Reactive ion beam etching method of large-size diffractive optical element and vacuum etching machine

Abstract

The invention relates to a reactive ion beam etching method of a large-size diffractive optical element and a vacuum etching machine. The method comprises the following steps: in a reactive ion beam main etching stage, a main ion source emits a high-energy main etching reactive ion beam to scan and etch the whole surface of the large-size diffractive optical element; in a selective area reaction ion beam ashing stage, an auxiliary ion source is controlled to emit a low-energy ashing reaction ion beam, and scanning ashing processing is carried out on a central effective area of the large-size diffractive optical element; in the reaction ion beam edge removal stage, the auxiliary ion source is controlled to emit edge removal reaction ion beams with set process parameters, and edge thickening photoresist of the large-size diffractive optical element is removed; and taking out the large-size diffraction optical element finished product after etching is completed. According to the technical scheme, the production cost of reactive ion beam etching of the large-size diffractive optical element can be reduced, and the production efficiency can be improved.

Description

Technical Field

[0001] This application relates to the field of ion beam etching technology, and in particular to a reactive ion beam etching method and vacuum etching machine for large-size diffractive optical elements. Background Technology

[0002] Reactive ion beam etching (RIBE) is an advanced dry etching process developed based on ion beam etching (IBE). It generates a beam containing reactive ions by introducing specific reactive gases (such as CHF3, CF4, Cl2, BCl3, etc.) into an ion source. During the etching process, not only physical sputtering occurs, but more importantly, chemically active ions react with the material surface to generate volatile products, thus achieving anisotropic and high-selectivity etching. RIBE combines the high precision of ion beam etching with the high efficiency of reactive ion beam etching (RIE), offering significant advantages in the fabrication of micro / nano optical components, especially large-area diffractive optical components (such as gratings) where extremely high uniformity of sidewall morphology and etching depth is required.

[0003] In the fabrication of large-area gratings, RIBE scanning etching is a crucial step in forming high-precision, high-fidelity grating grooves. By selecting appropriate reactive gases and precisely controlling ion beam energy, beam current density, incident angle, and the scanning motion of the sample stage, high-rate, highly uniform etching with smooth sidewalls can be achieved. Furthermore, by switching to oxygen and reducing beam current energy, RIBE technology can also be used for the "ashing" process of photoresist. The ashing process effectively smooths photoresist grating lines, removes burrs and residual substrate film, and can correct the grating duty cycle within a certain range, improving the yield of the front-end holographic lithography process.

[0004] Currently, in the complete fabrication process of large diffractive optical elements, each key process step usually needs to be carried out separately on different dedicated equipment. This process requires high equipment purchase and maintenance costs, resulting in high production costs. The transfer of samples between different equipment increases the risk of contamination, and the overall production efficiency is low, making it difficult to be widely used in the industry. Summary of the Invention

[0005] To address one of the aforementioned shortcomings, this application provides a reactive ion beam etching method and a vacuum etching machine for large-size diffractive optical elements, thereby reducing production costs and improving production efficiency.

[0006] A reactive ion beam etching method for large-size diffractive optical elements is applied to a multi-ion source vacuum etching machine. The ion beam etching system includes: a vacuum chamber, a sample stage, a main ion source, and at least one auxiliary ion source disposed within the vacuum chamber. The etching method includes: The large-size diffractive optical element that has been patterned by photolithography is mounted on the sample stage and fixed, the vacuum chamber is closed and evacuated to a high vacuum. In the reactive ion beam main etching stage, the main ion source is controlled to emit a high-energy main etching reactive ion beam, and the sample stage is controlled to move. The main etching reactive ion beam is used to scan and etch the entire surface of the large-size diffractive optical element. In the selected area reactive ion beam ashing stage, the auxiliary ion source is controlled to emit a low-energy ashing reactive ion beam, and the sample stage and auxiliary ion source are controlled to move. The ashing reactive ion beam is used to scan and ashing the central effective area of ​​the large-size diffractive optical element. In the reactive ion beam edge removal stage, the auxiliary ion source is controlled to emit an edge removal reactive ion beam with set process parameters. The sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source. The edge removal reactive ion beam is used to remove the thickened photoresist at the edge of the large-size diffractive optical element. After completing the reactive ion beam main etching stage, the selected area reactive ion beam ashing stage, and the reactive ion beam edge removal stage, the finished large-size diffractive optical element is taken out.

[0007] A reactive ion beam etching method for large-size diffractive optical elements is applied to a multi-ion source vacuum etching machine. The ion beam etching system includes: a vacuum chamber, a sample stage, a main ion source, and at least one auxiliary ion source disposed within the vacuum chamber. The etching method includes: The large-size diffractive optical element that has been patterned by photolithography is mounted on the sample stage and fixed, the vacuum chamber is closed and evacuated to a high vacuum. In the reactive ion beam edge removal stage, the auxiliary ion source is controlled to emit an edge removal reactive ion beam with set process parameters. The sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source. The edge removal reactive ion beam is used to pre-remove the thickened photoresist at the edge of the large-size diffractive optical element. After completion, the auxiliary ion source is turned off. In the reactive ion beam main etching stage, the main ion source is controlled to emit a high-energy main etching reactive ion beam, and the sample stage is controlled to move. The main etching reactive ion beam is used to scan and etch the entire surface of the large-size diffractive optical element. In the selected area reactive ion beam ashing stage, the auxiliary ion source is controlled to emit a low-energy ashing reactive ion beam, and the sample stage and auxiliary ion source are controlled to move. The ion beam spot of the ashing reactive ion beam is used to scan and ashing the central effective area of ​​the large-size diffractive optical element. After completing the reactive ion beam main etching stage, the selected area reactive ion beam ashing stage, and the reactive ion beam edge removal stage, the finished large-size diffractive optical element is taken out.

[0008] In some embodiments, the reactive ion beam etching method for large-size diffractive optical elements includes, in the main reactive ion beam etching stage: Start the main ion source and introduce the preset main etching reaction gas; Control the main ion source to emit a high-energy main etching reaction ion beam; The sample stage is controlled to perform a combination of uniform rotation and tilting motion, so that the surface of the entire large-size diffractive optical element is uniformly scanned and etched by reactive ion beam, transferring the morphology of the photoresist pattern into the substrate material. After the main etching is completed, the main ion source and the main etching reaction gas are turned off.

[0009] In some embodiments, the reactive ion beam etching method for large-size diffractive optical elements includes a selected area reactive ion beam ashing stage, comprising: Start the auxiliary ion source and introduce the ashing reaction gas; Control the auxiliary ion source to emit a low-energy ashing reaction ion beam; The sample stage is controlled to move so that the ion beam spot of the auxiliary ion source scans the central effective region of the large-size diffractive optical element, and the central effective region of the large-size diffractive optical element is ashed using the ashing reactive ion beam.

[0010] In some embodiments, the reactive ion beam etching method for large-size diffractive optical elements involves controlling the movement of the sample stage to scan the central effective region of the large-size diffractive optical element with the ion beam spot of the auxiliary ion source, and using the ashing reactive ion beam to ashing the central effective region of the large-size diffractive optical element, including: Calculate the second coordinate parameters of the central effective region that needs to be ashing; The sample stage is controlled according to the second coordinate parameters to drive the movement of the large-size diffractive optical element, so that the ion beam spot of the ashing reaction ion beam of the auxiliary ion source only covers the central effective optical area of ​​the large-size diffractive optical element, and the edge area of ​​the large-size diffractive optical element is always outside the coverage of the beam spot. During the ashing process, the sample stage is controlled to reciprocate for a preset time to remove residual photoresist film, smooth the grating sidewalls, correct the duty cycle, and eliminate standing wave effects.

[0011] In some embodiments, the reactive ion beam etching method for large-size diffractive optical elements includes a reactive ion beam edge removal stage comprising: Start the auxiliary ion source and introduce edge-removed reaction gases; The auxiliary ion source is adjusted to emit a medium-to-high energy edge removal reaction ion beam based on the edge thickness. The sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source, and the edge-removing reactive ion beam is used to scan the thickened photoresist at the edge of the large-size diffractive optical element.

[0012] In some embodiments, the reactive ion beam etching method for large-size diffractive optical elements involves controlling the sample stage movement to move the edge region of the large-size diffractive optical element under the ion beam spot of the auxiliary ion source, and using the edge-removing reactive ion beam to scan the edge-thickened photoresist of the large-size diffractive optical element, including: Calculate the third coordinate parameters of the edge region of a large-size diffractive optical element; The sample stage is moved according to the third coordinate parameters to move the outer edge region of the large-size diffractive optical element to directly below the ion beam spot of the auxiliary ion source. The sample stage is controlled to rotate continuously. A large-size diffractive optical element is used to perform uniform scanning by removing the annular edge region of the reactive ion beam.

[0013] In some embodiments, the reactive ion beam etching method for large-size diffractive optical elements further includes, before the main reactive ion beam etching stage: Start the auxiliary ion source and introduce the cleaning working gas; A low-energy cleaning reaction ion beam is emitted using an auxiliary ion source. The sample stage is controlled to move, and the surface of the entire large-size diffractive optical element is cleaned and activated by scanning the reactive ion beam of the auxiliary ion source.

[0014] A vacuum etching machine includes: a vacuum chamber, a sample stage, a main ion source, at least one auxiliary ion source, and a gas supply system; the vacuum etching machine is used to perform main etching, ashing, and edge removal processing on large-size diffractive optical elements using the reactive ion beam etching method described above.

[0015] In some embodiments, the main ion source of the vacuum etching machine is fixedly installed on the side wall of the vacuum chamber; The auxiliary ion source is mounted on the side wall of the vacuum chamber via a linear motion structure, which is used to push the auxiliary ion source in... z Move along the axis; The sample stage is mounted on the bottom surface of the vacuum chamber via a planar motion structure, which is used to push the sample stage in... xy It moves on a plane.

[0016] As in the above embodiments, An ion beam etching system with multiple ion sources is provided, comprising a vacuum chamber, a sample stage, a main ion source, and at least one auxiliary ion source housed within the vacuum chamber. After a large-size diffractive optical element is loaded onto this ion beam etching system, reactive ion beam main etching is performed. The main ion source is controlled to emit a high-energy reactive ion beam, and the sample stage is controlled to move, using the main reactive ion beam to scan and etch the entire surface of the large-size diffractive optical element. Then, selected area reactive ion beam ashing is performed. The auxiliary ion source is controlled to emit a low-energy ashing reactive ion beam, and the sample stage and auxiliary ion source are controlled to move, using the ashing reactive ion beam to ashing the center of the large-size diffractive optical element. The effective area is scanned and ashed; then reactive ion beam edge removal is performed. The auxiliary ion source is controlled to emit an edge removal reactive ion beam with set process parameters, and the sample stage is controlled to move the edge region of the large-size diffractive optical element under the ion beam spot of the auxiliary ion source. The edge removal reactive ion beam is used to remove the thickened photoresist at the edge of the large-size diffractive optical element; finally, the finished large-size diffractive optical element is obtained. This technical solution completes key processes such as edge removal, deep reactive ion beam etching, and selective area ashing and shaping in one vacuum cycle and one clamping, reducing production equipment costs and improving etching efficiency. It is suitable for widespread use in the industry.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a block diagram of an example vacuum etching machine. Figure 2 This is a flowchart of a reactive ion beam etching method for a large-size diffractive optical element according to one embodiment; Figure 3 This is a flowchart of a reactive ion beam etching method for a large-size diffractive optical element according to another embodiment; Figure 4 This is another example of a vacuum etching machine structure diagram. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0020] Those skilled in the art will understand that, unless otherwise stated, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the word “comprising” as used in this application’s specification means the presence of the stated feature, integer, step, or operation, but does not preclude the presence or addition of one or more other features, integers, steps, or operations.

[0021] This application addresses the drawbacks of high cost and low overall production efficiency in reactive ion beam etching (RIE) processes for large-size diffractive optical elements. It proposes a RIE method and vacuum etching machine for large-size diffractive optical elements. This etching process completes different steps in a single process, including etching, ashing, and edge removal to address the "edge effect" of photoresist coating. Through the coordinated operation of dual ion sources with flexible switching of reactive gases and independently adjustable parameters, multiple processes such as RIE, selective ashing, and edge removal are efficiently and accurately completed within the same vacuum chamber and in a single setup. This reduces production costs, lowers the risk of sample contamination, and improves overall production efficiency, making it suitable for widespread application in the industry.

[0022] refer to Figure 1 As shown, Figure 1 This is a block diagram of an example vacuum etching machine. Figure 1 This is a side view. The reactive ion beam etching method of this application embodiment is applied to the multi-ion source vacuum etching machine. As shown in the figure, the vacuum etching machine adopts a multi-ion source ion beam etching system, which may include: a vacuum chamber 01, and a sample stage 02, a main ion source 03 and at least one auxiliary ion source 04 disposed in the vacuum chamber. It also includes a gas supply system 05 for supplying gas to the vacuum chamber, vacuum pumping equipment matched with the vacuum chamber 01 and other related accessories necessary for the vacuum etching machine (not shown in the figure).

[0023] The main structural design of the multi-ion source ion beam etching system provided in the above example of this application can be as follows: Vacuum chamber 01 can provide a vacuum environment, which is evacuated by vacuum equipment to meet the requirements of the etching process.

[0024] The sample stage 02 can be used to support and fix the substrate of the large-size diffractive optical element 201. For example, the sample stage can have multi-degree-of-freedom motion capability, through corresponding motion mechanisms (such as...). xy Driven by planar motion mechanisms, three-dimensional platforms, etc., it can achieve rotation (θ direction) around its central axis and movement within a horizontal plane (bottom surface of the vacuum cavity). x, yThe directional translation function, along with an optional tilt function, allows for precise control of the ion beam's incident angle; the sample stage can be controlled by an independent controller or a unified control system.

[0025] The main ion source 03 can be an ion source capable of generating a high-density, large-area uniform ion beam. Preferably, the main ion source can be a large rectangular beam spot ion source. In some applications where the etching rate requirement is not extreme, the main ion source can also be a movable circular source. For example, the main ion source is fixedly installed, and its gas inlet is connected to the gas supply system, which can introduce highly chemically active gases required for the main etching (such as a CF4 / CHF3 / O2 mixed gas for etching SiO2 / Si, or a Cl2 / BCl3-based gas for etching III-V materials). The main ion source is the core component for performing high-rate, high-depth uniform main etching. The main ion source can be controlled by an independent controller or a unified control system.

[0026] For the auxiliary ion source 04, it can be an ion source whose energy and beam current can be finely adjusted and controlled independently of the main ion source, and there is at least one such source. Preferably, the auxiliary ion source can be a small to medium-sized circular beam spot ion source. The auxiliary ion source is installed through a motion mechanism and can perform precise up-and-down reciprocating motion in a direction perpendicular to the bottom surface of the vacuum cavity (z-axis). For example, the auxiliary ion source can also move in the horizontal direction to increase the degree of freedom of rotation angle and expand the processing flexibility. Its gas inlet is connected to the gas supply system and has the ability to quickly switch gases. When performing ashing or edge removal, the auxiliary ion source can be introduced with an inert gas (such as Ar) or a low-activity, high-selectivity reactive gas (such as a small amount of O2 for the mild oxidation removal of organic photoresist). The auxiliary ion source can also be controlled by an independent controller or a unified control system.

[0027] The beam coverage areas of the main ion source 03 and the auxiliary ion source 04 overlap within the movement range of the sample stage. By coordinating the movement of the sample stage and the position of the auxiliary ion source, a specific area on a large-size diffractive optical element can be bombarded by a specific ion beam.

[0028] The gas supply system 05 can provide various high-purity process gases to each ion source and has precise flow control and fast switching valves. It can be controlled by an independent controller or a unified control system to meet the gas supply requirements of different process steps. For ease of description of the embodiments, in the embodiments of this application, the sample stage 02, main ion source 03, auxiliary ion source 04, gas supply system 05, and vacuum pumping equipment of vacuum chamber 01 are all controlled by control system 06.

[0029] refer to Figure 2 As shown, Figure 2This is a flowchart of a reactive ion beam etching method for a large-size diffractive optical element according to one embodiment. The method includes the following steps: Step S11: Load the large-size diffractive optical element that has been patterned by photolithography onto the sample stage and fix it, close the vacuum chamber and evacuate to a high vacuum.

[0030] Specifically, a large-size diffractive optical element (such as a quartz substrate grating after holographic photolithography) that has been patterned by photolithography is mounted on a multi-degree-of-freedom sample stage and fixed. The vacuum chamber is closed, and the vacuum pumping equipment is controlled by the control system to pump the vacuum chamber to a high vacuum state, achieving the vacuum level required for the etching process.

[0031] In some embodiments, prior to the reactive ion beam main etching stage, the following steps are also included: The auxiliary ion source is activated, and the cleaning working gas is introduced; a low-energy cleaning reactive ion beam is emitted using the auxiliary ion source; the sample stage is moved, and the cleaning reactive ion beam from the auxiliary ion source is used to scan the entire surface of the large-size diffractive optical element for cleaning and activation.

[0032] Specifically, the control system activates the auxiliary ion source, controls the gas supply system to introduce argon (Ar) or an argon / oxygen mixture (Ar / O2), controls the auxiliary ion source to adjust to a low energy and beam state, and controls the sample stage to move so that the ion beam spot of the auxiliary ion source scans the entire surface of the large-size diffractive optical element. Through slight sputtering, contaminants and natural oxide layers on the surface of the large-size diffractive optical element are removed, providing a clean and activated surface for subsequent main etching. For example, low ion energy generally refers to 50-200 eV.

[0033] As described in the above embodiments, the in-situ pretreatment using a small source avoids the need to remove the sample for cleaning, greatly reducing the risk of contamination. Furthermore, the slight bombardment of the surface improves the initial uniformity of subsequent main etching. This achieves an integrated "cleaning-etching" process.

[0034] Step S12: In the main etching stage of the reactive ion beam, the main ion source is controlled to emit a high-energy main etching reactive ion beam, and the sample stage is controlled to move. The main etching reactive ion beam is used to scan and etch the entire surface of the large-size diffractive optical element. For example, high ion energy generally refers to 500-1500eV.

[0035] This step is the reactive ion beam main etching stage. The control system starts the main ion source and controls the gas supply system to introduce the preset main etching reactive gas into it, and sets the main ion source to high energy. First, a spatial coordinate system is constructed inside the vacuum cavity, and the first coordinate parameters of the large-size diffractive optical element are calculated. It is assumed that the center point of the large-size diffractive optical element is ( x 0 ,y 0 According to the radius of large-size diffractive optical elements r It is possible to calculate the coordinates of any point on the surface of a large-size diffractive optical element. x , y ):

[0036]

[0037] in, The motion range of the sample stage is determined based on the first coordinate parameters, and the sample stage is controlled to move within this range, so that the entire surface of the large-size diffractive optical element is uniformly scanned and etched by the reactive ion beam, and the morphology of the photoresist pattern is accurately transferred to the substrate material.

[0038] In some embodiments, the reactive ion beam main etching stage described above may include the following: S121, start the main ion source and introduce the preset main etching reaction gas.

[0039] For example, the control system can activate the main ion source and control the gas supply system to introduce the main etching reaction gas (such as a CHF3 / CF4 / O2 mixture) for the substrate material (such as SiO2).

[0040] S122 controls the main ion source to emit a high-energy main etching reaction ion beam.

[0041] Specifically, the control system sets the main ion source to a high-power and high-acceleration voltage state and controls it to emit the main etching reaction ion beam.

[0042] S123 controls the sample stage to perform a combined motion of uniform rotation and tilting, so that the surface of the entire large-size diffractive optical element is uniformly scanned and etched by reactive ion beam, transferring the morphology of the photoresist pattern into the substrate material.

[0043] For example, the control system drives the sample stage to rotate at a constant speed and perform two-dimensional motion scanning to perform uniform, high-rate etching over a large area, transferring the photoresist pattern to a quartz substrate.

[0044] S124, After the main etching is completed, the main ion source and the main etching reaction gas are shut down; specifically, after the main etching is completed, the main ion source is shut down and the gas supply system is cut off from supplying the main etching reaction gas to the main ion source.

[0045] Step S13: In the selected area reactive ion beam ashing stage, the auxiliary ion source is controlled to emit a low-energy ashing reactive ion beam, and the sample stage and auxiliary ion source are controlled to move. The ashing reactive ion beam is used to scan and ashing the central effective area of ​​the large-size diffractive optical element. For example, the low ion energy is generally 50-200 eV.

[0046] In this step, after the main etching, a suitable vacuum condition is achieved in the vacuum chamber. Then, the auxiliary reactive ion source is activated by the control system and adjusted to a low-energy ashing mode. A reactive gas optimized for ashing is introduced. By controlling the movement of the sample stage, the ion beam spot of the auxiliary ion source is precisely scanned to the central effective area of ​​the large-size diffractive optical element that needs to be ashed, while avoiding the edge area of ​​the large-size diffractive optical element. The chemical action of the reactive ions is used to gently remove the photoresist substrate and smooth the sidewalls. Furthermore, the photoresist can be selectively modified and the duty cycle can be corrected by adjusting the beam current parameters of the auxiliary ion source.

[0047] In some embodiments, the selected area reactive ion beam ashing stage described above may include: S131, start the auxiliary ion source and introduce the ashing reaction gas.

[0048] For example, the control system can activate the auxiliary ion source and control the gas supply system to switch the process gas to a gas suitable for photoresist ashing, such as oxygen (O2) or a mixture of oxygen and inert gas (O2 / Ar).

[0049] S132 controls the auxiliary ion source to emit a low-energy ashing reaction ion beam.

[0050] For example, the control system adjusts the energy and beam current of the auxiliary ion source to a low-energy-level ashing mode and controls it to emit an ashing reactive ion beam.

[0051] S133, control the movement of the sample stage so that the ion beam spot of the auxiliary ion source scans the central effective region of the large-size diffractive optical element, and use the ashing reactive ion beam to ashing the central effective region of the large-size diffractive optical element.

[0052] As an example, the above-mentioned ashing process may include the following: (1) Calculate the second coordinate parameters of the central effective area that needs to be ashing.

[0053] Specifically, during the ashing process, it is essential to precisely align the ion beam spot of the auxiliary ion source with the central effective region of the large-size diffractive optical element. Therefore, based on the size of the large-size diffractive optical element and process requirements, the second coordinate parameter of the central effective region needs to be calculated. This second coordinate parameter determines the coordinate range of the center of the large-size diffractive optical element. Assuming the radius of the central effective region is... r 1. The center point of a large-size diffractive optical element is ( x 0 , y 0 ), which allows us to calculate the coordinates of any point in the central effective region of a large-size diffractive optical element ( ). x 1, y 1):

[0054]

[0055] in, .

[0056] (2) The sample stage is controlled according to the second coordinate parameters to drive the movement of the large-size diffractive optical element, so that the ion beam spot of the ashing reaction ion beam of the auxiliary ion source only covers the central effective optical area of ​​the large-size diffractive optical element, and the edge area of ​​the large-size diffractive optical element is always outside the coverage range of the beam spot.

[0057] Specifically, the control system controls the sample stage to move the large-size diffractive optical element according to the second coordinate parameters, so that the ion beam spot of the auxiliary ion source only covers the central effective optical area of ​​the large-size diffractive optical element and performs reciprocating scanning, while the edge area of ​​the large-size diffractive optical element is always outside the coverage of the ion beam spot.

[0058] (3) During the ashing process, the sample stage is controlled to reciprocate for a preset time to remove the photoresist residue, smooth the grating sidewalls, correct the duty cycle, and eliminate the standing wave effect.

[0059] Specifically, the ashing process is preset for a certain duration according to the etching process requirements, in order to thoroughly remove residual photoresist film, smooth the grating sidewalls, correct the duty cycle, and eliminate the standing wave effect.

[0060] As described in the above embodiments, the scheme utilizes a movable auxiliary ion source to achieve precise selective processing, only performing ashing and shaping on the central area requiring high optical quality, avoiding unnecessary edge area processing, saving process time and consumables (gas), while protecting the integrity of the edge structure, and realizing the integration of "etching-selective ashing".

[0061] Step S14: In the reactive ion beam edge removal stage, the auxiliary ion source is controlled to emit an edge removal reactive ion beam with set process parameters, and the sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source. The edge-thickened photoresist of the large-size diffractive optical element is removed by using the edge removal reactive ion beam.

[0062] This step, performed after the ashing process (or before the main etching process), addresses the edge effects of large-size diffractive optical elements. The control system moves the sample stage, guiding the edge region of the large-size diffractive optical element under the ion beam spot of the auxiliary ion source. By adjusting the height of the auxiliary ion source and process parameters (energy and beam current, reactive gas flow rate, etc.), precise and efficient removal of the thickened photoresist at the edges is achieved. The activity of the reactive ions enhances the removal rate and effectiveness.

[0063] In some embodiments, the reactive ion beam edge removal stage described above may include the following: S141, start the auxiliary ion source and introduce the edge removal reaction gas.

[0064] For example, the control system activates the auxiliary ion source and introduces a gas suitable for removing photoresist (such as O2).

[0065] S142, the auxiliary ion source is adjusted to emit a medium-to-high energy edge removal reactive ion beam according to the edge thickness.

[0066] For example, the process parameters of the auxiliary ion source can be set according to the thickness of the edge adhesive. In this embodiment, the auxiliary ion source is set to a medium-high energy. For example, medium-high generally means an ion energy of 200-300 eV.

[0067] S143, control the movement of the sample stage to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source, and use the edge removal reactive ion beam to scan the edge thickened photoresist of the large-size diffractive optical element.

[0068] As an example, the above-described scanning process for edge-thickened photoresist of large-size diffractive optical elements may include the following steps: (1) Calculate the third coordinate parameters of the edge region of the large-size diffractive optical element.

[0069] Specifically, since the ion beam spot of the auxiliary ion source needs to be precisely aligned with the edge region of the large-size diffractive optical element, for example, assuming that the edge region is the edge part other than the central effective region, the third coordinate range can be obtained by subtracting the first and second coordinate ranges calculated above, which represents the annular region of the edge region of the large-size diffractive optical element.

[0070] (2) Control the sample stage to move according to the third coordinate parameters to move the outer edge region of the large-size diffraction optical element to directly below the ion beam spot of the auxiliary ion source.

[0071] Specifically, the control system controls the movement of the sample stage, precisely moving the outer edge region of the large-size diffractive optical element to directly below the ion beam spot of the auxiliary ion source, and ensuring that the ion beam spot is outside the central effective region.

[0072] (3) Control the sample stage to continuously rotate the large-size diffraction optical element and use the edge removal of the annular edge region of the reactive ion beam for uniform scanning.

[0073] Specifically, the control system can control the sample stage to rotate continuously, so that the ion beam spot can uniformly scan the entire annular edge region; at the same time, it can dynamically adjust the height of the auxiliary ion source on the z-axis to optimize the effect of the ion beam spot on the edge surface, so as to achieve efficient and smooth edge removal.

[0074] As described in the above embodiments, by precisely positioning the auxiliary ion source, controlling the movement of the sample stage, and adjusting the height of the auxiliary ion source, the defect concentration area at the edge of the large-size diffractive optical element can be precisely removed. This avoids the thick adhesive at the edge from cracking and contaminating the cavity in subsequent processes, thereby improving the overall yield and realizing the full-process integration of "edge processing-etching-ashing".

[0075] Step S15: After completing the reactive ion beam main etching stage, the selected area reactive ion beam ashing stage, and the reactive ion beam edge removal stage, the finished large-size diffractive optical element is taken out.

[0076] Specifically, after completing the above-mentioned process steps, the control system shuts down each ion source and cuts off the gas supply system, breaks the vacuum in the vacuum chamber, and then takes out the finished large-size diffraction optical element.

[0077] As in the embodiment of this application, key processes such as edge removal, reactive ion beam deep etching, and selective area ashing and shaping are completed sequentially within one vacuum cycle and one clamping. This maximizes efficiency, reduces costs and pollution risks, and ensures optimal performance of the final large-size diffractive optical element through "customized" processing of different areas.

[0078] refer to Figure 3 As shown, Figure 3 This is a flowchart of a reactive ion beam etching method for a large-size diffractive optical element according to another embodiment. The method includes the following steps: Step S21: Load the large-size diffractive optical element that has been patterned by photolithography onto the sample stage and fix it, close the vacuum chamber and evacuate to a high vacuum.

[0079] Specifically, this step corresponds to step S11 in the aforementioned embodiment, which is to perform wafer loading and vacuuming. For detailed embodiments, please refer to the relevant description of step S11, which will not be repeated here.

[0080] Step S22: In the reactive ion beam edge removal stage, the auxiliary ion source is controlled to emit an edge removal reactive ion beam with set process parameters. The sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source. The edge removal reactive ion beam is used to pre-remove the thickened photoresist at the edge of the large-size diffractive optical element. After completion, the auxiliary ion source is turned off.

[0081] Specifically, this step is an edge removal process performed before the main etching stage, corresponding to step S14 in the aforementioned embodiment. For detailed embodiment content, please refer to the relevant description of step S14, which will not be repeated here.

[0082] Step S23: In the main etching stage of the reactive ion beam, the main ion source is controlled to emit a high-energy main etching reactive ion beam, and the sample stage is controlled to move. The main etching reactive ion beam is used to scan and etch the entire surface of the large-size diffractive optical element.

[0083] Specifically, this step is a process performed during the main etching stage, corresponding to step S12 in the aforementioned embodiment. For detailed embodiment content, please refer to the relevant description of step S12, which will not be repeated here.

[0084] Step S24: In the selected area reactive ion beam ashing stage, the auxiliary ion source is controlled to emit a low-energy ashing reactive ion beam, and the sample stage and auxiliary ion source are controlled to move. The ion beam spot of the ashing reactive ion beam is used to scan and ashing the central effective area of ​​the large-size diffractive optical element.

[0085] Specifically, this step is the ashing process after the main etching stage, corresponding to step S13 in the aforementioned embodiment. For detailed embodiment content, please refer to the relevant description of step S13, which will not be repeated here.

[0086] Step S25: After completing the reactive ion beam main etching stage, the selected area reactive ion beam ashing stage, and the reactive ion beam edge removal stage, the finished large-size diffractive optical element is taken out.

[0087] Specifically, this step corresponds to step S15 in the aforementioned embodiment. For detailed embodiment content, please refer to the relevant description of step S15, which will not be repeated here.

[0088] In summary, the technical solution of this application is based on an integrated etching process, which integrates RIBE etching, ashing, and edge removal processes. This reduces equipment, space, and maintenance costs, avoids sample transfer, and integrates multiple discrete processes into a continuous automated process, significantly improving production efficiency. The single-mount, full-process processing method fundamentally eliminates the contamination risks associated with transport, which is crucial for the fabrication of high-sensitivity optical components, directly improving product consistency and yield. The use of chemical and physical synergy enhances the process; leveraging the chemical selectivity of RIBE, more refined and controllable ashing and shaping can be achieved after the main etching, reducing physical damage to the underlying substrate and gate sidewalls, resulting in smoother surfaces and sidewalls. Precise edge removal using a reactive ion beam from an auxiliary ion source is more efficient and effective than pure physical sputtering, reducing the negative impact of edge effects. The process is highly flexible, allowing for the selection of the optimal chemical-physical combination based on material composition and process objectives. It offers a wide process window and significant optimization potential. Each process step is completed under a unified benchmark, ensuring alignment accuracy and process repeatability, while automation reduces human error.

[0089] The following describes an embodiment of a vacuum etching machine.

[0090] Combination Figure 1 and Figure 4 As shown, Figure 2 This is another example of a multi-ion source ion beam etching system structure block diagram. Figure 4 This is a top-view schematic diagram, including: a vacuum chamber 01, a sample stage 02, a main ion source 03, at least one auxiliary ion source 04, and a gas supply system 05; the vacuum etching machine is used to perform main etching, ashing, and edge removal processing on the large-size diffractive optical element 201 using the reactive ion beam etching method of any of the aforementioned embodiments; the sample stage 02 is used to support the large-size diffractive optical element 201; and the control system 06 controls the various components of the vacuum etching machine.

[0091] In some embodiments, the main ion source 03 is fixedly mounted on the side wall of the vacuum chamber 01; the auxiliary ion source 04 is mounted on the side wall of the vacuum chamber via a linear motion structure 41, which is used to push the auxiliary ion source 04. z The sample stage 02 moves along the axial direction; it is mounted on the bottom surface of the vacuum chamber via a planar motion structure 21, which is used to push the sample stage 02 in the axial direction. xy It moves on a plane.

[0092] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A reactive ion beam etching method for large-size diffractive optical elements, applied to a multi-ion source vacuum etching machine, characterized in that, The ion beam etching system includes: a vacuum chamber, a sample stage, a main ion source, and at least one auxiliary ion source disposed within the vacuum chamber; the etching method includes: The large-size diffractive optical element that has been patterned by photolithography is mounted on the sample stage and fixed, the vacuum chamber is closed and evacuated to a high vacuum. In the reactive ion beam main etching stage, the main ion source is controlled to emit a high-energy main etching reactive ion beam, and the sample stage is controlled to move. The main etching reactive ion beam is used to scan and etch the entire surface of the large-size diffractive optical element. In the selected area reactive ion beam ashing stage, the auxiliary ion source is controlled to emit a low-energy ashing reactive ion beam, and the sample stage and auxiliary ion source are controlled to move. The ashing reactive ion beam is used to scan and ashing the central effective area of ​​the large-size diffractive optical element. In the reactive ion beam edge removal stage, the auxiliary ion source is controlled to emit an edge removal reactive ion beam with set process parameters. The sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source. The edge removal reactive ion beam is used to remove the thickened photoresist at the edge of the large-size diffractive optical element. After completing the reactive ion beam main etching stage, the selected area reactive ion beam ashing stage, and the reactive ion beam edge removal stage, the finished large-size diffractive optical element is taken out.

2. A reactive ion beam etching method for large-size diffractive optical elements, applied to a multi-ion source vacuum etching machine, characterized in that... The ion beam etching system includes: a vacuum chamber, a sample stage, a main ion source, and at least one auxiliary ion source disposed within the vacuum chamber; the etching method includes: The large-size diffractive optical element that has been patterned by photolithography is mounted on the sample stage and fixed, the vacuum chamber is closed and evacuated to a high vacuum. In the reactive ion beam edge removal stage, the auxiliary ion source is controlled to emit an edge removal reactive ion beam with set process parameters. The sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source. The edge removal reactive ion beam is used to pre-remove the thickened photoresist at the edge of the large-size diffractive optical element. After completion, the auxiliary ion source is turned off. In the reactive ion beam main etching stage, the main ion source is controlled to emit a high-energy main etching reactive ion beam, and the sample stage is controlled to move. The main etching reactive ion beam is used to scan and etch the entire surface of the large-size diffractive optical element. In the selected area reactive ion beam ashing stage, the auxiliary ion source is controlled to emit a low-energy ashing reactive ion beam, and the sample stage and auxiliary ion source are controlled to move. The ion beam spot of the ashing reactive ion beam is used to scan and ashing the central effective area of ​​the large-size diffractive optical element. After completing the reactive ion beam main etching stage, the selected area reactive ion beam ashing stage, and the reactive ion beam edge removal stage, the finished large-size diffractive optical element is taken out.

3. The reactive ion beam etching method for large-size diffractive optical elements according to claim 1 or 2, characterized in that, The reactive ion beam main etching stage includes: Start the main ion source and introduce the preset main etching reaction gas; Control the main ion source to emit a high-energy main etching reaction ion beam; The sample stage is controlled to perform a combination of uniform rotation and tilting motion, so that the surface of the entire large-size diffractive optical element is uniformly scanned and etched by reactive ion beam, transferring the morphology of the photoresist pattern into the substrate material. After the main etching is completed, the main ion source and the main etching reaction gas are turned off.

4. The reactive ion beam etching method for large-size diffractive optical elements according to claim 1 or 2, characterized in that, The selected area reactive ion beam ashing stage includes: Start the auxiliary ion source and introduce the ashing reaction gas; Control the auxiliary ion source to emit a low-energy ashing reaction ion beam; The sample stage is controlled to move so that the ion beam spot of the auxiliary ion source scans the central effective region of the large-size diffractive optical element, and the central effective region of the large-size diffractive optical element is ashed using the ashing reactive ion beam.

5. The reactive ion beam etching method for large-size diffractive optical elements according to claim 4, characterized in that, The sample stage is moved to scan the central effective region of a large-size diffractive optical element using the ion beam spot of the auxiliary ion source. The central effective region of the large-size diffractive optical element is then ashed using the ashing reactive ion beam, including: Calculate the second coordinate parameters of the central effective region that needs to be ashing; The sample stage is controlled according to the second coordinate parameters to drive the movement of the large-size diffractive optical element, so that the ion beam spot of the ashing reaction ion beam of the auxiliary ion source only covers the central effective optical area of ​​the large-size diffractive optical element, and the edge area of ​​the large-size diffractive optical element is always outside the coverage of the beam spot. During the ashing process, the sample stage is controlled to reciprocate for a preset time to remove residual photoresist film, smooth the grating sidewalls, correct the duty cycle, and eliminate standing wave effects.

6. The reactive ion beam etching method for large-size diffractive optical elements according to claim 1 or 2, characterized in that, The reactive ion beam edge removal stage includes: Start the auxiliary ion source and introduce edge-removed reaction gases; The auxiliary ion source is adjusted to emit a medium-to-high energy edge removal reaction ion beam based on the edge thickness. The sample stage is controlled to move the edge region of the large-size diffractive optical element to the ion beam spot of the auxiliary ion source, and the edge-removing reactive ion beam is used to scan the thickened photoresist at the edge of the large-size diffractive optical element.

7. The reactive ion beam etching method for large-size diffractive optical elements according to claim 6, characterized in that, The sample stage is moved to position the edge region of the large-size diffractive optical element under the ion beam spot of the auxiliary ion source. The edge-removing reactive ion beam is then used to scan the thickened photoresist at the edge of the large-size diffractive optical element, including: Calculate the third coordinate parameters of the edge region of a large-size diffractive optical element; The sample stage is moved according to the third coordinate parameters to move the outer edge region of the large-size diffractive optical element to directly below the ion beam spot of the auxiliary ion source. The sample stage is controlled to rotate continuously. A large-size diffractive optical element is used to perform uniform scanning by removing the annular edge region of the reactive ion beam.

8. The reactive ion beam etching method for large-size diffractive optical elements according to claim 1 or 2, characterized in that, Prior to the reactive ion beam main etching stage, the process also includes: Start the auxiliary ion source and introduce the cleaning working gas; A low-energy cleaning reaction ion beam is emitted using an auxiliary ion source. The sample stage is controlled to move, and the surface of the entire large-size diffractive optical element is cleaned and activated by scanning the reactive ion beam of the auxiliary ion source.

9. A vacuum etching machine, characterized in that, include: The vacuum chamber, sample stage, main ion source, at least one auxiliary ion source, and gas supply system are provided. The vacuum etching machine is used to perform main etching, ashing, and edge removal processing on large-size diffractive optical elements using the reactive ion beam etching method for large-size diffractive optical elements as described in any one of claims 1 to 9.

10. The vacuum etching machine according to claim 9, characterized in that, The main ion source is fixedly installed on the side wall of the vacuum chamber; The auxiliary ion source is mounted on the side wall of the vacuum chamber via a linear motion structure, which is used to push the auxiliary ion source in... z Move along the axis; The sample stage is mounted on the bottom surface of the vacuum chamber via a planar motion structure, which is used to push the sample stage in... xy It moves on a plane.

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