Silicon carbide single crystal for AR (Augmented Reality) glasses lens, growth method and growth device

Abstract

The invention provides a silicon carbide single crystal for an AR (Augmented Reality) glasses lens, a growth method and a growth device, according to the method and the device, the growth of the low-stress silicon carbide single crystal is realized through the cooperation of array distribution of a plurality of seed crystals and the flow guide effect of a flow guide cylinder, and the shape-controllable single crystal is obtained. When the single crystal is used for preparing AR glasses lenses, the cracking rate of the single crystal is lt; and the material utilization rate is increased to 85% or above, the cutting and grinding efficiency is improved, and the time consumed by machining is shortened.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology and relates to a silicon carbide single crystal for AR glasses lenses, a growth method and a growth device. Background Art

[0002] AR (Augmented Reality) glasses are head-mounted smart devices that use optical display technology to overlay virtual information such as images, text, and 3D models onto the user's field of view in real time, creating an interactive experience that blends the real and the virtual. Unlike fully immersive VR (Virtual Reality) glasses, AR glasses allow users to simultaneously perceive both the real environment and virtual content, serving as a bridge between the digital and physical worlds.

[0003] AR glasses' display layer technologies include waveguides, BirdBath (coaxial air guides), and MicroLEDs (micro-light-emitting diodes). Waveguides utilize the principle of total internal reflection to transmit light signals. This total internal reflection not only ensures clear and high-contrast images, but also provides users with a larger field of view (FOV). Regarding lens material selection, silicon carbide (SiC) offers higher hardness, thermal conductivity, and thermal stability than other materials, resulting in a longer lifespan and a more stable waveguide structure. Optically, SiC offers high transmittance, a high refractive index, and low dispersion, enabling higher clarity while making the glasses lighter. Furthermore, SiC manufacturing allows for nanoscale waveguide structures to be achieved through precision machining or CMP (chemical mechanical polishing) techniques, meeting complex optical requirements. Therefore, SiC is an ideal lens material for AR glasses.

[0004] At present, the silicon carbide single crystal growth technology has the following defects: (1) The problem of cracking of large diameter single crystals: When the wafer diameter is greater than 150mm, the axial and radial temperature gradients of the single crystal are significantly different, resulting in the accumulation of stress inside the crystal. The cracking rate during the cooling process after the growth is completed is as high as 30% or more. For example, the patent with publication number CN105525351A discloses a single crystal diameter expansion method. Although this method can increase the crystal diameter, the cracks at the seed crystal splicing will still exist during the subsequent growth, and a large number of crystal defects will be generated, resulting in the inability to prepare high-quality silicon carbide single crystals. For example, the patent with publication number CN116479527A discloses a silicon carbide crystal diameter expansion growth device, method and silicon carbide crystal. Although the device can achieve crystal diameter expansion growth, the device has a complex structure and requires multiple discharge ring grooves. It is difficult to accurately control the temperature gradient during the growth process, and the growth process control requirements are high, making it difficult to achieve large-scale production. (2) Low material utilization: When cutting AR lenses from traditional single crystal ingots, multiple circular lenses need to be cut from the entire piece, and the material waste rate in non-lens areas such as edges and lattice defect areas exceeds 60%. (3) Seed crystal cost constraints: For large-sized seed crystals with a diameter of ≥100mm, the preparation cost accounts for more than 45% of the total cost of single crystal growth, and the number of reuses is limited by surface thermal damage. (4) Low processing efficiency: The brittleness of silicon carbide crystals makes it easy to crack and damage during processing; at the same time, the processing speed of large-sized wafers is slow, time-consuming, and the cutting and grinding efficiency is low. For example, patent application number CN202320564544.5 discloses a multi-line and multi-station silicon carbide cutting device. Although this device can improve the cutting effect and stability during cutting, it still has problems such as low cutting efficiency and easy cracking and damage during processing for large-sized single crystals. Summary of the Invention

[0005] Based on the defects of the above-mentioned silicon carbide single crystal growth technology, the present invention provides a silicon carbide single crystal, a growth method and a growth device for AR glasses lenses.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a silicon carbide single crystal for AR glasses lenses. The growth method of the single crystal is to achieve the growth of low-stress, glasses lens-shaped silicon carbide single crystal by synergistically distributing at least one seed crystal in an array and guiding the flow of a guide tube, while also achieving high utilization of the crystal.

[0007] Specifically, the present application provides a method for growing a silicon carbide single crystal for AR glasses lenses, the method comprising: S01: After fixing at least one seed crystal on the seed crystal holder, place the side of the seed crystal holder with the seed crystal on the guide tube, and make the seed crystal located above the guide hole inside the guide tube, the cross section of the guide hole is in the shape of a glasses lens.

[0008] After fixing at least one seed crystal on the seed crystal holder by gluing, put silicon carbide powder at the bottom of the crucible. Place the side of the seed crystal holder with the seed crystal on the guide tube, and make sure the seed crystal is above the guide hole inside the guide tube. Place the crucible in the growth chamber, seal the growth chamber, and evacuate to 10 -4 Pa.

[0009] In this application, both the crucible and seed crystal holder are made of graphite. The seed crystals used are lens-grade seed crystals, with a lens-like shape, a surface roughness of Ra ≤ 0.5 nm, and high quality, free of micropipes and severe defects. Using small-sized seed crystals to grow single crystals can reduce thermal effects by over 60%, achieve a cracking rate of <5%, and eliminate severe defects during growth, thereby improving the quality of single crystals.

[0010] S02: In an argon atmosphere and at 300 Pa, an upper heater and a lower heater are used to heat the seed crystal and the area where the silicon carbide powder is located, respectively, so that the silicon carbide powder gas phase is deposited and grown on the seed crystal along the guide hole to obtain a glass lens-shaped silicon carbide crystal; wherein the heating temperature of the upper heater is lower than the heating temperature of the lower heater.

[0011] The growth chamber is heated and kept warm to facilitate the expulsion of other adsorbed gases and water vapor. -4 Pa, argon is filled in so that the interior of the growth chamber is in an argon atmosphere, and the pressure in the growth chamber is 300-15000Pa. The heating power of the upper heater and the lower heater on the outside of the crucible is adjusted to control the temperature gradient in the growth chamber, and then heat the areas where the seed crystal and silicon carbide powder are located, respectively. In the present application, the heating temperature of the upper heater is 2100-2300°C, and the heating temperature of the lower heater is 50-80°C higher than that of the upper heater. At the same time, the power density of the upper heater is 15-25% higher than that of the lower heater, and a temperature gradient can be formed between the upper heater and the lower heater, and the axial temperature gradient is ≤30°C / cm. In the present application, the growth rate of the crystal is controlled to be 0.2-0.5mm / h by controlling the temperature, so as to obtain high-quality, eyeglass-shaped single crystals.

[0012] Under heating, the silicon carbide powder at the bottom of the crucible sublimates into vapor-phase silicon carbide. This vapor-phase silicon carbide is directed along the guide holes inside the guide tube, causing the SiC vapor to preferentially deposit within 0.2-0.5mm of the seed crystal edge. When the silicon carbide single crystal reaches a thickness of 10-15mm, heating is stopped to terminate growth and obtain a crystal.

[0013] After the temperature of the growth chamber is lowered to room temperature at a cooling rate of 2.5°C / min, the crystal is taken out and cut into thin slices by wire cutting or laser cutting. The slices are then ground and CMP polished to meet the requirements for use.

[0014] The present application also provides a silicon carbide single crystal crystal growth device for AR eyeglass lenses, comprising a graphite crucible, a graphite seed crystal holder and a guide tube both located inside the graphite crucible, and an upper heater and a lower heater both located outside the graphite crucible, wherein the graphite seed crystal holder is located above the guide tube; the side of the graphite seed crystal holder facing the guide tube is provided with at least one groove, in which the seed crystal is placed; a plurality of guide holes are vertically provided through the guide tube, and each of the guide holes corresponds to one groove; silicon carbide powder is provided between the guide tube and the inner bottom of the graphite crucible; the cross-sectional shape of the guide hole is in the shape of an eyeglass lens; the heating temperature of the upper heater is lower than the heating temperature of the lower heater.

[0015] Preferably, the depth of the groove is 1 / 3-1 / 2 of the thickness of the seed crystal, the height of the guide tube is 1 / 5-1 / 3 of the height of the graphite crucible, and the horizontal distance between the inner wall of the guide hole and the edge of the seed crystal is 0.5-2 mm.

[0016] The present invention has the following beneficial effects: (1) Improvement of single crystal quality: The small-size growth of multiple seed crystals can reduce thermal stress by more than 60%, the cracking rate is less than 5%, and there are no serious defects during the growth process, thereby improving the quality of single crystals.

[0017] (2) Low cost: The use of small-sized seed crystals reduces seed crystal costs by 70% and overall production costs by 40-45%.

[0018] (3) Improved material utilization: The restriction of the guide holes on the guide tube can reduce the machining allowance of the edge of the grown silicon carbide single crystal from the conventional 3.0 mm to 0.5 mm, and the material utilization rate is increased to more than 85%.

[0019] (4) Controllable shape: The restriction of the guide holes on the guide tube enables the seed crystal to grow in a limited manner, obtaining a single crystal with controllable shape.

[0020] (5) High processing efficiency: The restriction of the guide holes on the guide tube can obtain smaller-sized, eyeglass lens-shaped single crystals, which can be cut by multi-wire cutting and other methods. The cutting and grinding efficiency is improved and the processing time is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A cross-sectional view of a silicon carbide single crystal growth apparatus provided in an embodiment of the present application when a single seed crystal is placed; Figure 2 A cross-sectional view of a silicon carbide single crystal growth apparatus provided in an embodiment of the present application when multiple seed crystals are placed; Figure 3 A bottom view of a single seed crystal graphite seed crystal holder provided in an embodiment of the present application; Figure 4 A cross-sectional view of a single seed crystal graphite seed crystal holder provided in an embodiment of the present application; Figure 5 A bottom view of a multi-seed graphite seed crystal holder provided in an embodiment of the present application; Figure 6 A cross-sectional view of a multi-seed graphite seed crystal holder provided in an embodiment of the present application; Figure 7 A top view of the guide tube provided in an embodiment of the present application; Symbols represent: 1-graphite crucible, 2-graphite seed crystal holder, 3-guide tube, 4-upper heater, 5-lower heater, 6-groove, 7-seed crystal, 8-guide hole. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0023] The embodiment of the present application provides a silicon carbide single crystal crystal growth device for AR glasses lenses, which includes a graphite crucible 1, a graphite seed crystal holder 2 and a guide tube 3 are provided inside the graphite crucible 1, and the graphite seed crystal holder 2 is located above the guide tube 3; an upper heater 4 and a lower heater 5 are provided outside the graphite crucible 1, and the upper heater 4 is located above the lower heater 5, as shown in the attached figure. Figure 1 、 2 shown.

[0024] The graphite crucible 1 is a component for setting the graphite seed crystal holder 2 and the guide tube 3. Silicon carbide powder is placed at the bottom of the graphite crucible. The surface of the graphite seed crystal holder 2 is provided with at least one groove 6, in which the seed crystal 7 is placed to fix the seed crystal 7. Figure 3-6As shown. In the embodiment of the present application, the depth of the groove 6 is 1 / 3-1 / 2 of the thickness of the seed crystal 7, so that the seed crystal 7 protrudes from the groove 6, thereby facilitating the growth of the seed crystal 7. Furthermore, the grooves 6 are evenly distributed in a honeycomb pattern on the surface of the graphite seed crystal holder 2 to avoid affecting the growth of adjacent seed crystals 7.

[0025] The guide tube 3 is a device for achieving directional flow of gaseous silicon carbide after the silicon carbide powder is gasified. A plurality of guide holes 8 are vertically penetrated in the guide tube 3, and the two ends of the guide holes 8 are respectively connected to the silicon carbide powder at the bottom of the graphite crucible 1 and the seed crystal 7 on the graphite seed crystal holder 2, so as to achieve directional flow of gaseous silicon carbide through the guide holes 8. Furthermore, in order to enable the prepared silicon carbide single crystal to be applied to AR glasses lenses, reduce material cutting waste, and improve processing efficiency, the cross-sectional shape of the guide hole 8 is the shape of a glasses lens, as shown in the attached figure. Figure 7 As shown, its shape is consistent with the bottom view of the multi-seed graphite seed crystal holder. Of course, the cross-sectional shape of the guide hole 8 in the embodiment of the present application can also be set to other shapes to suit different application scenarios.

[0026] In the embodiment of the present application, the guide tube 3 is made of high-purity graphite, and its height is 1 / 5-1 / 3 of the height of the graphite crucible 1, and the horizontal distance between the inner wall of the guide hole 8 and the edge of the seed crystal 7 is 0.5-2 mm.

[0027] During use, the side of the graphite seed crystal holder 2 with the grooves 6 is placed on the guide tube 3. Each guide hole 8 corresponds to a groove 6 above, and thus, each guide hole 8 corresponds to a seed crystal 7 above. Under the action of the guide holes 8 inside the guide tube 3, the silicon carbide powder at the bottom of the graphite crucible 1 is vaporized into gaseous silicon carbide, which flows upward along the guide holes 8 and is then deposited on the seed crystal 7, thereby achieving the growth of the seed crystal 7 and obtaining a silicon carbide single crystal.

[0028] In the embodiment of the present application, the upper heater 4 and the lower heater 5 are components for heating the seed crystal 7 and the area where the silicon carbide powder is located, respectively. The heating temperature of the upper heater 4 is lower than that of the lower heater 5, and the power density of the upper heater is 15-25% higher than that of the lower heater. A temperature gradient can be formed between the upper and lower heaters, and the axial temperature gradient is ≤30°C / cm.

[0029] Based on the above-mentioned silicon carbide single crystal crystal growth device, the present application also provides a silicon carbide single crystal crystal growth method for AR glasses lenses. The growth method is described below in the form of a specific embodiment.

[0030] Example 1 The present invention provides a method for growing a silicon carbide single crystal for AR glasses, the method comprising: S101: The processed high-quality seed crystals are fixed on the graphite seed crystal holder by gluing them in an array, and silicon carbide powder is placed at the bottom of the graphite crucible. The side of the graphite seed crystal holder with the seed crystal is placed on the guide tube, and the seed crystal is located above the guide hole in the shape of a spectacle lens inside the guide tube, and each guide hole corresponds to one seed crystal. The graphite crucible is placed in the growth chamber, and after the growth chamber is sealed, the vacuum is pumped to 10 -4 Pa.

[0031] S102: Heat the growth chamber to 1200°C and keep it warm for 10 hours to expel other adsorbed gases and water vapor. -4 Pa, high-purity argon is filled so that the interior of the growth chamber is in an argon atmosphere, and the pressure in the growth chamber is 300Pa. Continue heating to 1850℃, keep warm for 10 hours, increase the power of the upper heater and the lower heater to heat the area where the seed crystal and silicon carbide powder are located to 2100℃ and 2150℃ respectively, so that the seed crystal grows for 80 hours. Among them, the heating temperature of the upper heater is 2100℃, and the heating temperature of the lower heater is 2150℃. After the growth is completed, cool it to room temperature at a cooling rate of 2.5℃ / min, and take out the crystal. Use wire cutting or laser cutting to cut it into thin slices, and then grind and CMP polish to make it meet the use requirements of AR glasses lenses.

[0032] Example 2 The embodiment of the present application provides a method for growing a silicon carbide single crystal for AR glasses lenses. The method is the same as that of Example 1, except that the heating is continued to 1950°C.

[0033] Example 3 The embodiment of the present application provides a method for growing silicon carbide single crystals for AR glasses lenses. The method is similar to that of Example 1, except that the pressure in the growth chamber is 15,000 Pa and the temperature is kept at this temperature for 5 hours.

[0034] Example 4 An embodiment of the present application provides a method for growing silicon carbide single crystals for AR glasses lenses. The method is the same as that of Example 1, except that the heating temperature of the upper heater is 2100°C and the heating temperature of the lower heater is 2180°C.

[0035] Example 5 The embodiment of the present application provides a method for growing silicon carbide single crystals for AR glasses lenses. The method is similar to that of Example 1, except that after the growth is completed, high-purity argon gas is filled into the growth chamber until the pressure in the growth chamber reaches 100,000 Pa, so that the temperature of the growth chamber is quickly reduced to room temperature.

[0036] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for growing silicon carbide single crystals for AR glasses lenses, characterized in that: include: After fixing at least one seed crystal on the seed crystal holder, the side of the seed crystal holder provided with the seed crystal is placed on the guide tube, and the seed crystal is positioned above the guide hole inside the guide tube; the cross section of the guide hole is in the shape of a spectacle lens; Under argon atmosphere and pressure of 300 Pa, an upper heater and a lower heater are used to heat the seed crystal and the area where the silicon carbide powder is located, respectively, so that the silicon carbide powder gas phase is deposited and grown on the seed crystal along the guide hole, thereby obtaining a silicon carbide crystal in the shape of a spectacle lens; wherein the heating temperature of the lower heater is greater than the heating temperature of the upper heater.

2. The method for growing silicon carbide single crystals for AR glasses according to claim 1, wherein: The heating temperature of the upper heater is 2100-2300° C., and the heating temperature of the lower heater is 50-80° C. higher than that of the upper heater.

3. The method for growing silicon carbide single crystals for AR glasses according to claim 1, wherein: The power density of the upper heater is 15-25% higher than that of the lower heater, and the axial temperature gradient between the upper heater and the lower heater is ≤30° C. / cm.

4. The method for growing silicon carbide single crystals for AR glasses according to claim 1, wherein: The growth rate of the silicon carbide powder on the seed crystal is 0.2-0.5 mm / h, and the thickness of the silicon carbide single crystal is 10-15 mm.

5. The method for growing silicon carbide single crystals for AR glasses according to claim 1, wherein: The surface roughness of the seed crystal Ra is less than or equal to 0.5 nm.

6. A silicon carbide single crystal for AR glasses lenses, characterized in that: It is prepared according to any one of the growth methods in claims 1-5.

7. A silicon carbide single crystal crystal growth device for AR glasses lenses, characterized in that: It comprises a graphite crucible (1), a graphite seed crystal holder (2) and a guide tube (3) both located inside the graphite crucible (1), and an upper heater (4) and a lower heater (5) both located outside the graphite crucible (1), wherein: The graphite seed crystal holder (2) is located above the guide tube (3); at least one groove (6) is provided on the side of the graphite seed crystal holder (2) facing the guide tube (3), and a seed crystal (7) is placed in the groove (6); At least one guide hole (8) is vertically penetrated in the guide tube (3), and one groove (6) corresponds to the top of each guide hole (8); silicon carbide powder is provided between the guide tube (3) and the inner bottom of the graphite crucible (1); the cross-sectional shape of the guide hole (8) is shaped like a spectacle lens; The heating temperature of the upper heater (4) is lower than the heating temperature of the lower heater (5).

8. The silicon carbide single crystal crystal growth device for AR glasses according to claim 7, characterized in that: The depth of the groove (6) is 1 / 3-1 / 2 of the thickness of the seed crystal (7), the height of the guide tube (3) is 1 / 5-1 / 3 of the height of the graphite crucible (1), and the horizontal distance between the inner wall of the guide hole (8) and the edge of the seed crystal (7) is 0.5-2 mm.

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