A method for controlling oblique etching and application thereof

Abstract

This invention relates to a method and application for controlling tilted etching, belonging to the field of micro-etching technology. The invention modulates the electric field distribution near the etched area by adding a metal modulator, thereby altering the movement direction of etching ions. Controllable tilted etching can be achieved by customizing different types of metal modulators.

Description

Technical Field

[0001] This invention relates to the field of micro-etching technology, and in particular to a method and application for tilt etching control. Background Technology

[0002] Surface relief etching, due to its ability to flexibly control the phase, amplitude, and polarization of the light field, has important applications in fields such as augmented reality (AR), virtual reality (VR), and optical communication.

[0003] Existing tilting dry etching processes mainly employ substrate tilting, mask design, or customized etching equipment modifications. However, when processing high-refractive-index, high-hardness media, these methods inherently suffer from difficulties in simultaneously achieving precise angle control, sidewall quality, and etching uniformity. The actual etching angle of the substrate tilting method exhibits a non-linear relationship with the substrate tilt angle and is significantly affected by process parameters such as chamber pressure and RF power, resulting in poor angle controllability. Physical bombardment-based etching easily causes sidewall sputtering damage, leading to scattering losses. While mask design can achieve relatively smooth sidewalls, it has a narrow angle control range and tends to form curved profiles, failing to meet stringent structural dimensional requirements. Equipment modification significantly increases process complexity and cost. More importantly, none of the above methods can achieve structures with gradually varying tilt angles in different regions.

[0004] Therefore, there is an urgent need for an etching process that can precisely control the tilt angle and form a gradually tilted structure. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and application for controlling gradient tilt etching.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a tilting etching control method, comprising placing a metal modulator on at least one side of the area to be etched when the etching machine performs plasma etching on the area to be etched of the etching layer; the metal modulator is connected to the lower electrode of the etching machine.

[0007] This invention utilizes a specially designed metal modulator to alter the direction of the etched plasma, causing it to move at an angle to achieve tilted etching. The core function of the metal modulator is to establish a controlled local plasma environment on the surface of the sample to be etched, thereby changing the surrounding electric field distribution. Since the metal modulator is connected to the electrodes under the etching stage, its surface can be considered to have zero potential; therefore, the electric field of the etching cavity is modulated by the surface of the metal modulator. On surfaces far from the metal modulator, the electric field distribution is perpendicular to the surface of the area to be etched, and the plasma moves perpendicular to the electric field direction, etching a vertical structure. Near the metal modulator, the electric field distribution is altered by the modulator, tilting towards it, causing the plasma to move closer to the modulator and act at an angle on the surface of the material to be etched, achieving gradual tilted etching. Therefore, according to actual etching needs, a metal modulator of a specific shape and size can be placed near the sample to be etched to achieve gradual tilted etching.

[0008] In a preferred embodiment of the tilt etching control method of the present invention, the distance between the metal modulator and one edge of the region to be etched is 0~3000μm. This distance is the distance between the edge of the metal modulator near the region to be etched and the edge of the region to be etched near the metal modulator. When the distance is greater than this range, the control effect of the metal modulator weakens or even fails.

[0009] In a preferred embodiment of the present invention, the metal modulator comprises a metal, including one or more of aluminum alloy, stainless steel, and copper; the material of the etching layer includes any one of TiO2, Si3N4, Ta2O5, Si, SiO2, and GaN. These materials cover a wide range of choices from high refractive indices to traditional optical media, enabling this method to flexibly adapt to different application scenarios, from visible light AR / VR devices to infrared optical elements. The selected metal has good conductivity, ensuring a uniform distribution of the potential on the modulator surface, which is beneficial for forming a stable local electric field.

[0010] In a preferred embodiment of the present invention, the shape of the metal modulator includes any one of block, strip, and ring shapes; the vertical cross-section of the metal modulator is one or more of quadrilateral, polygon, semicircle, and triangle. Through differentiated design of the modulator shape and its cross-sectional geometry, the spatial distribution of the surrounding electric field can be effectively altered, thereby generating specific deflection control of the ion incident trajectory in different regions, providing a structural basis for flexible control of gradual angle changes or zoned angles. The metal modulator can be a cuboid with a length of 10-50 mm, a width of 5-20 mm, and a height of 2-5 mm, or a ring with an outer diameter of 5-15 mm, an inner diameter of 3-10 mm, and a height of 2-5 mm.

[0011] In a preferred embodiment of the present invention, the method further includes pretreatment of the area to be etched in the etching layer, comprising the following steps: S1. Deposit an etching layer material on a glass substrate; the glass substrate includes either K9 glass or ITO glass. S2. A chromium conductive layer is plated onto the substrate material; S3. Spin-coat photoresist onto the chromium conductive layer and dry it; S4. Transfer the planar structural pattern to be etched onto the photoresist for exposure and development; S5. Deposit a mask onto the developed substrate; S6. Remove the photoresist to obtain the etchable area of ​​the processed etching layer.

[0012] As a preferred embodiment of the above pretreatment method, the thickness of the etching layer material is 350-500 nm.

[0013] As a preferred embodiment of the above pretreatment method, the thickness of the chromium conductive layer is 10-20 nm.

[0014] As a preferred embodiment of the above pretreatment method, the mask material is either chromium or silicon dioxide, and the mask thickness is 15-25 nm.

[0015] As a preferred embodiment of the above pretreatment method, the mask deposition rate in step S5 is 0.3–0.5 Å / s. Using a lower deposition rate facilitates the full migration and orderly arrangement of mask atoms on the substrate surface, thereby obtaining a dense and uniform thin film.

[0016] Compared with existing technologies, the advantages of this invention are as follows: By introducing a metal modulator near the area to be etched, this invention changes the electric field distribution near the area to be etched, thereby changing the direction of plasma etching and achieving multi-directional, large-area gradient tilt etching. Furthermore, the shape of the metal modulator can be customized according to actual needs to achieve etching at different tilt angles and directions. Attached Figure Description

[0017] Figure 1 The simulation results of electric field modulation in the etching method of Example 1 are shown. Figure 2-1 ~4 are cross-sectional SEM images of the etching results obtained by the etching method in Example 1 at 0μm, 1000μm, 2000μm, and 3000μm from the edge of the etched area near the metal modulator, respectively. Figure 3-1~5 are cross-sectional SEM images of the etching results obtained by the etching method in Example 1 at 0 μm, 500 μm, 1500 μm, 2500 μm and 3000 μm from the edge of one of the metal modulators in the etched area. Figure 4-1 SEM images of the surface morphology of the etched area obtained by the etching method in Example 3 are shown in Figures 9, which are the upper left, upper, upper right, left, center, right, lower, lower and lower right portions of the etched area. The arrows in the figures indicate the tilt direction of the etched area. Figure 5 The relationship between the tilt angle obtained by the etching method in Example 1 and the distance between the metal modulator and the etched area; Figure 6 The relationship between the tilt angle and the distance between the metal modulator and the etched area obtained by the etching methods in Examples 3, 4, and 5; Figure 7 The images show cross-sectional SEM images of the etching results obtained by the etching method in Comparative Example 1 at distances of 500 μm, 1500 μm, and 2500 μm from one edge of the etched area. Detailed Implementation

[0018] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0019] The etching instrument used in this embodiment of the invention is the Oxford PlasmaPro.

[0020] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.

[0021] Example 1 One embodiment of the tilt etching control method of the present invention is as follows: S1. A 400 nm Si3N4 thin film was prepared on a K9 glass substrate by PECVD.

[0022] S2. A 15 nm chromium conductive layer is deposited on a Si3N4 thin film using electron beam evaporation.

[0023] S3. Spin-coat polymethyl methacrylate onto the film at a speed of 4000 r / s for 60 s, and then dry at 180℃ for 20 min.

[0024] S4. Transfer the planar structure pattern to be etched onto the photoresist and perform UV exposure curing. Rinse with developer for 30 seconds to develop.

[0025] S5. Electron beam evaporation was used to deposit 15 nm SiO2 as a mask on the surface of the developed substrate at a deposition rate of 0.4 Å / s.

[0026] S6. Remove the photoresist using a stripping solution; S7. Place a rectangular 6061 aluminum alloy metal modulator with a length of 30 mm, a width of 5 mm, and a height of 3 mm on one side edge of the area to be etched on the lower electrode platform of the etching machine.

[0027] S8. The substrate was etched using inductively coupled plasma reactive ion etching (ICP-RIE) with SF6 10 mL / min, CHF3 40 mL / min, and O2 6 mL / min as the etching gases. The radio frequency bias power was 50 W, the inductively coupled plasma source power was 1200 W, and the etching time was 210 s, resulting in a gradually tilted etched structure.

[0028] Example 2 One embodiment of the tilt etching control method of the present invention is as follows: S1. A 200 nm TiO2 thin film was prepared on an ITO glass substrate by electron beam evaporation.

[0029] S2. A 15 nm chromium conductive layer is deposited on the TiO2 thin film using electron beam evaporation.

[0030] S3. Spin-coat polymethyl methacrylate onto the film at a speed of 4000 r / s for 60 s, and then dry at 180℃ for 20 min.

[0031] S4. Transfer the planar structure pattern to be etched onto the photoresist and perform UV exposure curing. Rinse with developer for 30 seconds to develop.

[0032] S5. Electron beam evaporation was used to deposit 20 nm of chromium as a mask on the surface of the developed substrate at a deposition rate of 0.4 Å / s.

[0033] S6. Remove the photoresist using a stripping solution; S7. On the lower electrode platform of the etching machine, place a rectangular 6061 aluminum alloy metal modulator with a length of 30 mm, a width of 5 mm, and a height of 3 mm on each side at a distance of 1500 μm from the center of the area to be etched.

[0034] S8. The substrate was etched using inductively coupled plasma reactive ion etching (ICP-RIE) with SF6 10 mL / min, CHF3 15 mL / min, and O2 2 mL / min as the etching gases. The radio frequency bias power was 90 W, the inductively coupled plasma source power was 1200 W, and the etching time was 5 min, resulting in a gradually tilted etched structure.

[0035] Example 3 This invention provides an embodiment of the tilt etching control method. The difference between this embodiment and Embodiment 1 is that the metal modulator is a 6061 aluminum alloy 304 ring with an inner diameter of 5 mm and a height of 3 mm, and the etching area is inside the ring.

[0036] Example 4 This invention provides an embodiment of the tilt etching control method. The difference between this embodiment and Embodiment 1 is that the metal modulator is a 6061 aluminum alloy 304 ring with an inner diameter of 5 mm and a height of 2 mm, and the etching area is inside the ring.

[0037] Example 5 This invention provides an embodiment of the tilt etching control method. The difference between this embodiment and Embodiment 1 is that the inner diameter of the placed 6061 aluminum alloy metal modulator is 10 mm and the height is 3 mm, and the etching area is inside the ring.

[0038] Example 6 This invention provides an embodiment of the tilt etching control method. The difference between this embodiment and Embodiment 1 is that the metal modulator is located 1500 μm away from the edge of the area to be etched.

[0039] Comparative Example 1 This comparative example uses a substrate tilting method for etching. The only difference between this comparative example and Example 2 is that a metal modulator is not used in step S7. The prepared substrate is fixed on the lower electrode of the etching machine using a specific tilting carrier, so that the surface of the substrate forms a fixed 20° tilt angle with the plane of the lower electrode.

[0040] Example of effect This effect example examines the etching effect of the tilt etching control method in Examples 1-4 and Comparative Example 1. Specifically, it examines the relationship between the tilt angle and the distance between the metal modulator and the etching area. The results are shown in Tables 1-3. In Table 1, distance a is the distance from the edge of the etching area near the metal modulator in the etching structure. In Table 2, distance b is the distance from the center of the circular metal modulator in the etching structure. When the distance is negative, it is the distance extended in the opposite direction of the positive distance. In Table 3, distance c is the distance from the edge of the etching area. The tilt angle is the angle between the tilt direction near the metal modulator and the vertical direction. When the tilt angle is negative, it is the angle between the opposite direction of the tilt angle and the vertical direction.

[0041] Table 1 Table 2 Table 3 As can be seen from Tables 1 and 2, the etching method of the present invention can obtain a gradually tapered, tilted etched structure. For example... Figure 1 As shown, the metal regulator of this invention can change the surrounding electric field distribution, thereby changing the etching direction of the etching ions and obtaining an etched structure with a tilted gradient. The etching results of Example 1 are as follows. Figure 2 As shown, the metal modulator is in Figure 2-1 On the right side, from 1 to 4, are the etched structure cross-sections away from the metal modulator; the etching results of Example 2 are as follows. Figure 3 As shown, the metal modulator in Figure 3-1 left side and Figure 3-5 On the right side, the etched structure cross-sections, numbered 1 to 5, are located sequentially between the two metal modulators; the etching results obtained in Example 3 are as follows. Figure 4 As shown, the area to be etched is located in the center of the annular metal modulator. The resulting etched structure gradually tilts away from the metal modulator, and the angle of this gradually tilted etched structure is linearly related to the distance. The etching result obtained in Comparative Example 1 is shown below. Figure 7 As shown in Table 3, the tilt angle of the etched structure was uniform after etching. Measurements showed that the tilt angle throughout the entire area was around 20°, failing to achieve a gradual distribution of the tilt angle. This indicates that the substrate tilting method not only cannot achieve a gradual change in angle, but also that the tilt angle always exhibits a non-linear relationship with the substrate tilt angle, resulting in poor controllability.

[0042] Fitting the angle and distance of the gradually tilted etched structure, such as... Figure 5 , 6As shown, the closer the etched structure is to the metal modulator, the larger the tilt angle of the etching, and vice versa. Therefore, different metal modulators can be customized to etch specific gradient tilted etched structures as needed.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for controlling tilted etching, characterized in that, The method includes placing a metal modulator on at least one side of the area to be etched when performing plasma etching on the area to be etched using an etching machine; the metal modulator is connected to the lower electrode of the etching machine.

2. The tilt etching control method as described in claim 1, characterized in that, The distance between the metal modulator and one edge of the area to be etched is 0~3000μm.

3. The tilt etching control method as described in claim 1, characterized in that, The metal modulator comprises a metal, including one or more of aluminum alloy, stainless steel, and copper; the etching layer is made of TiO2, Si3N4, or Ta2O. 5、 Any one of Si, SiO2, and GaN.

4. The tilt etching control method as described in claim 1, characterized in that, The shape of the metal modulator can be any one of block, strip, or ring.

5. The tilt etching control method as described in claim 1, characterized in that, The vertical cross-section of the metal modulator is one or more of the following: quadrilateral, polygon, semicircle, and triangle.

6. The tilt etching control method as described in claim 1, characterized in that, It also includes pretreatment of the area to be etched in the etching layer, including the following steps: S1. Deposit an etching layer material on a glass substrate; the glass substrate includes either K9 glass or ITO glass. S2. A chromium conductive layer is plated onto the substrate material; S3. Spin-coat photoresist onto the chromium conductive layer and dry it; S4. Transfer the planar structural pattern to be etched onto the photoresist for exposure and development; S5. Deposit a mask onto the developed substrate; S6. Remove the photoresist to obtain the etchable area of ​​the processed etching layer.

7. The tilt etching control method as described in claim 6, characterized in that, The thickness of the etched layer material is 350~500 nm.

8. The tilt etching control method as described in claim 6, characterized in that, The thickness of the chromium conductive layer is 10~20nm.

9. The tilt etching control method as described in claim 6, characterized in that, The mask material is either chromium or silicon dioxide; the mask thickness is 15~25 nm.

10. The tilt etching control method as described in claim 6, characterized in that, In step S5, the mask deposition rate is 0.3~0.5 Å / s.

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