Cavity surface coating method of semiconductor laser
Through the methods of radio frequency ion source plasma cleaning and oxygen-free passivation layer deposition, the problems of optical catastrophic damage and other adverse effects of the cavity surface of semiconductor lasers are solved, and an efficient cavity surface coating process suitable for mass production is realized.
Patent Information
- Application Number
- CN202311265865.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-27
- Publication Date
- 2025-03-28
AI Technical Summary
The existing cavity surface coating method of semiconductor lasers has problems such as optical catastrophic damage, electrode degradation, quantum well degradation and cavity surface damage, which are difficult to effectively solve in mass production.
The plasma generated by the radio frequency ion source is used to clean the cleavage surface of the semiconductor laser cavity surface, and an oxygen-free passivation layer is deposited under an ultra-high vacuum environment, and finally an optical film layer is deposited on the passivation layer.
Through this method, optical catastrophic damage to the cavity surface of the semiconductor laser is effectively suppressed, electrode degradation and quantum well degradation are avoided, and it is suitable for mass production.
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Figure CN119710669A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a cavity surface coating method for a semiconductor laser. Background Art
[0002] During the cleavage process of semiconductor lasers, the cavity surface will be contaminated by oxygen atoms, carbon atoms or other pollutants in the air to form surface defects. When the laser is working continuously or used for a long time, the cavity surface temperature reaches the critical temperature under the combined effect of surface defects. Subsequently, thermal breakdown occurs near the cavity surface of the laser, the cavity surface or the body material melts locally, and the generated hot spots diffuse laterally, resulting in catastrophic optical damage at the cavity surface. In order to reduce catastrophic optical damage, high-power semiconductor lasers need to undergo cavity surface non-oxidation and passivation processes. The oxide layer and contamination formed on the surface during cleavage in the air are removed by wet passivation or dry passivation. Then, other atoms are introduced to combine with the dangling bonds on the surface of the semiconductor material to form a new chemically stable passivation layer, thereby reducing the non-radiative recombination centers of the laser cavity surface. One of the existing methods is to use a vacuum cleavage passivation coating process to cleave semiconductor laser chips in an ultra-high vacuum to fundamentally remove the cavity surface contamination formed during the cleavage process. However, this process has high requirements for equipment and is not easy to mass produce. Summary of the invention
[0003] 1. Technical issues to be resolved
[0004] In view of this, the present disclosure provides a semiconductor laser cavity surface coating method for at least partially solving the adverse effects of semiconductor laser cavity surface optical catastrophic damage, electrode degradation, quantum well degradation and cavity surface damage caused by the current semiconductor laser cavity surface coating method.
[0005] (II) Technical solution
[0006] In order to achieve the above-mentioned objectives, the present disclosure provides, on the one hand, a method for coating the cavity surface of a semiconductor laser, comprising: cleaving the cavity surface of a semiconductor laser chip to form a cleavage surface; cleaning the cleavage surface by plasma generated by a radio frequency ion source until oxides and contamination on the surface of the cleavage surface are removed; and depositing a passivation layer on the cleaned cleavage surface.
[0007] According to an embodiment of the present disclosure, after the cavity surface of the cleaved semiconductor laser chip is formed, the process includes: placing the cleaved semiconductor laser chip into a closed container and transferring it to a vacuum environment; heating the semiconductor laser chip to a first temperature and maintaining it for a first time period.
[0008] According to an embodiment of the present disclosure, the plasma is one of plasma argon, plasma hydrogen, argon-hydrogen mixed plasma and plasma helium.
[0009] According to an embodiment of the present disclosure, an optical thin film layer is deposited on the surface of the passivation layer.
[0010] According to an embodiment of the present disclosure, the cleaning of the cleavage surface by plasma generated by a radio frequency ion source includes: emitting the plasma by the radio frequency ion source, uniformly cleaning the cleavage surface and maintaining the cleaning for a second time period.
[0011] According to an embodiment of the present disclosure, depositing a passivation layer on the cleaned cleavage surface comprises: heating the material of the passivation layer to a second temperature in an ultra-high vacuum environment, and depositing the passivation layer on the cleavage surface.
[0012] According to an embodiment of the present disclosure, the material of the passivation layer is an oxygen-free passivation material.
[0013] According to an embodiment of the present disclosure, the vacuum degree of the ultra-high vacuum environment is 1×10 -10 -1×10 -11 Torr level.
[0014] According to an embodiment of the present disclosure, the material of the optical thin film layer is one or more combinations of Al2O3, TiO2, Ta2O5, Nb2O5, SiO2 and Si.
[0015] According to an embodiment of the present disclosure, the semiconductor laser chip is heated to a first temperature and maintained for a first time, wherein the first temperature is 100°C-280°C and the first time is 25min-35min; the cleavage surface is cleaned uniformly and maintained for a second time, wherein the second time is 100s-600s; in an ultra-high vacuum environment, the material of the passivation layer is heated to a second temperature, and the passivation layer is deposited on the cleavage surface, wherein the second temperature is 600°C-1100°C.
[0016] (III) Beneficial effects
[0017] The present disclosure overcomes the deficiencies in the prior art and provides a method for coating the cavity surface of a semiconductor laser. On the one hand, the plasma generated by a radio frequency ion source is used to clean the cleavage surface. The plasma has good uniformity, low energy and high density, which not only eliminates the need for high-temperature heating of the chip, but also avoids the effects of electrode degradation and quantum well degradation. On the other hand, the plasma bombards the cavity surface of the semiconductor laser without causing damage, effectively suppressing optical catastrophic damage to the cavity surface of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 The schematic diagram of the process of the cavity surface coating method of the semiconductor laser provided by the embodiment of the present disclosure is schematically shown;
[0019] Figure 2A schematic diagram of a specific structure of a semiconductor laser provided by an embodiment of the present disclosure is shown;
[0020] Figure 3 A specific structural diagram of a semiconductor laser provided by another embodiment of the present disclosure is schematically shown.
[0021] Description of reference numerals:
[0022] 1-Semiconductor laser chip;
[0023] 2-cleavage plane;
[0024] 3- passivation layer;
[0025] 4-Optical thin film layer. DETAILED DESCRIPTION
[0026] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.
[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.
[0028] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.
[0029] The present invention provides a method for coating a semiconductor laser cavity surface. Figure 1 , the method includes S11 to S13.
[0030] In operation S11 , a cavity facet of the semiconductor laser chip 1 is cleaved to form a cleaved facet 2 .
[0031] In operation S12 , the cleaved surface 2 is cleaned by plasma generated by a radio frequency ion source until oxides and contaminants on the surface of the cleaved surface 2 are removed.
[0032] In operation S13 , a passivation layer 3 is deposited on the cleaned cleaved surface 2 .
[0033] According to the embodiments of the present disclosure, when the cavity surface of the semiconductor laser is coated, the cavity surface of the semiconductor laser chip 1 is first cleaved, and the cleavage process can be carried out in an atmospheric environment. However, preferably, the cleavage process is carried out in an environment filled with nitrogen or an inert gas to minimize the contact between the cleavage surface 2 and the air, thereby reducing or even avoiding the generation of oxides on the cleavage surface 2 and contamination. When the cleavage surface 2 is plasma cleaned, the ion source used is mostly a Kaufman ion source, a Hall ion source or a gateless APS source, and the radio frequency ion source used in the present disclosure has the advantages of high ionization rate, no pollution, strong stability, easy maintenance, low ion energy, high density and good consistency. Therefore, when the plasma generated by the radio frequency ion source is used to clean the cavity surface of the semiconductor laser, on the one hand, there is no need to heat the chip at high temperature, which can avoid the effects of electrode degradation, quantum well degradation, etc.; on the other hand, the plasma bombardment of the semiconductor laser cavity surface will not cause damage. Finally, at a second temperature, i.e., 600°C-1100°C, a passivation layer 3 is deposited on the cleaned cleavage surface 2 by molecular beam epitaxial growth technology or thermal evaporation technology. Through this step, the cleaned cleavage surface 2 can be isolated from the external environment to prevent oxidation of the cleavage surface 2.
[0034] The film coating method for semiconductor lasers provided in the present disclosure can not only suppress optical catastrophic damage to the cavity surface of semiconductor lasers, but also avoid causing adverse effects such as electrode degradation, quantum well degradation and cavity surface damage during the film coating process.
[0035] Furthermore, after operation S11 and before operation S12, the process further includes placing the cleaved semiconductor laser chip 1 into a closed container and transferring it to a vacuum environment, and then heating the semiconductor laser chip 1 to a first temperature and maintaining the temperature for a first time period.
[0036] In the embodiment of the present disclosure, the semiconductor laser chip 1 that has completed the cleavage process is transferred from the atmospheric environment or the preferred nitrogen or inert gas environment during the cleavage process to the vacuum environment required for plasma cleaning of the cavity surface. In practical applications, in order to improve process efficiency during mass production, the cleaved chips can be transferred in batches to a transitional low vacuum environment (1×10 -2 torr, and then transferred to an ultra-high vacuum environment (vacuum degree 1×10 -10 -1×10 - 11 When heating the semiconductor laser chip 1, the heating temperature is a first temperature, i.e., 100°C-280°C, and the heating time is a first time length, i.e., 25min-35min, i.e., about 30min. The specific heating temperature and time are appropriately adjusted according to the actual situation.
[0037] Before cleaning the cleaved surface 2, the semiconductor laser chip 1 that has completed the cleavage process is transferred to a vacuum environment, which can effectively reduce the probability of contamination of the cleaved surface 2. Heating the laser chip to 100°C-280°C can effectively reduce the contamination adsorbed on its surface and improve the effect of plasma cleaning.
[0038] In operation S12 , the plasma generated by the radio frequency ion source is one of plasma argon, plasma hydrogen, argon hydrogen mixed plasma, and plasma helium.
[0039] In the embodiment of the present disclosure, hydrogen, argon, argon-hydrogen mixed gas or helium is used as the process gas of the RF ion source, and one of the plasma hydrogen, plasma argon, argon-hydrogen mixed plasma and plasma helium formed therefrom is used to clean the cleavage surface 2 without chemically reacting with the semiconductor laser material to produce harmful products.
[0040] Optionally, after forming the passivation layer 3 on the cleavage plane 2, an optical thin film layer 4 may be formed on the passivation layer 3. The optical thin film layer 4 is used to adjust the cavity surface reflectivity of the semiconductor laser, and the coating material used may be Al2O3, TiO2, Ta2O5, Nb2O5, SiO2 or Si.
[0041] In the embodiment of the present disclosure, cleaning the cleavage surface 2 by plasma generated by a radio frequency ion source includes: emitting plasma by the radio frequency ion source to uniformly clean the cleavage surface 2 and maintain the cleaning time for a second period of time.
[0042] The cleavage surface 2 of the semiconductor laser chip 1 is cleaned by the plasma generated by the radio frequency ion source. The radio frequency ion source generates high-density, large-caliber and uniform plasma through magnetic induction. The duration of cleaning the cleavage surface 2 is the second duration, which is about 100-600s. The specific duration is appropriately adjusted according to the actual conditions of the equipment and devices. The radio frequency ion source uses magnetic induction to generate plasma, so it can work for a long time in the reaction gas without a filament, which greatly reduces the pollution to the system. Since the plasma generated by radio frequency induction has only singly charged ions and almost no doubly charged ions, it can reduce pollution and increase the uniformity of the radio frequency ion source system. In the embodiment disclosed in the present invention, in an ultra-high vacuum environment, the material of the passivation layer is heated to the second temperature, i.e., 600°C-1100°C, and the semiconductor laser chip is maintained at the first temperature, and then a single layer of passivation layer is deposited on the cleaned cleavage surface 2.
[0043] Furthermore, the material of the passivation layer 3 is an oxygen-free passivation material with a thickness of 4 nm-50 nm.
[0044] The material used for the passivation layer 3 is an oxygen-free material. The passivation materials conventionally used in the prior art include oxygen-containing materials such as Ga2O3, TiO2, BeO and Al2O3. In order to ensure the material composition and film quality, oxygen needs to be introduced during deposition, which may cause secondary oxidation of the cleavage surface 2. The oxygen-free passivation material in the embodiment of the present disclosure can be directly thermally evaporated without the need to introduce other gases for assistance, thereby avoiding secondary contamination of the cleavage surface 2 after the cleaning process, and the vacuum conditions are easy to control during the process. The specific oxygen-free passivation material can be selected according to the material of the semiconductor laser. For example, for gallium arsenide-based semiconductor lasers, wide bandgap materials such as ZnSe, ZnS, CdS and Si3N4 can be selected.
[0045] Furthermore, the vacuum degree of the ultra-high vacuum environment is 1×10 -10 -1×10 -11 torr level, better than 1×10 -9 Torr level.
[0046] The plasma generated by the radio frequency ion source is used to clean the cleavage surface 2, heat the semiconductor laser chip 1, and deposit the passivation layer 3 on the cleavage surface 2. These steps are all carried out in an ultra-high vacuum chamber (vacuum degree of 1×10 -10 -1×10 -11 To improve process efficiency, the above steps can be respectively arranged in different chambers of the same sequence, or the above three processes can be implemented in the same chamber.
[0047] In the disclosed embodiment, the plasma generated by the radio frequency ion source has good uniformity, low energy and high density. On the one hand, there is no need to heat the chip at high temperature, which can avoid the effects of electrode degradation and quantum well degradation; on the other hand, the plasma bombardment of the semiconductor laser cavity surface will not cause damage. Therefore, through the semiconductor laser cavity surface coating method, it can effectively suppress the optical catastrophic damage of the semiconductor laser cavity surface, and will not cause adverse effects such as electrode degradation, quantum well degradation and cavity surface damage during the coating process.
[0048] Another aspect of the present disclosure provides a semiconductor laser. Figure 2 The structural diagram of the semiconductor laser provided by the embodiment of the present disclosure is schematically shown.
[0049] like Figure 2 As shown, the semiconductor laser is manufactured by the above-mentioned semiconductor laser cavity surface coating method, and includes a semiconductor laser chip 1, a cleavage surface 2 and a passivation layer 3.
[0050] In the embodiment of the present disclosure, both side end faces of the semiconductor laser chip 1 are cleaved to form cleavage planes 2, and a passivation layer 3 is deposited on the cleavage planes 2. The steps of forming the passivation layer 3 are the same as steps S11-S13 in the above embodiment.
[0051] Figure 3 A specific structural diagram of a semiconductor laser provided by another embodiment of the present disclosure is schematically shown.
[0052] like Figure 3 As shown, based on the specific structure of the semiconductor laser described above, optionally, an optical thin film layer 4 is further included, which is prepared on the upper surface of the passivation layer 3.
[0053] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.
[0054] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.
Claims
1. A method for coating the cavity surface of a semiconductor laser, characterized in that: include: Cleavage the cavity surface of the semiconductor laser chip to form a cleavage surface; Cleaning the cleaved surface by plasma generated by a radio frequency ion source until oxides and contamination on the surface of the cleaved surface are removed; A passivation layer is deposited on the cleaned cleaved surface.
2. The cavity surface coating method according to claim 1, characterized in that: After the cavity surface of the semiconductor laser chip is cleaved to form a cleaved surface, the following steps are included: Putting the cleaved semiconductor laser chip into a closed container and transferring it to a vacuum environment; The semiconductor laser chip is heated to a first temperature and maintained for a first time period.
3. The cavity surface coating method according to claim 1, characterized in that: The plasma is one of plasma argon, plasma hydrogen, argon-hydrogen mixed plasma and plasma helium.
4. The cavity surface coating method according to claim 1, characterized in that: Also includes: An optical thin film layer is deposited on the surface of the passivation layer.
5. The cavity surface coating method according to claim 1, characterized in that: The cleaning of the cleavage surface by plasma generated by a radio frequency ion source comprises: The plasma is emitted by the radio frequency ion source to uniformly clean the cleavage surface and maintain it for a second time period.
6. The cavity surface coating method according to claim 1, characterized in that: Depositing a passivation layer on the cleaned cleaved surface comprises: In an ultra-high vacuum environment, the material of the passivation layer is heated to a second temperature, and the passivation layer is deposited on the cleavage surface.
7. The cavity surface coating method according to claim 1, characterized in that: The material of the passivation layer is an oxygen-free passivation material.
8. The cavity surface coating method according to claim 6, characterized in that: The vacuum degree of the ultra-high vacuum environment is 1×10 -10 -1×10 -11 torr level.
9. The cavity surface coating method according to claim 4, characterized in that: The material of the optical thin film layer is one or more combinations of Al2O3, TiO2, Ta2O5, Nb2O5, SiO2 and Si.
10. The cavity surface coating method according to claim 1, characterized in that: Heating the semiconductor laser chip to a first temperature and maintaining it for a first time, wherein the first temperature is 100° C.-280° C. and the first time is 25 min-35 min; Uniformly cleaning the cleavage surface and maintaining the cleaning process for a second time period, wherein the second time period is 100s-600s; In an ultra-high vacuum environment, the material of the passivation layer is heated to a second temperature, and the passivation layer is deposited on the cleavage surface, wherein the second temperature is 600° C.-1100° C.