Silicon carbide crystal ingot laser fragmentation device based on spatial light modulator

Abstract

The utility model relates to a silicon carbide crystal ingot laser splitting device based on a spatial light modulator, which is characterized in that a beam expander and the spatial light modulator are sequentially arranged on an output light path of a laser, and a first lens, a first reflecting mirror, a second lens and a second reflecting mirror are sequentially arranged on an output light path of the spatial light modulator; an objective lens is arranged on a reflecting light path of the second reflecting mirror and is over against a silicon carbide crystal ingot to be processed; the focal length of the first lens is twice that of the second lens. The spatial light modulator loads a generated circular flat-topped light beam and a holographic phase diagram combined by multiple transverse focuses, the holographic phase diagram is focused in silicon carbide to generate a transverse double-focus circular flat-topped light beam with an adjustable distance, the phase diagram loaded by the spatial light modulator is controlled, multiple transverse focuses are generated, and the distance between the focuses is adjusted through the phase diagram; light spots of the spatial light modulator are shaped and focused into transverse double focuses in the silicon carbide crystal ingot, the round flat-topped light beams are used for fragmentation, the silicon carbide crystal ingot is processed in a fragmentation mode, and the fragmentation efficiency is improved.

Description

Technical Field

[0001] The utility model relates to a silicon carbide ingot laser slicing device based on a spatial light modulator, belonging to the technical field of laser processing. Background Art

[0002] At present, silicon carbide (SiC), as a typical third-generation semiconductor material, has the characteristics of large bandgap, high breakdown electric field, high saturated electron drift velocity and high thermal conductivity. It is an ideal material for preparing optoelectronic devices and power electronic devices, and can be widely used in semiconductor, new energy and consumer electronics industries. SiC crystal is an ideal substrate material for GaN-based devices because it has a highly matched lattice constant and thermal expansion coefficient with the epitaxial layer material gallium nitride (GaN) and good thermal conductivity. Since SiC has a very high hardness, advanced ingot cutting technology is required to obtain good semiconductor wafers. The traditional processing method is to use a wire saw to cut the ingot into slices, then grind and thin it to a specific thickness. This processing method is not only very inefficient (taking 6-inch SiC as an example, it takes 110-120 hours to cut an ingot), but also brings a lot of material loss (40% to 50%). Therefore, exploring high-efficiency and high-quality SiC ingot slicing methods is a crucial factor in promoting the development of the SiC industry.

[0003] The laser invisible slicing method is to focus the laser beam to a certain depth inside the material. The material absorbs the laser energy in a short period of time, causing local heat rise, melting and vaporization, and finally forming a modified layer inside the material, and finally slicing and peeling it through ultrasonic vibration. As a non-contact processing, the laser invisible slicing method has significant advantages such as high efficiency and low loss for SiC ingot slicing. Patent No. JP2018159320 discloses the "KABRA" silicon carbide laser slicing method, which realizes low-loss and high-efficiency silicon carbide ingot slicing through secondary laser processing; Patent No. US16606540 ​​discloses a cold cutting method. After the laser modifies the inside of the ingot, the polymer and the ingot are quickly cooled to automatically separate the wafers. This method causes the damage to a single wafer to be about 80um. Patent publication number CN214024100U discloses a silicon carbide crystal laser slicing device. After the laser cuts and modifies the inside of the SiC ingot, the SiC ingot is heated by a vertical radiation light source and a side radiation light source to finally separate the wafers. The processing process is complicated and reduces the processing efficiency. Patent publication number CN117139865A discloses a low-loss silicon carbide ingot laser slicing method. The laser scans the inside of the SiC ingot twice to expand the cracks and form a uniform modified layer.

[0004] None of the above methods mention the effect of beam shaping in SiC ingot laser slicing. As a new type of programmable optical shaping device, spatial light modulator plays an increasingly important role in laser processing. It can flexibly control the amplitude, phase, polarization and other optical parameters of the laser beam in a programmable manner, and cooperate with the external optical path system to obtain arbitrary light field intensity distribution inside the material. Different laser spots are focused inside the SiC ingot material, which has different effects on the modification and expansion of the material, and has different effects on improving the efficiency of SiC ingot slicing and reducing material loss. Utility Model Content

[0005] The utility model aims to overcome the shortcomings of the prior art and provide a silicon carbide ingot laser slicing device based on a spatial light modulator, aiming to improve the efficiency and loss of SiC ingot laser slicing.

[0006] The purpose of the utility model is achieved through the following technical solutions:

[0007] The device for laser slicing silicon carbide ingots based on a spatial light modulator is characterized in that a beam expander and a spatial light modulator are arranged in sequence on the output light path of the laser, a first lens, a first reflector, a second lens and a second reflector are arranged in sequence on the output light path of the spatial light modulator, an objective lens is arranged on the reflective light path of the second reflector, and the objective lens is directly opposite to the silicon carbide ingot to be processed; the focal length of the first lens is twice that of the second lens, and the spatial light modulator is connected to a computer.

[0008] Furthermore, in the above-mentioned silicon carbide ingot laser slicing device based on a spatial light modulator, the laser is a laser with an emitting laser wavelength of 1000nm to 1100nm, an emitting laser frequency continuously adjustable between 10KHz and 100KHz, an average power adjustable from 0 to 50W, and a pulse width adjustable from 100fs to 10ns.

[0009] Furthermore, in the above-mentioned silicon carbide ingot laser slicing device based on a spatial light modulator, the laser is a laser with an emission wavelength of 1064nm, a pulse width of 4ps, an average power of 20W, and a repetition frequency of 10KHz to 100KHz.

[0010] Furthermore, in the above-mentioned silicon carbide ingot laser slicing device based on a spatial light modulator, the spatial light modulator is a spatial light modulator with a wavelength range of 300nm to 1100nm, 1920×1080 pixels, and an effective area of ​​15.4mm×8.6mm.

[0011] Furthermore, in the above-mentioned silicon carbide ingot laser slicing device based on a spatial light modulator, the objective lens is an objective lens with a numerical aperture of 0.45 and a magnification of 50 times.

[0012] Compared with the prior art, the present invention has significant advantages and beneficial effects, which are specifically embodied in the following aspects:

[0013] ① The controllable lateral dual focus generated by the spatial light modulator is used for silicon carbide ingot slicing, which greatly improves the existing slicing efficiency and can be applied to the slicing process of semiconductor material ingots such as silicon wafers, gallium arsenide, indium phosphide and gallium nitride;

[0014] ② Through the spot shaping technology of the spatial light modulator, a circular flat-top beam is used. Due to its uniform energy distribution, it can form a uniform modified expansion during the internal processing of the silicon carbide ingot, which is beneficial to reduce the material loss caused by uneven processing;

[0015] ③ Use the GSW algorithm to generate a circular flat-top beam and a lateral dual-focus phase diagram to improve the energy utilization and spot consistency of the laser beam, increase the efficiency of SiC ingot laser slicing, and reduce losses.

[0016] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by implementing the specific implementation of the utility model. The purpose and other advantages of the utility model can be achieved and obtained by the structures specifically pointed out in the written description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 : Schematic diagram of the optical path structure of the utility model device;

[0019] Figure 2 :Schematic diagram of the process of generating holographic phase images of circular flat-top beam and lateral double focus;

[0020] Figure 3 :Schematic diagram of holographic phase image superposition;

[0021] Figure 4 : Schematic diagram of laser lateral dual focus. DETAILED DESCRIPTION

[0022] The technical scheme in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, rather than all the embodiments. The components of the embodiment of the utility model generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiment of the utility model provided in the drawings is not intended to limit the scope of the utility model claimed for protection, but merely represents the selected embodiment of the utility model. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the utility model.

[0023] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the utility model, directional terms and order terms are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0024] like Figure 1 As shown, in a silicon carbide ingot laser slicing device based on a spatial light modulator, a beam expander 2 and a spatial light modulator 3 are sequentially arranged on the output optical path of the laser 1. The laser 1 is a laser with an emitting laser wavelength of 1000nm to 1100nm, an emitting laser frequency continuously adjustable between 10KHz and 100KHz, an average power adjustable from 0 to 50W, and a pulse width adjustable from 100fs to 10ns. The spatial light modulator 3 is a spatial light modulator with a wavelength range of 300nm to 1100nm, 1920×1080 pixels, and an effective area of ​​15.4mm×8.6mm. A first lens 4, a first reflector 5, a second lens 6, and a second reflector 7 are sequentially arranged on the output optical path of the spatial light modulator 3. An objective lens 8 is arranged on the reflecting optical path of the second reflector 7. The objective lens 8 is directly opposite to the silicon carbide ingot to be processed. The objective lens 8 is an objective lens with a numerical aperture of 0.45 and a magnification of 50 times. The focal length of the first lens 4 is twice that of the second lens 6. The spatial light modulator 3 is connected to a computer 10 , and the computer 10 is installed with MATLAB software or PYTHON software.

[0025] Preferably, the laser 1 is a laser with an emission wavelength of 1064 nm, a pulse width of 4 ps, an average power of 20 W, and a repetition frequency of 10 KHz to 100 KHz.

[0026] The spatial light modulator 3 is a programmable optical shaping device that flexibly controls the amplitude, phase, polarization and other optical parameters of the laser beam through programming, and cooperates with the external optical path system to obtain arbitrary light field intensity distribution inside the material. Different laser spots are focused inside the SiC ingot material, which has different effects on the modification and expansion of the material, and has different effects on improving the efficiency of SiC ingot slicing and reducing material loss.

[0027] In specific applications, the light beam output by the laser 1 is magnified and collimated through the beam expander 2 to cover the effective window of the spatial light modulator 3. The phase input of the spatial light modulator 3 is a circular flat-top beam hologram, which is phase modulated by the spatial light modulator 3. The spatial light modulator 3 loads a computer-generated holographic phase diagram of 10 circular flat-top beams and transverse multi-focal points. The first reflector 5 and the second reflector 7 change the transmission direction of the light path. The focal length of the first lens 4 is twice the focal length of the second lens 6, forming a 4f system to transfer the image to the light entrance of the objective lens 8 for image transfer and beam reduction. The laser output by the objective lens 8 forms a transverse multi-focal point and a circular flat-top beam inside the silicon carbide ingot, which is focused inside the silicon carbide to generate a circular flat-top beam with adjustable transverse double focal points. By controlling the phase diagram loaded by the spatial light modulator 3, multiple transverse focal points are generated, and the focal spacing is adjusted by the phase diagram. The light spot of the spatial light modulator 3 is shaped and focused into a transverse double focal point inside the silicon carbide ingot, and the circular flat-top beam is used for slicing to process the silicon carbide ingot.

[0028] The Gerchberg-Saxton algorithm (GS algorithm) is a classic iterative algorithm used in spatial light field control technology to obtain holographic phase images. In order to obtain a more uniform light field distribution and improve energy utilization, a weight factor is introduced into the GS algorithm process, which is the Weighted-Gerchberg-Saxton-algorithm (GSW) algorithm, such as Figure 2 The computer uses the GSW algorithm through the installed MATLAB software or PYTHON software to generate a circular flat-top beam and a lateral double-focus combined holographic phase image, and loads them into the spatial light modulator.

[0029] The GSW algorithm is used to generate the holographic phase image of the circular flat-top beam and the lateral double focus, and then the phase is superimposed to form a combined phase image, such as Figure 3 , loaded into the spatial light modulator 3, and focused into the silicon carbide ingot to form a circular flat-top beam with a lateral double focus.

[0030] The computer 10 generates the holographic phase diagram of the circular flat-top beam and the lateral double focus by using the GSW algorithm through MATLAB software or PYTHON software. The specific steps are as follows:

[0031] 1) Initialization: the grayscale value of the input image is used as the amplitude input, and a random phase is assigned to each pixel of the image as the initial input image;

[0032] 2) Iterative process: First, perform Fourier transform on the initial restored image to obtain the target image, retain the phase of the target image, set the amplitude to 1, and then perform inverse Fourier transform on it to obtain the transformed restored image. The restored image is multiplied by the weight factor and used as the input image for iteration;

[0033] 3) End condition: when the preset number of iterations is reached or the restored image is the same as the preset value of the target image, the phase information of the target image is extracted, which is the obtained phase map.

[0034] like Figure 4 , focus the circular flat-top beam with a lateral dual focus at a depth inside the silicon carbide ingot, set the pulse energy to 10-100μJ, the pulse width to 100fs-10ns, and the lateral dual focus spacing to be adjustable from 10μm to 200μm. The pulse laser forms a pit at the focus inside the silicon carbide ingot and generates cracks around the pit to form a modified layer. The moving platform loaded with the silicon carbide ingot moves at a speed of 100-500mm / s. After scanning, a uniform modified layer is formed inside the silicon carbide ingot. The modified layer is completely broken by applying tension or ultrasonic vibration, and the silicon carbide wafer with a fixed thickness on the surface is completely separated from the ingot below.

[0035] In summary, the utility model uses a controllable lateral dual focus generated by a spatial light modulator for slicing silicon carbide ingots, which greatly improves the existing slicing efficiency and can be applied to the slicing process of semiconductor material ingots such as silicon wafers, gallium arsenide, indium phosphide and gallium nitride.

[0036] Through the spot shaping technology of the spatial light modulator and the use of a circular flat-top beam, due to its uniform energy distribution, a uniform modified expansion can be formed during the internal processing of the silicon carbide ingot, which is beneficial to reduce the material loss caused by uneven processing.

[0037] The GSW algorithm is used to generate a circular flat-top beam and a lateral dual-focus phase diagram, which improves the energy utilization rate and spot consistency of the laser beam, increases the efficiency of SiC ingot laser slicing, and reduces losses.

[0038] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. For those skilled in the art, the utility model may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0039] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention.

[0040] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A silicon carbide ingot laser slicing device based on a spatial light modulator, characterized in that: A beam expander (2) and a spatial light modulator (3) are sequentially arranged on the output light path of the laser (1); a first lens (4), a first reflector (5), a second lens (6) and a second reflector (7) are sequentially arranged on the output light path of the spatial light modulator (3); an objective lens (8) is arranged on the reflection light path of the second reflector (7); the objective lens (8) is directly opposite to the silicon carbide ingot to be processed; the focal length of the first lens (4) is twice that of the second lens (6); and the spatial light modulator (3) is connected to a computer (10).

2. The silicon carbide ingot laser slicing device based on a spatial light modulator according to claim 1, characterized in that: The laser (1) is a laser with an emission wavelength of 1000nm to 1100nm, an emission frequency of laser that is continuously adjustable between 10KHz and 100KHz, an average power that is adjustable between 0 and 50W, and a pulse width that is adjustable between 100fs and 10ns.

3. The silicon carbide ingot laser slicing device based on a spatial light modulator according to claim 2, characterized in that: The laser (1) is a laser with an emission wavelength of 1064nm, a pulse width of 4ps, an average power of 20W, and a repetition frequency of 10KHz to 100KHz.

4. The silicon carbide ingot laser slicing device based on a spatial light modulator according to claim 1, characterized in that: The spatial light modulator (3) is a spatial light modulator with a wavelength range of 300 nm to 1100 nm, 1920×1080 pixels, and an effective area of ​​15.4 mm×8.6 mm.

5. The silicon carbide ingot laser slicing device based on a spatial light modulator according to claim 1, characterized in that: The objective lens (8) has a numerical aperture of 0.45 and a magnification of 50 times.

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