JP2003110187A - Semiconductor laser and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor laser capable of forming an end face protective film formed of an alumina film having a good anti-moisture property on the end face of a semiconductor laser chip rapidly. SOLUTION: On a compound semiconductor substrate, a p-side electrode, an n-side electrode, and other layers are formed (steps S1-S7). The compound semiconductor substrate is cut into pieces corresponding to individual semiconductor laser elements by cleavage to turn them into chips (step S8). On both end faces of each semiconductor laser chip, end face protective films formed of alumina are formed in an inert gas (step S9). These semiconductor laser chips are dipped in water to attach water molecules H2 O to the end face protective films (step S10). Immediately after this, the semiconductor laser chips are inverse-bias-etched with the bias direction inversed in an oxygen atmosphere (step S11).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reading light source for optical disks such as CD-ROM and DVD-ROM,
The present invention relates to a semiconductor laser used as a writing light source for an optical disc such as a CD-R / RW and a DVD-RAM, a writing light source in a laser beam printer, and a light source for a laser pointer, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A semiconductor laser is a light emitting device in which light generated by recombination of electrons and holes is reflected inward on both end faces of a chip to generate laser oscillation. On both end faces of the semiconductor laser chip, that is, the laser emission side end face and the reflection side end face, end face protection films which also serve as reflection films are formed. The end face protective film is made of, for example, alumina (Al _x O _y (0 ≦ x ≦ 2, 0 ≦ y ≦ 3)). For example, only the end face protection film is formed on the laser emission side end face from which the laser light is taken out, but the reflection side end face which is the opposite end face is formed on the end face protection film with a film such as amorphous silicon. Are formed in multiple layers, and a reflective film that reflects more light inward of the chip is formed.

A typical method for forming an alumina film as an end face protective film is a sputtering method using alumina solid (Al ₂ O ₃ ) as a target. However, it is known that the alumina film formed by this sputtering method is in a state of lacking oxygen. The oxygen-deficient alumina film is chemically unstable and easily bonds with water molecules H ₂ O or hydroxyl groups OH. More specifically, boehmite (AlO. (OH)) is easily formed. Therefore, the oxygen-deficient alumina film cannot have good moisture resistance. Therefore, the semiconductor laser having the end face protective film made of such an alumina film cannot have satisfactory reliability.

In order to solve this problem, a method is known in which oxygen is introduced into the processing chamber when the alumina film is formed by sputtering in an argon atmosphere. That is, by adding oxygen to the argon atmosphere, oxygen vacancies in the formed alumina film are reduced. As a result, it is possible to form an alumina film that is less likely to bond with water molecules H ₂ O or hydroxyl groups OH, that is, an alumina film having good moisture resistance.

[0005]

However, according to this method, the film formation rate of the alumina film is remarkably reduced and the film formation rate becomes unstable. Therefore, the productivity of the semiconductor laser is poor and it is not necessarily suitable for mass production. Therefore, an object of the present invention is to solve the above-mentioned technical problems, and to provide a semiconductor laser manufacturing method capable of quickly forming an end face protective film including an alumina film having good moisture resistance on an end face of a semiconductor laser chip. Is to provide.

Another object of the present invention is to provide a semiconductor laser having a structure capable of rapidly forming an end face protective film containing a good alumina film on the end face of a semiconductor laser chip.

[0007]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, the invention according to claim 1 forms an alumina film as an end face protective film on the end face of a semiconductor laser chip by a sputtering method. And a step of supplementing the formed alumina film with oxygen atoms. According to the present invention, after forming the alumina film as the end face protective film by the sputtering method, oxygen atoms are supplemented to the alumina film. That is, when the alumina film is formed by the sputtering method, the alumina film is in a state of being deficient in oxygen, but by supplementing this with oxygen atoms, the oxygen deficiency can be reduced. As a result, an alumina film that does not easily bond with water molecules or hydroxyl groups, that is, an end face protective film including an alumina film having excellent moisture resistance can be formed on the end face of the semiconductor laser chip. As a result, the reliability of the semiconductor laser can be improved.

Moreover, since it is not necessary to introduce oxygen into the processing atmosphere when forming the alumina film by sputtering, the alumina film is formed by using an inert gas to which oxygen is not added. It can be performed by a sputtering method in an atmosphere. Thereby, the end face protective film including the alumina film having excellent moisture resistance can be rapidly formed. As a result, semiconductor lasers can be mass-produced with good productivity. According to a third aspect of the present invention, in the step of supplementing the oxygen atoms, the step of attaching water molecules to the surface of the alumina film after the formation of the alumina film and the step of immediately adding the water molecules to the alumina 3. The method of manufacturing a semiconductor laser according to claim 1, further comprising the step of bringing oxygen plasma into contact with the film.

In the present invention, water molecules are attached to the surface of the alumina film after the formation of the alumina film. As a result, oxygen vacancies in the alumina film are supplemented by water molecules. Immediately after this, when oxygen plasma is brought into contact with the alumina film, hydrogen atom bonds in water molecules attached to the alumina film are separated. In this way, it is possible to form an alumina film having good oxygen resistance and reduced oxygen vacancies. The invention according to claim 4 is the method for manufacturing a semiconductor laser according to claim 1 or 2, wherein the step of supplementing the oxygen atoms includes a step of bringing oxygen plasma into contact with the alumina film.

According to the present invention, oxygen is supplemented to the oxygen vacancy portion in the alumina film by bringing the oxygen film into contact with the sputtered alumina film. by this,
It is possible to obtain an alumina film having good moisture resistance with reduced oxygen vacancies. The invention according to claim 5 is characterized in that the step of bringing oxygen plasma into contact with the alumina film is performed by a reverse bias etching process in which a bias is applied so that oxygen atoms collide with the alumina film on the surface of the semiconductor laser chip. The method for manufacturing a semiconductor laser according to claim 3 or 4.

According to the present invention, oxygen atoms in a plasma state can be guided to the alumina film to supplement the oxygen atoms in the alumina film. The invention according to claim 6 is the method for manufacturing a semiconductor laser according to claim 5, wherein the reverse bias etching process is performed in a processing chamber in which the alumina film is formed. According to the present invention, by performing a reverse bias etching process in which the bias direction is the reverse direction in the same process chamber where the alumina film is formed by sputtering, the oxygen atoms in the oxygen plasma are directed in the opposite direction to the sputtering target. That is, it can be guided in the direction of the semiconductor laser chip which is the object of film formation. As a result, the formation of the alumina film and the process of supplementing the alumina film with oxygen atoms can be performed in the same processing chamber, so that the scale of the production facility can be reduced.

Particularly, in the case of the invention described in claim 4, since the reverse bias etching can be continuously performed following the sputter deposition of the alumina film, the productivity of the semiconductor laser can be improved. The invention according to claim 7 is characterized in that the step of supplementing the oxygen atoms includes a step of subjecting the formed alumina film to heat treatment in the air or an oxygen atmosphere. It is a method of manufacturing a semiconductor laser.

According to the present invention, in an atmosphere containing oxygen,
That is, heat treatment is applied to the alumina film in the air or the oxygen atmosphere, and thereby oxygen atoms are supplemented to the alumina film in which oxygen deficiency occurs. By this heat treatment, an alumina film having good moisture resistance can be obtained. However,
Since the heat treatment requires a relatively long time, it is preferable to supplement the alumina film with oxygen atoms by the process described in claim 3 or 4 in consideration of mass productivity.

According to an eighth aspect of the present invention, there is provided a semiconductor laser in which an alumina film as an end face protective film is formed on an end face of a semiconductor laser chip, wherein an oxygen content of a surface layer of the alumina film is equal to that of the alumina film. The semiconductor laser is characterized in that the oxygen content is higher than the deep part of the film.
The semiconductor laser having such a structure can be manufactured by the method described in any one of claims 1 to 7. That is, after the alumina film is formed by sputtering, oxygen atoms are supplemented from the surface of this alumina film, so that the alumina film contains more oxygen in the surface layer portion, and the surface layer portion in the film deep portion. Oxygen content is lower than that. If the oxygen deficiency in the surface layer portion is small, the alumina film can have good moisture resistance, so that the reliability of the semiconductor laser can be secured.

According to a ninth aspect of the present invention, the oxygen content in the surface layer portion is at a first level and the oxygen content in the film deep portion is at a second level lower than the first level, and the alumina film is 9. The semiconductor laser according to claim 8, wherein the change of the oxygen content with respect to the depth from the surface of the step shows a stepwise change between the first level and the second level. When oxygen atoms are supplemented from the surface of the alumina film formed by sputtering, the change in oxygen content between the surface layer portion and the film deep portion shows a step-like change as described in claim 9. .

Thus, the semiconductor laser of the present invention is
It can be manufactured by a manufacturing method that does not require the addition of oxygen to the processing atmosphere when the alumina film is formed by sputtering. Therefore, the alumina film as the end face protection film can be formed in a short time. In this way, a semiconductor laser having a structure suitable for mass production can be realized.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing a simplified structure of a semiconductor laser to be manufactured by a manufacturing method according to an embodiment of the present invention.
Further, FIG. 2 is a cross-sectional view of the semiconductor laser. This semiconductor laser is configured by forming end face protective films 11 and 12 on both end faces of a semiconductor laser chip 10, and further forming an amorphous silicon film 13 on the end face protective film 12 on one end face. The end face protective films 11 and 12 are
It is formed on the laser emission side end face from which laser light is extracted and on the reflection side end face that reflects most of the light generated in the semiconductor laser chip 10 into the chip, and is made of, for example, a single film of alumina sputter-deposited. . An amorphous silicon film 13 formed by sputtering is formed on the end face protective film 12 on the reflection side end face.
A reflective film having a two-layer structure is formed.

As shown in FIG. 2, the semiconductor laser chip 1
0 is constituted by laminating an n-type cladding layer 2, an active layer 3, a p-type cladding layer 4, and a p-type contact layer 5 in this order on a compound semiconductor substrate 1 such as GaAs. A current blocking layer 6 for narrowing the current flowing in the chip near the central axis of the semiconductor laser chip 10 is provided near the middle portion of the p-type cladding layer 4 in the film thickness direction. Further, the n-side electrode 7 is in ohmic contact with the surface of the compound semiconductor substrate 1 (the surface opposite to the n-type cladding layer 2). Similarly, the p-side electrode 8 is in ohmic contact with the exposed surface of the p-type contact layer 5.

FIG. 3 is a flow chart for outlining the manufacturing process of the semiconductor laser having the above structure. On the compound semiconductor substrate 1, the n-type cladding layer 2 (step S
1), active layer 3 (step S2), p-type cladding layer 4
(Step S3), the current blocking layer 6 (step S4), and the p-type contact layer 5 (step S5) are sequentially crystal-grown. These are formed on one large compound semiconductor substrate in a state where the individual portions of the semiconductor laser device shown in FIG. 2 are densely arranged.

Then, the compound semiconductor substrate 1 (the surface opposite to the n-type cladding layer 2) is subjected to a lapping process to thin the sample to a desired thickness (step S6). Then, the p-side electrode 8 is formed on the surface on which the p-type contact layer 5 is formed, and the n-side electrode 7 is formed on the compound semiconductor substrate 1 side (step S7). Then, it is cut into individual pieces corresponding to individual semiconductor laser elements by cleavage, and is made into chips (step S8). In the obtained semiconductor laser chip 10,
Alumina films forming the end face protective films 11 and 12 are formed on both end faces parallel to the cross section shown in FIG. 2 and side faces in the vicinity thereof (step S9). This alumina film is formed by sputtering film formation in an atmosphere of an inert gas to which oxygen is not added, for example, argon. Then, oxygen-deficient alumina Al _X O _Y (X = 2, 0 ≦ Y ≦ 3, Y / X <3/2)
Is formed.

Next, the obtained sample (a semiconductor laser chip having alumina films as the end face protective films 11 and 12 formed on both end faces) is immersed in water to form the end face protective films 11 and 12.
Water molecules H ₂ O are attached to the surface (step S10). Then, the oxygen atom O of the water molecule H ₂ O is in a state of being trapped in the oxygen vacancy portion of alumina. Immediately after this, the sample (semiconductor laser chip in which water molecules are attached to the end face protective films 11 and 12) is subjected to reverse bias etching in the oxygen atmosphere with the bias direction reversed (step S11). Then,
Oxygen plasma is generated, and activated oxygen atoms in the oxygen plasma are guided toward the sample and collide with water molecules H ₂ O attached to the alumina film. As a result, the bond of the hydrogen atom H of the water molecule H ₂ O is separated, and the oxygen atom O separated from the hydrogen atom H supplements the oxygen deficiency on the surface of the alumina film. The end face protective films 11, 12) are obtained.

The semiconductor laser is completed by forming the amorphous silicon film 13 on the one end face protective film 12 at an appropriate stage. For example, the amorphous silicon film 1 is formed immediately after the end face protective films 11 and 12 are formed (step S9).
3 may be formed, and thereafter, water molecules may be attached to the end face protective film 11 (step S10) and reverse bias etching (step S11) may be performed. Further, the end face protective films 11 and 12 are formed (step S9), water molecules are attached to the end face protective films 11 and 12 (step S10), and reverse bias etching (step S11) is performed, and then the amorphous silicon film 13 is formed. May be formed. The end face on the side where the amorphous silicon film 13 is formed is the reflection side end face, and the end face only on the end face protective film is the laser emission side end face.

FIG. 4 is a schematic sectional view showing the structure of a processing apparatus for carrying out the sputter deposition of the alumina film shown in step S9 of FIG. 3 and the reverse bias etching process of step S11. Inside the processing chamber 21, a plate electrode 22 and plate electrodes 23a and 23b are arranged opposite to each other. Semiconductor laser chips 10 (a plurality of in FIG. 4) are arranged on the surface of the electrode 22 on the one side, and the electrode 2 on the other side is arranged.
Backing plates 25a and 25b are provided on 3a and 23b.
Through the target 26a, 2 which is the raw material of the thin film.
6b is fixed.

During film formation, the flow rate control valve B1
Is opened, and an inert gas such as argon is introduced into the processing chamber 21 from the gas introduction part A to make the inside of the processing chamber 21 an inert gas atmosphere. At the same time, the pressure inside the processing chamber 21 is reduced by the exhaust system B connected to the processing chamber 21, and the inside of the processing chamber 21 is reduced to 10 ⁻¹ To.
The pressure is reduced to about rr or less. The targets 26a and 26b may be of different types. When the target 26a is used, that is, when the film is formed using the target 26a as a raw material (for example, step S9), the shutter 27a is opened,
The shutter 27b is closed, and the power source 28T is used for the target 2
The potential of the electrode 23a on the 6a side is controlled. Target 26
The power source 28T is not connected to the electrode 23b on the b side. The switch S is turned on so that the electrode 22 is grounded. Then, a voltage is generated between the electrodes 22 and 23a. When the power source 28T is an AC power source, an AC voltage is generated between the electrodes 22 and 23a. Due to the action of this AC voltage, the processing chamber 2
The gas in 1 becomes a plasma state and is discharged.

The matching box 29T functions to adjust the circuit constants so that the efficiency of the high frequency power consumed in the processing chamber 21 becomes high even if the impedance inside the processing chamber 21 changes. . Inert gas atom with kinetic energy is the target 26a
By colliding with the surface of, the atoms forming the target 26a are ejected, reach the surface of the semiconductor laser chip 10 facing and are deposited. As a result, a thin film made of the constituent material of the target 26a is formed on the surface of the semiconductor laser chip 10.

During reverse bias etching (step S1
In 1), switch S is turned off and power supply 28S is connected to electrode 2
2, the potential of the electrode 22 is controlled, and the potential of the electrode 23a on the target 26a side is controlled in the same manner as in the sputtering film formation. At this time, the matching box 29S adjusts the efficiency of the high frequency power from the power source 28S to be high. Then, a bias voltage is applied to the semiconductor laser chip 10 side, and gas atoms mainly collide with the semiconductor laser chip 10. Step S11
In the step of, the flow control valve B2 is opened to perform reverse bias etching in an atmosphere containing oxygen,
Oxygen gas is introduced into the processing chamber 21 from the gas introduction part A to adjust the inside of the processing chamber 21 to an appropriate oxygen partial pressure.

The controller 30 controls the high frequency power from the power supplies 28T and 28S and the matching boxes 29T and 29S, the argon gas flow rate from the flow rate control valve B1, the oxygen gas flow rate from the flow rate control valve B2, and the opening and closing of the switch S. FIG. 5 is a graph showing changes in the oxygen content with respect to the depth from the surface of the alumina film forming the end face protective films 11 and 12 (particularly the end face protective film 11). Surface layer (depth from the surface is 30 nm
The average oxygen content at ˜50 nm) is at the first level, which is a relatively high value. In FIG. 5, the oxygen content is shown by the ratio Y / X (atomic ratio) of the O amount Y to the Al amount X, but at the first level, Y / X is about 1.5,
It shows a state where there is almost no oxygen deficiency. The ratio Y / X of the O amount Y to the Al amount X sharply decreases when the depth from the surface becomes deep to some extent, and becomes a substantially constant value in the deeper portion of the film. Deep part of the film (depth from the surface is 30 nm ~
The average oxygen content at 50 nm and above) is a second level lower than the first level.

As described above, the depth distribution of the oxygen content which changes stepwise is such that after the alumina film containing a large amount of oxygen deficiency whose oxygen content is almost the second level is formed, the oxygen is removed from the surface of the alumina film. Is supplied, and only in a shallow region near the surface, the oxygen content reaches a high first level. By the manufacturing method according to the first embodiment of the present invention, a semiconductor laser having an alumina film, which is an end face protective film having such an oxygen content distribution, can be obtained.

Table 1 shows a summary of the measured reflectance of the alumina film before and after the pressure cooker test, which is an accelerated moisture resistance test. For the test, three types of samples having different methods for forming the end face protective film were used. One is when the first embodiment is applied, the other is when the conventional method for improving the moisture resistance is applied, and the other is when the processing is performed without the moisture resistance improving treatment. The conventional method for improving moisture resistance is a method for forming an alumina film, which is an end face protective film, by sputtering in an argon atmosphere containing oxygen. The term “without moisture resistance improving treatment” means that the alumina film, which is the end face protective film, is formed by sputtering in an argon atmosphere in which oxygen is not added, and thereafter the treatment for supplementing oxygen atoms is not performed. When the sample corresponding to the first embodiment was created, the sputtering atmosphere was argon alone.

The condition of the pressure cooker test is that the sample is kept in an environment of 121 ° C., relative humidity of 100% and 2 atm.
I decided to leave it for an hour.

[0031]

[Table 1]

The reflectance of the end face protective film was greatly decreased after the test as compared with that before the test in the case without the moisture resistance improving treatment, whereas in the case of applying the first embodiment and the conventional moisture resistance. When the property improving method was applied, the reflectance after the test maintained the same value as the reflectance before the test. That is, when the first embodiment is applied and when the conventional moisture resistance improving method is applied, the end face protective film having good moisture resistance is obtained.

When an atmosphere in which oxygen is added to argon is used as the atmosphere for forming the alumina film by sputtering, the film forming rate is significantly reduced and the film forming rate is unsatisfactory as compared with the case of using argon alone. Be stable. Therefore, the conventional method for improving moisture resistance has poor productivity and is difficult to be mass-produced. Further, since the reflectance of the end face protective film changes depending on the film thickness, if the film formation rate is not constant, the film thickness varies, and the reflectance of the end face protective film cannot be accurately controlled.

On the other hand, in this embodiment, since the sputter film formation (step S9) is performed in an atmosphere of argon alone, the film formation rate can be made sufficiently high and the film formation rate is stable. The film thickness can be controlled accurately. Step of attaching water to the alumina film (step S10) and step of reverse bias etching in an oxygen atmosphere (step S11)
Ends in a relatively short time. Therefore, according to the present embodiment, it is possible to quickly form the end face protective film including the alumina film having good moisture resistance. Further, it is possible to reduce variations in the reflectance of the obtained end face protective film.

Further, in this embodiment, the alumina film forming the end face protective film is formed by sputtering (step S9).
The processing chamber 21 for performing the reverse bias etching process (step S11) includes a power source 28S.
The same can be used by controlling the bias direction by. This makes it possible to reduce the scale of production equipment. FIG. 6 is a flowchart for outlining the manufacturing process of the semiconductor laser according to the second embodiment of the present invention.

The steps up to the step of forming the end face protective films 11 and 12 (steps S1 to S9) are the same as those in the first embodiment (FIG. 3). The end face protective films 11 and 12 are formed by sputter deposition in an inert atmosphere such as argon (step S9), and then a sample (alumina films constituting the end face protective films 11 and 12 are formed on both end faces of the semiconductor laser chip). While maintaining the same (formed material) in the same processing chamber 21 (see FIG. 4), the atmosphere in the processing chamber 21 is replaced with oxygen and reverse bias etching is performed (step S20).

Since the end face protection films 11 and 12 are formed in an inert atmosphere, oxygen vacancies are not present in the alumina film forming the end face protection films 11 and 12 at the stage of sputtering film formation (step S9). There are many. Therefore, by performing reverse bias etching in an oxygen atmosphere (step S20), oxygen plasma is generated and activated oxygen atoms are supplied to the oxygen vacancy portion of alumina. As a result, the surface layer portion of the alumina film is in a state in which there is almost no oxygen deficiency. Therefore, because boehmite is not formed on the surface due to bonding with water molecules or hydroxyl groups,
Such an alumina film has high humidity resistance.

Also according to the second embodiment, the depth distribution of the oxygen content as shown in FIG. 5, that is, the oxygen amount is large in the surface layer portion, the oxygen amount is small in the film deep portion, and the interval is stepwise. End face protective films 11, 12 having varying distribution
A semiconductor laser provided with is obtained. End face protective film 11, 1
The processing chamber 21 for sputter-depositing the alumina film (step S9) and the processing chamber 21 for performing the reverse bias etching process (step S20) are controlled by the power supply 28S in the bias direction. , It is possible to use the same one. This makes it possible to reduce the scale of production equipment.

Further, in the second embodiment, the alumina film is formed (step S9) and oxygen is supplied to the oxygen deficient portion (step S20) while the sample is held in the processing chamber 21 of the sputtering apparatus. Can be performed continuously. Therefore, it is possible to significantly improve the productivity. Figure 7
9 is a flowchart for outlining the manufacturing process of the semiconductor laser according to the third embodiment.

The steps up to the step of forming the end face protective films 11 and 12 (steps S1 to S9) are the same as those in the first embodiment (FIG. 3). Then, heat treatment is performed in the air or an oxygen atmosphere (step S30). Since the end face protective films 11 and 12 are formed in an inert atmosphere such as argon, at the stage of sputtering film formation (step S9), oxygen vacancies are not present in the alumina film forming the end face protective films 11 and 12. There are many. Therefore, by performing a heat treatment in the air or in an oxygen atmosphere (step S30), oxygen in the atmosphere is supplied to the oxygen deficiency portion of alumina, so that the surface of the alumina film has almost no oxygen deficiency. Therefore, since boehmite is not formed by bonding with water molecules or hydroxyl groups, such an alumina film has high moisture resistance.

Also in the third embodiment, the depth distribution of the oxygen content as shown in FIG. 5, that is, the oxygen amount is large in the surface layer portion, the oxygen amount is small in the film deep portion, and the interval is stepwise. End face protective films 11, 12 having varying distribution
A semiconductor laser provided with is obtained. In Table 1 above, the measurement results of the reflectance of the alumina film before and after being subjected to the pressure cooker test are shown for the samples when the third embodiment is applied to the end face protective films 11 and 12.

In the pressure cooker test, 1 sample was used.
It was carried out by leaving it for 2 hours in an environment of 21 ° C., 100% relative humidity and 2 atm. In the sample prepared by applying the third embodiment, the reflectance after the test maintained the same value as the reflectance before the test. In the case of applying the third embodiment, since the sputter film formation (step S9) is performed in an argon atmosphere in which oxygen is not added, the film formation rate can be sufficiently increased and the film formation rate can be stabilized. Therefore, the film thickness can be controlled accurately. Heat treatment (step S30)
It takes 1 to 2 hours to process, but since a large amount of samples can be processed at once, the productivity does not drop significantly. Therefore, by applying the third embodiment, it is possible to quickly form the end face protective film containing alumina having good moisture resistance. Further, it is possible to reduce the variation in the reflectance of the obtained end face protective films 11 and 12.

The above is an example of the embodiment of the present invention, and various modifications can be made within the scope of the matters described in the claims. For example, the end face protective film may be formed by sputtering by adding a small amount of oxygen to the argon atmosphere within a range that does not reduce the film forming rate. Also in this case, it is possible to quickly form the end face protective film having good moisture resistance by compensating oxygen atoms in the oxygen vacancy portion on the surface of the alumina film after forming the alumina film.

The semiconductor laser chip to which the present invention is applied is not limited to the structure shown in FIG. 2, but the present invention can be applied to semiconductor laser chips having various other structures. In the above embodiment, the laser emission side end face has a single layer structure in which only the end face protection film 11 is formed, and the reflection side end face has a two layer structure in which the amorphous silicon film 13 is formed on the end face protection film 12. It was said that,
The present invention is not limited to this. For example,
One or both of these may be a multilayer film in which the end face protective film 12 (11) and the amorphous silicon film 13 are alternately laminated. In that case, since the reflectance can be adjusted by the layer thickness of each layer, one of the layers can function as a reflection-side end surface, and the other can function as a laser emission-side end surface.

In the semiconductor laser having such a structure, the end face protective film 12 (1
It can be obtained by alternately and repeatedly forming 1) and the amorphous silicon film 13. In this case, processing for compensating for oxygen vacancies in the alumina film forming the end face protective films 11 and 12 (steps S10, S11, S20, S
30) may be performed, for example, each time the step (step S9) of forming the end face protective films 11 and 12 is completed, and the step of forming the outermost surface side end face protective films 11 and 12 (step 9) may be performed. It may be performed only later.

[Brief description of drawings]

FIG. 1 is a perspective view showing a simplified configuration of a semiconductor laser to be manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the semiconductor laser.

FIG. 3 is a flowchart showing a method for manufacturing a semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a structure of a sputtering film forming apparatus used in a manufacturing method according to an embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a depth distribution of an O amount / Al amount ratio in an end face protective film of a semiconductor laser to be manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 6 is a flowchart showing a method for manufacturing a semiconductor laser according to the second embodiment of the present invention.

FIG. 7 is a flowchart showing a method for manufacturing a semiconductor laser according to the third embodiment of the present invention.

[Explanation of symbols]

10 Semiconductor laser chip 11 Edge protection film (alumina film) 12 Edge protection film (alumina film) 21 Processing room 22 electrodes 23a electrode 23b electrode 25a backing plate 25b backing plate 26a target 26b target 27a shutter 27b shutter 28T power supply 28S power supply 29T matching box 29S Matching Box 30 controller

Claims (9)

[Claims] 1. A method comprising: forming an alumina film as an end face protective film on an end face of a semiconductor laser chip by a sputtering method; and supplementing the formed alumina film with oxygen atoms. Of manufacturing a semiconductor laser. 2. The method for manufacturing a semiconductor laser according to claim 1, wherein the alumina film is formed by a sputtering method in an inert gas atmosphere to which oxygen is not added. 3. The step of supplementing the oxygen atoms comprises the steps of, after forming the alumina film, attaching water molecules to the surface of the alumina film and immediately after attaching the water molecules to the oxygen film. 3. The method of manufacturing a semiconductor laser according to claim 1, further comprising the step of contacting with plasma. 4. The method of manufacturing a semiconductor laser according to claim 1, wherein the step of supplementing the oxygen atoms includes a step of bringing oxygen plasma into contact with the alumina film. 5. The step of bringing oxygen plasma into contact with the alumina film is performed by a reverse bias etching process in which a bias is applied so that oxygen atoms collide with the alumina film on the surface of the semiconductor laser chip. 3. The method for manufacturing a semiconductor laser according to 3 or 4. 6. The method of manufacturing a semiconductor laser according to claim 5, wherein the reverse bias etching process is performed in a processing chamber in which the alumina film is formed. 7. The method of manufacturing a semiconductor laser according to claim 1, wherein the step of supplementing the oxygen atoms includes a step of subjecting the formed alumina film to a heat treatment in the air or an oxygen atmosphere. Method. 8. A semiconductor laser having an alumina film as an end face protective film formed on an end face of a semiconductor laser chip, wherein an oxygen content of a surface layer portion of the alumina film is an oxygen content of a deep portion of the alumina film. Semiconductor lasers characterized by more than 9. The oxygen content of the surface layer portion is at a first level, the oxygen content of the film deep portion is at a second level lower than the first level, and the depth from the surface of the alumina film is 9. The semiconductor laser according to claim 8, wherein the change of the oxygen content with respect to the above-mentioned shows a stepwise change between the first level and the second level.