JPS5931998B2 - Manufacturing method of optical semiconductor device with monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the manufacture of an optical semiconductor device having an optical output stabilization function, which can be an effective technique for optical semiconductor devices, particularly semiconductor laser devices whose output state fluctuates greatly due to changes in ambient conditions. It is about the method.

Optical semiconductor devices, like other semiconductor devices, use electrons in solids to generate light, so they have low power consumption, and from the point of view of reliability, they inherently have no consumable parts. It is said to have a long lifespan.

However, when considered from an application perspective, the optical output of optical semiconductor devices such as light emitting diodes and laser diodes generally changes depending on the deterioration of element characteristics or the environment and usage conditions such as operating current, temperature, humidity, and vibration. It becomes difficult to maintain a constant output state all the time, resulting in an unstable output state. Therefore, when it is necessary to put it to practical use as a stable light output source, a light output stabilization mechanism is conventionally employed that detects changes in the light output of a light emitting element and corrects excesses and deficiencies in the amount of output. To explain this in more detail regarding semiconductor lasers, the output state of semiconductor lasers generally fluctuates depending on the environment such as temperature, humidity, vibration, and current used, usage conditions, and changes over time. Therefore, if it is necessary to use it practically as a stable laser output source, a part of the output laser light is extracted as a sample, the output state of the laser light is detected, and the driving current of the semiconductor laser is controlled. It is necessary to correct the fluctuations in the output amount. For this reason, in conventional lasers in which both resonant surfaces of a resonator that perform optical amplification are parallel to each other and output laser light from both resonant surfaces, the laser light output from one of the resonant surfaces is used for practical purposes. In order to detect the output state of the laser light, the laser light output from the other resonant surface is used as a sampling laser light to control the drive current of the semiconductor laser and maintain the laser light output state stably. Was. Since the amount of laser light output from each resonant surface has a proportional relationship in principle, by measuring the amount of output of the sampling laser beam, it is possible to determine the amount of laser light output from the other side of the resonator. This means that the output amount can be detected. The specific configuration of this system is shown in FIG. Explaining FIG. 1, a photodetector 3 is installed on a heat sink 2 to which a semiconductor laser 1 is attached, and the light-receiving surface of the photodetector 3 is parallel to the resonance plane of the semiconductor laser 1, that is, the heat sink 2 mounting surface. It is arranged vertically and at a certain distance from the opposing resonant surface of the semiconductor laser 1 . As shown in Fig. 2, the radiation pattern of the laser beam emitted from the semiconductor laser 1 is a coherent beam that is oscillated in a spot shape on the resonant surface and expanded conically along the direction of light propagation. In order to efficiently detect light reception, it is desirable that the light receiving surface of the photodetector 3 be provided perpendicular to the traveling direction of the laser beam.
On the other hand, in the case of the above configuration, since the lead-out electrode surface of the photodetector 3 and the lead-out electrode surface of the semiconductor laser 1 are perpendicular to each other, the lead wires can be attached at the same time by the nail head bonder method, ultrasonic bonder method, etc. This becomes a factor that hinders mass productivity on the manufacturing line.

In view of the above-mentioned current situation, the present invention provides a method for manufacturing a new and useful optical semiconductor device with a monitor, which uses semiconductor materials such as Si single crystal and utilizes technical means to improve mass production. The purpose is to

One embodiment of the present invention will be described in detail below with reference to the drawings, taking a semiconductor laser as an example.

FIG. 3, FIG. 4, FIG. 5, and FIG. 6 are manufacturing process diagrams showing, in order of process, a method for manufacturing an optical semiconductor device with a monitor, which is an embodiment of the present invention. 3A, 4A, and 5A are sectional views, and FIGS. 3B, 4B, and 5B are plan views corresponding to the above. As shown in Figure 3, p-type Si
A SlO2 film 5 having a thickness of about 1000 to 20008 is formed on the surface of a single crystal substrate 4 by CVD or thermal oxidation, and then formed into stripes with a width of 2 m1 by a commonly used photolithography method. Pitch interval approx. 571t7
! The SiO2 film 5 is removed at t.

Next, using the remaining SiO2 film 5 as a protective film, a concave groove 6 with a depth of about 10 to 20 μm is formed in the portion where the SlO2 film 5 has been removed by chemical etching. Furthermore, as shown in FIG. 4, after removing the SiO2 film 5, a SlO2 film 7 is again formed on the entire surface, and a layer of 1 m is formed along the side end surface of the concave groove 6.
Approximately 771 parts of this SiO2 film 7 is removed to form a light receiving surface of a photodetector to be described later. The remaining SiO2 film 7 is used as a diffusion prevention film, and As is grown by vapor phase growth using S! It is diffused into the p-type Sl single-crystal substrate 4 from the removed surface of the 02 film 7, forming an n-type layer 8 and a pn junction on the Si single-crystal substrate 4, and forming a light-receiving diode. This light-receiving diode acts as a photodetector, and the light-receiving surface of the photodetector is installed on the side end surface of the concave groove 6. The n-type diffusion region formed on the back surface of the S1 single crystal substrate 4 is removed by chemical etching. The SiO2 film 7 at the bottom of the concave groove 6 is etched and removed in a stripe shape with a width of 171 Lm, and the bottom surface of the concave groove 6 on which the n-type electrode 9 and the semiconductor laser element are mounted on the top surface of the n-type layer 8 of the photodetector is formed using photolithography. The p-type electrode 10 is made of Au, and the p-type electrode 11 of the photodetector is made of Au on the back surface of the S1 single crystal substrate 4.
Vacuum deposition is performed using a -Si eutectic alloy. Furthermore, a low melting point metal film 12 such as In or Sn is deposited to a thickness of 1 to 5 μm as a brazing material on the p-type electrode 10 formed on the bottom surface of the concave groove 6 in which the semiconductor laser element is mounted. The above steps are shown in FIG. Next, the center position of the concave groove 6 and the concave groove 6
The Sl single crystal substrate 4 is divided into pellets at the center position of the array pitch interval (ie, the position indicated by the broken line in FIG. 5).

A semiconductor laser element 13 is placed on the metal film 12 of this pellet.
Mount using heat fusion or thermocompression method. The semiconductor laser element 13 is arranged with one resonant surface facing the end surface of the concave groove 6, that is, the light receiving surface of the photodetector. The pellet on which the semiconductor laser element 13 is mounted is attached to the stem 14.
, Sn, etc., and the n of the semiconductor laser element 13 is
A lead wire 17 is attached to the type electrode 16 and the n-type electrode 9 of the photodetector by an ultrasonic bonder method, a nail head bonder method, etc., and is connected to a stem terminal. Through the above steps, a semiconductor laser device with a monitor according to the present invention is manufactured as shown in FIG.

An n-type electrode 1 is attached to the semiconductor laser element 13 having the above configuration.
6 and the p-type electrode 10, stimulated emission of light occurs based on recombination of electron-hole pairs excited between both resonance surfaces of the semiconductor laser device 13, and multiple reciprocating movements occur between the resonance surfaces. The emitted light is rapidly amplified and output as laser light from each resonant surface in opposite directions.

The laser light output from one resonant surface is used for practical use, and the laser light output from the other resonant surface is irradiated as sampling laser light onto the light-receiving surface of the opposing photodetector. The photodetector detects the irradiated laser light, converts its output state into an electrical signal, and supplies the electrical signal to the control circuit. The control circuit adjusts the drive circuit of the semiconductor laser element 13 according to the output state of the laser beam, thereby maintaining a constant laser output state. Although the above embodiment describes a method for manufacturing a semiconductor laser, the present invention is not limited thereto and can be widely applied to optical semiconductor devices in general.

Further, the photodetector formed on the single crystal substrate can be made of any material other than Si as long as it can serve as a light receiving element. It goes without saying that the monitor structure of the present invention can be manufactured by using an n-type single crystal substrate and diffusing a p-type element such as B, contrary to the above. According to the present invention, since both the lead extraction electrode of the photodetector and the lead extraction electrode surface of the semiconductor laser can be arranged in the upper surface direction, lead wire attachment can be manufactured at the same time, and the manufacturing process is suitable for mass production lines. can be obtained.

Furthermore, when a semiconductor laser and a photodetector are mounted on the same heat sink, operations such as alignment become easier, which greatly contributes to reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional monitor structure. FIG. 2 is an explanatory diagram showing a radiation pattern of a semiconductor laser. 3, 4, 5, and 6 are 1 of the present invention.
FIG. 2 is a manufacturing process diagram showing a method for manufacturing an optical semiconductor device with a monitor according to an embodiment in order of steps. 4... S1 single crystal substrate, 6... Concave groove, 8... N-type layer,
9... N-type electrode of photodetector, 10...
p-type electrode of semiconductor laser device, 11... p-type electrode of photodetector, 13... semiconductor laser device, 16... n-type electrode of semiconductor laser device, 1
7...Lead wire.

Claims (1)

[Claims] 1. A method for manufacturing an optical semiconductor device with a monitor, which is equipped with a photodetector that detects a part of the output light of an optical semiconductor element, and whose optical output state is controlled and adjusted in response to a detection signal from the photodetector. In this process, a step is etched into a semiconductor base substrate, and an impurity is diffused from the sidewall of the step to form a p-
forming an n-junction and configuring the photodetector using the side wall of the stepped portion as a light-receiving surface; A monitor comprising the steps of arranging and fixing an optical semiconductor element to the base substrate, and connecting a lead wire for extracting the electromotive force of the photodetector and a lead wire for feeding power to the optical semiconductor element. A method for manufacturing an optical semiconductor device.