JP2002176194A - Light receiving element and optical semiconductor device comprising it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light receiving element in which good output characteristics are sustained and heat dissipation is improved while preventing electrostatic breakdown, and an optical semiconductor device comprising it. SOLUTION: The light receiving element 1 is arranged, on the upper surface thereof, with an electrode 10 for placing the light emitting element and a light receiving region 4 wherein a heavily doped impurity layer 11 is formed along the edge of the electrode 10 for placing the light emitting element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving element suitable for output monitoring of a semiconductor laser device and the like, and an optical semiconductor device having the same.

[0002]

2. Description of the Related Art Conventionally, as typified by a semiconductor laser device, an optical semiconductor device for controlling the optical output of an element to a constant value has a light receiving element for monitoring the element output. In a semiconductor laser device, a semiconductor laser element is provided as a light emitting element, and this element is disposed on a submount (for example, see Japanese Patent Application Laid-Open No. 6-53603). There is a case where a silicon light receiving element is built in the submount by utilizing the fact that the submount is mainly made of silicon. In this case, an electrode for arranging the laser element is formed in a region outside the light receiving region on the surface of the submount. This electrode is formed on the upper surface of the submount via an insulating film such as silicon oxide.

[0003]

As described above, when an electrode for arranging a laser element is formed on the upper surface of a submount having a built-in light-receiving element, electric charges formed by a voltage applied to the electrode for arranging the element and the like are charged to the light-receiving element. The first that adversely affects the output
There are disadvantages. Further, as described above, since the laser element is disposed on the submount with the insulating film interposed therebetween, there is a second disadvantage that the heat radiation characteristic is poor and the temperature of the laser element becomes high.

[0004] Further, the light emitting element arranged on the submount has a third disadvantage that it is easily destroyed by, for example, static electricity accumulated by an operator during an assembling operation.
In view of the foregoing, the present invention provides a light receiving element and an optical semiconductor device including the light receiving element, which maintain good output characteristics of the light receiving element, have good heat radiation characteristics, and are unlikely to be damaged by static electricity, in consideration of the conventional disadvantages.

[0005]

According to a first aspect of the present invention, there is provided a light receiving element having an electrode for arranging a light emitting element and a light receiving area on an upper surface. A high concentration impurity layer was formed along the edge.

According to the second aspect of the present invention, the electrode for arranging the light emitting element is arranged in an adjacent area adjacent to the light receiving area, and penetrates the insulating film so as to be in contact with a semiconductor layer forming the adjacent area. It is arranged.

According to a third aspect of the present invention, the electrode for arranging the light emitting elements is arranged in an adjacent area adjacent to the light receiving area and on an insulating film covering the adjacent area.

According to a fourth aspect of the present invention, the high-concentration impurity layer is formed below the insulating film.

According to a fifth aspect of the present invention, the high-concentration impurity layer is disposed in a region between the light emitting element disposing electrode and the light receiving region.

According to the present invention, the high-concentration impurity layer is arranged so as to cover the entire periphery of the light emitting element arrangement electrode.

According to a seventh aspect of the present invention, in the optical semiconductor device in which the light emitting element is arranged on the light receiving element, any one of the light receiving elements according to any one of the first to third aspects is used as the light receiving element. Was.

According to an eighth aspect of the present invention, in the optical semiconductor device having the light emitting element disposed on the light receiving element, the light receiving element according to the second aspect is used as the light receiving element.

According to a ninth aspect of the present invention, in the light-receiving element, the high-concentration impurity layer is formed under the insulating film, or the high-concentration impurity layer is formed between the light-emitting element disposing electrode and the light-emitting element disposing electrode. The high-concentration impurity layer is disposed in a region between the light-receiving regions, or is disposed so as to cover the entire periphery of the light-emitting element disposing electrode.

According to a tenth aspect of the present invention, the surface electrode of the light emitting element and the back electrode of the light receiving element have the same potential or the ground potential.

According to the eleventh aspect of the present invention, a predetermined voltage is applied or a predetermined current is supplied between the light emitting element disposing electrode and the back electrode of the light receiving element.

According to a twelfth aspect of the present invention, the resistance from the light emitting element disposing electrode to the back surface of the semiconductor layer is 50 to 50.
Assume 15,000 ohms.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A light receiving element 1 according to a first embodiment of the present invention will be described below with reference to FIGS. FIG.
Is a cross-sectional view of the light receiving element 1, and FIG. 2 is a plan view of the light receiving element 1. FIG. 1 is a sectional view taken along the line II of FIG.

The light-receiving element 1 is formed of a PN-type or PIN-type light-receiving element, and selectively diffuses a p-type impurity such as boron (B) into a silicon substrate 2 to form a p-type high-concentration impurity layer 3 as an island. It is formed in a shape. This p-type high-concentration impurity layer 3 substantially becomes the light receiving region 4 of the light receiving element 1.

The silicon substrate 2 can be formed only of an n-type high-concentration impurity layer (n + silicon layer) in the case of a PN-type light receiving element. An n-type low-concentration impurity layer (n-silicon layer) 6 is laminated on a high-concentration impurity layer (n + silicon layer) 5.

The area adjacent to the light receiving area 4 of the light receiving element 1 is called an adjacent area 7. That is, the upper surface of the silicon substrate 2 that is not covered by the p-type high-concentration impurity layer 3 substantially becomes the adjacent region 7. The upper surface of the light receiving element 1, that is, the light receiving region 4 and the adjacent region 7 are substantially covered with an insulating film 8 such as silicon oxide (SiO2). A signal electrode 9 made of aluminum (A1) or the like is provided on the upper surface of the light receiving element 1 through the hole 8a of the insulating film 8 on the light receiving region 4 so as to be connected to the high-concentration impurity layer 3.

Further, an element arrangement electrode 10 made of gold (Au) or the like is provided through the hole 8b of the insulating film 8 on the adjacent region 7. The electrode 10 generally penetrates through the insulating film 8 which is not excellent in thermal conductivity and most of the electrode 10 is in direct contact with the substrate 2. Can improve the heat radiation characteristics of the element disposed on the substrate.

On the upper surface of the silicon substrate 2, a high-concentration impurity layer 11 having an impurity concentration equal to or higher than that of the p-type high-concentration impurity layer 3 is formed along the edge of the element arrangement electrode 10. Has formed. This high concentration impurity layer 11
It is formed by selectively diffusing an n-type impurity such as phosphorus (P).
The conductivity type can be selectively changed according to the polarity of the voltage applied to the electrode 10 and the like.

Then, the high concentration impurity layer 11 is
The electrode 10 is formed so as to be spaced apart from the electrode 10 and surround the periphery of the electrode 10. This high-concentration impurity layer 11
Is formed between the p-type high-concentration impurity layer 3 and the electrode 10, and serves as a region for absorbing unnecessary charges generated on the surface of the silicon substrate 2 by the voltage applied to the electrode 10 effectively. Function. Therefore, the electrode 10
, The electric charge generated on the surface of the silicon substrate 2 due to the voltage or the like applied to the signal electrode 9 affects the output of the signal electrode 9 and adversely affects the illuminance-output current characteristic of the light receiving element 1.

Further, the distance between the light receiving region 4 and the electrode 10 is set short, so that the element shape can be reduced. Note that a back surface electrode 12 of gold or the like is formed on the back surface of the light receiving element 1. As described above, in the light receiving element 1, the case where the electrode 10 is formed so as to penetrate the insulating film 8 is taken as an example.

Next, a light receiving element 1a according to a second embodiment of the present invention will be described with reference to the sectional view of FIG. The light receiving element 1a shown in FIG. 3 is an example in which the electrode 10a is arranged only on the insulating film 8, and the other configuration is the same as the previous embodiment. The second embodiment is effective when an element disposed on the electrode 10a has little need for heat radiation, or when the insulating film 8 has good thermal conductivity.

According to this embodiment, the electrode 10a is formed only on the insulating film 8, and the high-concentration impurity layer 11 is
Since it is arranged between Oa and the high-concentration impurity layer 3, it is possible to reduce the adverse effect of the voltage applied to the electrode 10a on the illuminance-output current characteristics of the light receiving element 1, as in the above case. Thus, the high-concentration impurity layer 11 is formed so as to surround the entire periphery of the electrode 10.

Next, a light receiving element 1b according to a third embodiment of the present invention will be described with reference to the plan view of FIG. The light receiving element 1b shown in FIG. 4 is an example in which the high-concentration impurity layer 11a is partially provided only on the side of the electrode 10 facing the light receiving region 4, and otherwise the same as the second embodiment. it can.

In FIG. 4, the high-concentration impurity layer 11a is partially covered with the electrode 10a and partially
Although it is not covered by the electrode 10a, if it is located substantially between the electrode 10a and the light receiving region 4, all of the
a, or may be entirely exposed without being covered with the electrode 10a in plan view.

Next, a light receiving element 1c according to a fourth embodiment of the present invention will be described with reference to FIGS. In these figures, the high-concentration impurity layer 11a is an example in which the high-concentration impurity layer 11a is partially provided only on the side facing the light-receiving region 4 of the electrode 10, and the rest is the same as the configuration of the light-receiving element 1 of the first embodiment. .

That is, the electrodes 10 for arranging the light emitting elements are arranged in the adjacent area 7 adjacent to the light receiving area 4. The electrode 10 is disposed so as to penetrate the insulating film 8 so as to be in contact with the semiconductor layer 6 forming an adjacent region.

The high concentration impurity layer 11a is formed below the insulating film 8. The high-concentration impurity layer 11 a is arranged in a region between the light emitting element arrangement electrode 10 and the light receiving region 4.

The resistance R from the bottom surface of the light emitting element arrangement electrode 10 to the back surface of the semiconductor layer 6 is set to be 50 to 15,000 ohms. That is, the area where the electrode 10 is in direct contact with the semiconductor layer 6 is defined as S,
Is d, and the resistivity of the semiconductor layer 6 is k, the following equation holds. R = k × (d / S) Expression (1).

In this way, the thickness d, the area S, and the resistivity k are selected so that R = 50 to 15,000 ohms. The light receiving element 1c is constituted by the above layers.

In the above-described light-receiving element 1 according to Embodiment 1 of the present invention, the resistance R from the bottom surface of the light-emitting element arrangement electrode 10 to the back surface of the semiconductor layer 6 is 50 to 1
It is provided to be 5000 ohms. Therefore, the thickness d, the area S, and the resistivity k of the semiconductor layer 6 are selected.

Next, an optical semiconductor device (for example, a semiconductor laser device) 13 according to a fifth embodiment of the present invention will be described with reference to the plan view of FIG. In FIG. 7, a semiconductor laser element 18 is provided as a light emitting element, and the light receiving element 1 is provided as a light receiving element also serving as a submount.

In the optical semiconductor device 13, the light emitting element 18 is arranged on the light receiving element 1. Optical semiconductor device 1
3, any of the light receiving elements 1 or 1a or 1b or 1c can be used.
The following description is based on the assumption that the following is used.

The laser device 13 includes a plurality of leads 1
The light receiving element 1 and the semiconductor laser element 1 are mounted in a package in which the light receiving elements 4, 15, and 16 are connected and fixed by a resin frame 17.
8 are arranged and wire-bonded. The leads 14, 15, 16 are of a lead frame type, and a pair of sub-leads 14, 16 are arranged on the left and right of the main lead 15 having an element arrangement region at the tip.

The main lead 15 is integrally formed with radiating wings on the left and right sides, which project from the resin frame 17 on the left and right sides. The light receiving element 1 has its back electrode 12 fixed to the element arrangement portion at the tip of the main lead 15 by bonding with a conductive adhesive such as silver paste.

The laser element 18 is fixed on the electrode 10 on the upper surface of the light receiving element 1 by using a conductive agent 18a such as solder or silver paste. Thereby, the back surface electrode of the laser element 18 is electrically connected to the element arrangement electrode 10. A wiring 19 made of a wire bond line is provided between the main lead 15 and a portion of the element arrangement electrode 10 that is exposed without being covered by the laser element 18.

A wiring 21 composed of a wire bond line is provided between the surface electrode 20 of the laser element 18 and the sub lead 16. A wiring 22 composed of a wire bond line is provided between the signal electrode 9 of the light receiving element 1 and the sub lead 14.

In the laser device 13, when a predetermined laser drive voltage is applied between the main lead 15 and the sub-lead 16, the drive voltage is supplied to the front and back electrodes of the laser element 18, the laser element 18 oscillates, and the laser light Is output along the axis X. Part of the laser light output in the backward direction is the light receiving element 1
And a predetermined monitor signal is generated at the signal electrode 9.

This signal is taken out from between the sub lead 14 and the main lead 15 to the outside and subjected to a predetermined process,
The voltage applied to the laser element 18 can be controlled.

In the above embodiment, the case where the semiconductor laser element 18 is used as the light emitting element is taken as an example. However, the present invention can be applied to the case where a light emitting element other than the laser element such as an LED element is used. it can. Further, the present invention can also include the case where the conductivity of P and N is reversed in each of the above embodiments.

Next, an optical semiconductor device (for example, a semiconductor laser device) 13a according to a sixth embodiment of the present invention will be described with reference to the plan view of FIG. In the optical semiconductor device 13a, a light emitting element (laser element) 18 is arranged on the light receiving element 1. In the optical semiconductor device 13a, the light receiving element 1 or 1
Although either one of c can be used, the following description will be made assuming that the light receiving element 1 is used.

The laser device 13a includes a plurality of leads 1
The light receiving element 1 and the semiconductor laser 1
8 are arranged and wire-bonded. The leads 14, 15, 16 are of a lead frame type, and a pair of sub-leads 14, 16 are arranged on the left and right of the main lead 15 having an element arrangement region at the tip.

The main leads 15 are integrally formed with left and right radiating wings, which project from the resin frame 17 to the left and right. The light receiving element 1 has its back electrode 12 fixed to the element arrangement portion at the tip of the main lead 15 by bonding with a conductive adhesive such as silver paste. The laser element 18 is fixed on the electrode 10 on the upper surface of the light receiving element 1 using a conductive agent 18a such as solder or silver paste.

As a result, the back electrode of the laser element 18 is electrically connected to the element arrangement electrode 10. A wiring 19 a made of a wire bond line is provided between a portion of the element disposing electrode 10 which is exposed without being covered by the laser element 18 and the sub lead 16. Between the surface electrode 20 of the laser element 18 and the main lead 15, a wiring 21a made of a wire bond line is provided. A wiring 22 composed of a wire bond line is provided between the signal electrode 9 of the light receiving element 1 and the sub lead 14.

In the laser device 13a, when a predetermined current or a predetermined laser driving voltage is applied between the main lead 15 and the sub-lead 16, a driving voltage is supplied to the front and back electrodes of the laser element 18 so that the laser element 18 is driven. Oscillates and the laser beam is
Is output along. A part of the laser light output in the backward direction enters the light receiving region 4 of the light receiving element 1 and a predetermined monitor signal is generated on the signal electrode 9.

By taking out this signal from the space between the sub lead 14 and the main lead 15 to the outside and performing a predetermined process,
The voltage applied to the laser element 18 can be controlled.

In the above embodiment, the case where the semiconductor laser element 18 is used as the light emitting element is taken as an example. However, the present invention can be applied to the case where a light emitting element other than the laser element such as an LED element is used. it can. Further, the present invention can also include the case where the conductivity of P and N is reversed in each of the above embodiments.

The characteristics of the semiconductor laser device 13a are summarized below. A wiring 21 a is provided between the surface electrode 20 of the laser element 18 and the main lead 15. As a result, the back electrode 12 of the light receiving element 1 arranged on the main lead 15 and the front electrode 20 of the light emitting element (laser element) 18 have the same potential.

Desirably, by using the main lead 15 as a ground electrode, the surface electrode 20 of the light emitting element 18 and the light receiving element 1
Are both at the ground potential.

As described above, a predetermined voltage or a predetermined current is applied between the sub lead 16 and the main lead 15. That is, a predetermined voltage is applied between the light emitting element arrangement electrode 10 and the back electrode 12 of the light receiving element 1, or
It is configured such that a predetermined current is supplied. The semiconductor laser device 13a is constituted by the above components.

Next, the operation of the semiconductor laser device 13a will be described with reference to FIG. As described above, for example, a predetermined voltage is applied between the light emitting element arrangement electrode 10 and the back surface electrode 12 of the light receiving element 1.

That is, the sub lead 16, the wiring 19a, the electrode 10, the laser element 18, the surface electrode 20, the wiring 2
1a and the main lead 15 form a first current passing circuit.

As a result, a predetermined current flows through the laser element 18, the laser element 18 oscillates, and laser light is output in the forward direction of the axis X.

The sub lead 16, the wiring 19a, the electrode 10, the semiconductor layer 6 of the light receiving element 1, and the n of the light receiving element 1
-Type high-concentration impurity layer 5, back electrode 12, main lead 15
Thus, a second current passing circuit is formed. Thus, a current flows in the semiconductor layer 6 of the light receiving element 1.

The resistance value R from the electrode 10 to the semiconductor layer 6
Is smaller than 50 ohms, the current flowing through the second current passing circuit increases. As a result, the current flowing through the first current passing circuit becomes too small, and the laser element 18 does not oscillate. Therefore, in the semiconductor laser device 13a,
The resistance value R of the light receiving element 1 is set to 50 ohms or more.

The inventor measured the electrostatic characteristics of the semiconductor laser device 13a (see FIG. 9). The horizontal axis in FIG. 9 indicates the electrostatic withstand voltage (volt) of the semiconductor laser device 13a, and the vertical axis indicates the magnitude of the resistance value R.

E + 02, E + 03, E + 04, E on the vertical axis
+05 indicates that the resistance value R is 100, 1000, and 1000, respectively.
0, indicating 100,000 ohms. In FIG.
The group indicated by A indicates the characteristic values of the comparative example for the present invention. In the semiconductor laser device shown in this comparative example, the resistance value R is 16000 ohm.

In FIG. 9, the group indicated by B indicates characteristic values of the semiconductor laser device 13a of the present invention. The resistance value R of the semiconductor laser device 13a is 50 to 150.
00 ohm.

FIG. 9 shows that the electrostatic withstand voltage depends on the resistance value R, and when the resistance value R exceeds 15000 ohms, it rapidly decreases.

Therefore, in the semiconductor laser device 13a, the resistance value R of the light receiving element 1 is set to 50 to 15000 ohms.

In the semiconductor laser device disclosed in JP-A-6-53603, when a surge (static electricity) occurs on the surface electrode of the laser element, the surge flows directly into the laser element and the laser element is destroyed. I do. The electrostatic withstand voltage at this time is determined by the withstand voltage of the laser element itself.

When the resistance value R is relatively large (16
Again, a surge flows inside the laser element and is destroyed.

On the other hand, when the resistance value R is relatively small (15,000 ohms or less) as in the present invention, the generated surge flows through the laser element 18 only a little, and more to the light receiving element 1. As a result, the semiconductor laser device 13a can obtain a high electrostatic breakdown voltage.

[0067]

According to the first to seventh aspects of the present invention, a light receiving element having excellent thermal characteristics can be provided. Further, a light receiving element having excellent light receiving sensitivity characteristics can be provided. Further, a light receiving element suitable for miniaturization can be provided.
Further, the optical semiconductor device including such a light receiving element can have good characteristics.

According to the present invention, by setting the resistance value R to a relatively small value (15,000 ohms or less), the generated static electricity (surge) flows only a little to the light emitting element and a large amount to the light receiving element. Flows. As a result, a high electrostatic withstand voltage can be obtained without breaking the light emitting element.

[Brief description of the drawings]

FIG. 1 is a sectional view of a light receiving element 1 according to Embodiment 1 of the present invention.

FIG. 2 is a plan view of the light receiving element 1. FIG.

FIG. 3 is a sectional view of a light receiving element 1a according to a second embodiment of the present invention.

FIG. 4 is a plan view of a light receiving element 1b according to Embodiment 3 of the present invention.

FIG. 5 is a sectional view of a light receiving element 1c according to Embodiment 4 of the present invention.

FIG. 6 is a plan view of the light receiving element 1c.

FIG. 7 shows an optical semiconductor device 13 according to a fifth embodiment of the present invention.
FIG.

FIG. 8 is an optical semiconductor device 13 according to a sixth embodiment of the present invention.
It is a top view of a.

FIG. 9 is an electrostatic characteristic diagram.

[Explanation of symbols]

 Reference Signs List 1 light-receiving element 4 light-receiving area 7 adjacent area 8 insulating film 10 electrode for element arrangement 11 high-concentration impurity layer (unnecessary charge absorption layer) 13 semiconductor laser device 18 laser element

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Koji Ueyama 3-201 Minamiyoshikata, Tottori-shi, Tottori F-term (reference) in Sanyo Electric Co., Ltd.

Claims (12)

[Claims] 1. A light-receiving element having an electrode for arranging a light-emitting element and a light-receiving region on an upper surface, wherein a high-concentration impurity layer is formed along an edge of the electrode for arranging the element. 2. The light emitting element disposing electrode is disposed in an adjacent region adjacent to the light receiving region, and is disposed so as to penetrate an insulating film so as to be in contact with a semiconductor layer forming the adjacent region. The light receiving element according to claim 1, wherein: 3. The light-emitting element arranging electrode is arranged in an adjacent area adjacent to the light-receiving area, and is arranged on an insulating film covering the adjacent area. Light receiving element. 4. The light receiving element according to claim 3, wherein said high concentration impurity layer is formed below said insulating film. 5. The light-receiving element according to claim 3, wherein the high-concentration impurity layer is disposed in a region between the light-emitting element arrangement electrode and the light-receiving region. 6. The light-receiving element according to claim 3, wherein the high-concentration impurity layer is arranged so as to cover the entire periphery of the light-emitting element arrangement electrode. 7. An optical semiconductor device in which a light emitting element is disposed on a light receiving element, wherein the light receiving element is used as the light receiving element.
An optical semiconductor device using any one of the light-receiving elements described in 4, 5, and 6. 8. An optical semiconductor device in which a light emitting element is arranged on a light receiving element, wherein the light receiving element according to claim 2 is used as said light receiving element. 9. The light-receiving element, wherein the high-concentration impurity layer is formed below the insulating film, or the high-concentration impurity layer is a region between the light-emitting element arrangement electrode and the light-receiving region. 9. The optical semiconductor device according to claim 8, wherein the high-concentration impurity layer is disposed so as to cover the entire periphery of the light emitting element disposing electrode. 10. The optical semiconductor device according to claim 8, wherein a front electrode of said light emitting element and a rear electrode of said light receiving element have the same potential or a ground potential. 11. A predetermined voltage is applied or a predetermined current is supplied between the light emitting element disposing electrode and the back electrode of the light receiving element.
Optical semiconductor device. 12. The optical semiconductor device according to claim 8, wherein a resistance value from the light emitting element disposing electrode to the back surface of the semiconductor layer is 50 to 15000 ohm.