An internal tilting grating for optical glasses and its manufacturing method

Abstract

This application relates to the field of precision manufacturing technology for semiconductor optical devices, and discloses a tilted grating inside optical glasses and its manufacturing method. The method includes forming a tilted imprinted adhesive pattern on a mask layer of a substrate and performing a first processing step; then, tilting the mask layer using the imprinted adhesive pattern to form a mask pattern tilted in the same direction, followed by a second processing step to form a first oxide layer; forming a second oxide layer on the surface of the mask pattern and performing a back etching step to form a sidewall structure; using the mask pattern with the sidewall structure as a mask, tilting the exposed surface of the substrate to form a first grating tilted in the same direction; forming a low-refractive-index material layer covering the first grating on the surface of the substrate; and removing the top of the first grating by planarization to form a second grating. This application, by optimizing the patterning process, can improve the overall etching morphology of the grating and achieve smooth treatment of the tilted sidewalls, making it suitable for enhancing optical performance, improving diffraction efficiency, and long-term stability.

Description

Technical Field

[0001] This application relates to the field of precision manufacturing technology for semiconductor optical devices, and in particular to a tilted grating inside optical glasses and a method for manufacturing the same. Background Technology

[0002] Currently, when fabricating silicon carbide (SiC) tilted gratings for optical glasses using conventional processes, the high sidewall roughness of the photoresist mask patterns created by photolithography or imprinting processes leads to a rough surface on the sidewalls of the final tilted grating during pattern transfer when etching the grating trenches. This roughness is sequentially transferred to the sidewalls of the hard mask and the grating trenches. Furthermore, when using vertical hard masks and ion beam etching to etch silicon carbide in a tilted direction, significant residue remains after the hard mask is consumed, causing morphological curvature and surface roughness on the sidewalls of the grating trenches (i.e., the tilted grating sidewalls). This results in high light scattering loss and reduced diffraction efficiency, impacting device performance. Therefore, it is necessary to investigate a novel method for fabricating tilted gratings inside optical glasses to enhance optical performance, improve diffraction efficiency, and improve long-term stability. Summary of the Invention

[0003] The purpose of this application is to overcome the above-mentioned problems existing in the prior art and provide an internal tilted grating for optical glasses and a method for manufacturing the same, so as to optimize the patterning process of the tilted structure of the tilted grating, improve the overall etching morphology of the grating, and achieve smoothing of the tilted sidewalls, thereby enhancing optical performance, improving diffraction efficiency and long-term stability.

[0004] To achieve the above objectives, the technical solution of this application is as follows:

[0005] According to a first aspect of this application, an embodiment of this application provides a method for manufacturing a tilted grating inside optical glasses, comprising the following steps:

[0006] A mask layer is formed on the substrate;

[0007] Multiple embossed patterns inclined in the same direction are formed on the mask layer;

[0008] The surface of the embossed pattern is subjected to a first treatment to remove burrs;

[0009] By performing the imprinted adhesive pattern after the first processing and etching the mask layer along its tilt direction, multiple mask patterns tilted in the same direction are formed on the substrate.

[0010] The surface of the mask pattern is subjected to a second treatment to form a first oxide layer;

[0011] A second oxide layer is formed on the surface of the mask pattern after the second treatment using an atomic layer deposition process;

[0012] The second oxide layer is etched back to form a smooth sidewall structure on both sides of the mask pattern.

[0013] Using the mask pattern with the sidewall structure as a mask, the exposed surface of the substrate is etched along its tilt direction until the mask pattern is completely etched away, forming a plurality of grating trenches tilted in the same direction on the substrate, and forming a first grating between two adjacent grating trenches.

[0014] A low-refractive-index material layer is formed on the surface of the substrate and fills the grating trench;

[0015] A planarization process is used to remove excess low-refractive-index material layers and the top of the first grating from the substrate surface, forming a second grating between two adjacent grating trenches.

[0016] In some embodiments, when etching the exposed surface of the substrate, when the first oxide layer is completely etched away, the processes of forming the first oxide layer, forming the second oxide layer, forming the sidewall structure, and etching the exposed surface of the substrate are repeated until the mask pattern is completely etched away, the first grating is formed on the substrate below the mask pattern, and the smooth surface topography of the sidewall structure is transferred to the two sidewalls of the first grating through pattern transfer.

[0017] In some embodiments, before forming a low-refractive-index material layer on the surface of the substrate, the following steps are further included:

[0018] The surface of the first grating is subjected to a third treatment to improve its smoothness;

[0019] The surface of the first grating is subjected to a fourth process to remove the enriched layer on the surface;

[0020] Then, the low-refractive-index material layer is formed.

[0021] In some embodiments, the substrate includes a silicon carbide substrate; the third process is performed by employing a high-temperature annealing process to melt the sidewall surface of the first grating, thereby driving the melting of the surface atomic layer and making the sidewall surface smooth; the fourth process is performed by employing a dry etching process to remove the carbon-rich layer formed on the surface of the first grating due to silicon sublimation caused by high-temperature annealing.

[0022] In some embodiments, when performing the third process, an H2 and N2 atmosphere is used, the temperature is above 800°C, and the time is 30 minutes to 2 hours.

[0023] In some embodiments, when performing the fourth process, the process gas includes H2 and N2, the temperature is 200°C to 300°C, the pressure is 500 mTorr to 5000 mTorr, the source power is 500 W to 3000 W, and the bias power is turned off.

[0024] In some embodiments, a dry etching process is used, and the first treatment is performed on the sidewall surface of the imprinted adhesive pattern along the tilt direction of the imprinted adhesive pattern. The process gas includes O2, the temperature is 60℃~100℃, the pressure is 5mTorr~50mTorr, the source power is 500W~1000W, and the bias power is 50W~200W.

[0025] In some embodiments, the second treatment is performed using a thermal oxidation process at a temperature of 500°C to 1000°C for a time of 5 to 60 seconds.

[0026] In some embodiments, when performing the atomic layer deposition process, the temperature is 600°C to 800°C, the pressure is 100 mTorr to 5000 mTorr, the silicon source precursor includes SiH4 or tetraethyl orthosilicate, and the oxygen source includes at least one of N2O, O2, and O3.

[0027] In some embodiments, a dry etching process is used to etch back the second oxide layer. The process gas includes CF4, C4F8, NF3 and O2, the temperature is 0℃~80℃, the pressure is 5mTorr~500mTorr, the source power is 500W~1000W, and the bias power is 50W~500W.

[0028] In some embodiments, a dry etching process is used to etch and pattern the mask layer at a temperature of -10°C to 20°C, a pressure of 5 mTorr to 100 mTorr, a source power of 100 W to 1000 W, a bias power of 5 W to 100 W, and process gases including Cl2, HBr, SF6, and O2.

[0029] In some embodiments, a plasma dry etching process is used to etch the exposed surface of the substrate at a temperature of 0°C to 60°C, a pressure of 1 mTorr to 1 Torr, a source power of 50 W to 3000 W, a bias power of 50 W to 200 W, and process gases including a mixture of SF6, HBr, H2 and N2, Cl2 and O2.

[0030] In some embodiments, a deposition process is used to form a low refractive index material layer of silicon dioxide on the surface of the substrate at a temperature of 200°C to 450°C and a pressure of 100 mTorr to 5000 mTorr. The silicon source precursor includes SiH4 or tetraethyl orthosilicate, and the oxygen source includes at least one of N2O, O2, and O3.

[0031] According to a second aspect of this application, embodiments of this application also provide an internal tilted grating for optical glasses, which is obtained using the manufacturing method of the internal tilted grating for optical glasses provided in any of the embodiments of the first aspect described above.

[0032] The embodiments of this application may have, or at least have, the following advantages:

[0033] (1) By pre-defining the mask morphology of the tilted grating, a tilted imprinted adhesive pattern is formed, which facilitates the subsequent tilted etching of the substrate. This allows the mask pattern to be completely etched away, forming a first grating with smooth sidewalls and a good morphology. This solves the problem that when the existing vertical mask is used to etch silicon carbide in a tilted direction, a lot of residue will be generated when the mask is consumed, resulting in a curved morphology and rough surface of the sidewalls of the formed trench (i.e., the sidewalls of the tilted grating). Furthermore, by filling the grating trench with a low refractive index material layer and planarizing it, the top of the first grating, which may have defects, is removed, so that the second grating formed has smooth and straight sidewalls and a sharp corner shape at the top. Thus, by optimizing the patterning process of the tilted grating, the overall morphology of the tilted grating is improved, the sidewall roughness is improved, and the process difficulty is reduced. This achieves reduced light scattering loss, improved diffraction efficiency, enhanced optical performance, and long-term stability.

[0034] (2) By performing a first treatment on the sidewall surface of the imprinted adhesive pattern along the tilt direction of the imprinted adhesive pattern, burrs, residues and other defects on the surface of the imprinted adhesive pattern can be removed, reducing surface roughness and improving surface quality. This can improve the accuracy of the tilt structure morphology of the mask pattern formed by etching the mask layer through the imprinted adhesive pattern. By performing a second treatment on the surface of the mask pattern to form a first oxide layer, the roughness defects on the surface of the mask pattern can be improved, so as to initially reduce the surface roughness. By using an atomic layer deposition process to form a second oxide layer on the surface of the mask pattern, the roughness defects on the surface of the mask pattern can be further filled at the atomic level layer by layer, and the atomic level surface flatness can be achieved. By etching back the second oxide layer, a smooth sidewall structure can be formed on both sides of the mask pattern, which significantly improves the smoothness of the overall sidewall of the mask. Therefore, when the exposed surface of the substrate is etched to form a tilted grating (first grating), the smooth morphology of the sidewall structure can be transferred to the two sidewalls of the first grating through pattern transfer, resulting in a tilted grating structure with smooth sidewalls. Thus, the embodiments of this application effectively solve the problem that when conventional etching processes are used to fabricate tilted grating structures in optical glasses, the high-roughness imprinted mask pattern is transferred to the sidewalls of the grating trenches during the pattern transfer process of etching silicon carbide, causing a rough sidewall surface of the final tilted grating. Furthermore, when etching the exposed surface of the substrate, when the first oxide layer is completely etched away, by repeatedly performing the process of forming the first oxide layer, the second oxide layer, the sidewall structure, and continuing to etch the exposed surface of the substrate, not only can the morphology of the mask pattern be maintained at all times, forming smooth and straight grating trenches, but the mask pattern can also be completely etched away in the end. This avoids the problem that when the existing vertical hard mask and ion beam etching process is used to etch silicon carbide in an inclined direction, a lot of residue will be generated when the hard mask is consumed, which causes the sidewalls of the formed grating trench (i.e., the sidewalls of the inclined grating) to have a curved morphology and a rough surface.

[0035] (3) By using a high-temperature annealing process to perform a third treatment on the surface of the first grating, the high temperature can be used to melt the sidewall surface of the first grating to drive the melting of the surface atomic layer, making the sidewall surface smooth. Furthermore, by using a dry etching process to perform a fourth treatment on the surface of the first grating, the carbon enrichment layer formed on the surface of the first grating due to silicon sublimation caused by high-temperature annealing can be removed. Thus, by combining high-temperature annealing and surface treatment, the sidewall roughness can be reduced and the Si / C ratio of the sidewall surface can be adjusted. This avoids the problem of thermal damage (surface Si loss) and new defects (Si / C ratio imbalance) on the silicon carbide surface that would occur when using high-temperature annealing to reduce sidewall roughness in the past, thereby ensuring the accuracy of the optical element.

[0036] Other advantages of this application will be described in the following detailed description. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating a preferred embodiment of the manufacturing method of an internal tilted grating for optical glasses.

[0038] Figure 2 This is a schematic diagram of the structure after forming a mask layer and an imprint adhesive layer on the surface of a substrate, according to a preferred embodiment of this application.

[0039] Figure 3 This is a schematic diagram of the structure after forming a unidirectionally inclined imprinted adhesive pattern on the surface of a mask layer, according to a preferred embodiment of this application.

[0040] Figure 4 This is a schematic diagram of the structure after forming a mask pattern with the same tilt on the surface of a substrate, which is a preferred embodiment of this application.

[0041] Figure 5 This is a schematic diagram of a structure after a sidewall structure is formed on the side of a mask pattern, according to a preferred embodiment of this application.

[0042] Figure 6 This is a schematic diagram of the structure after etching a substrate to form a trench intermediate structure, which is a preferred embodiment of this application.

[0043] Figure 7 This is a schematic diagram of a structure after a sidewall structure is re-formed on the side of a mask pattern, according to a preferred embodiment of this application.

[0044] Figure 8 This is a schematic diagram of the structure after forming a first grating tilted in the same direction on a substrate, according to a preferred embodiment of this application.

[0045] Figure 9 This is a schematic diagram of a structure after a low refractive index material layer is formed on a substrate, according to a preferred embodiment of this application.

[0046] Figure 10 This is a schematic diagram of the structure after planarization and the formation of a second grating tilted in the same direction on a substrate, according to a preferred embodiment of this application.

[0047] In the figure: 10. Substrate; 11. Mask layer; 111. Mask pattern; 12. Imprinting adhesive layer; 121. Imprinting adhesive pattern; 13. Second oxide layer; 131. Sidewall structure; 14. Trench center structure; 15. Grating trench; 16. First grating; 17. Low refractive index material layer; 18. Second grating. Detailed Implementation

[0048] To address the problems existing in the prior art, this application provides a method for manufacturing a tilted grating inside optical glasses, comprising the following steps:

[0049] A mask layer is formed on the substrate;

[0050] Multiple embossed patterns inclined in the same direction are formed on the mask layer;

[0051] The surface of the embossed pattern is subjected to a first treatment to remove burrs;

[0052] By performing the imprinted adhesive pattern after the first processing and etching the mask layer along its tilt direction, multiple mask patterns tilted in the same direction are formed on the substrate.

[0053] The surface of the mask pattern is subjected to a second treatment to form a first oxide layer;

[0054] A second oxide layer is formed on the surface of the mask pattern after the second treatment using an atomic layer deposition process;

[0055] The second oxide layer is etched back to form a smooth sidewall structure on both sides of the mask pattern.

[0056] Using the mask pattern with the sidewall structure as a mask, the exposed surface of the substrate is etched along its tilt direction until the mask pattern is completely etched away, forming a plurality of grating trenches tilted in the same direction on the substrate, and forming a first grating between two adjacent grating trenches.

[0057] A low-refractive-index material layer is formed on the surface of the substrate and fills the grating trench;

[0058] A planarization process is used to remove excess low-refractive-index material layers and the top of the first grating from the substrate surface, forming a second grating between two adjacent grating trenches.

[0059] This application also provides an internal tilt grating for optical glasses obtained using the above-described method for manufacturing an internal tilt grating for optical glasses.

[0060] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0061] refer to Figure 1 This application provides a method for manufacturing a tilted grating inside optical glasses, comprising the following steps:

[0062] Step S11: Provide a substrate.

[0063] refer to Figure 2 A substrate 10 is provided for fabricating a tilted grating for optical eyeglasses having smooth sidewalls on the substrate 10.

[0064] In some embodiments, substrate 10 includes a silicon carbide (SiC) substrate. For example, substrate 10 is a silicon carbide substrate, that is, the material of substrate 10 is silicon carbide, used to fabricate a tilted grating for optical glasses with smooth sidewalls on the silicon carbide substrate 10. The embodiments of this application will be described in detail below with the example of substrate 10 being made of silicon carbide.

[0065] Step S12: Form multiple mask patterns that are tilted in the same direction on the surface of the substrate.

[0066] refer to Figure 2 In some embodiments, firstly, a mask layer 11 and an imprinting adhesive layer 12 are sequentially formed on the surface of the substrate 10.

[0067] In some embodiments, a deposition process is used to form a mask layer 11 on the surface of the substrate 10.

[0068] In some embodiments, the mask layer 11 is made of polycrystalline silicon. That is, a polycrystalline silicon layer is formed on the surface of the substrate 10 as the mask layer 11. However, it is not limited to this.

[0069] In some embodiments, a spin coating process is used to form an imprinting adhesive layer 12 on the surface of the mask layer 11. The imprinting adhesive of the imprinting adhesive layer 12 can be a UV-curable imprinting adhesive or a thermosetting imprinting adhesive.

[0070] Then, a template (not shown) with a preset tilted grating pattern is aligned and pressed against the surface of the imprinting adhesive layer 12, and an imprinting process is used to imprint the pattern onto the imprinting adhesive layer 12, copying the tilted grating pattern on the template onto the imprinting adhesive layer 12. After demolding, multiple periodically arranged, unidirectionally tilted imprinting patterns 121 are formed on the surface of the mask layer 11, such as... Figure 3 As shown. Figure 3 An example is shown where the various imprinted patterns 121 are arranged at an angle to the right. This application does not limit the number of imprinted patterns formed.

[0071] By pre-defining the mask morphology of the tilted grating, a tilted imprinted resist pattern 121 is formed, which facilitates the subsequent tilted etching of the substrate 10. This allows the mask pattern to be completely etched away, forming a first grating with smooth sidewalls and a good morphology. This solves the problem that existing methods of using vertical masks to etch silicon carbide in a tilted direction result in more residue when the mask is consumed, causing the sidewalls of the formed trench (i.e., the sidewalls of the tilted grating) to have a curved morphology and a rough surface.

[0072] The surface of the embossed pattern 121 often has defects such as burrs and residues, resulting in a high surface roughness. To avoid passing on the surface roughness of the embossed pattern 121 during subsequent pattern transfer processes, the surface of the embossed pattern 121 can be pre-treated to remove burrs, residues, and other defects, thereby reducing its surface roughness.

[0073] refer to Figure 3 In some embodiments, a dry etching process is employed, and at a relatively low temperature below 100°C, a first treatment is performed on the sidewall surface of the imprinted adhesive pattern 121 along its inclined direction to remove burrs, residues, and other defects present on the sidewall surface of the imprinted adhesive pattern 121, thereby reducing the surface roughness of the sidewall surface and smoothing it out. Using a relatively low temperature below 100°C to perform the first treatment on the sidewall surface of the imprinted adhesive pattern 121 will not damage the overall structure of the imprinted adhesive pattern 121.

[0074] By tilting the base on which the substrate 10 is placed at a certain angle, the corresponding processes that need to be carried out in a tilted manner can be performed on the surface of the substrate 10 and its film layer structure along the corresponding tilt direction. Figure 3 The downward-sloping arrows indicate the processing direction during the first processing step.

[0075] In some embodiments, when performing the first process, the process gas includes O2, the dilution and dissociation gas includes N2, the temperature is 60°C to 100°C, the pressure is 5 mTorr to 50 mTorr, the source power is 500 W to 1000 W, and the bias power is 50 W to 200 W. However, it is not limited to these embodiments.

[0076] In some embodiments, when performing the first process, O2 plasma is formed by exciting O2 and ion filtering is turned on to filter out charged particles in the O2 plasma, and the resulting O free radicals (oxygen free radicals) are used to process and remove defects such as burrs and residues on the surface of the imprinted adhesive pattern 121.

[0077] By performing a first treatment on the sidewall surface of the imprinting adhesive pattern 121, the surface roughness of the imprinting adhesive pattern 121 is reduced and the surface quality of the imprinting adhesive pattern 121 is improved. This can improve the morphological accuracy of the tilted structure of the mask pattern formed by etching and patterning the mask layer 11 through the imprinting adhesive pattern 121.

[0078] refer to Figure 4In some embodiments, the imprinted resist pattern 121 is used as a mask, and the mask layer 11 is etched and patterned along its tilt direction to transfer the tilted pattern features of the imprinted resist pattern 121 onto the mask layer 11, forming a plurality of periodically tilted mask patterns 111 arranged in the same direction on the surface of the substrate 10. The plurality of periodically arranged mask patterns 111 formed serve as masks for subsequent etching of the substrate 10, and openings as etching windows are formed between two adjacent mask patterns 111, exposing the surface of the substrate 10 located between adjacent mask patterns 111.

[0079] In some embodiments, a dry etching process is used to etch and pattern the mask layer 11. The process gas includes Cl2, HBr, SF6, and O2, and the dilution and dissociation gas includes at least one of N2 and Ar. The temperature is -10°C to 20°C, the pressure is 5 mTorr to 100 mTorr, the source power is 100 W to 1000 W, and the bias power is 5 W to 100 W. However, it is not limited to these embodiments.

[0080] refer to Figure 4 In some embodiments, a dry etching process is employed, and the surface of the mask pattern 111 is cleaned along the tilt direction of the mask pattern 111. The process gas includes O2, and the dilution and dissociation gas includes at least one of N2 and He. An ion filter is turned on, and O2 plasma is formed by exciting O2. After filtering out charged particles in the O2 plasma, the resulting oxygen free radicals are used to clean the surface of the polycrystalline silicon mask pattern 111. Figure 4 The downward-sloping arrows indicate the direction of the cleaning process.

[0081] In some embodiments, when cleaning the surface of the mask pattern 111, the temperature is 150°C to 250°C, the pressure is 100 mTorr to 1 Torr, the source power is 500 W to 3000 W, and the bias power is turned off. However, it is not limited to these.

[0082] Using oxygen free radicals to perform a gentle cleaning process on the surface of the mask pattern 111 avoids damage to the surface of the mask pattern 111, which helps to maintain the morphological accuracy of the mask pattern 111 and avoids aggravating the surface roughness of the mask pattern 111. This forms a good processing bottom surface on the mask pattern 111, thus laying a good foundation for subsequent surface oxidation (second processing) of the mask pattern 111 to form a first oxide layer, and further forming a second oxide layer on the oxidized surface of the mask pattern 111, achieving atomic-level surface smoothness.

[0083] Step S13: Form a first oxide layer on the surface of the mask pattern.

[0084] refer to Figure 5 In some embodiments, a thermal oxidation process is used to perform a second surface oxidation-based treatment on the mask pattern 111, forming a dense silicon dioxide (SiO2) layer on the surface of the polycrystalline silicon mask pattern 111 as a first oxide layer (not shown). When performing the thermal oxidation process, the process gas includes O2 (dry oxygen), or O2 and H2 (wet oxygen synthesis), with N2 as the carrier gas or dilution gas, at a temperature of 500°C to 1000°C, for a time of 5 to 60 seconds, and at atmospheric pressure. However, this is not a limitation.

[0085] refer to Figure 5 In some embodiments, a dry etching process is employed, and a second treatment is performed on the surface of the mask pattern 111 along its tilt direction to form a dense silicon dioxide layer on the surface of the polysilicon mask pattern 111 as a first oxide layer (not shown). The process gas includes O2, and O2 plasma is formed by exciting the O2, and charged particles in the O2 plasma are filtered out to obtain O radicals. These radicals are then used to perform a mild oxidation treatment on the surface of the mask pattern 111 to form a dense first oxide layer. The temperature is 150°C to 200°C, the pressure is 500 mTorr to 1 Torr, the source power is 1000 W to 2000 W, and the bias power is turned off. However, this method is not limited to these steps.

[0086] By performing a second treatment on the surface of the mask pattern 111 to form a first oxide layer, the roughness defects on the surface of the mask pattern 111 can be improved, thereby initially reducing the surface roughness. This lays the foundation for the subsequent formation of a second oxide layer on the oxidized surface of the mask pattern 111 and the achievement of atomic-level surface smoothness.

[0087] Step S14: Form a second oxide layer on the surface of the mask pattern.

[0088] refer to Figure 5 In some embodiments, an atomic layer deposition process is used to form multiple layers of second oxide layers 13 on the oxidized surface (top surface and two side surfaces) of the mask pattern 111, so as to further fill the roughness defects still existing on the surface of the mask pattern 111 at the atomic level, and finally fill the rough surfaces of different depths on the side surfaces of the mask pattern 111, so that the sidewalls of the mask pattern 111 achieve atomic-level flatness, thereby repairing the roughness of the sidewalls of the mask pattern 111.

[0089] In some embodiments, the second oxide layer 13 comprises a silicon dioxide layer. For example, the material of the second oxide layer 13 is silicon dioxide.

[0090] In some embodiments, when performing the atomic layer deposition process, the temperature is 600°C to 800°C, the pressure is 100 mTorr to 5000 mTorr, the silicon source precursor includes SiH4 or tetraethyl orthosilicate (TEOS), and the oxygen source includes at least one of N2O, O2, and O3. However, it is not limited to these.

[0091] Step S15: Form smooth sidewall structures on both sides of the mask pattern.

[0092] refer to Figure 5 In some embodiments, a dry etching process is used, and the second oxide layer 13 formed in the previous step is etched back along the tilt direction of the mask pattern 111 to form smooth sidewall structures 131 on both sides of the mask pattern 111, which can significantly improve the smoothness of the overall sidewalls of the mask. In this way, when the exposed surface of the substrate 10 is subsequently etched to form a tilted grating (first grating), the smooth morphology of the sidewall structure 131 can be transferred to the two sidewalls of the first grating through pattern transfer, resulting in a tilted grating structure with smooth sidewalls.

[0093] In some embodiments, after the second oxide layer 13 is etched back, and sidewall structures 131 are formed on both sides of the mask pattern 111, a certain thickness of the second oxide layer 13 can be retained on the top surface of the mask pattern 111, such as... Figure 5 As shown.

[0094] In some embodiments, after the second oxide layer is etched back, the second oxide layer located on the top surface of the mask pattern can be completely removed, exposing the top surface of the mask pattern, and forming sidewall structures on both sides of the mask pattern.

[0095] When etching back the second oxide layer 13, it is necessary to ensure that the second oxide layer 13 located on the surface of the substrate 10 is etched away so that the surface of the substrate 10 is exposed. Furthermore, even if the second oxide layer 13 located on the top of the sidewall of the mask pattern 111 is partially removed during the etching back process, the characteristics of the etching back process can be utilized to make the exposed top of the sidewall of the mask pattern 111 as smooth as the surface of the formed sidewall structure 131.

[0096] In some embodiments, when the second oxide layer 13 is etched back using a dry etching process, the process gas includes CF4, C4F8, NF3, and O2, the dilution and dissociation gas includes at least one of N2 and Ar, the temperature is 0°C to 80°C, the pressure is 5 mTorr to 500 mTorr, the source power is 500 W to 1000 W, and the bias power is 50 W to 500 W. However, it is not limited to these embodiments.

[0097] The mask pattern 111, the first oxide layer, and the sidewall structure 131 constitute a composite mask pattern.

[0098] Step S16: Using the mask pattern with sidewall structure as a mask, etch the exposed surface of the substrate to form multiple grating trenches that are tilted in the same direction on the substrate.

[0099] refer to Figure 6 In some embodiments, a plasma dry etching process is used, with a composite mask pattern (composed of mask pattern 111, a first oxide layer and sidewall structure 131) as the mask, and the surface of the substrate 10 exposed in the opening between adjacent composite mask patterns is etched downward along the inclined direction of mask pattern 111 until the sidewall structure 131 and the first oxide layer are completely etched and the surface of mask pattern 111 is exposed, forming a trench intermediate structure 14 of a certain depth in the substrate 10, and the smooth morphology of the surface of the sidewall structure 131 is transferred to the sidewall of the trench intermediate structure 14 through pattern transfer, thereby forming a trench intermediate structure 14 with smooth sidewalls on the surface of the substrate 10.

[0100] Furthermore, when etching the exposed surface of the substrate 10, when the sidewall structure 131 and the first oxide layer are completely etched away, the process of forming the first oxide layer, forming the second oxide layer 13, and forming the sidewall structure 131 is repeatedly performed (steps S13 to S15). Figure 7 As shown, and using the mask pattern 111 with the re-formed sidewall structure 131 as a new composite mask pattern, the process of repeatedly etching the exposed surface of the substrate 10 (the bottom surface of the trench intermediate structure 14) is repeated (step S16). During the repeated etching process, the mask pattern 111 itself will be gradually etched away until the mask pattern 111 is completely etched away. Multiple grating trenches 15 with the same direction of inclination are formed on the surface of the substrate 10, which are evolved from the trench intermediate structures 14. Below the original mask pattern 111, that is, on the substrate 10 between two adjacent grating trenches 15, a first grating 16 with the same direction of inclination is formed, as shown. Figure 8 As shown.

[0101] In each cycle, the mask pattern 111 can be surface-oxidized again (second processing) to form a first oxide layer, and a second oxide layer 13 can be formed again on the surface of the mask pattern 111 to repair the roughness of the sidewalls of the mask pattern 111. By forming smooth sidewall structures 131 on both sides of the mask pattern 111, the smooth surface morphology of each sidewall structure 131 can be transferred to the sidewalls of the corresponding trench intermediate structure 14 during each repeated etching of the substrate 10. Therefore, the smooth surface morphology of the sidewall structure 131 can be continuously transferred through pattern transfer to the sidewalls of the finally formed grating trench 15, thereby forming the tilted structure of the first grating 16 with smooth sidewalls.

[0102] In some embodiments, a plasma dry etching process is used to etch the exposed surface of the substrate 10. The process gas includes a mixture of SF6, HBr, H2, and N2, Cl2, and O2. The dilution and dissociation gas includes at least one of Ar, N2, and He. The temperature is 0°C to 60°C, the pressure is 1 mTorr to 1 Torr, the source power is 50 W to 3000 W, and the bias power is 50 W to 200 W. However, the process is not limited to these embodiments.

[0103] In summary, the embodiments of this application can effectively solve the problem that when using conventional etching processes to fabricate tilted grating structures in optical glasses, the high-roughness imprinted mask pattern is transferred to the sidewalls of the grating trenches during the pattern transfer process when etching silicon carbide, resulting in rough sidewall surfaces of the final tilted grating. Furthermore, when performing tilted etching on the exposed surface of the substrate 10, when the first oxide layer is completely etched away, by repeatedly performing the process of forming the first oxide layer, the second oxide layer 13, the sidewall structure 131, and continuing to etch the exposed surface of the substrate 10, not only can the tilted shape of the mask pattern 111 be maintained at all times, forming a tilted grating trench 15 with smooth and straight sidewalls, but the mask pattern 111 can also be completely etched away in the end. This avoids the problem that when the existing vertical hard mask and ion beam etching process is used to etch silicon carbide in the tilted direction, a lot of residue will be generated when the hard mask is consumed, which causes the sidewalls of the formed grating trench (i.e. the sidewalls of the tilted grating) to have a curved shape and a rough surface.

[0104] Step S17: Fill the grating trench with a low refractive index material layer and planarize it to form a tilted grating between two adjacent grating trenches.

[0105] In some embodiments, in order to further reduce the surface roughness of the sidewall of the first grating 16 formed in the previous step and to further improve the smoothness of the sidewall, the surface of the first grating 16 may be treated before forming the low refractive index material layer, and then the low refractive index material layer may be formed.

[0106] refer to Figure 8 In some embodiments, a high-temperature annealing process is first used to perform a third treatment on the surface of the first grating 16, causing the SiC on the sidewall surface of the first grating 16 to melt, thereby driving the melting of the atomic layer on the sidewall surface and making the sidewall surface of the first grating 16 smooth, thus reducing the surface roughness of the sidewall and improving the surface smoothness. Since high-temperature annealing causes the sublimation of Si in the SiC material on the surface of the first grating 16, resulting in the loss of Si in the SiC material on the surface of the first grating 16, a C (carbon) enriched layer (not shown) will be formed on the surface of the first grating 16. Therefore, a dry etching process can be used, and a fourth treatment can be performed on the surface of the first grating 16 after high-temperature treatment along the tilt direction of the first grating 16, to remove the carbon enriched layer formed on the surface of the first grating 16 due to silicon sublimation caused by high-temperature annealing, thus avoiding the generation of new defects with an imbalanced Si / C ratio on the silicon carbide surface.

[0107] In some embodiments, when performing the third process, a mixed atmosphere of H2 and N2 is used, the temperature is above 800°C, for example, the temperature can be 800°C to 900°C, or the temperature can be 800°C to 1000°C, or the temperature can be 800°C to 1200°C, etc., and the time is 30 minutes to 2 hours. However, it is not limited to this.

[0108] In some embodiments, a dry etching process is used, and a high-temperature, unbiased etching method is employed to perform a fourth treatment on the surface of the first grating 16. The process gas includes a mixture of H2 and N2, and Ar is used as a dilution and dissociation gas. The temperature is 200°C to 300°C, the pressure is 500 mTorr to 5000 mTorr, the source power is 500 W to 3000 W, and the bias power is turned off, so that the C chains in the carbon-enriched layer break and volatilize and are removed.

[0109] After removing the carbon-enriched layer from the surface of the first grating 16, the Si / C ratio in the exposed SiC material of the new surface of the first grating 16 will be in a normal state. Thus, through the effective combination of high-temperature annealing and surface etching, the sidewall roughness and the Si / C ratio of the sidewall surface are simultaneously reduced. This avoids the problems of thermal damage (surface Si loss) and new defects (Si / C ratio imbalance) on the silicon carbide surface that would occur when using high-temperature annealing to reduce sidewall roughness in the past, thereby ensuring the accuracy of the optical element.

[0110] When etching to form the first grating 16, the top of the first grating 16 may have defects such as insufficiently straight sidewalls or insufficiently sharp corners. Furthermore, when the first grating 16 is processed by high-temperature annealing, the top shape of the first grating 16 may become rounded (which is also a defect). Therefore, it is necessary to remove the high portion of the first grating 16 with defects to improve the morphological quality of the final tilted grating.

[0111] refer to Figure 9 In some embodiments, firstly, a low-refractive-index material layer 17 is formed on the surface of the substrate 10 and fills the grating trench 15 to cover the top of the first grating 16.

[0112] In some embodiments, the low-refractive-index material layer 17 includes a silicon dioxide layer. For example, the material of the low-refractive-index material layer 17 is silicon dioxide.

[0113] In some embodiments, a low-refractive-index material layer 17 of silicon dioxide is formed on the surface of the substrate 10 using a deposition process at a temperature of 200°C to 450°C and a pressure of 100 mTorr to 5000 mTorr. The silicon source precursor includes SiH4 or tetraethyl orthosilicate, and the oxygen source includes at least one of N2O, O2, and O3. However, the method is not limited to these.

[0114] Then, a chemical mechanical polishing (CMP) process can be used to planarize the surface of the substrate 10, that is, to chemically mechanically polish the surface of the low-refractive-index material layer 17 of silicon dioxide on the substrate 10, removing the excess low-refractive-index material layer 17 on the surface of the substrate 10, that is, removing the excess low-refractive-index material layer 17 above the first grating 16, and removing the defective top of the first grating 16 through polishing, thereby forming a tilted second grating 18, i.e., a tilted grating, between two adjacent grating trenches 15 by removing the defective top of the first grating 16. Figure 10 As shown.

[0115] By employing a planarization process, the top surface of the second grating 18 is flush (or substantially flush) with the surface of the remaining low-refractive-index material layer 17, which allows the top of the second grating 18 to have a sharp corner shape, and the sidewalls of the second grating 18 (i.e. the remaining part of the first grating 16) will be more flat and smooth, thereby helping to reduce light scattering loss, improve diffraction efficiency, enhance optical performance, and have long-term stability for use.

[0116] The flattened low-refractive-index material layer 17 is filled in the grating groove 15 between adjacent tilted gratings (second grating 18) and can be retained as a light transmission enhancement layer.

[0117] In some other embodiments, the material of the low-refractive-index layer 17 may be a resin having a specific refractive index. The refractive index of the resin having a specific refractive index may be, for example, 1.2 to 1.4, but is not limited thereto.

[0118] In some embodiments, the surface roughness of the sidewall of the second grating 18 is 1 nm to 10 nm (Ra).

[0119] This application also provides an internal tilt grating for optical glasses, which is obtained using the manufacturing method of the internal tilt grating for optical glasses provided in any of the above embodiments.

[0120] refer to Figure 10 In some embodiments, the tilted grating inside the optical glasses includes a second grating 18 protruding from the surface of the substrate 10. The second grating 18 is tilted on the surface of the substrate 10 and integrally connected to the substrate 10. The tilted sidewalls of the second grating 18 have smooth surfaces with low surface roughness, and the sidewalls are generally flat. The top of the sidewalls maintains a sharp corner shape, which reduces light scattering loss, improves diffraction efficiency, enhances optical performance, and provides long-term stability.

[0121] In some embodiments, the grating trench 15 between adjacent second gratings 18 (tilted gratings) may be filled with a low refractive index material layer 17 as a light transmission enhancement layer. The refractive index of the low refractive index material layer 17 (e.g., silicon dioxide) is lower than that of the substrate 10 (e.g., silicon carbide).

[0122] In some embodiments, the optical glasses may be AI glasses.

[0123] In summary, this embodiment of the application predefines the mask morphology of the tilted grating to form a tilted imprinted adhesive pattern 121, which facilitates subsequent tilted etching of the substrate 10 and allows the mask pattern 111 to be completely etched away. By performing a first treatment on the imprinted adhesive pattern 121, the surface roughness can be reduced, and the morphological accuracy of the formed mask pattern 111 can be improved. By oxidizing the surface of the mask pattern 111 (second treatment), forming a second oxide layer 13 on the surface of the mask pattern 111, and forming sidewall structures 131 on both sides of the mask pattern 111, the smoothness of the overall sidewalls of the composite mask can be significantly improved, and a tilted grating structure with smooth sidewalls can be obtained through pattern transfer. By removing the top of the first grating 16, which may have defects, the formed second grating 18 has smooth and straight sidewalls and a sharp corner shape at the top. By optimizing the patterning process of the tilted grating, this invention effectively solves the problem of rough sidewall surfaces in the tilted grating structure fabricated in optical glasses using conventional etching processes. This is because the high-roughness imprinted mask pattern is transferred to the sidewalls of the grating trenches during the pattern transfer process when etching silicon carbide, resulting in rough sidewall surfaces. Furthermore, it addresses the issue that when using vertical hard masks and ion beam etching processes to etch silicon carbide in a tilted direction, significant residue remains after the hard mask is consumed, causing morphological curvature and surface roughness on the sidewalls of the grating trenches (i.e., the sidewalls of the tilted grating). Therefore, this invention improves the overall morphology of the tilted grating fabricated according to the embodiments of this application, reduces sidewall roughness, lowers process difficulty, reduces light scattering loss, increases diffraction efficiency, enhances optical performance, and provides long-term stability.

[0124] The above are merely preferred embodiments of this application. These embodiments are not intended to limit the scope of protection of this application. Therefore, any equivalent changes made based on the description and drawings of this application should also be included within the scope of protection of this application.

Claims

1. A method for manufacturing a tilted grating inside optical glasses, characterized in that, In order, they include: A mask layer is formed on the substrate; Multiple embossed patterns inclined in the same direction are formed on the mask layer; The surface of the embossed pattern is subjected to a first treatment to remove burrs; By performing the imprinted adhesive pattern after the first processing and etching the mask layer along its tilt direction, multiple mask patterns tilted in the same direction are formed on the substrate. The surface of the mask pattern is subjected to a second treatment to form a first oxide layer; A second oxide layer is formed on the surface of the mask pattern after the second treatment using an atomic layer deposition process; The second oxide layer is etched back to form a smooth sidewall structure on both sides of the mask pattern. Using the mask pattern with the sidewall structure as a mask, the exposed surface of the substrate is etched along its tilt direction until the mask pattern is completely etched away, forming a plurality of grating trenches tilted in the same direction on the substrate, and forming a first grating between two adjacent grating trenches. A low-refractive-index material layer is formed on the surface of the substrate and fills the grating trench; A planarization process is used to remove excess low-refractive-index material layers and the top of the first grating from the substrate surface, forming a second grating between two adjacent grating trenches.

2. The method for manufacturing the tilted grating inside optical glasses according to claim 1, characterized in that, When etching the exposed surface of the substrate, when the first oxide layer is completely etched away, the process of forming the first oxide layer, forming the second oxide layer, forming the sidewall structure, and etching the exposed surface of the substrate is repeated until the mask pattern is completely etched away. The first grating is formed on the substrate below the mask pattern, and the smooth surface topography of the sidewall structure is transferred to the two sidewalls of the first grating through pattern transfer.

3. The method for manufacturing the tilted grating inside optical glasses according to claim 1, characterized in that, Before forming a low-refractive-index material layer on the surface of the substrate, the following steps are also performed sequentially: The surface of the first grating is subjected to a third treatment to improve its smoothness; The surface of the first grating is subjected to a fourth process to remove the enriched layer on the surface; Then, the low-refractive-index material layer is formed.

4. The method for manufacturing the tilted grating inside the optical glasses according to claim 3, characterized in that, The substrate includes a silicon carbide substrate; by employing a high-temperature annealing process, the third treatment is performed to melt the sidewall surface of the first grating, thereby driving the melting of the surface atomic layer and making the sidewall surface smooth; The fourth process is performed using a dry etching process to remove the carbon-rich layer formed on the surface of the first grating due to silicon sublimation caused by high-temperature annealing.

5. The method for manufacturing the tilted grating inside optical glasses according to claim 4, characterized in that, When performing the third process, an atmosphere of H2 and N2 is used, the temperature is above 800°C, and the time is 30 minutes to 2 hours; and / or, when performing the fourth process, the process gas includes H2 and N2, the temperature is 200°C to 300°C, the pressure is 500 mTorr to 5000 mTorr, the source power is 500 W to 3000 W, and the bias power is turned off.

6. The method for manufacturing the tilted grating inside optical glasses according to claim 1, characterized in that, The first treatment is performed on the sidewall surface of the imprinted adhesive pattern using a dry etching process along the tilt direction of the pattern. The process gas includes O2, the temperature is 60℃~100℃, the pressure is 5mTorr~50mTorr, the source power is 500W~1000W, and the bias power is 50W~200W. The second treatment is performed using a thermal oxidation process at a temperature of 500℃~1000℃ for a time of 5s~60s.

7. The method for manufacturing the tilted grating inside optical glasses according to claim 1, characterized in that, When performing the atomic layer deposition process, the temperature is 600℃~800℃, the pressure is 100mTorr~5000mTorr, the silicon source precursor includes SiH4 or tetraethyl orthosilicate, and the oxygen source includes at least one of N2O, O2, and O3; and / or, a dry etching process is used to etch back the second oxide layer, the process gas includes CF4, C4F8, NF3, and O2, the temperature is 0℃~80℃, the pressure is 5mTorr~500mTorr, the source power is 500W~1000W, and the bias power is 50W~500W.

8. The method for manufacturing the tilted grating inside optical glasses according to claim 1, characterized in that, The mask layer is etched and patterned using a dry etching process at a temperature of -10℃ to 20℃, a pressure of 5 mTorr to 100 mTorr, a source power of 100W to 1000W, and a bias power of 5W to 100W. The process gases include Cl2, HBr, SF6, and O2. Alternatively, the exposed surface of the substrate is etched using a plasma dry etching process at a temperature of 0℃ to 60℃, a pressure of 1 mTorr to 1 Torr, a source power of 50W to 3000W, and a bias power of 50W to 200W. The process gases include a mixture of SF6, HBr, H2, and N2, Cl2, and O2.

9. The method for manufacturing the tilted grating inside optical glasses according to claim 1, characterized in that, A low-refractive-index material layer of silicon dioxide is formed on the surface of the substrate using a deposition process at a temperature of 200°C to 450°C and a pressure of 100 mTorr to 5000 mTorr. The silicon source precursor includes SiH4 or tetraethyl orthosilicate, and the oxygen source includes at least one of N2O, O2, and O3.

10. A tilted grating inside optical glasses, characterized in that, It is obtained using the manufacturing method of the tilted grating inside the optical eyeglasses as described in any one of claims 1-9.

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