Deep reactive ion etching method for organic silicon

Abstract

A deep reactive ion etching method for organic silicon comprises the following steps: S110, providing an organic silicon substrate, and forming a patterned mask layer on the surface of the substrate; s120, putting the organic silicon substrate on which the mask layer is formed into an etching system, setting etching parameters, and introducing etching gas to etch the organic silicon substrate; and S130, removing the mask layer to obtain the organic silicon material subjected to ion etching. By selecting the etching gas combination and accurately controlling the flow of the etching gas, the etching precision, the etching depth-to-width ratio and the etching speed which are far higher than those of an existing means for etching can be obtained.

Description

Deep reactive ion etching method for silicone Technical Field

[0001] The present application relates to the field of micromachining technology, and in particular to a method for deep reactive ion etching of organic silicon. Background Art

[0002] Silicones, represented by polydimethylsiloxane (PDMS), are the most common flexible materials in microfluidics and flexible electronics. Silicone microstructures are typically fabricated by forming a pattern on a hard substrate and then applying a mold or embossing process. However, in some special cases, such as when the entire multilayer structure cannot withstand pressure or when the device pattern is unusual, mold or embossing is not feasible. Therefore, it is necessary to consider whether direct etching can be used to form the microstructure.

[0003] In the prior art, ICP etching technology is used. After aluminum is used as a patterned mask on the surface of PDMS, etching is performed in an inductively coupled plasma machine. SF6 and oxygen are used as etching gases. At a power of 1800 W and room temperature etching, the etching rate is 0.85 μm / min (Maria-Elena Vlachopoulou, George Kokkoris, et al. Plasma Etching of Poly(dimethylsiloxane): Roughness Formation, Mechanism, Control, and Application in the Fabrication of Microfluidic Structures. Plasma Process. Polym., 2013, 10, 29–40). Alternatively, wet etching can be used. After a patterned mask is applied to the surface of the PDMS, a tetrabutylammonium fluoride (TBAF) solution is used for immersion etching (Maya Kleiman, Keun Ah Ryu, Aaron P. Esser-Kahn, Determination of Factors Influencing the Wet Etching of Polydimethylsiloxane Using Tetra-n-butylammonium Fluoride. Macromol. Chem. Phys., 2016, 217, 284-291).

[0004] When fabricating microfluidic structures using PDMS substrates, conventional reactive plasma etching methods make it difficult to achieve micron-scale etching. Microstructures obtained using high-power inductively coupled plasma (ICP) etching have a rough surface, which increases flow resistance and reduces the reliability of the mechanical structure. Wet etching has almost no anisotropy, so high aspect ratios cannot be achieved using wet etching. Furthermore, both ICP and wet etching use metal masks. Due to the significant difference in thermal expansion coefficients between metal and PDMS, the mask can produce localized stress cracks, resulting in low precision in the resulting microfluidic pattern.

[0005] Therefore, developing a direct etching method for PDMS microfluidic structures with high aspect ratio, high precision and low roughness is a technical problem that needs to be solved urgently in this field.

[0006] Summary of the Invention

[0007] The present application provides a deep reactive ion etching method applied to organosilicon to obtain an organosilicon microfluidic structure with a high aspect ratio and low roughness.

[0008] The present application provides a method for deep reactive ion etching of organic silicon, which comprises the following steps:

[0009] S110, providing an organic silicon substrate, and forming a patterned mask layer on a surface of the substrate;

[0010] S120, placing the organic silicon substrate with the mask layer formed thereon into an etching system, setting etching parameters, and introducing etching gas to etch the organic silicon substrate;

[0011] The etching gas comprises sulfur hexafluoride, carbon tetrafluoride and oxygen. The sulfur hexafluoride, carbon tetrafluoride and oxygen are introduced simultaneously. The total volume flow rate of the etching gas plasma is in a range of 25 sccm to 105 sccm; the volume flow rate of the sulfur hexafluoride is in a range of 10 sccm to 40 sccm, the volume flow rate of the carbon tetrafluoride is in a range of 10 to 40 sccm, and the volume flow rate of the oxygen is in a range of 5 to 25 sccm.

[0012] Alternatively, the etching gas comprises sulfur hexafluoride, oxygen, and argon, and the sulfur hexafluoride, oxygen, and argon are introduced simultaneously, and the total volume flow rate of the etching gas plasma ranges from 20 sccm to 85 sccm; the volume flow rate of sulfur hexafluoride ranges from 10 sccm to 40 sccm, the volume flow rate of oxygen ranges from 5 sccm to 25 sccm, and the volume flow rate of argon ranges from 5 sccm to 20 ccm;

[0013] Alternatively, the etching gas comprises carbon tetrafluoride, oxygen, and argon, and the carbon tetrafluoride, oxygen, and argon are introduced simultaneously, and the total volume flow rate of the etching gas plasma ranges from 20 sccm to 85 sccm; the volume flow rate of carbon tetrafluoride ranges from 10 sccm to 40 sccm, the volume flow rate of oxygen ranges from 5 sccm to 25 sccm, and the volume flow rate of argon ranges from 5 sccm to 20 sccm;

[0014] S130, removing the mask layer to obtain an ion-etched organic silicon material.

[0015] Preferably, the components of the etching gas include sulfur hexafluoride, carbon tetrafluoride, oxygen and argon, and sulfur hexafluoride, carbon tetrafluoride, oxygen and argon are introduced simultaneously. The total volume flow rate of the etching gas plasma ranges from 30 sccm to 125 sccm; the volume flow rate of sulfur hexafluoride ranges from 10 sccm to 40 sccm, the volume flow rate of carbon tetrafluoride ranges from 10 to 40 sccm, the volume flow rate of oxygen ranges from 5 to 25 sccm; and the volume flow rate of argon ranges from 5 sccm to 20 sccm.

[0016] Preferably, in the etching gas, the volume flow rate of sulfur hexafluoride ranges from 20 sccm to 35 sccm, the volume flow rate of carbon tetrafluoride ranges from 20 sccm to 35 sccm, and the volume flow rate of oxygen ranges from 10 sccm to 20 sccm; the total volume flow rate of the etching gas plasma ranges from 50 sccm to 90 sccm.

[0017] Preferably, in the etching gas, the volume flow rate of sulfur hexafluoride ranges from 20 sccm to 35 sccm, the volume flow rate of oxygen ranges from 10 sccm to 20 sccm, and the volume flow rate of argon ranges from 5 sccm to 15 sccm; the total volume flow rate of the etching gas plasma ranges from 35 sccm to 70 sccm.

[0018] Preferably, in the etching gas, the volume flow rate of carbon tetrafluoride ranges from 20 sccm to 35 sccm, the volume flow rate of oxygen ranges from 10 sccm to 20 sccm, and the volume flow rate of argon ranges from 5 sccm to 15 sccm; the total volume flow rate of the etching gas plasma ranges from 35 sccm to 70 sccm.

[0019] Preferably, in the etching parameters, the source power is 800-1300W.

[0020] Preferably, the source power is 1150-1250W.

[0021] Preferably, in the etching parameters, the platen power is 80-200W.

[0022] Preferably, in the etching parameters, the pressure in the chamber is 5-10 mtorr.

[0023] Preferably, in the etching parameters, the pressure in the chamber is 5-8 mtorr.

[0024] Preferably, among the etching parameters, the etching temperature is 20-30°C.

[0025] Preferably, when forming the patterned mask layer, the photoresist is a negative photoresist.

[0026] Preferably, the negative photoresist is SU-8 negative photoresist or nlof negative photoresist.

[0027] Preferably, when SU-8 negative photoresist is used as the photoresist, mechanical stripping and degumming are used; when nlof negative photoresist is used as the photoresist, acetone ultrasonic stripping and degumming are used.

[0028] Preferably, the silicone is polydimethylsiloxane.

[0029] In summary, the present application provides a method for deep reactive ion etching of organic silicon, which has the following beneficial effects.

[0030] 1. Deep reactive ion etching (DRI) technology for silicon substrates is relatively mature. For example, Patent: Deep Reactive Ion Etching Method and Gas Flow Control Device Thereof (Publication No.: CN101988196B) discloses a method for etching bulk silicon using DRI. In addition, Patent: Grating Preparation Method (Publication No.: CN103086607A) discloses a method for etching quartz using DRI. However, there are currently no patents documenting the application of DRI to organic silicon etching and achieving good etching results.

[0031] 2. Since CF4 has a passivating effect on the side walls; SF6 is a catalyst for oxygen chemical etching, and Ar can participate in both etching and passivation of the side walls, the gas for oxygen chemical etching is a combination of at least three gases including SF6, O2, CF4, and Ar, including O2, which can obtain a better etching effect.

[0032] 3. Under a certain reaction pressure, by precisely controlling the flow rate of the etching gas and the etching power, it is possible to achieve much higher precision, etching aspect ratio, and etching speed than those achieved using existing methods. The verticality of the etching can reach 90°±1°, the surface roughness of the etched structure can be reduced to less than 50nm, the etching aspect ratio can reach 25um / 1.5um, and the etching speed can reach above 1um / min.

[0033] 4. Use photoresist to pattern the silicone substrate to be etched as a mask. Since the thermal expansion coefficient of photoresist is closer to that of silicone than that of metal (within one order of magnitude), it can effectively avoid the occurrence of mask stress lines on the silicone substrate during the etching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] FIG1 is a flow chart of a method for deep reactive ion etching of organic silicon provided in an embodiment of the present application;

[0036] FIG2 is a flow chart of a method for deep reactive ion etching of organic silicon provided in an embodiment of the present application;

[0037] Figure 3 is a surface effect diagram after PDMS etching;

[0038] Figure 4 is a fracture surface diagram of PDMS after etching. DETAILED DESCRIPTION

[0039] In order to make the above and other features and advantages of the present application more clear, the present application is further described below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are only exemplary and not restrictive.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0041] In the following description, many specific details are set forth to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that specific details are not required to practice the present application. In other cases, well-known steps or operations are not described in detail to avoid obscuring the present application.

[0042] It should be noted that the method of the present application is applicable to silicone, and in order to facilitate understanding by those skilled in the art, the applicant will use polydimethylsiloxane (PDMS) as an example in the following discussion and examples. Therefore, the use of PDMS as an example in the following discussion and examples should not be understood as a limitation of the present application. It should be understood that those skilled in the art can easily think of applying the technical solutions described in the examples of the present application to the preparation of microfluidic structures of other silicones.

[0043] Referring to FIG. 1 , before deep reactive ion etching is performed on the PDMS membrane, the present application first discloses a method for preparing the PDMS membrane.

[0044] Specifically, a silicon wafer is subjected to a silanization treatment to render the surface hydrophobic; the silane is preferably 1H,1H,2H,2H-perfluorooctyltriethoxysilane (sigma). A PDMS (DOW) matrix and a hardener are mixed uniformly in a ratio of 10:1 and then vacuumed to obtain a bubble-free mixture. The mixture is dropwise applied to the surface of the silicon wafer and spin-coated, followed by baking at 100-120°C for 5-10 minutes to obtain a silicon wafer coated with a PDMS film. The spin-coating conditions are 800-1200 rpm / min for 1-2 minutes, with the spin-coating speed and time depending on the thickness of the PDMS film to be prepared.

[0045] After preparing the PDMS film, referring to FIG2 , the present application provides a method for deep reactive ion etching of organic silicon, the etching method comprising:

[0046] S110 , providing an organic silicon substrate, and forming a patterned mask layer on a surface of the substrate.

[0047] In the existing methods, whether it is ICP etching or wet etching, metal is used as a mask. However, due to the large difference in thermal expansion coefficients between metal and organosilicon, it is almost impossible to avoid local stress cracks in the mask, causing the etched structure to deviate from the designed shape. In the solution provided by the present application, a photoresist is used to pattern the organosilicon substrate to be etched. Since the thermal expansion coefficient of the photoresist is closer to that of the organosilicon (within an order of magnitude) than that of the metal, the occurrence of mask stress lines can be avoided. Furthermore, in order to obtain a higher etching selectivity (etching speed of organosilicon / etching speed of the photoresist), the thickness of the photoresist required for the mask is reduced to facilitate etching, and the photoresist is selected as a negative photoresist, preferably SU-8 negative photoresist or nlof negative photoresist. When the organic silicon substrate is a PDMS film and the photoresist is SU-8 negative photoresist, the etching selectivity ratio of PDMS to SU8 is 1.9; when the organic silicon substrate is a PDMS film and the photoresist is NL0F negative photoresist, the etching selectivity ratio of PDMS to NL0F is 1.7.

[0048] Specifically, using a PDMS film as an example, a silicon wafer spin-coated with the PDMS film is provided as a silicone substrate. A negative photoresist (SU8 or nlof series, etc.) is used to create a patterned mask. The already formed PDMS film surface is treated with oxygen plasma to make it hydrophilic, facilitating bonding with the negative photoresist. A standard negative photoresist lithography process is then performed, i.e., coating, pre-baking, mask exposure, post-baking, developing, and thermal curing, forming a photoresist pattern on the silicone substrate. Finally, plasma is used to remove any residual resist, leaving the areas not covered by the photoresist as the areas to be etched.

[0049] S120, placing the organic silicon substrate with the mask layer formed thereon into an etching system, setting etching parameters, and introducing etching gas to etch the organic silicon substrate;

[0050] The etching gas comprises sulfur hexafluoride (SF6), carbon tetrafluoride (CF4) and oxygen (O2). Sulfur hexafluoride, carbon tetrafluoride and oxygen are introduced simultaneously. The total volume flow rate of the etching gas plasma ranges from 25 sccm to 105 sccm; the volume flow rate of sulfur hexafluoride ranges from 10 sccm to 40 sccm, the volume flow rate of carbon tetrafluoride ranges from 10 to 40 sccm, and the volume flow rate of oxygen ranges from 5 to 25 sccm.

[0051] Alternatively, the etching gas comprises sulfur hexafluoride, oxygen, and argon (Ar), and the sulfur hexafluoride, oxygen, and argon are introduced simultaneously, and the total volume flow rate of the etching gas plasma ranges from 20 sccm to 85 sccm; the volume flow rate of sulfur hexafluoride ranges from 10 sccm to 40 sccm, the volume flow rate of oxygen ranges from 5 sccm to 25 sccm, and the volume flow rate of argon ranges from 5 sccm to 20 ccm;

[0052] Alternatively, the components of the etching gas include carbon tetrafluoride, oxygen and argon, and carbon tetrafluoride, oxygen and argon are introduced simultaneously, and the total volume flow rate of the etching gas plasma ranges from 20 sccm to 85 sccm; the volume flow rate of carbon tetrafluoride ranges from 10 sccm to 40 sccm, the volume flow rate of oxygen ranges from 5 sccm to 25 sccm, and the volume flow rate of argon ranges from 5 sccm to 20 sccm.

[0053] Alternatively, the components of the etching gas include sulfur hexafluoride, carbon tetrafluoride, oxygen and argon, and sulfur hexafluoride, carbon tetrafluoride, oxygen and argon are introduced simultaneously, and the total volume flow rate of the etching gas plasma ranges from 30 sccm to 125 sccm; the volume flow rate of sulfur hexafluoride ranges from 10 sccm to 40 sccm, the volume flow rate of carbon tetrafluoride ranges from 10 to 40 sccm, the volume flow rate of oxygen ranges from 5 to 25 sccm; and the volume flow rate of argon ranges from 5 sccm to 20 sccm.

[0054] The etching parameters include not only the volume flow rate of the etching gas, but also source power, platen power, chamber pressure, and etching temperature. To ensure good etching results, the source power range is 800-1300W, preferably 1150-1250W. The platen power range is 80-200W. The chamber pressure range is 5-10mtorr, preferably 5-8mtorr. The etching temperature range is 20-30°C.

[0055] The etching system of the present application includes a deep reactive ion etcher, which needs to be vacuumed before etching, and after vacuuming, the pressure in the etching chamber is less than 10-5 Pa, so as to avoid other gases affecting the etching process.

[0056] The solution of the present application is to perform oxygen chemical etching by utilizing the corrosiveness of F. Since CF4 has a sidewall passivation effect on the dry etching of silicon-containing materials, a very small amount of SF6 can greatly increase the etching speed. Ar can cooperate with CF4 to participate in the passivation of the sidewalls, and can also cooperate with SF6 to participate in the etching. Therefore, the etching gas is selected to be a combination of at least three gases including O2 among SF6, O2, CF4, and Ar; such as SF6, CF4, O2; SF6, O2, Ar; CF4, O2, Ar; and a combination of SF6, O2, CF4, and Ar.

[0057] Furthermore, the applicant has concluded through a large number of experimental tests that the volume flow rate of etching gas in different gas combinations during the etching process will also affect the etching results.

[0058] For example, in one test experiment, a PDMS membrane was used as the silicone substrate, and a combination of SF6, O2, and CF4 was used as the etching gas. When the flow rates of the three gases were fixed at 16 sccm for O2, 35 sccm for SF6, and 16 sccm for CF4, varying the source power from 1000W to 1250W had little effect on the surface roughness of the bottom layer of the PDMS membrane after etching, ranging from 18nm to 24nm. At source powers of 1150W and 1200W, the surface roughness of the bottom layer was 18nm. As shown in Figures 3 and 4, the bottom layer of the PDMS membrane was relatively smooth after etching, and the etched perpendicularity was close to 90°.

[0059] Furthermore, at a fixed source power of 1200W, varying the CF4 flow rate affects the roughness of the substrate. When the CF4 flow rate exceeds 50 sccm, the etching effect approaches that of ICP etching, with the roughness increasing to over 50nm. Therefore, when selecting the etching gas combination of SF6, O2, and CF4, the CF4 flow rate should be controlled within 10-40 sccm.

[0060] Therefore, in order to achieve the ideal etching effect, when the etching gas combination is SF6, CF4, and O2, the volume flow rate needs to be controlled at 10 sccm to 40 sccm for SF6, 10 to 40 sccm for CF4, and 5 to 25 sccm for O2, respectively, and the total volume flow rate is controlled at 25 sccm to 105 sccm;

[0061] When the etching gas combination is SF6, O2, and Ar, the volume flow rate needs to be controlled at 10 sccm to 40 sccm for SF6, 5 to 25 sccm for O2, and 5 to 20 sccm for Ar, respectively, and the total volume flow rate is controlled at 20 sccm to 85 sccm;

[0062] When the etching gas combination is CF4, O2, and Ar, the volume flow rates need to be controlled at 10 sccm to 40 sccm for CF4, 5 to 25 sccm for O2, and 5 to 20 sccm for Ar, respectively, with a total volume flow rate of 25 sccm to 85 sccm.

[0063] The etching gases selected are sulfur hexafluoride, carbon tetrafluoride, oxygen and argon, and the volume flow rates of SF6 are controlled at 10 sccm to 40 sccm, CF4 at 10 to 40 sccm, O2 at 5 to 25 sccm, and Ar at 5 to 20 sccm, respectively, and the total volume flow rate is controlled at 30 sccm to 125 sccm.

[0064] In addition, the pressure plate power of 80-200W can ensure the verticality of the particle bombardment etching surface; high source power and reasonable etching gas flow ratio ensure the etching speed and the roughness of the etched surface; temperature control at 20-30℃ can avoid local overheating of the etching area.

[0065] S130, removing the mask layer to obtain an ion-etched organic silicon material.

[0066] Specifically, after etching is complete, the injection of etching gas is stopped, the vacuum state of the etching container is released, and the organosilicon is removed. Depending on the photoresist, chemical or mechanical means can be used to remove the organosilicon-like material photoresist to obtain the etched organosilicon. When using SU-8 negative photoresist for patterning the mask, the SU-8 negative photoresist at the edge of the organosilicon material can be treated with an ultraviolet excimer laser, and then mechanical stripping and debonding can be performed. When using NL0F negative photoresist for patterning the mask, debonding can be performed using acetone ultrasonic cleaning.

[0067] In order to make the purpose, technical solutions and beneficial effects of the present application clearer, the present application is further described in detail below in conjunction with specific embodiments. Among them, PDMS is taken as an example of silicone, but the specific embodiments described are only used to explain the present application and are not used to limit the present application. Those skilled in the art can easily think of applying the technical solutions described in the embodiments of the present application to the preparation of microfluidic structures of other silicones.

[0068] Referring to the test experiments, the applicant designed the following embodiment based on the influence of the changing rules of the volume flow rate of the etching gas, source power, etc. on the etching effect. For different combinations of etching gases, the endpoint values ​​of the etching gas volume flow rate and source power and some preferred values ​​were selected to conduct etching tests, and the corresponding etching effects were recorded.

[0069] Among them, the deep reactive ion etching machine uses the PlasmaPro 100 Estrelas platform of Oxford Instruments; the surface effect detection instrument uses the Olympus MX63 large semiconductor detection microscope; and the roughness detection instrument uses the Keyence VK-X3000 laser microscope.

[0070] Example 1

[0071] Preparation of the PDMS membrane: First, a silicon wafer was silanized with FOTS (1H,1H,2H,2H-perfluorooctyltriethoxysilane) to render the surface hydrophobic. The PDMS (DOW) matrix and hardener were mixed in a 10:1 ratio and vacuum-evacuated to obtain a bubble-free mixture. The PDMS was then dropwise spin-coated on the silicon wafer at 1000 rpm for 2 minutes, followed by heating on a hotplate at 120°C for 10 minutes.

[0072] Mask Preparation: First, spin-coat a layer of MCC primer 80 / 20 (Microchem) onto the PDMS layer of the silicon wafer at 500 rpm for 5 seconds and 1000 rpm for 30 seconds, then bake on a 105°C hotplate for 1 minute. The SU8 layer was prepared using a standard process. For example, a 60 µm thick layer of SU8 2050 was prepared using the following spin-coating conditions: 500 rpm for 5 seconds and 2500 rpm for 30 seconds. Scraping the edges after spin coating is recommended. Pre-baking was then performed at 65°C for 3 minutes and 95°C for 4 minutes. After cooling the silicon wafer on a dust-free cloth, the mask was mounted and the wafer was fixed to the photolithography machine for 20 seconds of exposure. Post-baking was performed at 65°C for 3 minutes and 95°C for 4 minutes and 30 seconds. After developing for 3 minutes and 30 seconds, the wafer was immediately rinsed in isopropyl alcohol, air-dried, and heat-cured at 150°C for 10 minutes, then cooled on a dust-free cloth.

[0073] Etching: Place the masked silicon wafer into the deep reactive ion etcher. After passing through the transfer chamber, the wafer enters the etching chamber. Wait for the chamber pressure to drop below 10-5 Pa. On the etcher interface, set the following parameters: SF6, 30 sccm; CF4, 35 sccm; O2, 18 sccm; chamber pressure, 8 mtorr; source power, 1100 W; platen power, 160 W; temperature, 25°C; He backing plate adsorption pressure, 10 mtorr. Set the etching time to 20 minutes and start etching. After etching is complete, transfer the wafer to the transfer chamber. Release the vacuum in the transfer chamber and remove the wafer.

[0074] Debonding: After treating the SU8 at some edges using an ultraviolet excimer laser (ATL), the remaining SU8 adhesive layer was directly peeled off the silicon wafer. The silicon wafer was then placed in a reactive ion etcher (Oxford Instruments) and treated with plasma using the following parameters: pressure 10 mtorr, oxygen flow rate 5 sccm, SF6 flow rate 20 sccm, power 250 W, and treatment time 90 seconds. The silicon wafer was then removed.

[0075] To close the channel, another 100µm-thick PDMS membrane and a silicon wafer were placed in a reactive ion etcher and treated with oxygen plasma using the following parameters: pressure 700mtorr, oxygen flow rate 45sccm, power 60W, and treatment time 20s. After treatment, the two layers of PDMS membranes were quickly pressed in a hot press (Microtech) for 30s at 1MPa and 65°C. After cooling to room temperature, the membranes were peeled off the silicon wafer, resulting in the microchannel.

[0076] Parameter measurement data: channel pressure resistance is greater than 125kPa, etching verticality is 89.6°, PDMS and SU8 etching selectivity is 1.9, PDMS etching speed is 1.00um / min, and the surface roughness of the bottom side of the channel is 16nm.

[0077] Example 2

[0078] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0079] The difference is: the etcher operation interface setting parameters are: SF6, 40sccm; CF4, 40sccm; O2, 25sccm; chamber pressure, 10mtorr; source power, 1250w; pressure plate power, 200w; temperature, 30℃; He back plate adsorption pressure, 15mtorr.

[0080] Parameter measurement data: etching verticality 89.4°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 1.05um / min, bottom side surface roughness of 26nm.

[0081] Example 3

[0082] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0083] The difference is: the parameters set in the etcher operation interface are: SF6, 10sccm; CF4, 10sccm; O2, 5sccm; chamber pressure, 10mtorr; source power, 800w; pressure plate power, 80W; temperature, 20℃.

[0084] Parameter measurement data: etching verticality 89.5°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 0.90um / min, bottom side surface roughness of 25nm.

[0085] Example 4

[0086] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0087] The difference is: the parameters set in the etcher operation interface are: SF6, 35sccm; CF4, 35sccm; O2, 20sccm; chamber pressure, 10mtorr; source power, 1300w; pressure plate power, 150W.

[0088] Parameter measurement data: etching verticality 89.5°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 1.02um / min, bottom side surface roughness of 22nm.

[0089] Example 5

[0090] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0091] The difference is: the parameters set in the etcher operation interface are: SF6, 20sccm; CF4, 20sccm; O2, 10sccm; chamber pressure, 10mtorr; source power, 1150w; pressure plate power, 100W.

[0092] Parameter measurement data: etching verticality 89.7°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate 0.95um / min, bottom side surface roughness of 23nm.

[0093] Example 6

[0094] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0095] The difference is: the parameters set in the etcher operation interface are: SF6, 40sccm; O2, 25sccm; Ar, 20sccm; chamber pressure, 10mtorr; source power, 1250w; pressure plate power, 200w; temperature, 30℃.

[0096] Parameter measurement data: etching verticality 89.5°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 1.01um / min, bottom side surface roughness of 28nm.

[0097] Example 7

[0098] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0099] The difference is: the parameters set in the etcher operation interface are: SF6, 10sccm; O2, 5sccm; Ar, 5sccm; chamber pressure, 5mtorr; source power, 1000w; pressure plate power, 150W; temperature, 30℃.

[0100] Parameter measurement data: etching verticality 89.4°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate 0.91um / min, bottom side surface roughness 26nm.

[0101] Example 8

[0102] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0103] The difference is: the parameters set in the etcher operation interface are: SF6, 35sccm; O2, 20sccm; Ar, 15sccm; chamber pressure, 8mtorr; source power, 1150W; pressure plate power, 120W; temperature, 30℃.

[0104] Parameter measurement data: etching verticality 89.8°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 1.01um / min, bottom side surface roughness of 24nm.

[0105] Example 9

[0106] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0107] The difference is: the parameters set in the etcher operation interface are: SF6, 20sccm; O2, 10sccm; Ar, 5sccm; chamber pressure, 5mtorr; source power, 1000w; pressure plate power, 100W; temperature, 30℃.

[0108] Parameter measurement data: etching verticality 89.4°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 0.92um / min, bottom side surface roughness of 26nm.

[0109] Example 10

[0110] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0111] The difference is: the parameters set in the etcher operation interface are: CF4, 40sccm; O2, 25sccm; Ar, 20sccm; chamber pressure, 10mtorr; source power, 1200w; pressure plate power, 200w; temperature, 30℃.

[0112] Parameter measurement data: etching verticality 89.6°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 1.03um / min, bottom side surface roughness of 27nm.

[0113] Example 11

[0114] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0115] The difference is: the parameters set in the etcher operation interface are: CF4, 10 sccm; O2, 5 sccm; Ar, 5 sccm; chamber pressure, 5 mtorr; source power, 900 W; pressure plate power, 100 W; temperature, 20°C.

[0116] Parameter measurement data: etching verticality 89.4°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 0.90um / min, bottom side surface roughness of 25nm.

[0117] Example 12

[0118] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0119] The difference is: the parameters set in the etcher operation interface are: CF4, 35sccm; O2, 20sccm; Ar, 15sccm; chamber pressure, 8mtorr; source power, 1250W; pressure plate power, 120W; temperature, 30℃.

[0120] Parameter measurement data: etching verticality 89.8°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 1.01um / min, bottom side surface roughness of 23nm.

[0121] Example 13

[0122] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0123] The difference is: the parameters set in the etcher operation interface are: CF4, 20sccm; O2, 10sccm; Ar, 5sccm; chamber pressure, 5mtorr; source power, 1000w; pressure plate power, 100W; temperature, 30℃.

[0124] Parameter measurement data: etching verticality 89.5°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 0.94um / min, bottom surface roughness of 24nm.

[0125] Example 14

[0126] The steps of preparing the PDMS membrane, preparing the mask, etching and degumming are the same as those in Example 1;

[0127] The difference is: the parameters of the etcher operation interface setting are: the etching gas also includes Ar, 15sccm.

[0128] Parameter measurement data: etching verticality 89.5°, PDMS and SU8 etching selectivity ratio of 1.9, PDMS etching rate of 1.00um / min, bottom side surface roughness of 15nm.

[0129] Comparative Example 1

[0130] ICP etching was used. After aluminum was used as a patterned mask on the surface of PDMS, etching was performed in an inductively coupled plasma machine. The etching gas was SF6 30sccm and O2 18sccm. The etching rate was 0.85um / min at room temperature with a power of 1800W. The surface roughness of the bottom side was 56nm, and stress cracks appeared on the surface of the mask and the etched surface.

[0131] Table 1

[0132] Referring to Table 1, Examples 1 to 14 adopt the deep reactive ion etching method provided in the present application, and Comparative Example 1 adopts the conventional ICP etching method. It can be seen that the gas combination (including: SF6, CF4, O2; SF6, O2, Ar; CF4, O2, Ar; and SF6, O2, CF4, Ar) using the method provided in the present application can all be used to etch the PDMS film, and the verticality of the etching is within 90°±1°, the surface roughness of the bottom side of the etched structure is stable below 50nm, and when the appropriate source power is selected, the etching speed can reach more than 0.90um / min, and there are no stress cracks on the mask and the etched surface, and the etching aspect ratio can reach 25um / 1.5um.

[0133] Moreover, by comparing the examples of different volume flow rates of the same gas combination in Examples 1-5, 6-9 and 10-13, it can be found that the etching effect is better when the volume flow rate of the etching gas is in the middle of the volume flow rate range.

[0134] Furthermore, comparing Example 1 with Comparative Example 1, the deep reactive ion etching method provided by this application exhibits a higher etching rate and lower bottom-side surface roughness at lower power compared to conventional ICP etching methods. Furthermore, Comparative Example 1 uses aluminum as a patterned mask. Due to the significant difference in thermal expansion coefficients between the metal and PDMS, stress cracks appeared on both the mask and the etched surface.

[0135] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for deep reactive ion etching of organic silicon, comprising the following steps: S1, providing an organic silicon substrate, and forming a patterned mask layer on the surface of the substrate; S2, placing the organic silicon substrate with the mask layer formed thereon into an etching system, setting etching parameters, and introducing etching gas to etch the organic silicon substrate; The etching gas comprises sulfur hexafluoride, carbon tetrafluoride and oxygen. The sulfur hexafluoride, carbon tetrafluoride and oxygen are introduced simultaneously. The total volume flow rate of the plasma of the etching gas is in the range of 25 sccm to 105 sccm; the volume flow rate of sulfur hexafluoride is in the range of 10 sccm to 40 sccm, the volume flow rate of carbon tetrafluoride is in the range of 10 to 40 sccm, and the volume flow rate of oxygen is in the range of 5 to 25 sccm; Alternatively, the etching gas comprises sulfur hexafluoride, oxygen and argon, and the sulfur hexafluoride, oxygen and argon are introduced simultaneously, and the total volume flow rate of the plasma of the etching gas is in the range of 20 sccm to 85 sccm; the volume flow rate of sulfur hexafluoride is in the range of 10 sccm to 40 sccm, the volume flow rate of oxygen is in the range of 5 sccm to 25 sccm, and the volume flow rate of argon is in the range of 5 sccm to 20 ccm; Alternatively, the etching gas comprises carbon tetrafluoride, oxygen and argon, and the carbon tetrafluoride, oxygen and argon are introduced simultaneously, and the total volume flow rate of the plasma of the etching gas is in the range of 20 sccm to 85 sccm; the volume flow rate of carbon tetrafluoride is in the range of 10 sccm to 40 sccm, the volume flow rate of oxygen is in the range of 5 sccm to 25 sccm, and the volume flow rate of argon is in the range of 5 sccm to 20 sccm; S3, removing the mask layer to obtain an ion-etched organic silicon material.

2. The method for deep reactive ion etching of organic silicon according to claim 1, characterized in that: The etching gas comprises sulfur hexafluoride, carbon tetrafluoride, oxygen and argon. Sulfur hexafluoride, carbon tetrafluoride, oxygen and argon are introduced simultaneously. The total volume flow rate of the plasma of the etching gas is in the range of 30 sccm to 125 sccm; the volume flow rate of sulfur hexafluoride is in the range of 10 sccm to 40 sccm, the volume flow rate of carbon tetrafluoride is in the range of 10 to 40 sccm, the volume flow rate of oxygen is in the range of 5 to 25 sccm; and the volume flow rate of argon is in the range of 10 to 40 sccm. The volume flow rate of the gas ranges from 5 sccm to 20 sccm.

3. The method for deep reactive ion etching of organic silicon according to claim 1, characterized in that: In the etching gas, the volume flow rate of sulfur hexafluoride ranges from 20 sccm to 35 sccm, the volume flow rate of carbon tetrafluoride ranges from 20 sccm to 35 sccm, and the volume flow rate of oxygen ranges from 10 sccm to 20 sccm; the total volume flow rate of the plasma of the etching gas ranges from 50 sccm to 90 sccm.

4. The method for deep reactive ion etching of organic silicon according to claim 1, characterized in that: In the etching gas, the volume flow rate of sulfur hexafluoride ranges from 20 sccm to 35 sccm, the volume flow rate of oxygen ranges from 10 sccm to 20 sccm, and the volume flow rate of argon ranges from 5 sccm to 15 sccm; the total volume flow rate of the plasma of the etching gas ranges from 35 sccm to 70 sccm.

5. The method for deep reactive ion etching of organic silicon according to claim 1, characterized in that: In the etching gas, the volume flow rate of carbon tetrafluoride ranges from 20 sccm to 35 sccm, the volume flow rate of oxygen ranges from 10 sccm to 20 sccm, and the volume flow rate of argon ranges from 5 sccm to 15 sccm; the total volume flow rate of the plasma of the etching gas ranges from 35 sccm to 70 sccm.

6. The method for deep reactive ion etching of organic silicon according to any one of claims 1 to 5, characterized in that: Among the etching parameters, the source power is 800-1300W.

7. The method for deep reactive ion etching of organic silicon according to any one of claims 1 to 6, characterized in that: Among the etching parameters, the source power is 1150-1250W.

8. The method for deep reactive ion etching of organic silicon according to claims 1 to 7, characterized in that: Among the etching parameters, the platen power is 80-200W.

9. The method for deep reactive ion etching of organic silicon according to any one of claims 1 to 8, characterized in that: Among the etching parameters, the pressure in the chamber is 5-10 mtorr.

10. The method for deep reactive ion etching of organic silicon according to any one of claims 1 to 9, characterized in that: Among the etching parameters, the pressure in the chamber is 5-8 mtorr.

11. The method for deep reactive ion etching of organic silicon according to any one of claims 1 to 10, characterized in that: Among the etching parameters, the etching temperature is 20-30°C.

12. The method for deep reactive ion etching of organic silicon according to any one of claims 1 to 11, characterized in that: When forming a patterned mask layer, a negative photoresist is selected as the photoresist.

13. The method for deep reactive ion etching of organic silicon according to claim 12, characterized in that: The negative photoresist is SU-8 negative photoresist or nlof negative photoresist.

14. The method for deep reactive ion etching of organic silicon according to claim 13, characterized in that: When the photoresist is the SU-8 negative photoresist, mechanical stripping and degumming are used; when the photoresist is the nlof negative photoresist, acetone ultrasonic stripping and degumming are used.

15. The method for deep reactive ion etching of organic silicon according to any one of claims 1 to 14, characterized in that: The organic silicon is polydimethylsiloxane.

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