A method for regulating the light-emitting angle of a VCSEL chip

Abstract

The application relates to a VCSEL chip light-emitting angle regulation method, which comprises the following steps: based on a target divergence angle, a standard transverse temperature distribution template capable of realizing the divergence angle through a thermo-optic effect is determined; an integrated heat dissipation structure which actively adjusts the transverse temperature distribution around a light-emitting unit through its own pattern and layout is prepared in a semiconductor layer around the light-emitting unit; the light-emitting unit is driven to work, and the actual transverse temperature distribution is compared with the standard transverse temperature distribution template; when the deviation of the actual transverse temperature distribution from the standard transverse temperature distribution template exceeds a tolerance, the pattern and layout of the integrated heat dissipation structure are micro-processed and adjusted to correct the heat flow guiding function, so that the actual transverse temperature distribution generated by the integrated heat dissipation structure approaches the standard transverse temperature distribution template. The application can realize efficient and stable control of the light beam divergence angle by actively constructing and accurately calibrating the transverse temperature field formed by the integrated heat dissipation structure.

Description

Technical Field

[0001] This invention relates to the field of VCSEL chip fabrication technology, and in particular to a method for controlling the emission angle of a VCSEL chip. Background Technology

[0002] In the industrialization of Vertical-Cavity Surface-Emitting Lasers (VCSELs), especially in their application to fields with extremely high beam quality requirements such as 3D sensing and LiDAR, a long-standing core challenge has consistently plagued the industry: how to maintain a low beam divergence angle for a single emitting unit or even the entire array of a VCSEL chip under high-power drive. Traditionally, thermal effects are considered the nemesis of optical devices. As the drive current increases, the heat generated in the active region of the VCSEL increases dramatically, triggering a severe thermal lensing effect, leading to a significant increase in beam divergence angle and mode instability. This performance degradation caused by heat directly limits the performance and reliability of VCSELs in high-end applications.

[0003] Faced with this challenge, existing technologies focus on combating heat by enhancing heat dissipation to ensure the chip operates at the most uniform and lowest possible temperature. Engineers invest heavily in optimizing packaging structures and using substrate materials with high thermal conductivity, with the core objective of rapidly extracting and dissipating heat from the chip's interior. However, this passive heat dissipation strategy has inherent limitations: First, it cannot fundamentally eliminate the lateral temperature gradient generated within the active region due to its own heat generation, which is precisely the source of the thermal lensing effect. Second, in the pursuit of large-scale, high-density VCSEL array production, unavoidable minor fluctuations in epitaxial growth and micro-etching processes lead to structural differences among thousands of light-emitting units. This structural inhomogeneity translates into inconsistent thermal field distribution during operation, ultimately manifesting as uneven beam divergence angles across the entire chip. Traditional homogenized heat dissipation solutions are ineffective in addressing this issue because they lack the ability to independently and precisely control the thermal field of each unit. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of VCSEL chips in the prior art, which are caused by the thermal lensing effect, resulting in an increased divergence angle and difficulty in uniform control. The invention provides a method for adjusting the light emission angle of VCSEL chips, which can achieve efficient and stable control of the beam divergence angle by actively constructing and precisely calibrating the lateral temperature field formed by the integrated heat dissipation structure.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for controlling the emission angle of a VCSEL chip, comprising the following steps:

[0006] Based on the target divergence angle, a standard lateral temperature distribution template that can achieve the divergence angle through the thermo-optic effect is determined;

[0007] In the manufacturing process of VCSEL chips, an integrated heat dissipation structure is fabricated within the semiconductor layer surrounding the light-emitting unit; the integrated heat dissipation structure is configured to actively adjust the lateral temperature distribution around the light-emitting unit through its own pattern and layout.

[0008] After the integrated heat dissipation structure is fabricated, the light-emitting unit is driven to work, and the actual lateral temperature distribution generated by it is monitored in real time. The actual lateral temperature distribution is then compared with the standard lateral temperature distribution template.

[0009] When the deviation between the actual lateral temperature distribution and the standard lateral temperature distribution template exceeds the tolerance, the graphic and layout of the integrated heat dissipation structure are micro-processed and adjusted to correct its heat flow guiding function, so that the actual lateral temperature distribution it generates is close to the standard lateral temperature distribution template.

[0010] In one embodiment of the present invention, based on the target divergence angle, a standard lateral temperature distribution template that can achieve the divergence angle through the thermo-optical effect is determined, including:

[0011] After completing the growth of the VCSEL epitaxial wafer, a qualified epitaxial wafer is selected as a reference wafer, and the integrated heat dissipation structure is fabricated in the semiconductor layer around each light-emitting unit on it.

[0012] Under the preset standard test conditions, multiple light-emitting units on the reference chip are driven to work, and their far-field light intensity distribution is measured synchronously to determine the divergence angle. A high-resolution infrared thermal imager is used to collect the steady-state lateral temperature distribution of each light-emitting unit under the rated current.

[0013] All the measured divergence angles are correlated and compared with the corresponding transverse temperature distributions. The sample with the divergence angle closest to the target divergence angle is selected, and the transverse temperature distribution corresponding to the sample is established as the standard transverse temperature distribution template.

[0014] In one embodiment of the present invention, the stability verification of the selected standard transverse temperature distribution template includes the following steps:

[0015] For the selected candidate samples that meet the divergence angle standard, constant current driving aging is carried out for a continuous period of time;

[0016] During the aging process, the fluctuations in its lateral temperature distribution were continuously monitored, and its highest stable temperature was recorded;

[0017] Only when the lateral temperature distribution of the candidate sample remains stable during the aging process, and its highest stable temperature is lower than the preset safety threshold, will its corresponding lateral temperature distribution be finally determined as the standard lateral temperature distribution template.

[0018] In one embodiment of the present invention, the fabrication process of the integrated heat dissipation structure includes:

[0019] On a specific semiconductor layer of the p-type distributed Bragg reflector that forms the VCSEL chip, an aluminum nitride thin film is deposited conformally as a heat dissipation material layer by chemical vapor deposition.

[0020] Photoresist is coated on the aluminum nitride film, and a preset heat dissipation structure pattern is exposed and developed onto the photoresist through a photolithography process to form a patterned photoresist.

[0021] Using patterned photoresist as a mask, reactive ion etching is employed to selectively etch the aluminum nitride film in the exposed area until the surface of the underlying semiconductor layer is exposed. This allows the pre-defined heat dissipation structure pattern to be precisely copied onto the aluminum nitride film, forming an integrated heat dissipation structure.

[0022] In one embodiment of the present invention, an interface strengthening process is also included:

[0023] Plasma activation treatment is performed on the surface of a specific semiconductor layer of the p-type distributed Bragg reflector to which aluminum nitride thin films are deposited, in order to enhance its surface energy and form dangling bonds.

[0024] On the surface of the plasma-activated semiconductor layer, a silicon nitride layer is deposited at low temperature as an interface transition layer through an atomic layer deposition process. The interface transition layer has good chemical bonding and lattice matching with the underlying semiconductor layer and the upper aluminum nitride film.

[0025] In one embodiment of the present invention, the integrated heat dissipation structure is configured to actively adjust the lateral temperature distribution around the light-emitting unit through its own pattern and layout, including:

[0026] The integrated heat dissipation structure is designed as a non-closed ring structure with a specific width surrounding the light-emitting unit; the ring structure provides a highly conductive lateral dissipation channel for the heat generated in the active region in the direction perpendicular to the optical axis.

[0027] By controlling the radial width and ring spacing of the annular structure, a local low-temperature zone is formed below the annular region, thereby creating a specific radial temperature gradient between the high-temperature zone at the center of the light-emitting unit and the low-temperature zone of the annular region.

[0028] The radial temperature gradient is transformed into a corresponding radial refractive index distribution through the thermo-optic effect of the semiconductor material. This refractive index distribution applies a converging phase modulation to the propagating light wavefront, thereby compressing the divergence angle of the emitted beam.

[0029] In one embodiment of the present invention, a laser beam is used to micro-process and adjust the pattern and layout of the integrated heat dissipation structure, including:

[0030] Based on the deviation between the actual transverse temperature distribution and the standard template, determine the radial orientation on the annular heat dissipation structure where the thermal conductivity needs to be enhanced or weakened.

[0031] Based on the radial orientation, the adjustment path of the laser beam is planned. The path is located on the ring structure and parallel to the tangent direction of the ring.

[0032] The laser beam is controlled to scan and irradiate the annular structure along a planned path. By precisely controlling the laser energy, the aluminum nitride material in the irradiated area undergoes a microcrystalline or amorphous phase transformation, thereby locally and precisely reducing the thermal conductivity of the path area to correct the overall heat flow guiding capability of the annular structure.

[0033] In one embodiment of the present invention, a pulsed laser beam is used for adjustment, and during the interval of each laser pulse irradiation, the laser output is paused for a preset short time window.

[0034] Within a short time window, the light-emitting unit is driven to work and quickly acquires a frame of its current single-frame lateral temperature distribution.

[0035] Based on the real-time comparison results of the dynamically acquired single-frame lateral temperature distribution and the standard lateral temperature distribution template, the energy value of the next laser pulse is adaptively adjusted.

[0036] If the horizontal temperature distribution of multiple frames is rapidly approaching the standard horizontal temperature distribution template, the energy of subsequent pulses is reduced for fine-tuning; if the change is slow, the energy is appropriately increased to accelerate the adjustment process.

[0037] In one embodiment of the present invention, integrated heat dissipation structures with different annular parameters are prepared in different regions of the same VCSEL chip array according to the preset optical performance target of the region, so as to achieve regional control of the beam divergence angle of the entire chip array.

[0038] In one embodiment of the present invention, after completing the micromachining adjustment, a performance verification process is further included, comprising:

[0039] Under preset aging conditions, sampled accelerated aging tests were performed on the VCSEL chips that had been adjusted.

[0040] Before and after the aging test, the actual lateral temperature distribution and far-field beam divergence angle of the chip were measured respectively.

[0041] If the actual lateral temperature distribution and the change in beam divergence angle before and after aging are both maintained within the preset stability threshold, then the micromachining adjustment process is determined to be stable.

[0042] The technical solution of the present invention has the following advantages compared with the prior art:

[0043] The method for controlling the emission angle of VCSEL chips described in this invention achieves a leap from passive heat dissipation to active thermal field management by designing an integrated heat dissipation structure to actively adjust the lateral temperature distribution around the light-emitting unit. This transforms the most unfavorable factor, heat, into an effective tool for optical control. By combining real-time monitoring and micro-machining adjustments to achieve closed-loop control, it effectively solves the problems of traditional technologies that cannot eliminate lateral temperature gradients and lack unit-level control capabilities. This enables precise and active control of the emission angle of VCSEL chips, effectively suppressing thermally induced abnormal beam divergence. It also has the advantages of adapting to manufacturing discreteness to improve optical stability and mass production feasibility. Attached Figure Description

[0044] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0045] Figure 1 This is a flowchart of the steps of the method for adjusting the emission angle of the VCSEL chip according to the present invention;

[0046] Figure 2 This is a flowchart of the steps for determining the standard transverse temperature distribution template in this invention;

[0047] Figure 3 This is a flowchart illustrating the steps involved in preparing the integrated heat dissipation structure according to the present invention.

[0048] Figure 4 This is a flowchart illustrating the steps of using a laser beam to micro-process and adjust the graphics and layout of an integrated heat dissipation structure according to the present invention.

[0049] Figure 5 This is a flowchart of the performance verification process of the present invention. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0051] Reference Figure 1As shown, this invention discloses a method for controlling the emission angle of a VCSEL chip, comprising the following steps:

[0052] Based on the target divergence angle, a standard lateral temperature distribution template that can achieve the divergence angle through the thermo-optic effect is determined;

[0053] The control method in this embodiment abandons the traditional heat-resistant thinking and instead adopts a reverse engineering concept of using heat to treat heat. The first step of this scheme is to directly determine a standard lateral temperature distribution template corresponding to the desired target divergence angle. This actually transforms an optical problem into a more fundamental and controllable thermal problem.

[0054] In the manufacturing process of VCSEL chips, an integrated heat dissipation structure is fabricated within the semiconductor layer surrounding the light-emitting unit; the integrated heat dissipation structure is configured to actively adjust the lateral temperature distribution around the light-emitting unit through its own pattern and layout.

[0055] In the chip manufacturing process, it is not simply a matter of adding a homogeneous heat dissipation layer. Instead, an integrated heat dissipation structure with a specific pattern and layout is carefully fabricated within the semiconductor layer surrounding the light-emitting unit. The initial design purpose of this structure is not to achieve the lowest overall temperature, but to actively and purposefully shape the path of heat flow, thereby forming a beneficial lateral temperature field around the light-emitting unit that matches the standard template. Through the thermo-optic effect, this precisely controlled temperature field acts like a built-in microlens, effectively compressing the divergence angle of the light beam.

[0056] After the integrated heat dissipation structure is fabricated, the light-emitting unit is driven to work, and the actual lateral temperature distribution generated by it is monitored in real time. The actual lateral temperature distribution is then compared with the standard lateral temperature distribution template.

[0057] When the deviation between the actual lateral temperature distribution and the standard lateral temperature distribution template exceeds the tolerance, the graphic and layout of the integrated heat dissipation structure are micro-processed and adjusted to correct its heat flow guiding function, so that the actual lateral temperature distribution it generates is close to the standard lateral temperature distribution template.

[0058] Furthermore, even the most perfect design still faces the challenge of manufacturing tolerances. Therefore, the third step of this embodiment introduces a closed-loop feedback mechanism: after the structure is fabricated, by monitoring the actual temperature distribution of each light-emitting unit in real time and comparing it with an ideal standard template, it is possible to accurately identify which units are unqualified due to process fluctuations. When the deviation exceeds the tolerance, it is not simply discarded, but the integrated heat dissipation structure itself is precisely adjusted at the micron level. By locally changing the geometric features of its shape, it is essentially fine-tuning its heat flow guiding function, thereby calibrating the actual temperature field to the ideal target state.

[0059] The VCSEL chip emission angle control method described in this invention represents a leap from passive heat dissipation to active thermal field management, transforming the most detrimental factor—thermal energy—into an effective tool for optical control. Secondly, this method possesses strong individualized correction capabilities, effectively compensating for inherent process inconsistencies in mass production, and significantly improving chip performance uniformity and overall yield. Finally, this method synergistically resolves the contradiction between high power and low divergence angle, making it possible to fabricate high-end VCSEL chips with both high output power and high beam quality, laying a solid technological foundation for performance improvements in next-generation optoelectronic systems.

[0060] Reference Figure 2 As shown, this application further proposes a specific method for determining a standard lateral temperature distribution template that can achieve the target divergence angle through thermo-optical effect, based on the target divergence angle. The method includes the following steps: After completing the growth of the VCSEL epitaxial wafer, a qualified epitaxial wafer is selected as a reference wafer, and an integrated heat dissipation structure is prepared in the semiconductor layer around each light-emitting unit on it; under preset standard test conditions, multiple light-emitting units on the reference wafer are driven to work, and their far-field light intensity distribution is measured synchronously to determine the divergence angle, and the steady-state lateral temperature distribution of each light-emitting unit under rated current is collected using a high-resolution infrared thermal imager; all the measured divergence angles are correlated and compared with the corresponding lateral temperature distributions, and the sample with the divergence angle closest to the target divergence angle is selected, and the lateral temperature distribution corresponding to the sample is established as the standard lateral temperature distribution template.

[0061] Specifically, a reference wafer refers to an epitaxial wafer selected from completed VCSEL epitaxial wafers that meets the process requirements. It can be any qualified epitaxial wafer that has undergone rigorous quality testing. The purpose is to ensure that the reference wafer accurately reflects the actual manufacturing conditions and avoids discrepancies between the theoretical model and process deviations. Standard test conditions refer to a unified and stable combination of test parameters, which may include a constant temperature environment, a fixed drive current, and standardized optical measurement equipment configuration. The purpose is to eliminate the influence of external interference factors on the measurement results.

[0062] In detail, this scheme establishes a standard lateral temperature distribution template through a series of rigorous steps: First, a qualified reference sheet is selected and an integrated heat dissipation structure is fabricated on it. This process ensures that the measurement environment is highly consistent with the actual usage environment of the final product, thereby guaranteeing the comparability and applicability of the data. Second, under preset standard test conditions, the far-field light intensity distribution and steady-state lateral temperature distribution of the light-emitting unit are measured simultaneously. This synchronous acquisition method effectively avoids the time or conditional errors that may be introduced by individual measurements, ensuring the reliability of the correspondence between divergence angle and temperature distribution. Subsequently, by correlating and comparing all measurement data, the sample with the divergence angle closest to the target value is selected, and its corresponding lateral temperature distribution is established as the standard template. This method significantly improves the accuracy of the template. Finally, the template is selected using measured data rather than fixed parameters or simulation calculations. This method not only adapts to process fluctuations but also lays a solid empirical foundation for the control of thermo-optical effects.

[0063] In summary, the above method, through a systematic empirical measurement and screening mechanism, solves the problem of uncertainty in standard templates caused by process fluctuations, and provides a reliable benchmark for subsequent temperature distribution control.

[0064] In this embodiment, a step is further proposed to verify the stability of the selected standard transverse temperature distribution template, including the following: the selected candidate samples with qualified divergence angles are subjected to constant current driving aging for a period of time; during the aging process, the fluctuation of their transverse temperature distribution is continuously monitored and their highest stable temperature is recorded; only when the transverse temperature distribution of the candidate sample remains stable during the aging process and its highest stable temperature is lower than the preset safety threshold, is its corresponding transverse temperature distribution finally determined as the standard transverse temperature distribution template.

[0065] Specifically, constant current driven aging refers to driving candidate samples under a fixed current for an extended period to simulate the long-term thermal stress environment in real-world applications. This process can be implemented using a constant current source device, aiming to expose potential defects in the candidate samples under continuous thermal loads, such as structural changes caused by material aging or thermal stress accumulation. Continuous monitoring of lateral temperature distribution fluctuations can be achieved using a high-resolution infrared thermal imager, which can acquire dynamic temperature data in real time and capture subtle changes in the thermal field over time. The maximum stable temperature refers to the highest temperature value reached by the candidate sample during the aging process, which can be measured and recorded using temperature sensors or thermal imaging equipment. The safety threshold is an upper temperature limit set according to the heat resistance of semiconductor materials and device reliability requirements, aiming to avoid performance degradation caused by overheating.

[0066] Specifically, the above scheme ensures the reliability of the standard transverse temperature distribution template under long-term operating conditions by introducing a systematic stability verification process. First, during the constant-current driven aging stage, a fixed current is applied to the candidate samples to simulate the thermal stress environment in real-world applications, thereby identifying samples that initially pass the test but may be unstable during long-term operation. This process effectively exposes potential defects caused by material aging or thermal stress accumulation, providing a reliable basis for subsequent screening. Second, during the aging process, the stability of the temperature gradient is determined by continuously monitoring the fluctuations in the transverse temperature distribution and combining this with real-time acquired dynamic temperature data. This dynamic data-based analysis method ensures that the refractive index distribution generated by the thermo-optic effect does not affect the constancy of the beam divergence angle due to thermal distribution drift. Finally, by comparing the highest stable temperature with a preset safety threshold, truly reliable temperature distribution templates are selected. This dual verification mechanism not only ensures the stability of the template but also avoids performance degradation caused by overheating, thus ensuring that the final established template can maintain consistent beam quality in actual production.

[0067] Reference Figure 3 As shown, this application further proposes a fabrication process for an integrated heat dissipation structure, including: depositing an aluminum nitride thin film as a heat dissipation material layer on a specific semiconductor layer of the p-type distributed Bragg reflector forming the VCSEL chip using a chemical vapor deposition process; coating photoresist on the aluminum nitride thin film; exposing and developing a pre-defined heat dissipation structure pattern onto the photoresist using a photolithography process to form a patterned photoresist; using the patterned photoresist as a mask, selectively etching the exposed area of ​​the aluminum nitride thin film using a reactive ion etching process until the surface of the underlying semiconductor layer is exposed, thereby accurately replicating the pre-defined heat dissipation structure pattern onto the aluminum nitride thin film to form an integrated heat dissipation structure.

[0068] In practical applications, chemical vapor deposition (CVD) is a technique that generates solid thin films on a substrate surface through gas-phase chemical reactions. It can be achieved using various methods such as low-pressure CVD and plasma-enhanced CVD, aiming to ensure that the aluminum nitride film uniformly covers the semiconductor layer surface and adapts to the microstructure, avoiding uneven heat conduction caused by interface voids or stress concentration. Photolithography, on the other hand, utilizes the chemical changes in photosensitive materials under illumination to define micron-level patterns. It can be achieved through ultraviolet lithography, electron beam lithography, etc., aiming to completely capture and transform the design intent into a mask template. Specifically, reactive ion etching (RIE) is a selective removal technique based on plasma physical and chemical interactions. It can be achieved using inductively coupled plasma etching (ICP-E) and capacitively coupled plasma etching (CCP-E), aiming to precisely control the etching depth and ensure distortion-free replication of the heat dissipation structure pattern onto the aluminum nitride film.

[0069] In detail, the above scheme first involves depositing an aluminum nitride thin film on a specific semiconductor layer of a p-type distributed Bragg reflector using chemical vapor deposition (CVD). This process provides a highly reliable foundation for subsequent patterning, ensuring that the heat dissipation material layer can uniformly cover and adapt to the microstructure. Subsequently, the pre-defined heat dissipation structure pattern is transferred to photoresist using photolithography. The high resolution of photolithography enables micron-level pattern definition, thus forming a precise mask template. Based on this, reactive ion etching (RIE) is used, with the patterned photoresist as a mask, to selectively etch the aluminum nitride thin film in the exposed areas until the surface of the underlying semiconductor layer is exposed. This process not only ensures accurate replication of the heat dissipation structure pattern but also optimizes the lateral heat flow guidance path, enabling close physical contact between the heat dissipation structure and the semiconductor layer. These steps work together to solve the precision defects in heat dissipation structure fabrication, ensuring that the integrated heat dissipation structure can accurately perform heat flow control functions, thereby stably constructing the required radial temperature gradient and providing a reliable guarantee for compressing the beam divergence angle for the thermo-optical effect. Furthermore, this preparation process, combined with the aforementioned standard lateral temperature distribution template and subsequent microfabrication adjustment scheme, further enhances the ability to actively adjust the lateral temperature distribution around the light-emitting unit, effectively solving the problem of the thermo-optical effect deviating from expectations due to pattern replication distortion or poor material interface bonding.

[0070] In this embodiment, an interface strengthening process is further proposed: a plasma activation treatment is performed on the surface of a specific semiconductor layer of the p-type distributed Bragg mirror to which an aluminum nitride thin film is to be deposited, so as to enhance its surface energy and form dangling bonds; on the surface of the plasma-activated semiconductor layer, a silicon nitride layer is deposited at low temperature as an interface transition layer by atomic layer deposition process. The interface transition layer has good chemical bonding and lattice matching with the underlying semiconductor layer and the upper aluminum nitride thin film.

[0071] Specifically, plasma activation treatment refers to a process that uses plasma to modify the surface of a semiconductor layer, which can be achieved using oxygen plasma, nitrogen plasma, or argon plasma. The purpose of this step is to specifically increase the surface energy of the semiconductor layer and actively introduce highly active sites, creating the necessary conditions for the subsequent bonding of the interface transition layer, thereby avoiding heat flow scattering problems caused by interface porosity. The interface transition layer is a functional thin layer located between the semiconductor layer and the aluminum nitride film, which can be made of silicon nitride, silicon oxide, or other materials with similar properties. The key function of this layer is to eliminate interface stress and construct a continuous heat conduction path, ultimately ensuring that the heat dissipation structure maintains efficient heat flow guidance capabilities in dynamic operating environments.

[0072] In detail, the aforementioned interface strengthening process systematically optimizes the interface characteristics between the semiconductor layer and the heat dissipation material, laying the foundation for the reliable operation of the integrated heat dissipation structure. First, plasma activation treatment addresses the chemical inertness of the original semiconductor layer surface by introducing highly active sites, significantly increasing surface energy and forming dangling bonds. These dangling bonds provide the necessary bonding conditions for the strong chemical bonding of the subsequent interface transition layer. Based on this, an atomic layer deposition process is used to prepare the interface transition layer at low temperatures. This process not only avoids the potential damage risk to the semiconductor structure from high temperatures but also ensures uniform transition layer thickness and the absence of pinhole defects. Furthermore, the design of the interface transition layer fully considers the compatibility of the upper and lower materials. It achieves strong chemical bonding with the lower semiconductor layer through dangling bonds, while simultaneously forming a matching lattice structure with the upper aluminum nitride film, effectively eliminating interface defects and constructing a continuous heat conduction path. This overall solution not only solves the problem of insufficient interfacial bonding strength between the aluminum nitride film and the semiconductor layer but also significantly improves the long-term stability of the integrated heat dissipation structure, enabling it to better meet the requirements of high-performance VCSEL chips in practical applications.

[0073] In this embodiment, the integrated heat dissipation structure is designed as a non-closed ring structure with a specific width surrounding the light-emitting unit. The ring structure provides a highly conductive lateral dissipation channel for the heat generated in the active region in the direction perpendicular to the optical axis. By controlling the radial width and ring spacing of the ring structure, a local low-temperature region is formed below the ring region, thereby constructing a specific radial temperature gradient between the high-temperature region at the center of the light-emitting unit and the low-temperature region of the ring. The radial temperature gradient is converted into a corresponding radial refractive index distribution through the thermo-optic effect of the semiconductor material. This refractive index distribution applies a converging phase modulation to the light wavefront in the transmission, thereby compressing the divergence angle of the emitted beam.

[0074] Specifically, a ring structure refers to a closed-loop or open-loop geometry arranged around the light-emitting unit, which can achieve different heat conduction characteristics by adjusting parameters such as linewidth and spacing. A radial temperature gradient refers to the temperature difference distribution along the radial direction, which can be achieved by precisely controlling the geometric parameters and material properties of the heat dissipation structure. The purpose of introducing these features is to transform traditional passive heat dissipation into an actively controllable heat-optical coupling system, thereby solving the problem of insufficient divergence angle control precision caused by the uncontrollable lateral temperature gradient.

[0075] In detail, this scheme, through the innovative design and layout of the heat dissipation structure, transforms the thermal effect from a performance degradation factor into an active means of beam control. The non-closed ring structure design, based on its ring geometry and non-closed characteristics, creates a highly conductive lateral dissipation channel for heat in the direction perpendicular to the optical axis, preventing excessive heat accumulation in the central region. The ring structure provides a highly conductive lateral dissipation channel perpendicular to the optical axis, utilizing the continuity and directionality of the ring geometry to ensure efficient lateral heat conduction rather than longitudinal diffusion in the active region. By precisely controlling the radial width and spacing of the ring structure, a localized low-temperature region is formed. Precise adjustment of the width and spacing parameters creates a thermal resistance difference below the ring region, thereby constructing a customizable radial temperature gradient. This temperature gradient is transformed into a radial refractive index distribution through the thermo-optical effect of the semiconductor material. Utilizing the inherent influence of temperature changes on the material's refractive index, the difference in heat distribution is converted into optical phase modulation capability. Ultimately, this refractive index distribution applies convergent phase modulation to the transmitted light wavefront. Based on the optical path difference generated by the refractive index gradient, the beam wavefront naturally converges upon exit, effectively compressing the divergence angle and achieving synergistic optimization of thermal effects and beam control. Overall, this scheme upgrades the heat dissipation structure from a passive heat dissipation tool to an active optical control component, achieving precise control of thermal-optical coupling through graphical design.

[0076] Reference Figure 4 As shown, based on the aforementioned integrated heat dissipation structure with a ring structure, this application further proposes a method for micro-machining and adjusting the pattern and layout of the integrated heat dissipation structure using a laser beam. Specifically, this method includes the following steps: determining the radial orientation on the ring heat dissipation structure where the thermal conductivity needs to be enhanced or weakened based on the deviation between the actual lateral temperature distribution and the standard template; planning the adjustment path of the laser beam based on the radial orientation, with the path located on the ring structure and parallel to the tangent direction of the ring; controlling the laser beam to scan and irradiate the ring structure along the planned path, and by precisely controlling the laser energy, causing the aluminum nitride material in the irradiated area to undergo a microcrystalline or amorphous phase transformation, thereby locally and precisely reducing the thermal conductivity of the path region to correct the overall heat flow guiding capability of the ring structure.

[0077] Laser beam energy control is a core technology for achieving micromachining adjustments. In practical applications, precise control of laser energy can be achieved through pulse width modulation or power adjustment. The aim is to induce microcrystalline or amorphous phase transitions in aluminum nitride materials, thereby altering their thermal conductivity. Microcrystallineization refers to the process of reducing the grain size within the material, while amorphization refers to the process of the material changing from a crystalline state to an amorphous state. Both phase transitions lead to a significant decrease in the material's thermal conductivity. Furthermore, the heat flow guiding capability of a ring-shaped heat dissipation structure refers to its ability to conduct heat from high-temperature regions to low-temperature regions through specific geometry and material properties. Its correction process relies on local adjustments to the thermal conductivity.

[0078] Specifically, the above method accurately locates the radial direction requiring adjustment by real-time monitoring of the deviation between the actual lateral temperature distribution and the standard template, thus avoiding blind operation and improving correction efficiency. When planning the adjustment path, the path is designed parallel to the tangent direction of the ring, ensuring that the laser scan is uniform along the circumference of the ring. This not only maintains the geometric continuity of the ring structure but also avoids the disruption of the temperature gradient by radial interference, ensuring a smooth transition of heat flow guidance. During laser irradiation, precise control of energy parameters achieves a microscale phase transition in the aluminum nitride material. This energy-controlled phase transition mechanism can locally modify the heat flow path, thereby correcting the overall heat flow guidance capability and making the lateral temperature distribution approach the standard template.

[0079] The above technical solution solves the problem of deviation between the actual heat dissipation structure and design parameters caused by fluctuations in epitaxial growth and micro-etching processes, ensuring the consistency of the lateral temperature distribution with the standard template, thereby stabilizing the beam divergence angle. Simultaneously, this method compensates for the lack of independent and precise control capabilities in traditional homogenized heat dissipation schemes by dynamically correcting the fabricated heat dissipation structure, providing reliable technical support for achieving low beam divergence angles in single light-emitting units or even the entire array of VCSEL chips.

[0080] In this embodiment, pulsed laser beams are used for adjustment. During the interval between each laser pulse irradiation, the laser output is paused for a preset short time window. Within the short time window, the light-emitting unit is driven to work and a frame of its current single-frame lateral temperature distribution is quickly acquired. Based on the real-time comparison result of the dynamically acquired single-frame lateral temperature distribution with the standard lateral temperature distribution template, the energy value of the next laser pulse is adaptively adjusted. Multiple frames of lateral temperature distribution are continuously acquired. If the trend of the multiple frames of lateral temperature distribution is rapidly approaching the standard lateral temperature distribution template, the energy of subsequent pulses is reduced for fine-tuning. If the change is slow, the energy is appropriately increased to accelerate the adjustment process.

[0081] Specifically, a pulsed laser beam refers to a form of laser that achieves intermittent irradiation by periodically controlling laser output, which can be achieved by modulating a semiconductor laser or an acousto-optic modulator. In practical applications, a short time window refers to the time interval reserved between two laser pulses. Its length can be set according to the thermal response characteristics of the material and the response speed of the temperature acquisition device, typically in the millisecond or microsecond range, to ensure that temperature measurement is not interfered with by the laser's thermal effect. The single-frame lateral temperature distribution refers to the instantaneous temperature field distribution in the lateral direction around the emitting unit at a certain moment, which can be obtained using a high-resolution infrared thermal imager or other fast-response temperature sensing devices. Furthermore, adaptive adjustment refers to the process of dynamically changing the laser pulse energy based on real-time monitoring data. This can be achieved through a closed-loop control system combined with an algorithm model, aiming to improve adjustment accuracy and efficiency.

[0082] In detail, this technical solution constructs a closed-loop control dynamic adjustment process by introducing a pulsed laser adjustment and real-time temperature feedback mechanism. Specifically, utilizing the intermittent nature of pulsed lasers, the output is paused after each laser irradiation, forming a time window free from thermal interference, thereby accurately acquiring the lateral temperature distribution of the light-emitting unit under operating conditions. This design effectively avoids the interference of heat accumulation caused by continuous laser irradiation on temperature measurement, ensuring the authenticity and reliability of the acquired data. Based on this, by comparing the acquired single-frame lateral temperature distribution with a standard lateral temperature distribution template in real time, the system can intelligently adjust the energy value of the next laser pulse according to the deviation. For example, when the temperature distribution is detected to be rapidly approaching the target, the laser energy is reduced to prevent overcorrection; conversely, when the change is slow, the energy is appropriately increased to accelerate the adjustment process. This dynamic energy adjustment strategy based on multi-frame data trend analysis not only improves the accuracy of adjustment but also significantly optimizes the overall adjustment efficiency.

[0083] In practical applications, integrated heat dissipation structures with different annular parameters are fabricated in different regions of the same VCSEL chip array according to the preset optical performance target of the region, so as to achieve regional control of the beam divergence angle of the entire chip array.

[0084] Specifically, regionalized customized heat dissipation structure parameters refer to dividing the VCSEL chip array into multiple independently controllable regions and designing a heat dissipation structure tailored to the specific needs of each region. This can be achieved by identifying the physical locations within the chip array that require differentiated control, thereby avoiding the thermal field distribution mismatch problem caused by structural inhomogeneity in traditional solutions. The ring parameters can include key variables such as radial width and ring spacing, which can be adjusted through precise control of the process equipment. The aim is to ensure that each region can independently construct the required radial temperature gradient, thereby utilizing the thermo-optic effect to generate a matching refractive index distribution, ultimately achieving local phase modulation of the light wavefront.

[0085] Specifically, this technical solution effectively solves the core problem of inconsistent beam divergence angles in VCSEL chip arrays by regionally customizing heat dissipation structure parameters. First, different physical locations requiring differentiated control are identified within different regions of the same VCSEL chip array. This step avoids the thermal field distribution mismatch problem caused by fluctuations in epitaxial growth and micro-etching processes in traditional solutions. Second, based on the preset optical performance targets for each region, such as the required divergence angle or beam directivity, the parameter requirements of the heat dissipation structure are dynamically determined. This target-oriented design ensures that parameter adjustments directly serve optical performance optimization. Furthermore, based on the above targets, integrated heat dissipation structures with different ring parameters are fabricated. By precisely controlling key variables such as radial width and ring spacing, the required radial temperature gradient can be independently constructed in each region. This allows for the generation of a matching refractive index distribution using thermo-optical effects, achieving local phase modulation of the light wavefront. Finally, by regionally controlling the beam divergence angle of the entire chip array, the divergence angle of each region is adjusted to the preset target range, resulting in uniform or specifically distributed beam characteristics across the entire array.

[0086] Reference Figure 5 As shown, this application further proposes a performance verification process after completing the micromachining adjustment, including: performing a sampling accelerated aging test on the adjusted VCSEL chip under preset aging conditions; measuring the actual lateral temperature distribution and far-field beam divergence angle of the chip before and after the aging test; if the changes in the actual lateral temperature distribution and beam divergence angle before and after aging are both maintained within a preset stability threshold, then the micromachining adjustment process is determined to be stable.

[0087] Specifically, performance verification refers to a systematic verification process aimed at ensuring that the thermal field distribution and optical performance of the tuned VCSEL chip remain consistent during long-term operation. The preset aging conditions can simulate the extreme environments the chip encounters in real-world use through methods such as high temperature, high humidity, or high power driving to expose potential degradation risks. The stability threshold can be set to a reasonable range, such as ±0.1° or ±0.2°, based on the specific application requirements, to ensure that the chip's performance fluctuations remain within acceptable limits throughout its lifespan.

[0088] In detail, after microfabrication and tuning, a performance verification process is implemented. First, the tuned VCSEL chip undergoes accelerated aging testing under preset aging conditions. This process simulates the long-term stress environment the chip might experience in actual use, effectively identifying potential problems caused by material aging or thermal stress accumulation. Before and after the aging test, the actual lateral temperature distribution and far-field beam divergence angle are measured. This dual-parameter synchronous monitoring mechanism directly correlates thermal field distribution with optical performance, accurately capturing changes in thermo-optical effects caused by material aging. Finally, the stability of the tuning process is determined based on whether the changes in these two key parameters before and after aging are within preset stability thresholds. This quantitative acceptance standard not only ensures that the tuned chip meets long-term consistency requirements in both temperature distribution and beam divergence angle, but also fundamentally suppresses beam quality fluctuations caused by thermal field drift, providing process stability assurance for large-scale mass production.

[0089] In this embodiment, the performance verification process is combined with the aforementioned micromachining tuning process to form a closed-loop technical system. By introducing a systematic verification process after tuning, not only is the issue of the durability of the tuning effect resolved, but the reliability of the VCSEL chip in high-end applications is further improved. This technical solution is particularly suitable for fields with extremely high beam quality requirements, such as 3D sensing and LiDAR, and can significantly improve the long-term performance of the chip under high-power drive.

[0090] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for regulating the light emitting angle of a VCSEL chip, characterized in that, The method comprises the following steps: determining a standard transverse temperature distribution template that can achieve the target divergence angle through the thermo-optic effect based on the target divergence angle; During the manufacturing process of the VCSEL chip, an integrated heat dissipation structure is prepared in the semiconductor layer around each light emitting unit of the VCSEL chip; the integrated heat dissipation structure is configured to actively adjust the transverse temperature distribution around the light emitting unit through its own pattern and layout; the pattern of the integrated heat dissipation structure is designed as a non-closed ring structure with a specific width surrounding the light emitting unit; the ring structure provides a highly conductive transverse escape channel for the heat generated by the active region in the direction perpendicular to the optical axis; by controlling the radial width and ring spacing of the ring structure, a local low-temperature area is formed below the ring area, thereby constructing a specific radial temperature gradient between the high-temperature area in the center of the light emitting unit and the low-temperature area of the ring; the radial temperature gradient is converted into a corresponding radial refractive index distribution through the thermo-optic effect of the semiconductor material, the radial refractive index distribution exerts a convergent phase modulation on the light wave front in transmission, thereby compressing the divergence angle of the outgoing light beam; After the preparation of the integrated heat dissipation structure is completed, the light emitting unit is driven to work, and the actual transverse temperature distribution generated thereby is monitored in real time; the actual transverse temperature distribution is compared with the standard transverse temperature distribution template; When the deviation of the actual transverse temperature distribution from the standard transverse temperature distribution template exceeds the tolerance, the pattern and layout of the integrated heat dissipation structure are micro-machined and adjusted to correct the heat flow guiding function thereof, so that the actual transverse temperature distribution generated thereby tends to approach the standard transverse temperature distribution template; The pattern and layout of the integrated heat dissipation structure are micro-machined and adjusted by using a laser beam, including: determining the radial direction in which the thermal conductivity of the ring heat dissipation structure needs to be enhanced or weakened according to the deviation of the actual transverse temperature distribution from the standard template; Based on the radial direction, the adjustment path of the laser beam is planned, the path is located on the ring structure and is parallel to the tangent direction of the ring; the laser beam is controlled to scan and irradiate the ring structure along the planned path, and by accurately controlling the laser energy, the microcrystallization or amorphization phase transition of the aluminum nitride material in the irradiated area is caused, thereby locally and accurately reducing the thermal conductivity of the path area to correct the overall heat flow guiding ability of the ring structure.

2. The method of claim 1, wherein the method further comprises: Based on the target divergence angle, a standard transverse temperature distribution template that can achieve the target divergence angle through the thermo-optic effect is determined, including: After the growth of the VCSEL epitaxial wafer is completed, a qualified epitaxial wafer is selected as a reference wafer, and the integrated heat dissipation structure is prepared in the semiconductor layer around each light emitting unit on the reference wafer; Under the preset standard test conditions, the multiple light emitting units on the reference wafer are driven to work, the far-field light intensity distribution is measured synchronously to determine the divergence angle, and a high-resolution infrared thermal imager is used to collect the steady-state transverse temperature distribution of each light emitting unit under the rated current; The measured divergence angles are associated and compared with the corresponding transverse temperature distributions, and the sample with the divergence angle closest to the target divergence angle is selected from the transverse temperature distributions, and the transverse temperature distribution corresponding to the sample is established as the standard transverse temperature distribution template.

3. The method of claim 2, wherein the method further comprises: The selected standard transverse temperature distribution template is verified for stability, including the following steps: The selected candidate sample with a divergence angle that meets the standard is subjected to constant current driving aging for a period of time; During the aging process, the fluctuation of the transverse temperature distribution is continuously monitored, and the highest stable temperature is recorded; Only when the transverse temperature distribution of the candidate sample remains stable during the aging process and the highest stable temperature is lower than the preset safety threshold, the corresponding transverse temperature distribution is finally determined as the standard transverse temperature distribution template.

4. The method of claim 1, wherein the method further comprises: The preparation process of the integrated heat dissipation structure includes: A layer of aluminum nitride film is conformally deposited on the specific semiconductor layer of the p-type distributed Bragg reflector of the VCSEL chip as a heat dissipation material layer through a chemical vapor deposition process; A photoresist is coated on the aluminum nitride film, and a preset heat dissipation structure pattern is exposed and developed on the photoresist through a photolithography process to form a patterned photoresist; Using the patterned photoresist as a mask, the aluminum nitride film in the exposed area is selectively etched by a reactive ion etching process until the surface of the underlying semiconductor layer is exposed, thereby accurately copying the preset heat dissipation structure pattern onto the aluminum nitride film to form an integrated heat dissipation structure.

5. The method of claim 4, wherein the method further comprises: It also includes an interface strengthening process: The surface of the specific semiconductor layer of the p-type distributed Bragg reflector to be deposited with the aluminum nitride film is subjected to plasma activation treatment to enhance the surface energy and form dangling bonds; On the surface of the semiconductor layer after plasma activation, a layer of silicon nitride is deposited as an interface transition layer at low temperature through an atomic layer deposition process, which has good chemical bonding and lattice matching with the underlying semiconductor layer and the upper aluminum nitride film.

6. The method of claim 1, wherein: Adjustment is performed using a pulsed laser beam, and during the intermittent period of each laser pulse irradiation, the laser output is paused for a preset short time window; During the short time window, the light emitting unit is driven to work and a frame of its current single-frame transverse temperature distribution is quickly acquired; Based on the real-time comparison results of the dynamically acquired single-frame transverse temperature distribution and the standard transverse temperature distribution template, the energy value of the next laser pulse is adaptively adjusted; Multiple frames of transverse temperature distribution are continuously acquired, and if the trend of multiple frames of transverse temperature distribution is rapidly approaching the standard transverse temperature distribution template, the subsequent pulse energy is adjusted lower for fine tuning; If the change is slow, the energy is appropriately increased to speed up the adjustment process.

7. The method of claim 1, wherein the method further comprises: adjusting the angle of the light emitted from the VCSEL chip. In different regions of the same VCSEL chip array, according to the preset optical performance target of the region, integrated heat dissipation structures with different ring parameters are prepared to realize regional regulation of the beam divergence angle of the entire chip array.

8. The method of claim 1, wherein the method further comprises: adjusting the angle of the light emitted from the VCSEL chip. After microfabrication adjustment is completed, a performance verification process is also included, including: Under the preset aging conditions, the VCSEL chip after microfabrication adjustment is subjected to sampling accelerated aging test; Before and after the aging test, the actual transverse temperature distribution and the far-field beam divergence angle of the chip are measured; If the change amounts of the actual transverse temperature distribution and the beam divergence angle before and after aging are maintained within the preset stability threshold, it is determined that the adjustment process of the microfabrication adjustment is stable.

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