JP2006066523A - Semiconductor laser device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device in which a window area can be formed accurately. <P>SOLUTION: The semiconductor laser device is provided with a multilayer semiconductor film 3 on a semiconductor substrate 1 and, at the same time, the window area 5 in its light emitting end. The laser device is also provided with a marker 4 near the window area 5 on the multilayer semiconductor film 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser device having a window region and a method for manufacturing the same.

  FIG. 4 is a perspective view showing the structure of a conventional semiconductor laser device having a window region. In this semiconductor laser device, a semiconductor multilayer film 53 including a first clad layer 53a, an active layer 53b, a second clad layer 53c, and a cap layer 53d is formed on a substrate 51, and a window region 55 is formed at a position where it becomes a light emitting end. And a ridge region 57 is formed in the semiconductor multilayer film 53. The current is supplied to the active layer 53b through the ridge region 57, and an optical waveguide is formed in the vicinity of the ridge region 57. A terrace region 57 a is provided outside the adjacent region adjacent to the ridge region 57.

  A semiconductor laser device having a window region has a structure in which light absorption hardly occurs in the window region having a thin light exit surface. Since it has a structure that hardly absorbs light, it has an advantage of preventing deterioration of the end face.

  Such a semiconductor laser element is usually formed by arranging a plurality of elements side by side on the same semiconductor substrate and dividing them on a rectangular parallelepiped at the end of the manufacturing process.

  The above steps are usually performed by separately providing a marker portion forming region in addition to the laser element forming region and aligning with the marker portion formed in that region.

A window region in a semiconductor laser element having a window region is a region where gain cannot be obtained with respect to laser light emission, and the efficiency of laser light emission decreases as the window region becomes longer. On the other hand, it is said that if the window area is 15 μm or less, it cannot function as the window area. For this reason, the window region is usually made with a length of 20-30 μm from the end face.
In order to form the window region with a length as designed, it is necessary to carry out the above dividing step very accurately. However, the conventional method is not always sufficiently accurate.

  The present invention has been made in view of such circumstances, and provides a semiconductor laser device capable of accurately forming a window region.

  A semiconductor laser device according to the present invention is characterized in that a semiconductor laser device includes a semiconductor multilayer film on a semiconductor substrate and a window region at a light emitting end, and includes a marker portion in the vicinity of the window region on the semiconductor multilayer film. .

  Conventionally, a marker part forming region is separately provided in addition to the semiconductor laser element forming region, and the dividing step is performed using the marker part formed in that region. In this method, there are cases where the distance between the marker portion and the marking line for division is large, and an error may occur in the position where the marking line is drawn. In the present invention, the marker portion is provided in the vicinity of the window region. The marking line is usually drawn so that the window region is located at the light emitting end of the semiconductor laser element. Therefore, according to the present invention, the distance between the marker portion and the marking line is always close, the error in the position of drawing the marking line is reduced, and the window region can be accurately formed.

  Further, according to the present invention, since it is not necessary to provide a separate marker portion forming region, the number of mounted semiconductor laser elements can be increased accordingly.

  Conventionally, since the marker portion is only a part of the semiconductor substrate, if the marker disappears due to cracking of the semiconductor substrate, the subsequent alignment cannot be performed and the semiconductor substrate has become a defective product. However, according to the present invention, the marker portion can be formed in all the semiconductor laser elements on the semiconductor substrate, and even when the semiconductor substrate is cracked, there is an advantage that the subsequent steps can be advanced. .

  A semiconductor laser device according to the present invention is characterized in that a semiconductor laser device includes a semiconductor multilayer film on a semiconductor substrate and a window region at a light emitting end, and includes a marker portion in the vicinity of the window region on the semiconductor multilayer film. .

1. Semiconductor substrate As the semiconductor substrate of the present invention, those used in ordinary semiconductor laser elements can be used, and GaAs substrates and the like can be used.

2. Semiconductor Multilayer Film The semiconductor multilayer film includes an active layer to be a light emitting layer, and preferably includes a first cladding layer, an active layer, and a second cladding layer, but may have any structure capable of emitting a laser. .

  The semiconductor multilayer film preferably includes a ridge region, and includes a terrace region outside an adjacent region adjacent to the ridge region. In this way, when there is a terrace region in the laser element, when the ridge region side of the laser element is die-bonded, the advantage that the laser element is not damaged at the time of mounting without concentrating on the ridge portion is damaged. There is. Further, it is preferable that the ridge region and the adjacent region form an optical waveguide. In a laser device, as light output increases, light oozes out from the ridge region, so the optical and electrical characteristics can be improved by forming an optical waveguide including the ridge region and the adjacent region. There is.

3. Window region The window region is a region having a larger band gap than the original band gap of the active layer, and is formed at the light emitting end. A window area | region may be provided only in one of the two light emission edge parts, and may be provided in both. Moreover, when providing in both, the length or structure of a window area | region may mutually differ. The window region can be formed by various known methods. For example, the window region can be formed by diffusing an impurity such as zinc in a portion where the window region is formed.

  The step of forming the window region is preferably performed continuously after the step of forming the marker portion described later. This is because the window region can be positioned with high accuracy without losing the shape of the marker by proceeding to the window region process after the marker portion is formed.

4). Marker Part The marker part may have any shape that can be used for alignment between a semiconductor substrate and a photomask, or a semiconductor substrate and a marking line drawing machine (such as a diamond cutter). The marker portion is formed in the vicinity of the window region on the semiconductor multilayer film, and makes it possible to accurately form the window region.

The marker portion preferably has a regular shape. In this case, the marker portion is preferably formed above the window region. The reason is as follows. Although the length of the window region has a large effect on the characteristics of the semiconductor laser, if you want to measure the length of the window region after dividing the chip, prepare a microscope with a length measurement function and start from the end of the electrode. The distance to the edge of the tip must be measured. When the chip is divided by the conventional method, a microscope with a length measurement function must be prepared for the length inspection of the window area, and the distance from the end of the electrode to the end of the chip must be measured. This increases the cost of the equipment and increases the cost of the chip due to the time required for measurement. In the present invention, since the marker portion has a regular shape, the length of the window region can be easily inspected by observing this shape. Note that “a shape having regularity” includes, for example, a step-like shape illustrated in FIG. 2A and a lattice-like shape illustrated in FIG. In each figure, the shaded portion is the marker portion.
The marker part may be formed by removing the semiconductor multilayer film in the hatched part, or may be formed by removing the semiconductor multilayer film other than the hatched part (leaving only the hatched part).

Moreover, it is preferable that a marker part has the relative positional information in a semiconductor substrate.
“Relative position information on the semiconductor substrate” is information on the position of the semiconductor laser element formed on the semiconductor substrate, such as the center of the semiconductor substrate or the upper end of the semiconductor substrate. Specifically, for example, “AB-12” illustrated in FIG. This indicates, for example, a semiconductor laser element formed in AB row and twelfth column. Note that the marker portion may be formed by removing the semiconductor multilayer film in the position information portion, or the marker portion may be formed by removing the semiconductor multilayer film other than the position information portion (leaving only the position information portion). Good.

By forming the position information in the marker portion, it is possible to track in which part of the semiconductor substrate an abnormality has occurred when a defect occurs, and the quality can be improved by improving the process.
In the past, position information was sometimes formed in the electrode formation process. However, when position information is formed in the marker part, cracks are missing in the intermediate process compared to the case where position information is formed in the electrode process. Further, since there is no influence of misalignment due to dirt on the wafer, there is an advantage that the position information is accurate.

  The marker portion having such relative position information is preferably formed by transferring a pattern formed on the photomask.

5. Insulating film It is preferable that an insulating film for making the window region a current non-injection part is further provided on the semiconductor multilayer film. By forming the insulating film in this way, heat generation in the window region can be suppressed.
The insulating film is preferably formed with respect to the marker portion.

Hereinafter, the manufacturing process of the semiconductor laser device according to the first embodiment of the present invention will be described with reference to FIG.
First, a semiconductor multilayer film 3 is formed by sequentially growing a first cladding layer 3a, an active layer 3b, a second cladding layer 3c having a conductivity type different from that of the first cladding layer 3a, and a cap layer 3d on the semiconductor substrate 1. To obtain the structure shown in FIG. The second cladding layer 3c has a three-layer structure including the etching stopper layer 6 (for the sake of convenience, only shown in FIG. 1D).

  Next, the marker portion 4 serving as a reference for positioning the window region is formed on the substrate on which the formation of the semiconductor multilayer film 3 has been completed, and the structure shown in FIG. 1B is obtained. Here, the marker portion 4 has a shape in which a part of the cap layer 3d is cut out, but may have a shape as shown in FIG. Examples of these shapes will be described in detail in Examples 2 and 3.

  The marker part forming method is to apply a resist to the semiconductor substrate after the semiconductor multilayer film 3 is formed, transfer the marker part shape of the photomask, form a resist mask, and use the resist mask thus formed. The cap layer (for example, GaAs layer) 3d which is the uppermost layer of the semiconductor substrate is etched, and the resist mask is removed by organic cleaning, whereby a semiconductor substrate can be formed.

  After the marker part formation is completed, the process proceeds to the process of forming the window region. One method for creating a red laser window region is to diffuse impurities into the active layer 3b. In this case, the first step is to form the ZnO film 5a only in the portion that becomes the window region. In this step, a resist pattern is formed on the basis of the previously created marker, and ZnO is removed from portions other than the window region (that is, a ZnO film is formed only in the portion to be the window region). Next, the obtained substrate is heat-treated, and impurities (in this case, Zn) are diffused into the active layer 3b to form the window region 5, thereby obtaining the structure shown in FIG. In such an impurity diffusion step, it is desirable that the wafer be flat, and it is easier to control the impurity diffusion before the optical waveguide and the current path are formed. For this reason, it is better to be flat at least in a region to be an optical waveguide.

  Next, a part of the semiconductor multilayer film 3 is removed by etching to form the ridge region 7 and the terrace region 7a, thereby obtaining the structure shown in FIG. The etching for forming the ridge region 7 can be performed so that the etching stopper layer 6 in the second cladding layer 3c is exposed. Thereafter, an insulating layer having an opening is formed in the ridge region 7 excluding the window region 5 portion, the window region 5 is used as a current non-injection portion, and an electrode is formed on the obtained substrate.

  If electrode formation is completed, a board | substrate will be divided | segmented on the basis of the marker part 4 formed in the window area vicinity. Since the distance between the marker portion 4 and the division position is short, an error is hardly generated in the division position, and the window region can be formed with a length as designed.

  An example of a shape in which the marker part has regularity is shown in FIG. In the example of FIG. 2A, a staircase shape is used, but a pattern can be designed with a window length of 50 μm by setting 10 steps to one step of 5 μm. In the example of FIG. 2B, a lattice shape is used. However, by designing the pitch of the lattice to 5 μm and using 10 steps, the pattern can be designed with a window length of 50 μm. By performing surface observation after dividing the pattern into chips, the length of the window region can be inspected without using a microscope with a length measuring function.

  FIG. 3 shows an example in which the marker portion has relative position information on the semiconductor substrate. In the example of FIG. 3, when chips are arranged on a wafer in a matrix, AB indicates row information and 12 indicates column information. For example, if a total of 10000 chips of 100 rows × 100 columns are placed on the wafer, the row information is AA to AZ, BA to BZ, CA to CZ, DA to DV, and the column information is It becomes 00-99.

It is a perspective view which shows the manufacturing process of the semiconductor laser element concerning Example 1 of this invention. It is a top view which shows the structure of the semiconductor laser element based on Example 2 of this invention. It is a top view which shows the structure of the semiconductor laser element based on Example 3 of this invention. It is a perspective view which shows the structure of the conventional semiconductor laser element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,51: Semiconductor substrate 3,53: Semiconductor multilayer film 4: Marker part 5, 55: Window area 5a: ZnO film 6: Etching stopper film 7, 57: Ridge area 7a, 57a: Terrace area

Claims (9)

  What is claimed is: 1. A semiconductor laser device comprising a semiconductor multilayer film on a semiconductor substrate and a window region at a light emitting end portion, wherein the marker portion is provided near the window region on the semiconductor multilayer film.   The semiconductor laser device according to claim 1, wherein the semiconductor multilayer film includes a ridge region, and includes a terrace region outside an adjacent region adjacent to the ridge region.   3. The semiconductor laser device according to claim 2, wherein the ridge region and the adjacent region form an optical waveguide.   The semiconductor laser device according to claim 1, wherein the marker portion has a regular shape.   2. The semiconductor laser device according to claim 1, wherein the marker unit has relative position information on the semiconductor substrate.   The semiconductor laser device according to claim 1, further comprising an insulating film for forming the window region as a current non-injection portion on the semiconductor multilayer film.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein the step of forming the marker portion and the step of forming the window region using the formed marker portion are continuously performed. Method.   6. The method of manufacturing a semiconductor laser device according to claim 5, wherein the marker portion having relative position information is formed by transferring a pattern formed on a photomask. .   7. The method of manufacturing a semiconductor laser device according to claim 6, wherein the insulating film for making the window region a current non-injection portion is aligned with the marker portion. Manufacturing method.

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