JPH0476518B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a monitor photodiode external semiconductor laser that generates laser light using a light-emitting semiconductor chip, and a method of die bonding the light-emitting semiconductor chip to a block. The present invention relates to a method for setting the die bonding position when the die bonding position is set.

[Conventional technology]

In general, in a semiconductor laser with an externally attached monitor photodiode that uses a light-emitting semiconductor chip to generate laser light, this semiconductor laser 1 with an externally attached monitor photodiode is used in electrical equipment as shown in FIGS. 2 and 3. When a light-emitting semiconductor chip 4 is die-bonded via a submount 5 to the upper surface of a block 3 protruding from a stem 2 having a pipe 6 for attachment to the stem 2, the laser beam from the light-emitting semiconductor chip is transmitted to the stem 2. It is necessary to set the position accurately so that the signal is transmitted along the axis C passing through the reference fixed point O at .

That is, if the optical axis of the laser beam emitted from the light-emitting semiconductor chip is deviated from the axis C passing through the reference fixed point O in the stem 2, the laser beam will be distorted when the semiconductor laser attached to the electrical equipment is replaced. Therefore, when replacing the semiconductor laser, it is necessary to adjust the position so that the laser beam emission position returns to the original position each time the semiconductor laser is replaced.

The outside of the block 3 with the light-emitting semiconductor chip 4 in the semiconductor laser 1 is covered with a cap 8 with a glass window 7 as shown by the two-dot chain line, and from the other side of the stem 2 there is a P terminal. 1a is prominent.

Therefore, conventionally, when die-bonding the luminescent semiconductor chip 4 on the upper surface of the block 3, the optical axis of the laser beam emitted from the luminescent semiconductor chip 4 coincides with the axis C passing through the reference fixed point O in the stem 2. In order to set the die bonding position of the light-emitting semiconductor chip 4 with respect to the block 3, the following method was adopted.

That is, as shown in FIG.
While fixing the stem 2 with attached to the holding jig 9,
Semiconductor chip 4 placed on the top surface of the block 3
An operator magnifies and visually inspects the front end surface of the semiconductor chip 4 using a microscope 10, and places the semiconductor chip 4 into the vacuum chuck capillary 11 until the outer contour of the front end surface of the semiconductor chip 4 falls within a predetermined reference line. By moving the die bonding position, the die bonding position is set, and the die bonding is performed at the set position.

[Problem that the invention seeks to solve]

However, a light-emitting semiconductor chip 4 used in a semiconductor laser is formed into a multilayer crystal body having an active layer 4a in the middle, as shown in FIG. Laser light is emitted from the light emitting portion 4a' at the stripe 4b in the layer 4a, and
Arrows A,
A', and the deviation of the position of the stripe 4b with respect to the center of the width dimension S in the semiconductor chip 4, that is, the cleavage position accuracy, and the distance from the bottom surface of the semiconductor chip 4 to the light emitting portion 4a' There are considerable variations in the accuracy of the height dimension H during the manufacture of the semiconductor chips 4, and there are also variations and errors in the mounting position of the block 3 with respect to the stem 2.

Therefore, the die bonding position of the semiconductor chip 4 with respect to the block 3 is determined by an operator magnifying the front end surface of the semiconductor chip 4 with the microscope 10 and visually observing it as in the conventional method, and checking that the external contour of the front end surface of the semiconductor chip 4 is in a predetermined shape. Even if it is set to fall within the reference line, there is a gap between the optical axis of the laser beam emitted from the semiconductor chip 4 and the axis C passing through the reference fixed point O in the stem 2. A deviation inevitably occurs due to variations in the positional accuracy for the semiconductor chip 4, the cleavage position accuracy, and the height dimension H accuracy during the manufacturing of the semiconductor chip 4. According to conventional results, the optical axis line relative to the axis C The deviation varies by about 50 microns for each product, and it is extremely difficult to reduce the variation among products to less than this, and it is necessary to adjust the mounting position every time the semiconductor laser attached to the electrical equipment is replaced. However, the present invention requires the die bonding position of the light-emitting semiconductor chip to the block in the monitor photodiode externally attached semiconductor laser to be adjusted to the attachment accuracy of the block to the stem, the cleavage position accuracy and high accuracy during the manufacture of the semiconductor chip. The objective is to provide a method that allows accurate setting regardless of variations in the precision of the dimension H.

[Means for solving problems]

For this reason, the present invention provides a method for detecting wavelengths that are not absorbed by the active layer of the light-emitting semiconductor chip with respect to the front end surface of the light-emitting semiconductor chip placed on the top surface of the block protruding from the stem of a monitor photodiode externally attached semiconductor laser. A laser beam is irradiated along the axis passing through the reference fixed point of the stem of the semiconductor laser, while the other end is irradiated with light at the position of the axis passing through the reference fixed point of the stem. One end of an optical fiber is arranged so as to be exposed to a detector, and the light-emitting semiconductor chip is moved to a position where the output detected by the photodetector is maximized.

[Action/effect of the invention]

In this way, when the light-emitting portion of the active layer of the light-emitting semiconductor chip does not coincide with the axis passing through the reference fixed point of the stem of the semiconductor laser, the laser light irradiated onto the front end face of the semiconductor chip will As the semiconductor chip moves, the optical fiber does not reach one end of the optical fiber, and the light output cannot be detected by the photodetector at the other end of the optical fiber. When the light-emitting portion coincides with the axis passing through the reference fixed point of the stem in the semiconductor laser, the laser beam irradiated onto the front end face of the semiconductor chip passes through the light-emitting portion in the active layer of the light-emitting semiconductor chip and reaches one end of the optical fiber. Since the output detected by the photodetector at the other end of the optical fiber reaches the maximum, the die bonding position of the light-emitting semiconductor chip with respect to the block can be determined at this time by the laser beam emitted from the light-emitting semiconductor chip. This allows the axis to be accurately set at a position that coincides with the axis passing through the reference fixed point of the stem.

In this way, the present invention utilizes the fact that laser light irradiated onto the front end face of a light-emitting semiconductor chip passes through the light-emitting portion of the active layer of the light-emitting semiconductor chip and reaches the optical fiber, thereby determining the die bonding position of the semiconductor chip. The setting of the die bonding position takes into account variations in the cleavage position accuracy and height dimension H precision and variations in the mounting accuracy of the block to the stem when manufacturing semiconductor chips as in the conventional method. Therefore, we have reduced the variation in the die bonding position of semiconductor chips to a range of several microns, and have improved product compatibility to the point where there is almost no need to adjust the mounting position when replacing a semiconductor laser attached to an electrical device. In addition, since the die bonding position of the semiconductor chip can be instantaneously set by maximizing the light output from the optical fiber, it has the effect of shortening the time required for setting.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings (FIG. 1).

In FIG. 1, 2 is a metal stem equipped with a pipe 6 for attaching the monitor photodiode external semiconductor laser 1 to electrical equipment.
The stem 2 is attached to a holding jig 9, and a metal block 3 for die-bonding the luminescent semiconductor chip 4 protrudes from the front surface thereof.
A light-emitting semiconductor chip 4 is mounted on the upper surface of the block 3 via a submount 5 made of silicon.

12 is a converging lens 1 that directs a laser beam of a wavelength that is not absorbed by the active layer of the luminescent semiconductor chip 4 onto the front end surface of the luminescent semiconductor chip 4.
3, and the position setting semiconductor laser 12 is such that the optical axis of the laser beam emitted from the position setting semiconductor laser 12 points to the reference fixed point O in the frame 2. It is arranged so as to be located on the axis C passing through it. Note that 14 is for applying a current to the PN terminal of the position setting semiconductor laser 12.
This is an APC power supply circuit.

Further, 15 indicates an optical fiber, one end of which is 1.
5a is disposed on the rear end surface of the light-emitting semiconductor chip 4 so as to be located on the axis C passing through the reference fixed point O of the stem 2, and the other end 15
b leads to a light output detector 16 with a photodiode or photomultiplier.

The laser beam irradiated from the position setting semiconductor laser 12 onto the front end face of the light emitting semiconductor chip 4 causes the light emitting portion of the active layer of the light emitting semiconductor chip 4 on the upper surface of the block 3 to reach the reference fixed point O of the stem 2. When the optical fiber 15 does not coincide with the passing axis C, the optical fiber 15 on the rear end surface of the light-emitting semiconductor chip 4 is blocked by the semiconductor chip 4.
Since it does not reach one end 15a, the optical fiber 15
Although the output detected by the optical output detector 16 at the other end 15b is zero or a small value, the semiconductor chip 4 on the upper surface of the block 3 is attracted by the vacuum chuck capillary 11, and the axis C
When the light-emitting portion of the active layer of the light-emitting semiconductor chip 4 coincides with the axis C passing through the reference fixed point O of the stem 2, the front end surface of the semiconductor chip 4 is irradiated. The laser beam passes through the light-emitting portion of the active layer of the light-emitting semiconductor chip 4 and reaches one end 15 of the optical fiber 15.
a, and the highest output is detected by the optical output detector 16 at the other end 15b of the optical fiber 15.

Therefore, by moving the light-emitting semiconductor chip 4 to the point where the maximum output is detected by the light output detector 16, the die bonding position of the light-emitting semiconductor chip 4 can be adjusted to the position where the laser light emitted from the light-emitting semiconductor chip 4 is being applied. Since the optical axis of the block 2 can be accurately set at a position where it coincides with the axis C passing through the reference fixed point O of the stem 2, the light-emitting semiconductor chip 4 can be die-bonded to the block 3 in this state.

In the above embodiment, the light-emitting semiconductor chip 4 is irradiated with laser light by the position setting semiconductor laser 12, but other laser light emitting means may be used instead of the position setting semiconductor laser 12. Needless to say, you can use it.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is an enlarged longitudinal sectional front view of a semiconductor laser with an externally attached monitor photodiode, FIG. An enlarged perspective view of a semiconductor chip,
FIG. 5 is a diagram showing a conventional method. 1...Monitor photodiode external semiconductor laser, 2...Stem, 3...Block, 4...
...Light-emitting semiconductor chip, 9...Holding jig, 12
... Semiconductor laser for position setting, 15 ... Optical fiber, 16 ... Optical output detector.

Claims (1)

[Claims] 1. A laser beam of a wavelength that is not absorbed by the active layer of the light-emitting semiconductor chip is applied to the front end surface of the light-emitting semiconductor chip placed on the top surface of the block protruding from the stem of the externally attached monitor photodiode semiconductor laser. While the semiconductor laser is irradiated along the axis passing through the reference fixed point of the stem, the rear end surface of the light-emitting semiconductor chip is irradiated with light at the position of the axis passing through the reference fixed point of the stem.
One end of an optical fiber is disposed with the other end facing a photodetector, and the light emitting semiconductor chip is moved to a position where the output detected by the photodetector is maximized. A die bonding position setting method for a light-emitting semiconductor chip for a semiconductor laser, characterized by the following.