Semiconductor laser cleaning device and semiconductor laser cleaning method

Abstract

A holder (4) holds a semiconductor laser (1). A first nozzle (5) and a second nozzle (6) simultaneously cause air flows (8) including dry ice particles (7) to blow along different directions to the same region in an end surface (2). A housing (10) accommodates the holder (4), the first nozzle (5), and the second nozzle (6). Exhaust parts (11, 12) discharge foreign matter (3) removed from the end surface (2) out of the housing (10).

Description

Semiconductor laser cleaning device and semiconductor laser cleaning method

[0001] The present disclosure relates to a semiconductor laser cleaning apparatus and a semiconductor laser cleaning method.

[0002] When a semiconductor wafer on which multiple semiconductor lasers are formed is divided into bars, foreign matter such as wafer scraps adheres to the end faces of the semiconductor lasers. Such foreign matter cannot be removed by cleaning with liquids such as water due to the influence of electrical attraction. Therefore, dry ice cleaning, in which an airflow containing dry ice particles is blown onto the end faces, is used (see, for example, Patent Document 1). Because the sublimation energy generated by the vaporization of the dry ice particles is applied to the foreign matter, foreign matter is more easily removed than by simply blowing an airflow.

[0003] International Publication No. 2021 / 100626

[0004] However, conventional dry ice cleaning, in which an airflow containing dry ice particles is blown from one direction, sometimes fails to adequately remove foreign matter from the chip end surface.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a semiconductor laser cleaning device and a semiconductor laser cleaning method that can improve the cleaning power of dry ice cleaning.

[0006] The semiconductor laser cleaning device according to the present disclosure is characterized by comprising a holder for holding a semiconductor laser having an end face, a first nozzle and a second nozzle for simultaneously spraying airflows containing dry ice particles onto the same region of the end face from different directions, a housing for accommodating the holder, the first nozzle, and the second nozzle, and an exhaust unit for exhausting foreign matter removed from the end face from the housing.

[0007] In this disclosure, airflows containing dry ice particles are simultaneously blown onto the same region of the facet of a semiconductor laser from two different directions, which allows the sublimation energy generated when the dry ice particles collide and vaporize to be applied to the foreign matter from two different directions simultaneously, thereby improving the cleaning power of dry ice cleaning.

[0008] FIG. 1 is a diagram showing a semiconductor laser cleaning apparatus according to a first embodiment. FIG. 2 is a flowchart of a semiconductor laser cleaning method according to the first embodiment. FIG. 3 is a diagram for explaining two-flow dry ice cleaning. FIG. 4 is a diagram showing a modified example of a semiconductor laser cleaning apparatus according to the first embodiment. FIG. 5 is a perspective view showing a part of a semiconductor laser cleaning apparatus according to a second embodiment. FIG. 6 is a diagram showing a semiconductor laser cleaning apparatus according to a third embodiment. FIG. 7 is a diagram showing a semiconductor laser cleaning apparatus according to a fourth embodiment. FIG. 8 is a flowchart of a semiconductor laser cleaning method according to the fourth embodiment. FIG. 9 is a diagram showing a semiconductor laser cleaning apparatus according to a fifth embodiment. FIG. 10 is a flowchart of a semiconductor laser cleaning method according to the fifth embodiment. FIG. 11 is a diagram showing a semiconductor laser cleaning apparatus according to a sixth embodiment.

[0009] A semiconductor laser cleaning apparatus and a semiconductor laser cleaning method according to an embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0010] First Embodiment. Figure 1 is a diagram showing a semiconductor laser cleaning apparatus according to the first embodiment. The semiconductor laser 1 to be cleaned is a semiconductor wafer cleaved into bars. The semiconductor laser 1 has an end facet 2, which is a cleavage surface. The end facet 2 is the emission end face from which laser light is emitted or the rear end facet on the opposite side. A foreign substance 3 is attached to the end facet 2. The foreign substance 3 is wafer scraps or the like generated when the semiconductor wafer is cleaved, and is made of semiconductor material.

[0011] A holder 4 holds the semiconductor laser 1. Liquid carbon dioxide is supplied into a first nozzle 5 and a second nozzle 6, where it is transformed into dry ice particles 7. The first nozzle 5 and the second nozzle 6 simultaneously blow airflows 8 containing the dry ice particles 7 from different directions onto the same region of the end face 2. This removes foreign matter 3 from the end face 2.

[0012] Specifically, the first nozzle 5 blows the airflow 8 obliquely or parallel to the end face 2. That is, the first nozzle 5 blows the airflow 8 from a direction greater than 0 degrees and less than 90 degrees relative to the end face 2. The second nozzle 6 blows the airflow 8 perpendicular to the end face 2.

[0013] The housing 10 houses the holder 4, the first nozzle 5, and the second nozzle 6. An exhaust unit 11 is provided on the side of the housing 10, and an exhaust unit 12 is provided on the bottom surface of the housing 10. The exhaust units 11 and 12 exhaust the foreign matter 3 removed from the end face 2 from the housing 10 together with the air inside the housing 10. This allows the foreign matter 3 to be removed from the housing 10 so that it does not reattach to the semiconductor laser 1.

[0014] When dry ice cleaning is performed, the foreign matter 3 may become electrically charged. The charged foreign matter 3 is likely to reattach to the semiconductor laser 1 due to electrostatic force. Therefore, an ionizer 13 and an electrostatically charged sheet 14 are provided inside the housing 10. The ionizer 13 releases ions into the air inside the housing 10 to remove the charge from the foreign matter 3. The electrostatically charged sheet 14 is positively or negatively charged, and removes the charge from the foreign matter 3 that comes into contact with the electrostatically charged sheet 14. The foreign matter 3 from which the charge has been removed is discharged from the exhaust sections 11 and 12 without reattaching to the semiconductor laser 1.

[0015] Next, a semiconductor laser cleaning method using the semiconductor laser cleaning apparatus according to this embodiment will be described. FIG. 2 is a flowchart of the semiconductor laser cleaning method according to the first embodiment. First, ions are generated by the ionizer 13 (step S1). Two-flow dry ice cleaning is performed by using the first nozzle 5 and the second nozzle 6 to simultaneously blow airflows 8 containing dry ice particles 7 from two different directions onto the same region of the facet 2 of the semiconductor laser 1 (step S2). After cleaning for a predetermined time, the blowing of the airflow 8 is stopped (step S3). Finally, the ionizer 13 is stopped (step S4). In two-flow dry ice cleaning, it is preferable to set the difference in air volume between the first nozzle 5 and the second nozzle 6 to zero and to synchronize the start and end timing of the blowing of the first nozzle 5 and the second nozzle 6.

[0016] FIG. 3 illustrates two-flow dry ice cleaning. Airflows 8 containing dry ice particles 7 are simultaneously blown from two different directions onto the same area of ​​the facet 2 of the semiconductor laser 1. The dry ice particles 7 are approximately 10 μm in size. The dry ice particles 7 collide with the foreign matter 3, vaporizing and expanding approximately 750 times. The resulting sublimation energy is applied to the foreign matter 3 simultaneously from two different directions. This improves the cleaning power of dry ice cleaning compared to blowing the airflow 8 containing dry ice particles 7 from a single direction. As a result, visual defects due to foreign matter adhesion can be reduced during visual inspection of the facet 2 of the semiconductor laser 1. The dry ice particles 7 have low hardness and therefore do not damage the facet 2 of the semiconductor laser 1.

[0017] Furthermore, the kinetic energy of the dry ice particles 7 when they collide with the foreign object 3 is proportional to the mass and the square of the velocity of the dry ice particles 7. However, if the collision angle deviates from 90 degrees, part of the kinetic energy slides sideways along the end surface 2. Therefore, since the angle at which the kinetic energy of the collision is maximized is vertical, it is preferable that the second nozzle 6 blow the airflow 8 perpendicular to the end surface 2.

[0018] 4 is a diagram showing a modification of the semiconductor laser cleaning apparatus according to embodiment 1. The first nozzle 5 and the second nozzle 6 simultaneously spray airflows 8 containing dry ice particles 7 from diagonal directions on the left and right, respectively, onto the same region of the end face 2. In this case as well, sublimation energy is simultaneously applied to the foreign matter 3 from two different directions, thereby improving the cleaning power of dry ice cleaning.

[0019] 5 is a perspective view showing a portion of a semiconductor laser cleaning apparatus according to a second embodiment. A holder 4 holds a plurality of semiconductor lasers 1 stacked together with their respective end faces 2 facing the same direction. Two nozzle pairs, each including a first nozzle 5 and a second nozzle 6, are provided. One of the two nozzle pairs blows an airflow onto one end face of the plurality of semiconductor lasers 1. The other of the two nozzle pairs blows an airflow onto the other end face of the plurality of semiconductor lasers 1.

[0020] The width of the area onto which the airflow is blown is several tens of microns, which is the width of one bar of semiconductor laser 1. Therefore, when cleaning multiple bars of semiconductor laser 1 attached to the holder 4 using only one nozzle pair, it is necessary to move the nozzle pair by the number of bars. In contrast, in this embodiment, there are two nozzle pairs, so two of the multiple bars of semiconductor laser 1 held by the holder 4 can be cleaned simultaneously. As a result, the processing capacity of the semiconductor laser cleaning device can be improved. The other configurations and effects are the same as those of embodiment 1.

[0021] Embodiment 3 Fig. 6 is a diagram showing a semiconductor laser cleaning apparatus according to embodiment 3. A plurality of sets, each including a holder 4, a first nozzle 5, and a second nozzle 6, are provided in a single housing 10. This allows semiconductor lasers 1 held by a plurality of holders 4 to be cleaned simultaneously. As a result, the processing capacity of the semiconductor laser cleaning apparatus can be improved. The other configurations and effects are the same as those of embodiment 1. Note that each set may be provided with two nozzle pairs as in embodiment 2.

[0022] 7 is a diagram showing a semiconductor laser cleaning apparatus according to a fourth embodiment. In this embodiment, a laser irradiator 15 locally irradiates the end face 2 with high-energy laser light to heat it. A nozzle 16 sprays an airflow 8 containing dry ice particles 7 onto the heated portion of the end face 2 irradiated with the laser light. The laser irradiator 15 is, for example, a deep ultraviolet laser (wavelength 355 nm), and the irradiation time is optional. The heated portion of the end face 2 has a diameter of, for example, several tens of microns. The other configurations are the same as those of the first embodiment.

[0023] 8 is a flowchart of a semiconductor laser cleaning method according to the fourth embodiment. First, ions are generated by the ionizer 13 (step S11). Next, the laser irradiator 15 irradiates the end face 2 with laser light to heat it (step S12). An airflow 8 containing dry ice particles 7 is sprayed from the nozzle 16 onto the heated portion of the end face 2 irradiated with the laser light (step S13). After cleaning is performed for a predetermined time, the spraying of the airflow 8 and the irradiation of the laser light are stopped (step S14). Finally, the ionizer 13 is stopped (step S15).

[0024] As described above, in this embodiment, an airflow 8 containing dry ice particles 7 is blown onto the heated portion of the end face 2 irradiated with laser light. This increases the temperature difference ΔT between the dry ice particles 7 and the end face 2, thereby increasing the sublimation energy of the dry ice particles 7. This improves the cleaning power of dry ice cleaning. Furthermore, while heating the entire chip to a high temperature affects device characteristics, the effect on device characteristics can be reduced by locally heating the end face 2 with laser light.

[0025] Furthermore, if the laser light is ultraviolet, it is difficult for the laser light to penetrate into the device interior, and therefore it is possible to heat only the foreign matter 3 and the surface layer of the end face 2. This improves the foreign matter removal effect on the end face 2 without affecting the device characteristics. Note that the laser light irradiation of this embodiment may be combined with the two-flow dry ice cleaning of embodiments 1-3.

[0026] 9 is a diagram showing a semiconductor laser cleaning apparatus according to a fifth embodiment. In this embodiment, a vibrator 17 ultrasonically vibrates a nozzle 16. For example, the vibrator 17 irradiates the nozzle 16 with parallel energy beams of different frequencies. This phase interference causes interference fringes on the surface of the nozzle 16, and the nozzle 16 is ultrasonically vibrated in response to the resulting mechanical strain. The frequency of the ultrasonic vibration is 20 kHz or higher. The other configurations are the same as those of the first embodiment.

[0027] 10 is a flowchart of a semiconductor laser cleaning method according to the fifth embodiment. First, ions are generated by the ionizer 13 (step S21). Next, the vibrator 17 ultrasonically vibrates the nozzle 16 (step S22). An airflow 8 containing dry ice particles 7 is blown from the ultrasonically vibrated nozzle 16 onto the end face 2 (step S23). After cleaning for a predetermined time, the vibration of the nozzle 16 and the blowing of the airflow 8 are stopped (step S24). Finally, the ionizer 13 is stopped (step S25).

[0028] As described above, in this embodiment, the nozzle 16 is ultrasonically vibrated, which also vibrates the airflow 8 ejected from the nozzle 16. The vibration effect of the dry ice particles 7 vibrating together with the airflow 8 can improve the cleaning power of dry ice cleaning.

[0029] Furthermore, the higher the vibration frequency, the shorter the wavelength, making it more difficult for the vibration to propagate inside the object. In particular, if the vibration frequency is 1 MHz or higher, the vibration is less likely to propagate inside the device, so it is possible to vibrate only the foreign matter 3 and the surface layer of the end face 2. Therefore, it is preferable that the vibrator 17 vibrates the nozzle 16 at a frequency of 1 MHz or higher. This can improve the foreign matter removal effect on the end face 2 without affecting the device characteristics. Note that this embodiment may be combined with the laser light irradiation of embodiment 4 or the two-flow dry ice cleaning of embodiments 1-3.

[0030] 11 is a diagram showing a semiconductor laser cleaning device according to a sixth embodiment. In this embodiment, a vibrator 17 ultrasonically vibrates the holder 4. The frequency of the ultrasonic vibration is 20 kHz or higher. The other configurations are the same as those of the first embodiment. By ultrasonically vibrating the holder 4, the semiconductor laser 1 held by the holder 4 is also ultrasonically vibrated. The dry ice particles 7 collide with the end face 2 of the ultrasonically vibrated semiconductor laser 1, thereby improving the cleaning power of the dry ice cleaning.

[0031] Note that, since vibrating the holder 4 may cause the semiconductor laser 1 held by the holder 4 to break apart, it is preferable to ultrasonically vibrate the nozzle 16 as in embodiment 5. Furthermore, this embodiment may be combined with the laser light irradiation of embodiment 4 or the two-flow dry ice cleaning of embodiments 1 to 3.

[0032] REFERENCE SIGNS LIST 1 Semiconductor laser, 2 End face, 4 Holder, 5 First nozzle, 6 Second nozzle, 7 Dry ice particles, 8 Air flow, 10 Housing, 11 Exhaust section, 13 Ionizer, 14 Charging sheet, 15 Laser irradiator, 16 Nozzle, 17 Vibrator

Claims

1. A semiconductor laser cleaning device comprising: a holder for holding a semiconductor laser having an end face; a first nozzle and a second nozzle for simultaneously spraying airflows containing dry ice particles onto the same area of ​​the end face from different directions; a housing for accommodating the holder, the first nozzle, and the second nozzle; and an exhaust unit for exhausting foreign matter removed from the end face from the housing.

2. The semiconductor laser cleaning device according to claim 1, characterized in that the first nozzle blows the airflow from a direction greater than 0 degrees and less than 90 degrees relative to the end face, and the second nozzle blows the airflow from a direction perpendicular to the end face.

3. A semiconductor laser cleaning device as described in claim 1 or 2, characterized in that the holder holds a plurality of the semiconductor lasers, two nozzle pairs each including the first nozzle and the second nozzle are provided, one of the two nozzle pairs blows the air flow onto the end face of one of the plurality of semiconductor lasers, and the other of the two nozzle pairs blows the air flow onto the end face of another one of the plurality of semiconductor lasers.

4. A semiconductor laser cleaning device as described in any one of claims 1 to 3, characterized in that a plurality of sets each including the holder, the first nozzle, and the second nozzle are provided inside one of the housings.

5. A semiconductor laser cleaning device comprising: a holder for holding a semiconductor laser having an end face; a laser irradiator for irradiating the end face with laser light to heat it; a nozzle for spraying an airflow containing dry ice particles onto the heated portion of the end face irradiated with the laser light; a housing for accommodating the holder and the nozzle; and an exhaust unit for exhausting foreign matter removed from the end face from the housing.

6. A semiconductor laser cleaning device according to claim 5, wherein the laser light is ultraviolet light.

7. A semiconductor laser cleaning device comprising: a holder for holding a semiconductor laser having an end face; a nozzle for spraying an airflow containing dry ice particles onto the end face; a vibrator for ultrasonically vibrating the nozzle or the holder; a housing for accommodating the holder and the nozzle; and an exhaust unit for exhausting foreign matter removed from the end face from the housing.

8. The semiconductor laser cleaning device according to claim 7, wherein said vibrator vibrates said nozzle at a frequency of 1 MHz or more.

9. The semiconductor laser cleaning device according to any one of claims 1 to 8, further comprising an ionizer that releases ions into the housing to remove the charge of the foreign matter.

10. A semiconductor laser cleaning device according to any one of claims 1 to 9, further comprising an electrostatically charged sheet provided inside the housing for removing the charge of the foreign matter.

11. A semiconductor laser cleaning method comprising the steps of: holding a semiconductor laser having an end face with a holder; and simultaneously blowing an airflow containing dry ice particles onto the same area of ​​the end face from two different directions.

12. A semiconductor laser cleaning method according to claim 11, wherein one of the two directions is a direction greater than or equal to 0 degrees and less than 90 degrees relative to the facet, and the other of the two directions is a direction perpendicular to the facet.

13. A semiconductor laser cleaning method comprising the steps of: holding a semiconductor laser having an end face with a holder; irradiating the end face with laser light to heat it; and blowing an airflow containing dry ice particles onto the heated portion of the end face irradiated with the laser light.

14. A semiconductor laser cleaning method according to claim 13, wherein the laser light is ultraviolet light.

15. A semiconductor laser cleaning method comprising the steps of: holding a semiconductor laser having an end face with a holder; and blowing an airflow containing dry ice particles from a nozzle onto the end face, wherein the nozzle or the holder is ultrasonically vibrated.

16. A semiconductor laser cleaning method according to claim 15, wherein the nozzle is vibrated at a frequency of 1 MHz or more.

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