JPH0476238B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor laser with a built-in monitor photodiode that generates laser light using a light-emitting semiconductor chip, in which the light-emitting semiconductor chip is die-bonded into a block. The present invention relates to a method for setting a die bonding position in a case where the die bonding position is set.

[Conventional technology]

Generally, in a semiconductor laser with a built-in monitor photodiode that uses a light-emitting semiconductor chip to generate laser light, the semiconductor laser with a built-in monitor photodiode 1 is attached to an electrical device as shown in FIGS. 2 and 3. When a luminescent semiconductor chip 4 is die-bonded via a submount 5 to the upper surface of the block 3 protruding from the stem 2 for the It is necessary to set the position accurately so that it is transmitted along the axis (C) through which it passes.

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 semiconductor laser attached to the electrical equipment may be replaced. In this case, the emission position of the laser beam will shift, so when replacing the semiconductor laser, it is necessary to adjust the position so that the emission position of the laser beam 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 7 with a glass window 6 as shown by the two-dot chain line, and from the other side of the frame 2,
The PN terminals 1a and 1b protrude, and the terminal 1c for the monitor photodiode 8 also protrudes.

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

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
Arrow (A) along the optical axis line extending in the longitudinal direction of b.
(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 light emitting portion from the bottom surface of the semiconductor chip 4. There is considerable variation in the accuracy of the height dimension (H) up to 4a' during the manufacturing of the semiconductor chip 4, and there is also considerable variation in the accuracy of the height dimension (H) up to 4a'
There are variations in the mounting position.

Therefore, the die bonding position of the semiconductor chip 4 with respect to the block 3 can be determined by visually inspecting the front end surface of the semiconductor chip 4 by an operator by magnifying it with a microscope 10 as in the conventional method, and by checking the external contour of the front end surface of the semiconductor chip 4 according to a predetermined standard. Even if it is set so that it falls within the line, the optical axis line of the laser beam emitted from the semiconductor chip 4 and the reference fixed point (O) on the stem 2
There is a deviation between the block 3 and the axis (C) passing through the stem 2 due to variations in the positional accuracy of the block 3 with respect to the stem 2 and the cleavage position accuracy and height dimension (H) accuracy during the manufacturing of the semiconductor chip 4. This inevitably occurs, and according to past results, the deviation of the optical axis from the axis (C) is
There is a variation of about 50 microns, and it is extremely difficult to reduce the variation in products to less than this, and it is necessary to adjust the mounting position every time the semiconductor laser attached to an electrical device is replaced.

The present invention allows the die bonding position of the light-emitting semiconductor chip to the block in the semiconductor laser to be independent of the mounting accuracy of the block to the stem and variations in the cleavage position accuracy and height dimension (H) accuracy during the manufacturing of the semiconductor chip. This provides a method that allows accurate settings.

[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 semiconductor laser with a built-in photodiode for monitoring. Laser light is irradiated along an axis passing through a reference fixed point of a stem in the semiconductor laser, while the light-emitting semiconductor chip is moved to a position where the output of a monitoring photodiode in the semiconductor laser is maximized. It is something.

[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 However, as the semiconductor chip moves, the light output is not detected by the monitor photodiode.
When the light-emitting portion of the active layer of the light-emitting semiconductor chip coincides 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 passes through the light-emitting portion of the active layer of the light-emitting semiconductor chip. The laser beam transmitted from the luminescent semiconductor chip reaches the monitor photodiode, and the output at the monitor photodiode reaches its maximum. The optical axis of the stem can 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 the laser light irradiated onto the front end face of the light-emitting semiconductor chip passes through the light-emitting portion of the active layer of the light-emitting semiconductor chip and reaches the monitoring photodiode. This is to set the die bonding position, and the setting of the die bonding position takes into account variations in cleavage position accuracy and height dimension (H) accuracy when manufacturing semiconductor chips as in the conventional method, and the mounting accuracy of the block to the stem. Since there is no variation in the die bonding position of the semiconductor chip, it is necessary to limit the variation in the die bonding position of the semiconductor chip to a range of several microns, and to ensure product compatibility, it is almost necessary to adjust the mounting position when replacing the semiconductor laser attached to electrical equipment. In addition, since the die bonding position of the semiconductor chip can be instantaneously set by maximizing the output of the monitor photodiode, 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, reference numeral 2 denotes a metal stem for attaching the semiconductor laser 1 with a built-in monitor photodiode to an electrical device.The stem 2 is attached to a holding jig 9, and a A metal block 3 for die-bonding the light-emitting semiconductor chip 4 protrudes, and the light-emitting semiconductor chip 4 is placed on the upper surface of the block 3 via a silicon submount 5. 2, a monitor photodiode 8 is die-bonded in advance at a position corresponding to the rear end surface of the light-emitting semiconductor chip 4, and a terminal 1c connected to the monitor photodiode 8 is connected to an ammeter, voltmeter, etc. An output detector 12 is connected.

13 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.
4, the position setting semiconductor laser 13 is such that the optical axis of the laser beam emitted from the installation setting semiconductor laser 13 is located at a reference fixed point (O ) is arranged so as to be located on the axis (C) passing through the axis (C). Note that 15 is an APC power supply circuit for applying a current to the PN terminal of the position setting semiconductor laser 13.

The laser beam irradiated from the position setting semiconductor laser 13 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. If it does not match the axis (C) passing through,
Because it is blocked by the semiconductor chip 4, it cannot reach the monitor photodiode 8.
Although the output detected by the output detector 12 is a small value, the semiconductor chip 4 on the upper surface of the stem 3 is attracted by the vacuum chuck capillary 11, and 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 laser beam irradiated onto the front end face of the semiconductor chip 4 The light passes through the light-emitting portion of the active layer of the light-emitting semiconductor chip 4 and reaches the monitor photodiode 8, where its output detector 12 detects the highest output.

Therefore, the light emitting semiconductor chip 4 is connected to the output detector 1.
By moving the die-bonding position of the light-emitting semiconductor chip 4 to the point where the maximum output is detected in the light-emitting semiconductor chip 2, the optical axis of the laser beam emitted from the light-emitting semiconductor chip 4 aligns with the reference fixed point (O) of the frame 2. Since the light-emitting semiconductor chip 4 can be accurately set at a position that coincides with the passing axis (C), 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 13, but other laser beam transmitting means may be used instead of the position setting semiconductor laser 13. Needless to say, you can use it.

[Brief explanation of the drawing]

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 a built-in photodiode for monitoring, Fig. 3 is a side view from - side of Fig. 2, and Fig. 4 is a luminescent An enlarged perspective view of a semiconductor chip,
FIG. 5 is a diagram showing a conventional method. 1... Semiconductor laser with built-in monitor photodiode, 2... Stem, 3... Block, 4...
Luminescent semiconductor chip, 9... Holding jig, 8...
Monitor photodiode, 12... Output detector, 13... Semiconductor laser for position setting.

Claims (1)

[Claims] 1. 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 the semiconductor laser with built-in photodiode for monitoring,
Laser light of a wavelength that is not absorbed by the active layer of the light-emitting semiconductor chip is irradiated along an axis passing through a reference fixed point of the stem of the semiconductor laser, while the light-emitting semiconductor chip is exposed to a monitoring photodiode of the semiconductor laser. 1. A die bonding position setting method for a light-emitting semiconductor chip for a semiconductor laser, characterized in that the die bonding position is moved to a position where the output of the chip is maximized.