Processing method of gradient film layer and processing method of gradient depth micro-nano structure

Abstract

The invention relates to a processing method of a gradient film layer and a processing method of a gradient depth micro-nano structure, and the processing method of the gradient film layer comprises the following steps: fixing a planar film layer on the surface of a substrate; forming a sacrificial film layer with gradually changed thickness on the surface of the planar film layer through gradually changed film coating and / or exposure development; based on the etching selection ratio, the sacrificial film layer and the plane film layer above the gradient surface are sequentially removed through dry etching, and a substrate with a gradient film layer is obtained; the processing method of the gradually-changed depth micro-nano structure comprises the following steps: forming a photoresist film on the surface of a gradually-changed film layer, and patterning the photoresist film in a gradually-changed structure region; and removing the photoresist film and the gradual change film layer in the gradual change structure area in sequence through etching and photoresist removal, and obtaining the gradual change depth micro-nano structure through post-processing after etching is finished. The method has the advantages that the processing flexibility is improved, the thickness regulation and control range of the gradient film layer is enlarged, and the gradient depth micro-nano structure with continuous depth change is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of optical element processing, and in particular to a method for processing a gradient film layer and a method for processing a gradient depth micro-nano structure. Background Art

[0002] Gradient thickness films have shown broad application prospects due to their unique optical properties and excellent performance. The main application areas include: 1. Optical thin films: Gradient thickness films can accurately control reflection and transmission properties and are widely used in anti-reflective coatings, filters, etc.; 2. Sensors: Suitable for gas, temperature and humidity sensors, thanks to their high sensitivity to environmental changes; 3. Display technology: In liquid crystal displays and OLED screens, gradient thickness films can improve image quality and color performance; 4. Solar cells: In photovoltaic technology, gradient films can enhance light capture efficiency and thus improve energy conversion rate; 5. Biomedicine: In biosensors and drug release systems, gradient thickness films are favored for their excellent biocompatibility and controllability. With the continuous advancement of materials science and manufacturing technology, the application potential of gradient thickness films will be further expanded.

[0003] As a consumer electronic product that may replace smartphones in the future, the optical system of AR glasses can expand the image generated by the optical machine from a small projection source to a larger display area for users to watch clearly. Therefore, the gradient coating process will become a key link in the manufacture of AR glasses. At present, there are two main methods to achieve the gradient coating process: one is to keep the substrate stationary during the magnetron sputtering coating process, and to achieve gradient coating by adjusting the relative position of the target gun and the substrate and fixing the irradiation direction of the sputtering glow; the other is to use a shielding plate with a specific shape of openings to achieve gradient coating. Both methods belong to the technology of directly depositing a film layer with a gradient thickness. In the magnetron sputtering inclined coating scheme, the coating rate is higher in the area closer to the target gun on the substrate. However, due to space limitations, the rate difference of each point on the substrate is limited, which leads to poor controllability of the gradient range of the film layer. In addition, since the actual coating results are difficult to accurately predict through theoretical calculations, every time the gradient film layer needs to be adjusted, a large number of experiments must be relied on to determine the coating parameters, which reduces the flexibility of operation. When using the baffle plate method with openings of specific shapes, the baffle plate fixture must be redesigned and processed each time the demand for the gradient film layer is adjusted. This not only reduces flexibility but also increases costs and needs to be improved.

[0004] In the field of AR optical waveguide technology, gradient depth micro-nanostructure refers to a continuous and progressive geometric form formed by finely controlling the gradual change of structure depth at the micro-nano scale. This type of structure plays an important role in many fields such as optics, materials science and surface engineering. The notable feature of gradient depth micro-nanostructure is that the structure depth changes along a specific direction, thus producing unique physical properties, which provides broad application prospects for fields such as optics, acoustics and surface engineering. At present, the mainstream technical method is to divide the structure into regions with different etching depths, and realize the processing of three-dimensional structures by alternating photolithography and etching. However, this partition etching scheme has the following defects: First, in order to obtain a more uniform display effect, more depth partitions are required when preparing the grating template, which not only increases the processing steps, but also makes the overall processing cycle longer, thereby affecting the overall processing yield; secondly, multiple overlays in the photolithography process are prone to overlay accuracy errors between partitions, thereby affecting the display effect; finally, although the partition etching achieves depth consistency in the same area, the depth changes between different areas still show a step-by-step change, and it is impossible to achieve a truly continuous depth change. Summary of the invention

[0005] In view of the shortcomings of the prior art, the first object of the present invention is to provide a method for processing a gradient film layer, which has the advantages of simple processing, improved processing flexibility, and increased thickness control range of the gradient film layer.

[0006] The second object of the present invention is to provide a method for processing a micro-nano structure with a gradient depth, which has the advantage of producing a micro-nano structure with a gradient depth that changes continuously.

[0007] To achieve the above first object, the present invention provides the following technical solutions:

[0008] A method for processing a gradient film layer comprises the following steps:

[0009] S11 prepares a substrate, and fixes a planar film layer on the surface of the substrate;

[0010] S12 forms a sacrificial film layer with a gradient thickness on the surface of the planar film layer by gradient coating and / or exposure and development, and an etching selectivity ratio exists between the planar film layer and the sacrificial film layer;

[0011] S13 removes the sacrificial film layer and the planar film layer above the gradient surface in sequence through dry etching based on the etching selectivity, and obtains a substrate with a gradient film layer through post-processing after the etching is completed.

[0012] Furthermore, in the S11, the substrate is first immersed in acetone and isopropanol in turn, and cleaned with 40KHz ultrasound for 8-12 minutes, blown dry with nitrogen, and then baked at 100-130°C for 25-35 minutes, and then the substrate is evenly split to obtain a long strip substrate.

[0013] Furthermore, in the S11, a planar film layer is fixed on the surface of the substrate by coating, plating (electron beam evaporation, Sputter, PECVD, etc.), bonding, adsorption, or bonding.

[0014] Further, in the S11, a planar film layer is fixed on the surface of the substrate by electron beam evaporation, the electron beam current is controlled to be 50-70 mA, the evaporation rate is 5-15 A / s, the coating thickness is 100-1000 nm, and the evaporation material is Si, SiO 2 、SiN x 、TiO 2 、Al 2 O 3 , AlN or a combination of these materials.

[0015] Furthermore, in S12, a sacrificial film layer with a gradient thickness is directly formed on the surface of the planar film layer by gradient coating, and the sacrificial film layer is a composite film of one or more of Cr, Ti, Al, Si, and Mo.

[0016] Alternatively, in S12, a sacrificial film layer with uniform thickness is first formed on the surface of the planar film layer, and the sacrificial film layer is a photoresist film (1~10μm, AZ1500 photoresist, AZ1518 photoresist, APR-5350 photoresist, AZ4562 photoresist, etc.), and then an optical mask with a gradient thickness is prepared, and the sacrificial film layer with uniform thickness is exposed and developed to obtain a sacrificial film layer with a gradient thickness.

[0017] Furthermore, in S12, if the sacrificial film layer is a photoresist film, the etching selectivity ratio between the planar film layer and the sacrificial film layer is controlled to be in the range of 1:8~60; otherwise, the etching selectivity ratio between the planar film layer and the sacrificial film layer is controlled to be in the range of 5~83:1.

[0018] Furthermore, in S12, a mask layer with a gradient thickness is formed directly on the surface of the blank mask by gradient coating in advance, and the mask layer is a composite thin film of one or more of Cr, Ti, Al, and Mo to obtain an optical mask with a gradient thickness.

[0019] Furthermore, in S12, the specific implementation method of the gradient coating is to first install the target gun on one side of the substrate or the blank mask in a manner that the sputtering direction is at an angle to the substrate or the blank mask, and then obtain the sacrificial film layer or the mask layer by magnetron sputtering. Among them, since the atoms or atomic groups of the sputtered thin film material have good directionality, the closer the position on the substrate is to the target gun, the faster the film deposition rate is, and conversely, the farther the position is from the target gun, the slower the film deposition rate is, and the deposition rate changes linearly and uniformly with the position. It is only necessary to keep the substrate still during sputtering to deposit a film layer with a continuously and uniformly changing thickness; by changing the angle between the target gun and the substrate plane (30~60°, preferably 45°), the relative position of the target gun and the substrate, and the sputtering time, the degree of change in the film thickness can be adjusted to a certain extent.

[0020] Furthermore, in S12, the exposure and development are specifically implemented by first using a contact photolithography machine (Suss MA6) and using an optical mask with a gradient thickness to expose a sacrificial film layer with a uniform thickness, wherein the sacrificial film layer is a 5-10 μm AZ4562 photoresist film, and controlling the exposure dose to use 300-800 mJ / cm 2 Then, the exposed sacrificial film layer is developed with AZ300-MIF developer for 30 to 150 seconds to remove part of the photoresist and obtain a sacrificial film layer with a gradient thickness.

[0021] Furthermore, in S13, the dry etching is specifically implemented by performing dry etching through a RIBE device, controlling the BMV of RIBE to be 300-600V, the BMI to be 40-400mA, the Ar gas flow rate to be 0-80sccm, and the CF 4 The gas flow rate is 0~30sccm, CHF 3 The gas flow rate is 0~30sccm, O 2 The gas flow rate is 0~30sccm, SF 6 The gas flow rate is 0~30sccm.

[0022] Alternatively, in S13, the dry etching is specifically implemented by performing dry etching through an ICP-RIE device, controlling the Source Power of the ICP to be 300-600W, the Bias Power to be 100-200W, the Ar gas flow rate to be 0-80sccm, and the CF 4 The gas flow rate is 0~30sccm, CHF 3 The gas flow rate is 0~30sccm, O 2 The gas flow rate is 0~30sccm, SF 6The gas flow rate is 0~30sccm.

[0023] The principle of RIBE and ICP to control the etching selectivity is the same. For different combinations of sacrificial film layers and planar film layers, the process gas can select several of the gases mentioned above. Among the selected process gases, there is a gas that has a strong etching effect on one of the sacrificial film layer and the planar film layer, but a weak etching effect on the other film layer. The etching selectivity between the sacrificial film layer and the planar film layer can be changed by changing the gas flow rate of the gas. Assuming that the etching selectivity of the sacrificial film layer and the planar film layer is k, the gradient thickness difference of the sacrificial film layer is x, and the final gradient film thickness difference is x / k. It can be obtained that when k>1, the gradient thickness difference of the sacrificial film layer can be reduced by etching and then transferred to the planar film layer; when k<1, the gradient thickness difference of the sacrificial film layer can be amplified by etching and then transferred to the planar film layer, thereby adjusting the gradient thickness difference within the same range by adjusting the etching selectivity.

[0024] Furthermore, in S13, after the dry etching is completed, N-methyl-2-pyrrolidone (NMP) or acetone is used for degumming and cleaning, and then plasma treatment is performed at 100-300W for 1-10 minutes.

[0025] To achieve the above first object, the present invention provides the following technical solutions:

[0026] A method for processing a gradient depth micro-nano structure comprises the following steps:

[0027] S1, obtaining a substrate with a gradient film layer according to the above-mentioned gradient film layer processing method;

[0028] S2 forms a photoresist film on the surface of the gradient film layer, and patterns the photoresist film in the gradient structure area;

[0029] S3 removes the photoresist film and the gradient film layer in the gradient structure area in sequence by etching and removing the resist. After the etching is completed, post-processing is performed to obtain a gradient depth micro-nano structure.

[0030] Further, in S2, the thickness of the photoresist film is controlled to be 0.1-10.0 μm, and the photoresist of the photoresist film is Zep520 photoresist, AZ1500 photoresist, AZ1518 photoresist, APR-5350 photoresist or AZ4562 photoresist.

[0031] Furthermore, in S2, the specific implementation method of the patterning is to first expose the photoresist film using an EBL device, a laser direct writing lithography machine or a contact lithography machine, then develop the sample using a developer, and then plasma treat for 1 to 5 minutes at 100 to 300 W to form grating grooves in the gradient structure area of ​​the photoresist film.

[0032] Furthermore, in S3, the specific implementation method of the etching and degumming is to perform etching and degumming by ICP-RIE equipment, and control the gas flow rate of Ar to 0-80 sccm, CF 4 The gas flow rate is 0~30sccm, CHF 3 The gas flow rate is 0~30sccm, O 2 The gas flow rate is 0~30sccm, SF 6 The gas flow rate is 0~30sccm, the RF power is 100~800W, the Bias power is 50~300W, the chamber pressure is 5~20mTorr, and the etching rate is 3~10nm / s. After etching the gradient film layer to the required depth, use N-methyl-2-pyrrolidone (NMP) or acetone for degumming and cleaning, and then plasma treat for 1~10min at 100~300W.

[0033] In summary, the beneficial technical effects of the present invention are:

[0034] 1. Based on the existing gradient coating process, the present invention deposits a directly deposited high-slope gradient film as a sacrificial film layer on a uniform plane film layer. The coating parameters of the sacrificial film layer can be fixed at several specific values. The plane film layer is etched with the sacrificial film layer as a mask. The gradient range of the final plane film layer is regulated by adjusting the etching selectivity of the sacrificial film layer and the plane film layer. Since the range of the adjustable etching selectivity is large, the thickness variation range of the gradient film is greatly improved. In addition, due to the setting of the coating parameters of the sacrificial film layer, when facing a large range of gradient requirements, there is no need to design and process a large number of shielding plate jigs or do a large number of process verification experiments, thereby improving efficiency and reducing costs, and greatly improving processing flexibility.

[0035] 2. The present invention uses grayscale photolithography to obtain a grating structure with a gradient depth on the gradient film layer after one gradient film processing, one photoresist film patterning, and two photoresist film and gradient film etchings, which greatly shortens the process flow, improves the processing efficiency and processing yield, reduces the processing cost, does not require photolithography overlay for structural partitioning, and avoids the error caused by photolithography overlay;

[0036] 3. The present invention obtains an optical mask with a gradient thickness by means of gradient coating, and then uses the different effects of mask layers of different thicknesses on ultraviolet light transmittance to perform grayscale exposure to obtain a sacrificial film layer with a gradient thickness, and then obtains a substrate with a gradient film layer by etching, wherein the film thickness with different change trends can be obtained by adjusting the coating parameters and the etching parameters, which can cover a variety of needs, greatly simplify the process flow, improve the processing efficiency and processing yield, significantly reduce the processing cost, and avoid the precision error between structures in different areas caused by multiple overlays. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the method provided in Example 1 of the present invention.

[0038] Figure 2 This is a SEM image of the left area of ​​the gradient depth micro-nano structure prepared in Example 18 of the present invention.

[0039] Figure 3 This is a SEM image of the right area of ​​the gradient depth micro-nano structure prepared in Example 18 of the present invention.

[0040] Figure 4 This is a SEM image of the left area of ​​the gradient depth micro-nano structure prepared in Example 20 of the present invention.

[0041] Figure 5 This is a SEM image of the right area of ​​the gradient depth micro-nano structure prepared in Example 20 of the present invention. DETAILED DESCRIPTION

[0042] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further explained below in conjunction with the accompanying drawings and specific implementation methods.

[0043] Example 1: Reference Figure 1 , is a method for processing a gradient film layer disclosed in the present invention, comprising the following steps:

[0044] S11 prepares a substrate and fixes a planar film layer on the surface of the substrate;

[0045] S12 forms a sacrificial film layer with a gradient thickness on the surface of the planar film layer by gradient coating and / or exposure and development, and there is an etching selectivity ratio between the planar film layer and the sacrificial film layer;

[0046] S13 removes the sacrificial film layer and the planar film layer above the gradient surface in sequence through dry etching based on the etching selectivity, and obtains a substrate with a gradient film layer through post-processing after the etching is completed.

[0047] The present invention also discloses a method for processing a gradient depth micro-nano structure, comprising the following steps:

[0048] S1, obtaining a substrate with a gradient film layer according to the above-mentioned gradient film layer processing method;

[0049] S2 forming a photoresist film on the surface of the gradient film layer, and patterning the photoresist film in the gradient structure area;

[0050] S3 removes the photoresist film and the gradient film layer in the gradient structure area in sequence by etching and removing the resist. After the etching is completed, post-processing is performed to obtain a gradient depth micro-nano structure.

[0051] Embodiment 2 is a method for processing a gradient film layer disclosed in the present invention, which is different from Embodiment 1 in that it includes the following steps:

[0052] S11: First, immerse the substrate (silicon wafer) in acetone and isopropanol in turn, and clean it with 40KHz, 600W ultrasound for 8-12min, blow dry with nitrogen, and then bake it at 120℃ for 30min. Then, the substrate is evenly split to obtain four long strips of 12cm substrates. Then, a flat film layer is fixed on the surface of the substrate by electron beam evaporation. The electron beam current is controlled to be 55-60mA, the evaporation rate is 8A / s, the coating thickness is 600nm, and the evaporation material is SiO 2 , baked at 200 °C and assisted by an argon ion source;

[0053] S12: firstly, the target gun is installed above one side of the substrate in a manner that the sputtering direction forms an angle of 45° with the substrate, wherein the substrates are arranged in parallel on the coating carrier along the direction of the target gun, and the center of the entire group of substrates is located at the center of the coating carrier, and then a sacrificial film layer with a gradual thickness is obtained by magnetron sputtering, and the coating parameters are: DC200W, 80sccm of argon gas, sputtering gas pressure of 0.3Pa, coating time of 5min, the sacrificial film layer is a Cr film, and the thickness of the Si film is measured by a film thickness meter to change from 30.8nm to 52.2nm within a length range of 10cm, and the thickness difference is 21.4nm;

[0054] S13 performs dry etching through RIBE equipment, controlling RIBE's BMV to 500V, BMI to 320mA, and ACV to 80V; controlling CF 4 The gas flow rate of Ar is 6 sccm, and the gas flow rate of O 2 The gas flow rate varies in the range of 4~20sccm; among which, O 2 The larger the gas flow rate, the flat SiO 2 The higher the etching selectivity between the sacrificial film layer Cr, the higher the etching selectivity between the O 2The gas flow rate can achieve an adjustable etching selectivity ratio between the planar film layer and the sacrificial film layer in the range of 8 to 50:1, and finally obtain a gradient film layer grown directly on the substrate in the required area; after the dry etching is completed, N-methyl-2-pyrrolidone (NMP) or acetone is used for degumming and cleaning, and then plasma treatment is performed at 100 to 300 W for 1 to 10 minutes.

[0055] Embodiments 3 to 5 are a method for processing a gradient film layer disclosed in the present invention. The difference from Embodiment 2 is that the technical parameters of the planar film layer, the sacrificial film layer and the gradient film layer are as shown in Table 1.

[0056] Table 1

[0057] Planar film thickness / nm 10cm sacrificial film thickness difference / nm Etching selectivity 10cm gradient film thickness difference / nm 1cm gradient film thickness difference / nm Example 2 600 21.4 8：1 173.4 17.3 Example 3 600 21.4 14：1 295.3 29.5 Example 4 600 21.4 20：1 432.3 43.2 Example 5 600 21.4 26：1 550.9 55.1

[0058] Embodiments 6 to 9 are a method for processing a gradient film layer disclosed in the present invention. The difference from Embodiment 2 is that the coating materials of the planar film layer are Si, SiN x 、Al 2 O 3 、TiO 2 The process parameters of dry etching are shown in Table 2.

[0059] Table 2

[0060] Planar film material Sacrificial film material Etching process Power parameters Gas flow rate / sccm Etching selectivity range Example 6 Si Cr RIBE BMV=500V, BMI=80mA <![CDATA[Ar:SF 6 =10:10~60]]> 5~83：1 Example 7 <![CDATA[SiN x ]]> Cr RIBE BMV=500V, BMI=160mA <![CDATA[Ar:SF 6 =10:10~60]]> 5~56：1 Example 8 <![CDATA[Al 2 THE 3 ]]> Cr RIBE BMV=400V, BMI=160mA <![CDATA[Ar:CHF 3 =10:10~60]]> 5~40：1 Example 9 <![CDATA[TiO 2 ]]> Cr RIBE BMV=400V, BMI=100mA <![CDATA[Ar:CHF 3 :SF 6 =10:10:10~60]]> 5~36：1

[0061] Embodiments 10 to 13 are a method for processing a gradient film layer disclosed in the present invention. The difference from Embodiment 2 is that the coating materials of the sacrificial film are Si, Ti, Al, and Mo in sequence, and the process parameters of dry etching are shown in Table 3.

[0062] Table 3

[0063] Planar film material Sacrificial film material Etching process Power parameters Gas flow rate / sccm Etching selectivity range Example 10 <![CDATA[SiO 2 ]]> Si ICP Source Power=800W,Bias Power=150W <![CDATA[CHF 3 :THE 2 =20:5~60]]> 5~55：1 Embodiment 11 <![CDATA[SiO 2 ]]> Ti RIBE BMV=400V, BMI=320mA <![CDATA[CHF 3 :Ar=5~60:10]]> 5~73：1 Example 12 <![CDATA[SiO 2 ]]> Al RIBE BMV=400V, BMI=320mA <![CDATA[CHF 3 :Ar=5~60:10]]> 5~67：1 Example 13 <![CDATA[SiO 2 ]]> Mo RIBE BMV=400V, BMI=320mA <![CDATA[CHF 3 :Ar=5~60:10]]> 5~56：1

[0064] Embodiment 14 is a method for processing a gradient film layer disclosed in the present invention, which is different from Embodiment 1 in that it comprises the following steps:

[0065] S11: First, immerse the substrate (silicon wafer) in acetone and isopropanol in turn, and clean it with 40KHz, 600W ultrasound for 8-12min, blow dry with nitrogen, and then bake it at 120℃ for 30min. Then, the substrate is evenly split to obtain four long strips of 12cm substrates. Then, a flat film layer is fixed on the surface of the substrate by electron beam evaporation. The electron beam current is controlled to be 55-60mA, the evaporation rate is 8A / s, the coating thickness is 600nm, and the evaporation material is SiO 2 , baked at 200 °C and assisted by an argon ion source;

[0066] In S12, a layer of AZ4562 photoresist is evenly applied on the surface of the gradient film layer using a spin coating machine, the coating speed is controlled to be 4000 rpm, the baking temperature is 100°C, and the baking time is 60s, to obtain a sacrificial film layer with a thickness of about 6μm; then, a mask layer with a gradient thickness is formed on the surface of another blank optical mask plate by gradient coating, and the mask layer is a Cr film to obtain an optical mask plate with a gradient thickness. Alternatively, the substrate with a sacrificial film layer obtained by S12 of Example 2 can be directly selected as an optical mask plate with a gradient thickness; then, a contact photolithography machine (Suss MA6) is used, and the optical mask plate with a gradient thickness is used to expose the sacrificial film layer with uniform thickness, the sacrificial film layer is a 5-10μm AZ4562 photoresist film, and the exposure dose is controlled to be 300-800mJ / cm 2 Then, the sacrificial film layer after exposure was developed with AZ300-MIF developer for 120 seconds. Weak development was required to remove part of the photoresist to obtain a sacrificial film layer with a gradual thickness. The thickness of the sacrificial film layer was measured by a film thickness meter to be 2.59~3.58μm within a length range of 3cm.

[0067] S13 uses ICP equipment to etch and remove the glue, and control CHF 3 The gas flow rate is 10 sccm, O 2 The gas flow rate is 8~40sccm, Source Power is 600W, Bias Power is 180W, and the chamber pressure is 15mtorr. 2 The gas flow rate can make the etching selectivity between the planar film layer and the gradient photoresist film adjustable in the range of 1:8 to 60. After etching the gradient film layer to the required depth, it is soaked in N-methyl-2-pyrrolidone (NMP), ultrasonically soaked at 80°C and 40Khz for 1 hour, ultrasonically cleaned with isopropanol for 10 minutes, and then plasma treated at 100W for 5 minutes to finally obtain the gradient film layer in the required area.

[0068] Embodiments 15 to 17 are a method for processing a gradient film layer disclosed in the present invention, which is different from Embodiment 14 in that the mask layers are Ti, Al, and Mo films in sequence.

[0069] Embodiment 18 is a method for processing a micro-nano structure with a gradient depth disclosed in the present invention, which is different from Embodiment 1 in that it comprises the following steps:

[0070] S1, according to the processing method of the gradient film layer of Example 14, obtaining a substrate with a gradient film layer;

[0071] S2 first uses a spin coating machine to evenly coat a layer of AZ4562 photoresist on the surface of the gradient film layer to obtain a photoresist film, uses an EBL device, a laser direct writing lithography machine or a contact lithography machine to expose the photoresist film, and then uses a developer to develop the sample, and then plasma treats it at 100~300W for 1~5min to form a grating groove in the gradient structure area of ​​the photoresist film, and ensure that there is no residual glue in the grating groove;

[0072] S3 is etched and de-resisted by ICP equipment to obtain a straight grating. The Source Power of ICP is controlled to be 500W, BiasPower to be 150W, the cavity pressure to be 14mtorr, and CHF 3 The gas flow rate is 10 sccm, O 2 The gas flow rate is 16sccm, the etching rate of the gradient film is 7nm / s, and the etching stops after the substrate is reached, thus obtaining a straight grating with continuously changing depth. Figure 2 and Figure 3 , we can see the SEM images of the gradient depth straight grating at different depths, the magnification is 50K, and we can see that the depth does change and the change is uniform.

[0073] Example 19: is a method for processing a gradient depth micro-nano structure disclosed in the present invention. The difference from Example 18 is that in S1, a substrate with a gradient film layer is obtained according to the method for processing the gradient film layer of Example 2.

[0074] Example 20: A method for processing a gradient depth micro-nano structure disclosed in the present invention, which is different from Example 18 in that, in S3, etching and degumming are performed by a RIBE device to obtain a tilted grating, and the BMV of the RIBE device is controlled to be 500V, the BMI is 150mA, and the CHF 3 The gas flow rate of Ar is 8 sccm, the etching rate of the gradient film is 5.5 nm / s, and the etching stops after the substrate is etched, thus obtaining a tilted grating with a continuously changing depth. Figure 4 and Figure 5 , we can see the SEM images of the gradient depth tilted grating at different depths, the magnification is 50K, and we can see that the depth does change and the change is uniform.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for processing a gradient film layer, characterized in that: The following steps are included: S11 prepares a substrate, and fixes a planar film layer on the surface of the substrate; S12 forms a sacrificial film layer with a gradient thickness on the surface of the planar film layer by gradient coating and / or exposure and development, and an etching selectivity ratio exists between the planar film layer and the sacrificial film layer; S13 removes the sacrificial film layer and the planar film layer above the gradient surface in sequence through dry etching based on the etching selectivity, and obtains a substrate with a gradient film layer through post-processing after the etching is completed.

2. The method for processing a gradient film layer according to claim 1, characterized in that: In the S11, the planar film layer is Si, SiO2, SiN x , TiO2, Al2O3, AlN or a composite film of one or more thereof.

3. The method for processing a gradient film layer according to claim 1, characterized in that: In S12, a sacrificial film layer with a gradient thickness is directly formed on the surface of the planar film layer by gradient coating, and the sacrificial film layer is a composite film of one or more of Cr, Ti, Al, Si, and Mo, and the etching selectivity ratio between the planar film layer and the sacrificial film layer is controlled to be in the range of 5 to 83:

1.

4. The method for processing a gradient film layer according to claim 1, characterized in that: In the S12, a sacrificial film layer with uniform thickness is first formed on the surface of the planar film layer, and the sacrificial film layer is a photoresist film. Then, an optical mask with a gradient thickness is prepared, and the sacrificial film layer with uniform thickness is exposed and developed to obtain a sacrificial film layer with a gradient thickness. The etching selectivity ratio between the planar film layer and the sacrificial film layer is controlled to be in the range of 1:8~60.

5. The method for processing a gradient film layer according to claim 4, characterized in that: In S12, a mask layer with a gradient thickness is formed directly on the surface of the blank mask by gradient coating in advance, and the mask layer is a composite thin film of one or more of Cr, Ti, Al, and Mo to obtain an optical mask with a gradient thickness.

6. The method for processing a gradient film layer according to claim 1, characterized in that: In the S13, the specific implementation method of the dry etching is to perform dry etching through a RIBE device, control the BMV of RIBE to 300~600V, the BMI to 40~400mA, the gas flow rate of Ar to 0~80sccm, the gas flow rate of CF4 to 0~30sccm, the gas flow rate of CHF3 to 0~30sccm, the gas flow rate of O2 to 0~30sccm, and the gas flow rate of SF6 to 0~30sccm.

7. The method for processing a gradient film layer according to claim 1, characterized in that: In S13, the specific implementation method of the dry etching is to perform dry etching through ICP-RIE equipment, control the Source Power of ICP to 300~600W, the Bias Power to 100~200W, the gas flow rate of Ar to 0~80sccm, the gas flow rate of CF4 to 0~30sccm, the gas flow rate of CHF3 to 0~30sccm, the gas flow rate of O2 to 0~30sccm, and the gas flow rate of SF6 to 0~30sccm.

8. A method for processing a micro-nano structure with a gradient depth, characterized in that: The following steps are included: S1 The method for processing a gradient film layer according to any one of claims 1 to 7, to obtain a substrate with a gradient film layer; S2 forming a photoresist film on the surface of the gradient film layer, and patterning the photoresist film in the gradient structure area; S3 removes the photoresist film and the gradient film layer in the gradient structure area in sequence by etching and removing the resist. After the etching is completed, post-processing is performed to obtain a gradient depth micro-nano structure.

9. The method for processing a micro-nano structure with a gradient depth according to claim 8, characterized in that: In S2, the thickness of the photoresist film is controlled to be 0.1-10.0 μm, and the photoresist of the photoresist film is Zep520 photoresist, AZ1500 photoresist, AZ1518 photoresist, APR-5350 photoresist or AZ4562 photoresist.

10. The method for processing a micro-nano structure with a gradient depth according to claim 8, characterized in that: In S3, the specific implementation method of the etching and degumming is to perform etching and degumming through ICP-RIE equipment, control the gas flow rate of Ar to 0~80sccm, the gas flow rate of CF4 to 0~30sccm, the gas flow rate of CHF3 to 0~30sccm, the gas flow rate of O2 to 0~30sccm, the gas flow rate of SF6 to 0~30sccm, the RF power to 100~800W, the Bias power to 50~300W, the chamber pressure to 5~20mTorr, and the etching rate to 3~10nm / s. After etching the gradient film layer to the required depth, use N-methyl-2-pyrrolidone (NMP) or acetone for degumming and cleaning, and then perform Plasma treatment at 100~300W for 1~10min.

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