film 4 and forming a pad electrode 11 thereon. The conductor part 10 may be formed from a single metal, may be formed from a plurality of metals, so-called alloys, or may have a laminated structure in which a plurality of metal layers are combined. The pad electrode 11 can be formed of metal and can be connected to an external device by wire bonding.

  Also in the present embodiment, as in the first embodiment, by applying a reverse bias between the electrode 2 and the electrode 3, an electric signal can be extracted to the outside. Also, by inputting a modulation signal to the modulation signal input electrode 5, a modulation signal can be added to the bias, gain can be obtained by the element characteristics of the semiconductor light receiving element, and the S / N ratio of the optical signal. Can be improved. In the present embodiment, the modulation signal input electrode 5 is further composed of the conductor portion 10 and the pad electrode 11. For example, by increasing the area of the conductor portion 10, an insulating film is formed between the conductive semiconductor substrate 6 and the insulating film. 4 can function as an electrode plate for generating capacitance. Thereby, in the semiconductor light receiving element of this embodiment, the frequency range that can be passed with low loss can be expanded.

  In the present embodiment, the conductor portion 10 can be prevented from being formed in a portion inside the fixed distance from the end of the insulating film 4. Thereby, an allowable range of misalignment with respect to the insulating film 4 when the modulation signal input electrode 5 is formed on the insulating film 4 can be expanded. Further, a short circuit between the modulation signal input electrode 5 and the conductive semiconductor substrate 6 can be prevented, and an insulation state of the modulation signal input electrode 5 from the electrical signal extraction electrodes (2 and 3) can be secured. .

[Embodiment 3]
In this embodiment, another example of the semiconductor light receiving element of the present invention is shown. The semiconductor light receiving element of the present embodiment has the same configuration as that of the second embodiment, except that the signal light is incident from the lower surface (back surface) of the conductive semiconductor substrate. FIG. 5 shows the configuration of the semiconductor light receiving element of this embodiment. As shown in the figure, in the semiconductor light receiving element of this embodiment, the conductive semiconductor substrate 6 has a signal light passage region 12 through which signal light incident on the light receiving portion passes on the back surface, and the modulation signal input electrode 5. Is formed on the back surface of the conductive semiconductor substrate 6 outside the signal light passage region 12. Except for this, the semiconductor light receiving element of this embodiment is the same as the semiconductor light receiving element of FIG. In FIG. 5, the same components as those in FIG. 4 are denoted by the same reference numerals.

  Also in this embodiment, the same effect as in the second embodiment can be obtained. In this embodiment, in particular, since the modulation signal input electrode 5 is formed outside the signal light passage region of the conductive semiconductor substrate 6, the modulation signal input electrode 5 can improve the signal light detection capability of the semiconductor light receiving element. The influence can be suppressed. Specifically, for example, interference of signal light passing through the modulation signal input electrode 5 and the signal light passage region 12 can be prevented.

[Embodiment 4]
In this embodiment, another example of the semiconductor light receiving element of the present invention is shown. The semiconductor light receiving element of the present embodiment has the same configuration as that of the third embodiment except that an antireflection film formed of a dielectric is formed in the signal light passage region of the conductive semiconductor substrate. FIG. 6 shows the configuration of the semiconductor light receiving element of this embodiment. As shown in the figure, in the semiconductor light receiving element of this embodiment, an antireflection film 13 is formed on the signal light passage region 12 in the conductive semiconductor substrate 6, and the back surface of the conductive semiconductor substrate 6 is separated from the antireflection film 12. The third embodiment is the same as the third embodiment except that the insulating film 4 having a thickness smaller than that of the antireflection film 13 is formed on the outside of the signal light passage region 12 in FIG. For example, after forming the antireflection film 13 using a dielectric on the back surface of the conductive semiconductor substrate 6, the antireflection film 13 and the insulating film 4 are thinly formed by etching or the like only on the insulating film 4. Thus, the insulating film 4 can be formed. Further, after the antireflection film 13 is formed using a dielectric, the dielectric may be removed only at a portion that becomes a portion of the insulating film 4 and a new insulating film 4 may be formed. In addition, after the insulating film 4 is formed on the back surface of the conductive semiconductor substrate 6 using a dielectric, the dielectric is removed only at a portion where the antireflection film 13 is formed, and then the antireflection film is newly formed using the dielectric. 13 may be formed.

  As the insulating film is as thin as possible, the capacitance increases, and a broadband modulated signal can be passed through the semiconductor light receiving element of this embodiment. Therefore, when the antireflection layer 13 is formed as in this embodiment, for example, a modulation signal input electrode having the same capacity as the semiconductor light receiving element of the present invention using a thin insulating film without forming the antireflection layer is provided. In order to form, it is necessary to widen the formation area of the conductor part 10. Therefore, as in the present embodiment, by forming an insulating film having a thickness smaller than that of the antireflection film in a portion outside the signal light passage region, both the antireflection effect and the large capacitance can be obtained.

Next, in particular, the design aspect of the conductor part in the semiconductor light receiving element of the present invention in which the modulation signal input electrode includes the conductor part will be specifically described with reference to the second and third embodiments. That is, in the semiconductor light receiving element of the second embodiment, the light detection characteristics of the semiconductor light receiving element can be improved by increasing the capacitance of the conductor portion 10. Therefore, in the semiconductor element of this embodiment, the size and shape of the modulation signal input electrode 5 can be designed so that the capacitance of the conductor portion 10 is as large as possible. That is, for example, in the second embodiment, for example, when the conductive semiconductor substrate 6 is formed in a square shape having a surface with a size of 500 μm × 500 μm, the insulating film 4 is 490 μm × 490 μm on the back surface of the conductive semiconductor substrate 6. Can be formed to the extent. In this case, the conductor part 10 can be formed widely up to a size of 484 μm × 484 μm, for example, if it is formed 3 μm inside the end of the insulating film 4. Here, since the conductive semiconductor substrate 6 is a uniform conductor, the effective electrode area between the conductive semiconductor substrate 6 and the modulation signal input electrode 5 is defined by the area of the modulation signal input electrode 5. . Therefore, when the modulation signal input electrode 5 has the above-mentioned size, the effective electrode area between the conductive semiconductor substrate 6 and the modulation signal input electrode 5 can be expanded up to 2.34 × 10 ⁵ μm ² .

Further, for example, in the third embodiment, for example, the conductive semiconductor substrate 6 is formed in a square shape having a surface with a size of 500 μm × 500 μm, and the insulating film 4 is about 490 μm × 490 μm on the back surface of the conductive semiconductor substrate 6. The effective electrode area between the conductive semiconductor substrate 6 and the modulation signal input electrode 5 when formed to have an outer peripheral size is as follows. For example, the conductor 10 can be formed widely up to a size of 484 μm × 484 μm assuming that it is formed 3 μm inside from the end of the insulating film 4. When the light spot of the signal light is a circle having a diameter (light receiving diameter) of 20 μm, and the signal light passing region 12 for preventing the signal light and the modulation signal input electrode 5 from interfering is formed in a circle having a diameter of about 100 μm, It becomes as follows. That is, the effective electrode area is calculated from “the plane area of the modulation signal input electrode 5−the area of the signal light passing region 12”, and from 2.34 × 10 ⁵ μm ² −3.14 × 50 μm × 50 μm, It can be expanded to a maximum of 2.26 × 10 ⁵ μm ² .

For example, when mounting the semiconductor light receiving element of the second embodiment or the third embodiment in which the chip carrier is mounted on a TO-56 type stem, for example, three pins are used depending on the terminal arrangement of the stem. The size of the chip carrier that can be mounted on the stem where the terminals are arranged is about 1.5 mm × 1.5 mm. In the case where pads having a size of 100 μm × 100 μm are arranged as a terminal pattern in the peripheral portion on such a chip carrier, the semiconductor light receiving element of the embodiment can be arranged from the periphery of the chip carrier to the inside of 100 μm. Therefore, in this case, the maximum size of the semiconductor light receiving element of the embodiment that can be mounted on the chip carrier is 1.3 mm × 1.3 mm. In this case, the formation range of the insulating film 4 can be designed to a maximum size of 1.290 mm × 1.290 mm, for example. And the area of the formation range of the conductor part 10 can be expanded to 1.284 mm x 1.284 mm in the said Embodiment 2. FIG. In the case of the third embodiment, when the light receiving spot of the signal light has a circular shape with a diameter of 20 μm and the signal light passage region 12 has a circular shape with a diameter of about 100 μm, “the outer diameter area of the conductor portion 10− The area of the conductor 10 can be expanded to 1.284 mm × 1.284 mm−3.14 × 50 μm × 50 μm = 1.64 × 10 ⁶ μm ² calculated from “the area of the signal light passing region 12”.

For example, when the semiconductor light receiving element of the second embodiment or the third embodiment is mounted in a larger package such as a TO-8 type stem, the size of the conductor portion 10 is designed as follows. be able to. That is, since a larger mounting area (for example, about 5.72 mm × 5.72 mm) can be taken with the TO-8 type stem, the maximum size of the chip carrier can be formed to 5.72 mm × 5.72 mm. . The maximum size of the semiconductor light receiving element that can be mounted on such a chip carrier is 5.52 mm × 5.52 mm in terms of a planar area. The maximum area of the insulating film 4 that can be formed by the semiconductor light receiving element of this size is 5.51 mm × 5.51 mm. Therefore, in the case of the said Embodiment 2, the formation range of the conductor part 10 can be expanded to 5.504 mm x 5.504 mm. In the case of the third embodiment, when the light receiving spot of the signal light has a circular shape with a diameter of 20 μm and the signal light passage region 12 has a circular shape with a diameter of about 100 μm, “the outer diameter area of the conductor portion 10−signal light” The area of the conductor 10 can be expanded to 5.504 mm × 5.504 mm−3.14 × 50 μm × 50 μm = 3.03 × 10 ⁷ μm ² calculated from the “area of the passing region 12”. Although the semiconductor light receiving element of the present invention larger than that described above can be produced, the planar area of the conductor portion 10 is 1.6 × 10 ² μm ^{2 to} 3.03 × 10 from the viewpoint that it can be mounted on a package. It is preferably ⁷ μm ² .

  Next, the semiconductor light receiving device of the present invention will be described with reference to the drawings. However, the following embodiment is an exemplification, and the present invention is not limited or limited by the following embodiment.

[Embodiment 5]
In this embodiment, an example of the semiconductor light receiving device of the present invention is shown. In the present embodiment, an example of the semiconductor light receiving device of the present invention including the semiconductor light receiving element of the present invention and an inductor is shown. FIG. 7 is a circuit diagram showing the configuration of the semiconductor light receiving device of this embodiment. In the drawing, a portion 500 indicated by a one-dot chain line is a portion constituting the semiconductor light receiving device of the present embodiment. As illustrated, the semiconductor light receiving device of this embodiment includes a semiconductor light receiving element 508 and an inductor 507 of the present invention. In the present embodiment, the semiconductor light receiving element of the present invention is any one of the first to fourth embodiments. That is, the light receiving portion includes a conductive semiconductor layer 7 of the same type as that of the conductive semiconductor substrate 6 and a conductive semiconductor layer 9 of a different type from the conductive semiconductor substrate 6, and a conductive semiconductor is used as the electrical signal extraction electrode. The semiconductor light-receiving element of the present invention includes an electrode 2 connected to the layer 7 and electrically connected to the conductive semiconductor substrate 6 and an electrode 3 electrically connected to the atypical conductive semiconductor layer 9. . The inductor 507 is, for example, a solenoid connected to the electrode 2 that is electrically connected to the first conductive semiconductor layer 7. In the present embodiment, for example, when the light receiving unit receives an optical signal, a reverse bias is applied between the electrode 2 and the electrode 3 from, for example, an external DC bias power source. Thereby, the said light-receiving part converts an optical signal into an electric signal, and this electric signal is output from the electrode 2 and the electrode 3 as a signal current, Therefore The said electric signal can be taken out outside. Here, in this embodiment, for example, when the reverse bias is applied, a modulation signal can be input to the modulation signal input electrode 5 from the external modulation signal generator 501. Thereby, a modulation signal can be added to the bias, a gain can be obtained by the element characteristics of the semiconductor light receiving element of the present embodiment, and the S / N ratio of the received optical signal can be improved.

  In the semiconductor light receiving device of this embodiment, a modulation signal can be added to the bias applied to the semiconductor light receiving element without using the bias T. That is, in the semiconductor light receiving device 500 of the present invention, the circuit area of the photodetection circuit can be made smaller than that of the semiconductor light receiving device using the bias T, and the semiconductor light receiving device 500 can be manufactured in a small size and at low cost.

[Embodiment 6]
In the present embodiment, another example of the semiconductor light receiving device of the present invention is shown. In the present embodiment, an example of the semiconductor light receiving device of the present invention including the semiconductor light receiving element of the present invention and a modulation signal generating device for generating a modulation signal to be input to the modulation signal input electrode is shown. FIG. 7 is a circuit diagram showing the configuration of the semiconductor light receiving device of this embodiment. In the drawing, a portion 500 ′ indicated by a chain line is a portion constituting the semiconductor light receiving device of the present embodiment. As illustrated, the semiconductor light receiving device of this embodiment includes a semiconductor light receiving element 508 and a modulation signal generating device 501 of the present invention. Specifically, in the present embodiment, the semiconductor light receiving element of the present invention is any one of the first to fourth embodiments. The modulation signal generation device 501 is a device that can generate a modulation signal such as a sine wave or a pulse wave that can improve the signal-to-noise ratio of an optical signal in the semiconductor light receiving element 508 of the present invention. For example, a bias power source or a combination of a pulse source and an amplifier.

  In the semiconductor light receiving device of this embodiment, for example, the inductor 507 is connected to the electrode 2 electrically connected to the conductive semiconductor substrate 6 so that the modulation signal is not missed from the electric signal extraction electrode 2. As in the fifth embodiment, an excellent modulation bias operation can be realized. According to the semiconductor light receiving device of the present embodiment, the photodetection circuit for adding a modulation signal to the bias can be formed with a small circuit area and at a low cost as compared with the semiconductor light receiving device using the bias T.

[Embodiment 7]
In the present embodiment, another example of the semiconductor light receiving device of the present invention is shown. In the present embodiment, an example of a semiconductor light receiving device of the present invention including a semiconductor light receiving element of the present invention, an inductor, and a modulation signal generating device that generates a modulation signal input to a modulation signal input electrode is shown. FIG. 7 is a circuit diagram showing the configuration of the semiconductor light receiving device of this embodiment. In the drawing, a portion 500 ″ indicated by a one-dot chain line is a portion constituting the semiconductor light receiving device of the present embodiment. As illustrated, the semiconductor light receiving device of the present embodiment includes the semiconductor light receiving element 508 of the present invention and the inductor 507. And a modulation signal generator 501. Specifically, in the present embodiment, the semiconductor light receiving element of the present invention is any one of Embodiments 1 to 4. That is, the semiconductor light receiving element 508 of the present invention. The light receiving portion includes a conductive semiconductor layer 7 of the same type as that of the conductive semiconductor substrate 6 and a conductive semiconductor layer 9 of a different type from that of the conductive semiconductor substrate 6, and a conductive semiconductor is used as the electrical signal extraction electrode. The semiconductor light receiving element of the present invention includes an electrode 2 electrically connected to the substrate 6 and an electrode 3 electrically connected to the atypical conductive semiconductor layer 9. The inductor 507 is the conductive semiconductor substrate 6. And Den For example, the modulation signal generator 501 is a sine wave or pulse that can improve the signal-to-noise ratio of the optical signal in the semiconductor light receiving element of the present invention. A device capable of generating a modulated signal such as a wave, such as a modulation bias power supply or a combination of a pulse source and an amplifier.

  The semiconductor light receiving device 500 ″ of this embodiment can add a modulation signal to the bias without using the bias T, and can realize an excellent modulation bias operation in the same manner as in the fifth and sixth embodiments. Such a semiconductor light-receiving device of the present invention can be formed with a smaller circuit area of the photodetection circuit than a semiconductor light-receiving device using a bias T, and can be manufactured in a small size and at low cost.

  Next, the semiconductor light receiving element of the present invention and the semiconductor light receiving device of the present invention will be described more specifically with reference to the drawings. However, the following embodiment is an exemplification, and the present invention is not limited or limited by the following embodiment.

[Eighth embodiment]
In the present embodiment, still another example of the semiconductor light receiving element of the present invention is shown. In the present embodiment, an example of a mesa-type semiconductor light receiving element of the present invention in which signal light enters from the back surface of the semiconductor light receiving element is shown. The semiconductor light receiving element of this embodiment is an avalanche photodiode. FIG. 8 is a cross-sectional view showing the configuration of the semiconductor light receiving element of this embodiment. FIG. 9 is a rear view showing the back surface of the semiconductor light receiving element of this embodiment. FIG. 8 shows a cross section taken along line II-II in FIG. As shown in the figure, the semiconductor light-receiving element of this embodiment includes a conductive semiconductor substrate 6, a light-receiving unit formed from a semiconductor layer, and an electric signal extraction electrode (2 and 3) for extracting an electric signal converted by the light-receiving unit to the outside. And a modulation signal input electrode 5. Specifically, the light receiving portion and the electric signal extraction electrodes (2 and 3) are formed on the substrate 6, and the modulation signal input electrode 5 is provided on the substrate 6 for the light reception portion and the electric signal extraction. The electric signal extraction electrodes (2 and 3) are formed in an insulating state at a place different from the electrodes (2 and 3). The semiconductor light-receiving element of the present invention has an n-type buffer layer 7 (InAlAs, thickness 0.5 μm) and a multiplication on the N-type InP substrate 6 which is a conductive semiconductor substrate in order from the N-type InP substrate 6. Layer and electric field relaxation layer 8 ′ (InAlAs, multiplication layer thickness 1.0 μm, electric field relaxation layer thickness 0.1 μm), light absorption layer 8 (i-InGaAs, thickness 1.2 μm), p The p-type contact layer 9 ′ (p-InGaAs, thickness 0.2 μm) and the p-type buffer layer 9 (p-InAlAs, thickness 0.5 μm) are stacked. Such a semiconductor stacked body 1 includes, for example, an n-type buffer layer 7, a multiplication layer and an electric field relaxation layer 8 ′, a light absorption layer 8, a p-type buffer layer 9, and a p-type contact on an N-type InP substrate 6. The layer 9 ′ can be produced by epitaxial growth. In the present embodiment, the epitaxial layer side from the N-type InP substrate 6 is the surface side. The semiconductor light receiving element of this embodiment has a signal light passage region 12 that allows signal light incident on the light receiving portion to pass in the center of the back surface of the conductive semiconductor substrate 6. In the present embodiment, the light receiving portion is located above the signal light passage region 12, is formed on the conductive semiconductor substrate 6, and is formed of a stacked body of semiconductor layers including the light absorption layer 8. In this embodiment, two types of electrodes (2 and 3) connected to the epitaxial layer are formed as the electrical signal extraction electrodes. That is, the n-type electrode 2 connected to the n-type buffer layer 7 and electrically connected to the N-type InP substrate 6 and the p-type electrode 3 connected to the p-type buffer layer are formed on the conductive semiconductor substrate 6. Has been. An insulating film 4 (thickness 2000 mm) made of SiNx is formed on the back surface of the N-type InP substrate 6, and a modulation signal input electrode 5 is formed on the insulating film 4. The modulation signal input electrode 5 includes a conductor portion 10 and a pad electrode 11, and a conductor portion 10 in which a 500 Ｔｉ Ti layer and a 1000 Ａｕ Au layer are laminated is formed on the back surface of the insulating film 4. A pad electrode 11 made of 4000 Ａｕ Au is formed on a part of the conductor 10. The conductor portion 10 is formed at a distance (w1) from the signal light passage region 12 and is formed on the distance (w2) inside from the end of the insulating film 4. That is, the conductor portion 10 is not formed in the distance width (w2) from the end of the insulating film 4. The electrodes 2 and 3 are formed so as to be connectable to an external DC bias power source. The modulation signal input power source 5 can be connected, for example, by wire bonding the electrode pad 11 to an external modulation signal generator. The semiconductor light-receiving element of this embodiment can be used in, for example, the semiconductor light-receiving device of the present invention shown as an example in Embodiment 9 below. The semiconductor light receiving element of the present embodiment can be mounted on, for example, a chip carrier 905 shown as an example in FIG. As illustrated, the chip carrier 905 is equipped with three terminals (terminal 901, terminal 902, and terminal 903). For example, the three terminals are respectively assigned to the p-type electrode 3, the n-type electrode 2, and the modulation signal input electrode 5 of the semiconductor light receiving element of this embodiment. Such a chip carrier 905 can mount a semiconductor element having a size that falls within a range 904 (maximum limit of mountable chip size) indicated by a dotted line. The chip carrier 905 is mounted with the surface of the semiconductor light receiving element of the present embodiment and the surface of the chip carrier 905 facing each other. Next, the terminal corresponding to the modulation signal input electrode 5 on the chip carrier 905 and the modulation signal input electrode 5 are connected by a gold wire. The p-type electrode 3 and the n-type electrode 2 are also connected to corresponding terminals on the chip carrier. Thus, the semiconductor light receiving element of this embodiment mounted on the chip carrier is formed on the TO-56 stem 101 having at least three terminals (102, 103, 104) as shown in FIG. 11A as an example. Can be installed. That is, the three terminals (901, 902, 903) on the chip carrier 905 are connected to the three terminals of the stem 101 by the wires 106 so as to have the shortest distances. Finally, a lid with glass, for example, is sealed by welding or the like so as to cover the upper portion of the stem 101, the lens or fiber pigtail is aligned, and these are connected by welding or the like. It can be a module. The semiconductor light receiving element of this embodiment can operate at about 70V ± 10V, for example.

  The semiconductor light receiving element of this embodiment can be operated by connecting to a circuit shown in FIG. 12 using the light receiving module, for example. That is, for example, when detecting light, a DC bias is connected to the p-type electrode 3 and the n-type electrode 2. In the present embodiment, a DC bias is applied to the n electrode 2 from a DC bias power source 503 via a solenoid 507. Here, the DC bias can be set near the breakdown of the avalanche photodiode, for example. For example, a pulse voltage can be applied as a modulation signal from the pulse source 501 to the modulation signal input electrode 5 in accordance with the timing of receiving an optical signal. Thereby, it becomes possible to operate as a photodetector having sensitivity up to one photon. At this time, the sensitivity can be further improved by cooling the light receiving module as required. For example, a pulse voltage having a voltage amplitude of 5 V, a pulse width of 5 ns, and a repetition period of 50 ns can be applied to the modulation signal input electrode 5 from the modulation signal generator 501. The semiconductor light-receiving element of this embodiment that is operated in this manner can have a gain capable of detecting photons by, for example, appropriately setting the operating temperature and adjusting the DC bias. From the p-type electrode 3, a detection signal of a photon incident in accordance with the timing is output as an electric signal by a signal extraction resistor 506, for example. As described above, in the photodetection circuit using the semiconductor light receiving element 508 of the present embodiment, the bias T is unnecessary, and only the inductor 507 can be connected to add a modulation signal to the bias. Can be configured at cost.

[Embodiment 9]
In the present embodiment, still another example of the semiconductor light receiving element of the present invention is shown. The semiconductor light receiving element of this embodiment has the same configuration as that of the semiconductor light receiving element of Embodiment 8 except that the structure of the back surface portion of the conductive semiconductor substrate is different. FIG. 13 is a cross-sectional view showing the configuration of the semiconductor light receiving element of this embodiment. FIG. 14 is a rear view showing the back surface of the semiconductor light receiving element of this embodiment. FIG. 13 shows a cross section taken along line III-III in FIG. Further, FIG. 15 shows a side view of the semiconductor light receiving element of this embodiment. As shown in the figure, the semiconductor light receiving element of the present embodiment has an antireflection film 13 on the signal light passage region 12 on the back surface of the conductive semiconductor substrate 6, and has a conductive property on a portion outside the signal light passage region. The insulating film 4 is provided up to the end of the semiconductor substrate 6. The insulating film 4 outside the signal light passage region is formed thinner than the antireflection film 13. In this embodiment, since the antireflection film 13 is provided, the formation area of the conductor portion 10 is larger than that in the eighth embodiment. The semiconductor light receiving element of this embodiment can be manufactured as follows, for example. First, a dielectric film serving as the antireflection film 12 is formed on the entire back surface of the conductive semiconductor substrate 6 manufactured in the same manner as in the eighth embodiment. Next, the other part of the dielectric film is removed by, for example, etching, leaving the signal light passage region 12. Next, an insulating film 4 having a thickness of 500 mm is formed outside the signal light passage region and on the periphery of the back surface of the N-type InP substrate 6, and the modulation signal input electrode conductor is formed on the insulating film 4. The portion 10 (a laminate of a 500 Ｔｉ Ti layer and a 1000 Ａｕ Au layer) is formed in a portion from the end of the insulating film 4 to the inner side of a predetermined distance w3 (for example, 3 μm). A pad electrode 11 (100 μm × 100 μm planar area size) of a modulation signal input electrode is formed on the conductor portion 10 with a thickness of 4000 mm using Au.

The semiconductor light receiving element of this embodiment can be mounted on, for example, a chip carrier having a size of 5.72 mm × 5.72 mm, and can be mounted on a TO-8 type package. In the semiconductor light receiving element of this embodiment, the conductor portion 10 of the modulation signal input electrode 5 can be expanded to a plane area of 3.03 × 10 ⁷ μm ² , and the modulation signal input electrode 5 is connected to the conductive semiconductor substrate 6. Can have a capacity of about 69 nF. The semiconductor element of this embodiment can also be operated by being connected to the circuit shown in FIG. For example, in the photodetection circuit to which the semiconductor light receiving element of this embodiment is connected, an impedance of, for example, 2 MHz or more and 5Ω or less can be expected, and a modulation bias signal including a band of 2 MHz to 10 GHz can be applied to the conductive semiconductor substrate 6. . In the photodetection circuit using the semiconductor light receiving element of the present embodiment, the bias T is unnecessary, and the modulation bias operation can be performed only by adding an inductor to the external circuit, and the photodetection circuit can be configured compactly and at low cost. .

[Embodiment 10]
In the present embodiment, an example of the semiconductor light receiving device of the present invention including the semiconductor light receiving element of the present invention and an inductor is shown. FIG. 7 is a circuit diagram showing the configuration of the semiconductor light receiving device of this embodiment. In the figure, a portion 500 surrounded by a dotted line is a portion of the semiconductor light receiving device of this embodiment. As illustrated, the semiconductor light receiving device 500 of the present embodiment includes a semiconductor light receiving element 508 and an inductor 507 of the present invention. As the semiconductor light receiving element 508 of the present invention, for example, the semiconductor light receiving element of Embodiment 8 or Embodiment 9 can be used. The inductor 507 is a solenoid, for example, and is connected to the n-type electrode 2. In the semiconductor light receiving device 500 of this embodiment, a modulation signal can be added to the bias from the DC bias power source 503 without using the bias T, and the electric signal extraction resistor 506 can be used with a high signal-to-noise ratio (S / N ratio). The signal can be extracted. That is, the semiconductor light receiving device 500 of this embodiment can be formed with a smaller circuit area of the photodetection circuit, and can be manufactured at a lower cost, compared to the semiconductor light receiving device using the bias T.

[Embodiment 11]
In the present embodiment, an example of the semiconductor light receiving device of the present invention including the semiconductor light receiving element of the present invention and the modulation signal generating device is shown. FIG. 7 is a circuit diagram showing the configuration of the semiconductor light receiving device of this embodiment. In the figure, a portion 500 ′ surrounded by a dotted line is a portion of the semiconductor light receiving device of the present embodiment. As shown in the figure, a semiconductor light receiving device 500 ′ of this embodiment includes a semiconductor light receiving element 508 and a modulation signal generating device 501 of the present invention. As the semiconductor light receiving element 508 of the present invention, for example, the semiconductor light receiving element of Embodiment 8 or Embodiment 9 can be used. The modulation signal generator 501 is, for example, a modulation bias power source or a combination of a pulse source and an amplifier. In the semiconductor light receiving device 500 ′ of this embodiment, for example, as shown in the drawing, an inductor 507 is connected to the n-type electrode 2 so that the modulation signal does not escape from the n-type electrode 2 and the conductivity of the semiconductor light-receiving element 500 ′. A modulation signal can be input to the semiconductor substrate 6. That is, the modulation bias operation of the semiconductor light receiving element 500 ′ can be realized, and an electric signal can be extracted from the electric signal extraction resistor 506 with a high signal-to-noise ratio (S / N ratio). According to such a semiconductor light receiving device 500 ′ of the present invention, a photodetection circuit for adding a modulation signal to a bias can be formed with a small circuit area and at a low cost, as compared with a semiconductor light receiving device using a bias T. it can. A portion surrounded by a dotted line 500 "in the figure to which the inductor 507 is connected is the semiconductor light receiving device 500" of the present invention including the semiconductor light receiving element 508 of the present invention, the inductor 507, and the modulation signal generator 501.

DESCRIPTION OF SYMBOLS 1 Semiconductor laminated body 2, 3 Electrical signal extraction electrode 4 Insulating film 5 Modulation signal input electrode 6 Conductive semiconductor substrate 7 1st semiconductor layer 8 'Multiplication layer and electric field relaxation layer 8 Light absorption layer 9 2nd semiconductor Layer 9 'Semiconductor layer (passivation layer)
DESCRIPTION OF SYMBOLS 10 Conductor part 11 Pad electrode 12 Signal light passage area 13 Antireflection film 14 Part 101 including a light-receiving part Stem 102, 103, 104 Terminal 106 Wire 107 Semiconductor light receiving element 108 Optical fiber 109 Optical connector 501 Modulation signal generator 502 Modulation signal 503 Bias power supply 504 Bias T
505, 508 Semiconductor light receiving element 506 Electric signal extraction resistance (current-voltage conversion element)
507 Inductor 500, 500 ', 500 "Semiconductor light receiving device 901, 902, 903 Terminal 904 Maximum limit of mountable chip size 905 Chip carrier

Claims (14)

A conductive semiconductor substrate, a light receiving portion formed from a semiconductor layer that converts an optical signal into an electric signal, an electric signal extraction electrode that takes out the electric signal converted by the light receiving portion, and a modulation signal input electrode;
The light receiving portion and the electrical signal extraction electrode are formed on the conductive semiconductor substrate,
The modulation signal input electrode is formed in an insulated state from the electrical signal extraction electrode at a location different from the light receiving portion and the electrical signal extraction electrode on the conductive semiconductor substrate. A semiconductor light receiving element. The modulation signal input electrode further includes a conductor portion and a pad electrode, and the modulation signal input electrode is interposed between the light receiving portion and the electrical conductor of the conductive semiconductor substrate via the insulation film. Formed on the opposite side of the signal extraction electrode,
The semiconductor light receiving element according to claim 1, wherein the conductor portion is disposed between the insulating film and the pad electrode.   3. The semiconductor light receiving element according to claim 2, wherein the modulation signal input electrode is formed on a part of the insulating film.   4. The semiconductor light receiving element according to claim 2, wherein the modulation signal input electrode is not formed in a portion having a constant width inside from an end of the insulating film. On one substrate surface of the conductive semiconductor substrate, a signal light passage region that allows signal light incident on the light receiving portion to pass is formed,
5. The semiconductor light receiving element according to claim 1, wherein the modulation signal input electrode is formed on a portion of the one substrate surface outside the signal light passage region. 6. . An antireflection film is formed on the signal light passage region on the one substrate surface of the conductive semiconductor substrate, and an insulating film is formed on a portion outside the signal light passage region on the one substrate surface,
6. The semiconductor light receiving element according to claim 5, wherein the thickness of the insulating film outside the signal light passage region is thinner than the thickness of the antireflection film.   The semiconductor light receiving element according to claim 1, wherein the conductive semiconductor substrate is formed of an n-type semiconductor.   The semiconductor light-receiving element according to claim 1, wherein the conductive semiconductor substrate is formed of an InP substrate.   9. The semiconductor light receiving element according to claim 1, wherein the semiconductor light receiving element is an avalanche photodiode.   The modulation signal input electrode is formed on the conductive semiconductor substrate via an insulating film, and the insulating film is formed of at least one insulator selected from the group consisting of SiNx, SiOx, and SiOxNx. The semiconductor light-receiving element according to claim 1, wherein the light-receiving element is a semiconductor light-receiving element.   The light receiving portion includes a conductive semiconductor layer of the same type as the conductive semiconductor substrate, and a conductive semiconductor layer of a different type from the conductive semiconductor substrate, and is electrically connected to the conductive semiconductor substrate as the electric signal extraction electrode. The semiconductor light receiving element according to claim 1, further comprising: an electrode connected to the electrode; and an electrode electrically connected to the atypical conductive semiconductor layer. A semiconductor light receiving element according to claim 11;
A semiconductor light receiving device comprising an inductor connected to an electrode electrically connected to the conductive semiconductor substrate.   12. A semiconductor light receiving device comprising: the semiconductor light receiving element according to claim 1; and a modulation signal generating device that generates a modulation signal to be input to the modulation signal input electrode. 13. The semiconductor light receiving device according to claim 12, further comprising a modulation signal generating device that generates a modulation signal to be input to the modulation signal input electrode of the semiconductor light receiving element.

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