JPH11354829A - Optical semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the temp. and improve the response performance, by providing a temp. sensor below a position at which a optical element is fixed to an Si substrate, and monitoring the temp. of the optical element by a temp. sensor. SOLUTION: On an Si substrate 6 a photodiode 5 is fixed just beneath of which a temp. sensor is formed, the temp. of the photodiode 5 is monitored by the temp. sensor formed just beneath the fixed position to control the temp., using a temp. control element such as Peltier element, so that the photodiode 5 operates adequately wherein the temp. sensor is provided just beneath the photodiode 5 the temp. of which is desired to be monitored. Hence, the temp. measurement is accurate and the response performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device, and more particularly to an optical semiconductor device with an improved mounting method when a compound semiconductor is used.

[0002]

2. Description of the Related Art In a conventional optical semiconductor device, when a compound semiconductor is used as an optical device such as a light receiving device or a light emitting device, a compound semiconductor which is an optical device and a signal processing circuit are formed.
The i-substrate is connected via a submount or the like.

FIG. 4 is a plan view and a side view showing an example of such a conventional optical semiconductor device. In FIG. 4, 1 is a submount, 2 is a Si substrate, and 3 is an optical element InGa.
A photodiode array 4 composed of a compound semiconductor such as As is a thermistor. Further, 1 to 4 are enclosed in a package to constitute the optical semiconductor element 50.

[0004] A Si substrate 2 and a photodiode array 3 are mounted on the submount 1, and a thermistor 4 is mounted on the submount 1. Output signals from the Si substrate 2 and the photodiode array 3 are appropriately connected to pins of a package of the optical semiconductor device 50.

Here, the operation of the conventional example shown in FIG. 4 will be described. The output signal of the photodiode array 3 is the Si substrate 2
The optical semiconductor device 50 is appropriately amplified and processed by a signal processing circuit or the like formed above, and is extracted to the outside via pins of a package of the optical semiconductor element 50. The thermistor 4 monitors a temperature change of the photodiode array 3, and a temperature control circuit provided on an external circuit operates a Peltier element or the like so that the photodiode array 3 operates appropriately based on the output of the thermistor 4. The temperature is controlled using a temperature control element (not shown).

As a result, it becomes possible to always operate the photodiode array 3 at an appropriate temperature based on the thermistor 4 provided in the submount 1.

[0007]

However, in the conventional example shown in FIG. 4, since the thermistor 4 is provided at a position distant from the photodiode array 3 whose temperature is to be monitored, the response depends on the heat conduction of the submount 1. However, there is a problem that it is difficult to perform accurate temperature measurement due to poor performance. Also,
There is a problem in that a space for mounting the thermistor 4 is required on the submount 1, and further, the number of assembly steps for mounting the thermistor 4 is required. Therefore, an object of the present invention is to realize an optical semiconductor device that can accurately measure temperature, has good responsiveness, and can reduce the size and the number of assembly steps.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, there is provided an optical semiconductor device comprising: an optical device; and an Si device for fixing the optical device.
A substrate, comprising a temperature sensor provided below the position where the optical element is fixed on the Si substrate, by monitoring the temperature of the optical element with the temperature sensor,
Accurate temperature measurement and good responsiveness enable downsizing and reduction of assembly man-hours.

According to a second aspect of the present invention, in the optical semiconductor device according to the first aspect, the temperature sensor is a transistor formed on the Si substrate.
The temperature sensor can be easily formed on the Si substrate.

According to a third aspect of the present invention, in the optical semiconductor device according to the first and second aspects of the present invention, the optical element is a photodiode or a photodiode array. Accurate temperature measurement and improved responsiveness.

According to a fourth aspect of the present invention, in the optical semiconductor device according to the third aspect of the present invention, a signal processing circuit for the photodiode is formed on the Si substrate.
It is possible to reduce the size and the number of assembly steps.

According to a fifth aspect of the present invention, in the optical semiconductor device according to the third aspect of the present invention, a drive and signal processing circuit for the photodiode array is formed on the Si substrate, thereby reducing the size and the number of assembly steps. Becomes possible.

According to a sixth aspect of the present invention, in the optical semiconductor device according to the first and second aspects of the present invention, since the optical element is a laser diode, the temperature measurement of the laser diode is accurate and the response is high. Get better.

According to a seventh aspect of the present invention, in the optical semiconductor device according to the sixth aspect of the present invention, a drive circuit for the laser diode is formed on the Si substrate. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing one embodiment of the optical semiconductor device according to the present invention. In FIG. 1, reference numeral 5 denotes an optical element I.
An nP / InGaAs photodiode (hereinafter, simply referred to as a photodiode) 6 is a Si substrate.

In FIG. 1, a photodiode 5 is fixed on a Si substrate 6. A temperature sensor (not shown) is formed directly below the position of the Si substrate 6 to which the photodiode 5 is fixed.

The operation of the embodiment shown in FIG. 1 will now be described. The temperature of the photodiode 5 is monitored by a temperature sensor formed just below the fixed position, and the temperature is controlled using a temperature control element (not shown) such as a Peltier element so that the photodiode 5 performs an appropriate operation. Control.

In this case, since the temperature sensor is provided immediately below the photodiode 5 whose temperature is to be monitored as compared with the conventional example shown in FIG. 4, the responsiveness is improved and accurate temperature measurement is possible. In addition, there is an effect that a space for mounting a thermistor, which is a temperature sensor, is not required as in the conventional example, and man-hours for mounting the thermistor are not required.

As a result, by forming the temperature sensor directly below the position where the photodiode 5 is fixed on the Si substrate 6, accurate temperature measurement and good responsiveness can be achieved, and miniaturization and man-hour reduction can be achieved.

The details of the Si substrate 6 will be described with reference to FIG. FIG. 2 is a perspective view showing a detailed example of the Si substrate 6 and a sectional view taken along line AA ′. However, description of the fixed photodiode 5 is omitted for the sake of simplicity.

In FIG. 2, reference numeral 6 denotes the same reference numerals as in FIG. 1, reference numeral 7 denotes a signal extraction pad of the photodiode 5,
8 is a conductive layer for fixing, 9, 10 and 11 are pads for taking out signals of a temperature sensor, 12, 13 and 15 are insulating layers,
4 is a p-type Si substrate, 16 is a conductive layer, 17 is an n + -type impurity diffusion layer, 18 and 20 are n-type impurity diffusion layers, 19 is a p-type impurity diffusion layer, 21, 22, and 23 are electrodes.

Impurity diffusion layers 17, 18, 19 and 20 are sequentially formed on the p-type Si substrate 14 by impurity diffusion, etching and the like, and electrodes 23, 21 and 22 are provided on the impurity diffusion layers 18, 19 and 20. . The electrodes 21 to 23 are insulated by the insulating layer 13 and
22 and 23 are wired to pads 9, 10 and 11.

Further, the insulating layer 1 is provided on both sides of the Si substrate 14.
2 and 15 are formed, a conductive layer 16 is formed on the back surface of the Si substrate 14, and a fixing conductive layer 8 is formed on portions above the impurity diffusion layers 18-20.

Here, the operation of the Si substrate 6 shown in FIG. 2 will be described. As is apparent from the cross-sectional view of FIG. 2, an NPN transistor is formed by the impurity diffusion layers 17 to 20, and the upper surface thereof is covered with the insulating layer 12 and the fixing conductive layer 8.

As shown in FIG. 1, the photodiode is fixed to the fixing conductive layer 8, so that the heat of the photodiode conducts to the transistor arranged directly below. Since the temperature change at that time is monitored by the base-emitter voltage "Vbe" of the transistor, by taking out this voltage through the pads 9 to 11, the temperature measurement and temperature control become possible.

As a result, a transistor is formed as a temperature sensor directly below the position where the photodiode 5 is fixed on the Si substrate 6 and the voltage between the base and the emitter of the transistor is monitored, so that the temperature measurement is accurate and the response is good. In addition, the size and the number of assembly steps can be reduced. Further, by using a transistor as the temperature sensor, the temperature sensor can be easily formed on the Si substrate.

In the embodiment shown in FIG. 1, the photodiode 5 as an optical element is fixed on the Si substrate 6, but a laser diode as an optical element may be fixed instead of the photodiode 5. For example, FIG. 3 is a perspective view showing another embodiment in which a laser diode is fixed on a Si substrate. In FIG. 3, reference numeral 6 denotes the same symbol as in FIG.
Reference numeral 24 denotes a laser diode as an optical element.

Further, not only a temperature sensor such as a transistor but also various circuits may be formed on the Si substrate 6. For example, such a circuit may be a signal processing circuit for processing a light receiving output signal of a fixed photodiode 5, or a drive / signal for driving an array and extracting a detection signal when the photodiode 5 is a photodiode array. A processing circuit, a driving circuit for the fixed laser diode 24, and the like are conceivable.

In such a case, a circuit for performing signal processing and driving processing of an optical element such as a photodiode can be formed on the Si substrate, so that downsizing and reduction in the number of assembly steps can be achieved.

[0030]

As is apparent from the above description,
According to the present invention, the following effects can be obtained. According to the first aspect of the present invention, a temperature sensor is formed just below the position where the photodiode as the optical element on the Si substrate is fixed to monitor the temperature of the optical element, so that the temperature measurement is accurate and the response is good. In addition, an optical semiconductor device that can be reduced in size and the number of assembly steps can be reduced.

According to the second aspect of the present invention, the use of the transistor as the temperature sensor facilitates the formation of the temperature sensor on the Si substrate.

According to the third aspect of the present invention, by using a photodiode or a photodiode array as the optical element, the temperature of the photodiode or the photodiode array can be measured accurately and the response can be improved.

According to the fourth and fifth aspects of the present invention, the signal processing circuit for the photodiode and the driving / signal processing circuit for the photodiode array are formed on the Si substrate, thereby reducing the size and the number of assembly steps. Will be possible.

According to the sixth aspect of the present invention, by using a laser diode as the optical element, the temperature measurement of the laser diode is accurate and the response is improved.

According to the seventh aspect of the present invention, the laser diode drive circuit is formed on the Si substrate,
It is possible to reduce the size and the number of assembly steps.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of an optical semiconductor device according to the present invention.

FIG. 2 is a perspective view and a cross-sectional view illustrating a detailed example of a Si substrate.

FIG. 3 is a perspective view showing another embodiment in which a laser diode is fixed to a Si substrate.

FIG. 4 is a plan view and a side view showing an example of a conventional optical semiconductor device.

[Explanation of symbols]

 Reference Signs List 1 submount 2, 6 Si substrate 3 photodiode array 4 thermistor 5 photodiode 7, 9, 10, 11 pad 8 fixing conductive layer 12, 13, 15 insulating layer 14 p-type Si substrate 16 conductive layer 17 n + type impurity diffusion Layer 18, 20 N-type impurity diffusion layer 19 P-type impurity diffusion layer 21, 22, 23 Electrode 24 Laser diode 50 Optical semiconductor element

Continued on the front page (72) Inventor Akira Miura 2-93-2 Nakamachi, Musashino-shi, Tokyo Inside Yokogawa Electric Corporation (72) Inventor Kyoichi Akasaka 2-9-132 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd. In-company (72) Inventor Tadashige Fujita 2-9-132 Nakamachi, Musashino-shi, Tokyo Inside Yokogawa Electric Corporation

Claims (7)

[Claims] 1. An optical semiconductor device, comprising: an optical device; an Si substrate for fixing the optical device; and a temperature sensor provided on the Si substrate below a position where the optical device is fixed. An optical semiconductor device, wherein the temperature of the optical device is monitored by the temperature sensor. 2. The optical semiconductor device according to claim 1, wherein said temperature sensor is a transistor formed on said Si substrate. 3. The optical device according to claim 1, wherein said optical element is a photodiode or a photodiode array.
And an optical semiconductor device according to claim 2. 4. An optical semiconductor device according to claim 3, wherein a signal processing circuit for said photodiode is formed on said Si substrate. 5. An optical semiconductor device according to claim 3, wherein a drive / signal processing circuit for said photodiode array is formed on said Si substrate. 6. The optical semiconductor device according to claim 1, wherein said optical device is a laser diode. 7. An optical semiconductor device according to claim 6, wherein a drive circuit for said laser diode is formed on said Si substrate.