Glass via dry etching method and reactive ion etching apparatus

Abstract

The embodiment of the application relates to a dry etching method of a glass via, comprising: providing a glass substrate, the surface of the glass substrate having a mask opening; placing the glass substrate in a reaction cavity of a reaction ion etching device, alternately performing a main etching step and a sidewall passivation step until a glass via penetrating through the glass substrate is formed. By adopting the process strategy of alternately circulating the main etching step and the sidewall passivation step, the contradiction that the vertical etching rate and the sidewall protection capability are difficult to be considered in the traditional continuous etching process is effectively solved; the circulating mechanism not only significantly improves the sidewall perpendicularity of the glass via, avoids common “hourglass type” or conical defects, but also refreshes the hole bottom environment through periodic gas switching, helps to discharge reaction by-products in the deep hole, so that the micro channel effect is eliminated and stable processing of a high aspect ratio structure is realized. The application also provides a reaction ion etching device.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging and microfabrication technology, and in particular to a dry etching method and reactive ion etching equipment for glass through-holes. Background Technology

[0002] As advanced semiconductor packaging technology rapidly advances towards high-density, three-dimensional heterogeneous integration, glass substrates, with their superior high-frequency electrical properties, adjustable coefficient of thermal expansion, and lower material costs, are gradually replacing traditional silicon-based or organic substrates, becoming the preferred material for next-generation 2.5D / 3D packaging interposers. In three-dimensional interconnect technology using glass substrates, the forming quality of through-glass vias (TGVs), particularly the perpendicularity of the via shape, sidewall flatness, and aspect ratio, directly determines the reliability of subsequent metallization and the overall electrical performance of the device.

[0003] Currently, the mainstream technologies for fabricating TGV in the industry mainly include laser-induced wet etching (LIDE), sandblasting, and photosensitive glass processes. However, these non-dry technologies have inherent limitations in meeting the processing requirements of miniaturization and high aspect ratios. For example, wet etching, based on the isotropic nature of chemical reactions, easily leads to vias exhibiting an hourglass shape (narrow in the middle and wide at both ends) or sloping sidewalls with large cone angles, which severely limits the distribution density of vias. While laser drilling has a fast hole-forming speed, it is often accompanied by damage such as microcracks, recast layers, and heat-affected zones, and it is difficult to ensure the consistency of hole shape on large-area substrates. Summary of the Invention

[0004] One object of this application is to provide a dry etching method and reactive ion etching apparatus for glass through-holes, at least to solve the above-mentioned problems.

[0005] To achieve the above objectives, some embodiments of this application provide a dry etching method for glass through-holes, including:

[0006] A glass substrate is provided, the surface of which has a mask opening;

[0007] The glass substrate is placed in the reaction chamber of a reactive ion etching apparatus, and the main etching step and the sidewall passivation step are alternately and cyclically executed until a glass through-hole is formed through the glass substrate.

[0008] Some embodiments of this application also provide a reactive ion etching apparatus, including:

[0009] The reaction chamber is used to provide a closed etching environment;

[0010] A gas supply system, connected to the reaction chamber, is configured to alternately supply fluorine-containing etching gas and carbon-fluorine passivation gas to the reaction chamber;

[0011] A substrate support device is disposed in the reaction chamber for supporting a glass substrate. The substrate support device integrates a heating module and a cooling module to form a closed-loop temperature control system.

[0012] A plasma generation module, disposed above or to the side of the reaction chamber, is used to ionize the gas within the reaction chamber; and

[0013] A bias power supply, electrically connected to the substrate carrier, is used to apply a radio frequency bias voltage to the glass substrate;

[0014] The plasma generation module and the bias power supply are configured to be controlled independently, and the bias power supply is configured to output pulsed radio frequency bias.

[0015] Compared with related technologies, the solution provided in this application effectively solves the contradiction between vertical etching rate and sidewall protection capability in traditional continuous etching processes by adopting a process strategy of alternating between the main etching step and the sidewall passivation step. This method employs a time-sequential alternation mechanism, allowing the vertical etching process and the sidewall passivation process to proceed independently. In the main etching stage, the process conditions focus on using high-energy ions to vertically bombard and rapidly remove the glass material at the bottom of the glass via, ensuring the efficiency of deep hole processing. In the subsequent sidewall passivation stage, the focus is on depositing a polymer protective layer on the newly formed glass via sidewall, effectively blocking the isotropic erosion of the sidewall by chemical free radicals in subsequent etching cycles. This cyclical mechanism not only significantly improves the verticality of the glass via sidewalls, avoiding common "hourglass" or conical defects, but also refreshes the environment at the bottom of the hole through periodic gas switching, helping to remove reaction byproducts from the deep hole, thereby eliminating the micro-groove effect and achieving stable processing of high aspect ratio structures. Attached Figure Description

[0016] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0017] Figure 1 This is a schematic diagram of the main flow of the dry etching method provided in the embodiments of this disclosure;

[0018] Figure 2 This is a detailed flowchart illustrating the dry etching method provided in the embodiments of this disclosure;

[0019] Figure 3This is a schematic cross-sectional view of the alternating cycle of the main etching step and the sidewall passivation step provided in the embodiments of this disclosure;

[0020] Figure 4 This is a cross-sectional schematic diagram of the glass through-hole structure provided in the embodiments of this disclosure;

[0021] Figure 5 This is a schematic diagram of the reactive ion etching apparatus provided in the embodiments of this disclosure.

[0022] Figure label:

[0023] 10: Glass substrate; 20: Hard mask layer; 30: Through hole; 31: Sidewall; 32: Hole bottom; 40: Passivation layer; 100: Reaction chamber; 110: Plasma generation module; 120: Gas supply system; 130: Bias power supply; 140: Substrate support device; 141: Heating module; 142: Cooling module. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0026] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better description of the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this disclosure according to the specific circumstances.

[0027] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0028] Unless otherwise stated, the term "multiple" means two or more.

[0029] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0030] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.

[0032] Combination Figures 1 to 5 As shown in the embodiments of this disclosure, a dry etching method for glass through-holes includes:

[0033] A glass substrate 10 is provided, and the surface of the glass substrate 10 has a mask opening;

[0034] The glass substrate 10 is placed in the reaction chamber 100 of the reactive ion etching apparatus, and the main etching step and the sidewall passivation step are alternately and cyclically executed until a glass through-hole 30 is formed through the glass substrate 10.

[0035] The dry etching method provided in this disclosure effectively solves the contradiction between the vertical etching rate and the protection capability of the sidewall 31 in traditional continuous etching processes by adopting a process strategy of alternating between the main etching step and the sidewall passivation step. This method employs a time-sequential alternation mechanism, allowing the vertical etching process and the sidewall passivation process to proceed independently. In the main etching stage, the process conditions focus on using high-energy ions to vertically bombard and rapidly remove the glass material at the bottom of the glass via 30, ensuring the efficiency of deep hole processing. In the subsequent sidewall passivation stage, the focus is on depositing a polymer protective layer on the newly formed glass via sidewall 31, thereby effectively blocking the isotropic erosion of the sidewall 31 by chemical free radicals in subsequent etching cycles. This cyclical mechanism not only significantly improves the verticality of the glass via sidewall 31, avoiding common "hourglass" or conical defects, but also refreshes the environment at the bottom 32 of the hole through periodic gas switching, helping to remove reaction byproducts within the deep hole, thereby eliminating the micro-groove effect and achieving stable processing of high aspect ratio structures.

[0036] In the actual process, a smooth glass substrate 10 is first selected, and a mask opening with a preset pattern is prepared on its surface through a previous process. Then, the glass substrate 10 is placed in the vacuum reaction chamber 100 of a reactive ion etching (RIE) apparatus. The core of the process lies in running a cyclic program where the apparatus alternately executes the main etching step and the sidewall passivation step according to a preset sequence. For example, a main etching step is performed first to excavate the glass material downwards, followed immediately by a sidewall passivation step to protect the newly formed hole walls. This cycle is repeated until the etching depth penetrates the glass substrate 10. This step-by-step cyclic strategy solves the problem of simultaneously achieving "downward etching" and "lateral hollowing" in traditional continuous etching, effectively suppressing the tilting of the sidewalls 31 caused by isotropic etching, thereby fabricating a highly vertical through-hole 30 structure on the glass substrate 10.

[0037] Optionally, the main etching step includes: introducing a fluorine-containing etching gas into the reaction chamber 100, controlling the reaction chamber 100 to be at a first pressure, and applying a first bias power to the glass substrate 10 to remove the glass material at the bottom of the glass via 30.

[0038] The sidewall passivation step includes: introducing a fluorocarbon passivation gas into the reaction chamber 100, controlling the reaction chamber 100 to be at a second pressure, and applying a second bias power to the glass substrate 10 to form a polymer passivation layer 40 on the glass via sidewall 31.

[0039] The first bias power is greater than the second bias power, and the first pressure is less than the second pressure.

[0040] To achieve the aforementioned cyclic logic, the process parameters need to be significantly switched between the two steps. In the main etching step, a fluorine-containing etching gas is introduced into the reaction chamber 100, while the chamber pressure is maintained at a relatively low first pressure (e.g., low pressure state), and a high first bias power is applied to the glass substrate 10. The glass at the bottom of the hole 32 is rapidly removed by the vertical bombardment of high-energy ions. In the sidewall passivation step, the gas is switched to a fluorine-carbon passivation gas, the chamber pressure is increased to a relatively high second pressure (e.g., high pressure state), and the bias power is significantly reduced to the second bias power (even close to zero). This coordinated switching between "main etching (high bias / low pressure)" and "passivation (low bias / high pressure)" utilizes the competitive mechanism of physical bombardment and chemical deposition. The high bias ensures rapid depassivation and etching at the bottom, while the low bias / high pressure environment is conducive to the stable deposition of polymer on the sidewall 31, thereby precisely controlling the morphology of the glass via 30.

[0041] In the cyclic etching process of this embodiment, the reaction characteristics of the fluorinated carbon gas (CxHyFz) are not fixed and singular, but are controlled through a specific process window, causing a qualitative transition between the "etching mode" and the "passivation mode." This is significantly different from traditional silicon etching processes. In glass (mainly composed of silicon dioxide) systems, fluorinated gases are usually considered etchants. However, this embodiment achieves a reversal of gas function by synergistically adjusting the carbon-to-fluorine ratio (C / F ratio), oxygen participation, substrate bias, and cavity pressure. Specifically, in the sidewall passivation step, by selecting a gas with a high carbon-to-fluorine ratio (such as C4F8 or C5F8) and using "high pressure (25-50 mTorr)" and "low bias (0-20 W)" conditions, the chemical etching effect of fluorine free radicals on the glass material is effectively suppressed, while the adsorption capacity and polymerization efficiency of CFx groups are significantly enhanced. This environment allows the deposition rate of fluorocarbon groups on the glass surface to be much greater than their volatilization or sputtering rate, resulting in the growth of a polymer film at the microscopic level. During the main etching step, by introducing oxygen, reducing the pressure, and significantly increasing the bias voltage, the system rapidly switches back to a chemical reaction dominated by fluorine radicals and a high-energy ion bombardment mode. At this point, polymer formation is suppressed, and the glass material is efficiently removed. This regulation based on competitive reaction kinetics is the core mechanism by which this embodiment achieves anisotropic deep-hole processing using a fluorine-containing gas system within a single reaction chamber 100.

[0042] Optionally, the fluorine-containing etching gas includes at least one of carbon tetrafluoride, sulfur hexafluoride, or nitrogen trifluoride; the carbon-fluorine passivation gas includes at least one of octafluorocyclobutane, octafluorocyclopentene, or trifluoromethane.

[0043] The main etching step preferably uses carbon tetrafluoride (CTF). Sulfur hexafluoride () ) or nitrogen trifluoride ( Fluorine-containing etching gases, such as octafluorocyclobutane, release large amounts of fluorine radicals in plasma, which are the main reaction source for chemical etching of glass materials. For the sidewall passivation step, gases with a higher carbon-to-fluorine ratio, such as octafluorocyclobutane, are selected. ), octafluorocyclopentene ( ) or trifluoromethane ( These gases tend to undergo polymerization reactions under specific conditions to form Teflon-like polymer films. The effect of this specific gas combination is that the former provides a high etching rate, while the latter provides a dense and highly corrosion-resistant passivation layer 40. The cyclic switching and synergistic effect of the two constitutes the key chemical mechanism for constructing high aspect ratio vias 30.

[0044] Optionally, the main etching step further includes introducing oxygen into the reaction chamber 100 to inhibit polymer formation; the gas introduced in the sidewall passivation step does not contain oxygen, or the oxygen flow rate in the sidewall passivation step is lower than the oxygen flow rate in the main etching step, so as to promote the deposition of the polymer passivation layer 40.

[0045] To achieve precise control over the etching reaction, the gas used in the main etching step also contains a suitable amount of oxygen. The role of oxygen is to react with carbon to produce volatile organic compounds. or This inhibits excessive polymer buildup at the bottom of the aperture 32, maintaining a clean etching front. Conversely, during the sidewall passivation stage, the oxygen supply must be cut off or the oxygen flow rate reduced to an extremely low level. This on / off control strategy for oxygen flow directly dominates the mode shift in the reaction system. The introduction of oxygen effectively removes polymer, thus maintaining the etching reaction, while the cutoff of oxygen promotes the rapid deposition of the passivation layer 40. This improves the formation efficiency of the passivation layer 40 and prevents the sidewall protective film 31 from failing due to residual oxygen.

[0046] Optionally, the first bias power is applied in a pulsed manner, or the plasma source of the reaction chamber 100 is operated in a pulsed manner to dissipate the accumulated charge on the surface of the glass substrate 10.

[0047] Taking advantage of the non-conductive physical property of glass, the initial bias power applied to the substrate is preferably in pulse mode, or the plasma source is directly controlled to operate in pulse mode. During the pulse off-cycle, the positive charge accumulated on the glass surface and at the bottom 32 of the deep hole is neutralized by electrons. This eliminates the micro-groove effect and etching stagnation. By eliminating local electric field distortion, the ion beam can always maintain perpendicular incidence, ensuring the smoothness of the contour and the uniformity of the etching rate during deep hole processing.

[0048] Specifically, since the glass substrate 10 is a typical dielectric insulating material, excessive accumulation of positive charge easily occurs at the bottom of the via 30 under continuous high-density plasma bombardment. This distortion of the local electric field repels subsequently incident positive ions, causing ion trajectory deflection (causing microgrooving effect on the sidewall 31 due to ion collisions) or ion energy decay (leading to etching stagnation). To overcome this physical obstacle, this embodiment employs a dual charge dissipation mechanism. First, a metallic material (such as Cr, Ti, or Ni) is preferably used as the hard mask layer 20. The metallic mask is not only resistant to etching, but its excellent conductivity can also form an equipotential surface at the opening of the via 30, helping to dissipate some of the surface accumulated charge and reduce the electric field distortion at the opening. Second, combined with pulsed radio frequency bias technology, the pulse turn-off period provides a time window for electrons to neutralize the positive charge at the bottom of the deep hole. At the moment of turn-off, the electron temperature drops rapidly, allowing electrons to diffuse deeper into the bottom of the via 30 and neutralize the accumulated positive charge. The synergistic effect of this metal mask current guidance and pulse period neutralization ensures that the ion beam can still maintain vertical incidence and a stable etching rate even at aspect ratios as high as 15:1.

[0049] Optionally, during the alternating cycle of the main etching step and the sidewall passivation step, the temperature of the glass substrate 10 is maintained between -20°C and 90°C.

[0050] Throughout the cyclic etching process, the temperature of the glass substrate 10 is locked within a window of -20°C to 90°C by the temperature control system inside the substrate support device 140. For example, low-temperature control is achieved through liquid nitrogen channels or refrigerant circulation. Within this temperature range, the adsorption coefficient of the fluoropolymer on the sidewall 31 is at its optimal state, meaning that it will not be difficult to deposit or volatilize too quickly due to excessive temperature, resulting in insufficient lateral protection; nor will it cause excessive polymer accumulation and blockage of the orifice due to excessive temperature. This effectively balances the protective and removable properties of the passivation layer 40, which is a key environmental parameter to ensure process stability.

[0051] Optionally, the glass substrate 10 is borosilicate glass or aluminosilicate glass.

[0052] This embodiment is applicable to electronic-grade packaging substrates such as borosilicate glass (e.g., Pyrex, BF33) or aluminosilicate glass. These materials contain impurities such as boron and aluminum, which easily generate non-volatile residues during conventional etching. The cyclic process combined with high-energy ion bombardment in this embodiment effectively removes these difficult-to-etch byproducts, resulting in extremely high yield and practicality for these critical semiconductor packaging materials, meeting the industry's demand for high-performance glass substrate processing.

[0053] In some embodiments, the aperture of the glass through-hole 30 is 10 mm. Up to 80 The aspect ratio of the glass through-hole 30 is 3 to 15.

[0054] Through the combined effect of the above processes, the diameter of the final processed glass vias can be controlled between 10μm and 80μm, and the aspect ratio can reach 3 to 15. This means that the process can not only process micro-holes, but also achieve a large depth while maintaining a small diameter, meeting the requirements for high-density interconnects in advanced packaging, and realizing a fine processing capability that is difficult to achieve with traditional wet processes or mechanical drilling.

[0055] Optionally, the mask opening is formed by a hard mask layer 20 covering the surface of the glass substrate 10, and the material of the hard mask layer 20 is selected from at least one of chromium, titanium, nickel, silicon dioxide or silicon nitride.

[0056] In mask selection, metallic materials such as chromium (Cr), titanium (Ti), and nickel (Ni) are preferred, as well as hard inorganic media such as silicon dioxide and silicon nitride. For example, a layer of chromium is first sputtered onto the glass surface, and then the area to be etched is exposed by photolithography. Compared to soft photoresist masks, hard mask materials exhibit a much higher etching selectivity relative to the glass substrate 10 in fluorine-containing etching environments and can withstand long-term high-energy ion bombardment without wear. In particular, metal masks can also help to remove some surface charge, further improving the verticality of the sidewalls 31 and the flatness of the bottom 32 of the deep holes.

[0057] Optionally, the gas introduced in the main etching step may also include an inert gas, which is selected from at least one of argon, helium, or xenon.

[0058] In the main etching step, inert gases such as argon (Ar), helium (He), or xenon (Xe) are further introduced into the gas composition. These gases do not participate in chemical reactions, but under the influence of an electric field, they can be ionized into heavy ions, which then subject the bottom-hole glass material to purely physical impacts. This enhances the destructive power on the bottom-hole glass material and helps break the chemical bonds of the reaction byproducts, thereby increasing the overall etching rate, especially when etching glass containing complex oxide compositions.

[0059] Optionally, the reactive ion etching equipment is an inductively coupled plasma etching equipment, and is equipped with a plasma generation module 110 and a bias power supply 130 that are controlled independently.

[0060] The preferred hardware platform for implementing this method is an inductively coupled plasma etching (ICP) device, which must be equipped with independent plasma generation power supplies and substrate bias power supplies 130. This independent hardware architecture of source power and bias power forms the material basis for implementing this process. The source power controls the plasma density and chemical group concentration to ensure the reaction rate, while the bias power independently regulates the bombardment kinetic energy of the ions on the substrate. This dual-path control mechanism allows the process to freely switch between a high-density, low-damage mode during passivation and a high-density, high-bombardment mode during etching, thereby achieving adjustment of the profile of the deep hole sidewall 31.

[0061] In some embodiments, the first pressure is controlled between 5 mTorr and 15 mTorr, and the second pressure is controlled between 25 mTorr and 50 mTorr; the first bias power is controlled between 100 W and 200 W, and the second bias power is controlled between 0 W and 20 W. This specific parameter window represents the experimentally verified optimal working range. Within this range, low pressure combined with high bias maximizes ion directionality, ensuring perpendicular etching; while high pressure combined with near-zero bias maximizes free radical scattering and polymerization, ensuring uniform coverage of sidewall 31. This parameter combination minimizes sidewall roughness and cone angle while ensuring etching efficiency.

[0062] In some embodiments, the time for a single main etching step is 2 to 10 seconds, the time for a single sidewall passivation step is 1 to 10 seconds, and the main etching step and the sidewall passivation step are alternated 100 to 500 times. If the execution time is too long, the main etching will cause significant lateral hollowing, while excessive passivation will lead to difficulties in subsequent removal. The rapid switching at the second level can control the lateral etching amount in each cycle at the nanometer level, thereby presenting a smooth and flat sidewall profile 31 on a macroscopic scale.

[0063] Optionally, before providing the glass substrate 10, the method further includes: depositing a metal layer or an inorganic dielectric layer on the surface of the glass substrate 10, and patterning the metal layer or inorganic dielectric layer by photolithography and etching processes to form a hard mask layer 20.

[0064] At the front end of the process flow, a hard mask is fabricated using a standard semiconductor process of "deposition-photolithography-etching". Specifically, a mask material is first applied to the entire glass surface using PVD or CVD, then photoresist is coated and exposed and developed. Next, an etching process is used to transfer the pattern to the hard mask layer 20, and finally, the photoresist is removed. This standardized mask fabrication process ensures the sharpness and dimensional accuracy of the mask opening edges, avoiding defects such as flared tops of the vias 30 caused by mask edge burrs or shrinkage.

[0065] This disclosure also provides a reactive ion etching apparatus, comprising: a reaction chamber 100 for providing a sealed etching environment; a gas supply system 120 connected to the reaction chamber 100 and configured to alternately supply fluorine-containing etching gas and carbon-fluorine passivation gas to the reaction chamber 100; a substrate support device 140 disposed within the reaction chamber 100 for supporting a glass substrate 10, the substrate support device 140 integrating a heating module 141 and a cooling module 142 to form a closed-loop temperature control system; a plasma generation module 110 disposed above or to the side of the reaction chamber 100 for ionizing the gas within the reaction chamber 100; and a bias power supply 130 electrically connected to the substrate support device 140 for applying a radio frequency bias voltage to the glass substrate 10; wherein the plasma generation module 110 and the bias power supply 130 are configured to be independently controlled, and the bias power supply 130 is configured to output a pulsed radio frequency bias voltage.

[0066] The reactive ion etching apparatus of this embodiment mainly consists of five subsystems: a reaction chamber 100, a gas supply system 120, a substrate support device 140, a plasma generation module 110, and a bias power supply 130. In actual construction, the reaction chamber 100 is typically made of anodized aluminum or ceramic material to provide a high-cleanliness, sealed vacuum environment. The gas supply system 120 is directly connected to the reaction chamber 100 via pipelines and is responsible for alternately supplying fluorine-containing etching gas and carbon-fluorine passivation gas according to the process sequence. The substrate support device 140 (commonly referred to as an electrostatic chuck or ESC) is located at the bottom of the reaction chamber 100 and integrates resistance heating wires and fluid cooling channels, forming a closed-loop system with an external temperature control unit. The plasma generation module 110 is placed above or on the side wall 31 of the reaction chamber 100 and is responsible for ionizing the gas into high-density plasma, while the bias power supply 130 is independently connected to the substrate support device 140 and is specifically used to introduce radio frequency energy to control the bombardment of the substrate by ions. Crucially, the equipment's control system enables independent adjustment of the plasma source power and bias power.

[0067] This embodiment provides the material basis for the aforementioned dry etching method. The independently controlled power supply architecture enables the device to rapidly switch between two modes: high-density / low-bombardment (passivation step) and high-density / high-bombardment (etching step), which is impossible with conventional linked power supply devices. Furthermore, the introduction of pulsed radio frequency bias is a crucial hardware solution for addressing surface charge accumulation on insulating materials such as glass, eliminating etching stagnation, and mitigating microchannel effects.

[0068] In some alternative embodiments, the closed-loop temperature control system is configured to maintain the temperature of the glass substrate 10 within the range of -20°C to 200°C, and the cooling module 142 is a liquid nitrogen cooling module 142 or a refrigerant circulation cooling module 142.

[0069] In the specific implementation of the temperature control system, the internal flow channels of the substrate carrier 140 are connected to an external high-performance chiller or liquid nitrogen supply system. To cover a wide temperature range from -20℃ to 200℃, the system is typically designed with a dual-loop or cascaded cooling architecture: when deep cooling is required to enhance the adsorption of the sidewall passivation layer 40, the liquid nitrogen or cryogenic refrigerant circulation module is activated to rapidly cool the substrate surface to below zero; when a high-temperature cleaning chamber or specific polymer removal process is required, the heating module 141 is switched on. The closed-loop control logic, combined with an embedded temperature sensor, ensures that the substrate surface temperature fluctuation is controlled within ±1℃ under the impact of high plasma heat load. This wide-range and precise temperature control capability ensures that the equipment can not only adapt to current low-temperature high aspect ratio etching processes, but also accommodate various complex glass processing requirements, greatly expanding the equipment's process window.

[0070] Although the substrate carrier 140 of this embodiment has the hardware capability to be adjusted within a wide temperature range of -20°C to 200°C, this does not mean that a completely consistent etching effect can be obtained at any temperature point within this range. In order to achieve optimal process control for via 30 structures of different specifications, the present invention employs a specific temperature control window strategy in a preferred embodiment.

[0071] Specifically, depending on the processing requirements, the process temperature can be controlled within the following two preferred ranges: The first is a low-temperature window of -20℃ to +20℃. Within this temperature range, the adsorption capacity of fluoropolymers on the glass surface is significantly enhanced, and the passivation layer 40 becomes denser and less volatile. Therefore, this window is particularly suitable for processing through-holes 30 with high aspect ratios (e.g., greater than 10:1), effectively preventing lateral hollowing at the bottom of deep holes. The second is a medium-temperature window of +30℃ to +90℃. This range aims to achieve a balance between sidewall protection and polymer residue control. While ensuring the formation of an effective passivation layer 40 on the sidewall 31, the thermal excitation effect promotes the desorption and vaporization of reaction byproducts from the surface, thereby significantly reducing the risk of excessive polymer accumulation at the orifice or sidewall 31. This is suitable for process scenarios with high requirements for hole wall cleanliness. Through the above targeted temperature window selection, the relationship between main etching and sidewall passivation can be further optimized, ensuring the structural consistency of the glass through-hole 30.

[0072] In some embodiments, the plasma generation module 110 includes an inductively coupled coil disposed on top of the reaction chamber 100, or a parallel plate radio frequency electrode disposed inside the reaction chamber 100.

[0073] Regarding the plasma generation module 110, a preferred embodiment employs an inductively coupled architecture. Specifically, a planar or three-dimensional helical coil is arranged above the dielectric window of the reaction chamber 100 and coupled to a radio frequency source via an impedance matching network. The electric field induced by the alternating magnetic field is used to maintain the glow discharge. As an alternative, a parallel plate electrode structure located inside the reaction chamber 100 can also be used. The advantage of using an inductively coupled architecture lies in its ionization rate, enabling the generation of plasmas with densities as high as [insert density here] at relatively low pressures (e.g., 1-10 mTorr). The plasma. For deep hole etching of glass, this means that sufficient fluorine radicals can be provided per unit time for chemical reactions, thereby maintaining a low ion energy to reduce damage to the photoresist mask while ensuring a high etching rate.

[0074] In some embodiments, the gas supply system 120 includes multiple independent gas delivery pipelines, which are respectively connected to a fluorine-containing gas source, a carbon-fluorine gas source, an inert gas source, and an oxygen source, and each gas delivery pipeline is equipped with a flow controller for quickly switching gas flow rates.

[0075] Every gas – whether , Waiting for the etching gas, or Passivating gases, or Ar, The auxiliary gases each have independent delivery lines and are equipped with high-response flow controllers before entering the manifold. These flow controllers typically use differential pressure or fast thermal sensors with sub-second response times. During process execution, the control system sends commands to the flow controllers, enabling a complete replacement from etching to passivation within seconds. This achieves a steep gas transition, avoiding gas residue and mixing within the chamber, ensuring the purity of each etching or passivation microcycle, and thus guaranteeing the flatness and perpendicularity of the final glass via sidewall 31.

[0076] For example, the etching of a high aspect ratio through-hole 30 in a 100μm thick borosilicate glass is taken as an example.

[0077] In this embodiment, the object to be processed is an electronic-grade borosilicate glass substrate 10 with a thickness of 100 μm. The goal is to fabricate vertical interconnect vias 30 with a diameter of 30 μm that penetrate the glass substrate 10. The process begins with the fabrication of a hard mask. First, a chromium (Cr) metal layer with a thickness of approximately 200 nm is deposited on the clean surface of the glass substrate 10 using a magnetron sputtering process. Subsequently, photoresist is applied using a standard photolithography process, followed by exposure and development to define a circular array of openings with a diameter of 30 μm. Then, the chromium layer in the exposed areas is removed by wet etching, forming mask openings with sharp edges. The choice of a metal hard mask not only provides excellent etching resistance but also plays a role in assisting in the conduction of surface charges during subsequent plasma processing.

[0078] Once the glass substrate 10 is ready, it is fed into an inductively coupled plasma (ICP) etching apparatus equipped with an independent plasma source and a bias power supply 130. The glass substrate 10 is placed on an electrostatic chuck (ESC) by a robotic arm, and its temperature is stably controlled at 10°C through a back-mounted helium cooling system and a built-in refrigerant circulation module. This low-temperature environment is crucial for the success of subsequent processes, as it significantly enhances the adsorption efficiency of fluoropolymers on the glass sidewalls 31 and prevents lateral voiding.

[0079] The etching process employs a time-divided cyclic strategy, alternating between the main etching step and the sidewall passivation step. During the main etching stage, a mixed gas—carbon tetrafluoride (…)—is rapidly introduced into the chamber via a flow controller. The flow rate is 45 sccm, and the oxygen ( The flow rate of fluorine ions was 6 sccm, and the flow rate of argon (Ar) as an auxiliary physical bombardment was 25 sccm. At this time, the control system adjusted the cavity pressure to a lower 8 mTorr, set the ICP source power to 1200 W to generate high-density plasma, and applied a 120 W pulsed radio frequency bias. The duty cycle of the pulse bias was set to 50% to 80%, and during the pulse off period, the accumulated charge at the bottom of the deep hole was dissipated, ensuring that the ion beam could continuously bombard the bottom of hole 32 vertically. This step lasted for 6 seconds, using high-energy fluorine ions and argon ions to rapidly remove the glass at the bottom of hole 32.

[0080] Immediately afterwards, the system switched to the sidewall passivation stage within seconds. The gas source was changed to octafluorocyclobutane ( The flow rate of ICP source was set to 60 sccm and the flow rate of argon (Ar) to 10 sccm, with the oxygen supply completely cut off to create a reducing atmosphere. At this point, the key process parameters were reversed: the chamber pressure was increased to 35 mTorr to increase free radical scattering and residence time; the bias power was significantly reduced to 10 W to maintain only the minimum energy required for the plasma to reach the glass substrate 10 surface, avoiding physical damage to the deposited film. With the ICP source power reduced to 900 W, A Teflon-based protective film is rapidly polymerized on the sidewalls 31 and bottom of the glass through-hole. This step lasts for 4 seconds.

[0081] The aforementioned 6-second main etching and 4-second passivation constitute a complete process cycle. At the moment the next main etching step begins, the high-bias ion beam preferentially penetrates the thinner passivation layer 40 at the bottom of the hole 32, continuing to etch downwards into the glass. The thicker passivation layer 40 on the sidewalls 31 is preserved due to the extremely small ion incident angle, thus blocking lateral etching. This cycle is repeated approximately 250 times, taking a total of about 40 minutes. Finally, a vertical via 30 with an aspect ratio greater than 3:1, a sidewall cone angle less than 3°, and no obvious microchannel effect is successfully etched onto the glass substrate 10. The sample is then cleaned using conventional resist and mask removal processes.

[0082] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims, and the foregoing embodiments should be considered exemplary and non-limiting.

Claims

1. A dry etching method for glass through-holes, characterized in that, include: A glass substrate is provided, the surface of which has a mask opening; The glass substrate is placed in the reaction chamber of a reactive ion etching apparatus, and the main etching step and the sidewall passivation step are alternately and cyclically executed until a glass through-hole is formed through the glass substrate.

2. The dry etching method according to claim 1, characterized in that, The main etching step includes: introducing a fluorine-containing etching gas into the reaction chamber, controlling the reaction chamber to be at a first pressure, and applying a first bias power to the glass substrate to remove the glass material at the bottom of the glass via. The sidewall passivation step includes: introducing a fluorocarbon passivation gas into the reaction chamber, controlling the reaction chamber to be at a second pressure, and applying a second bias power to the glass substrate to form a polymer passivation layer on the sidewall of the glass via. Wherein, the first bias power is greater than the second bias power, and the first pressure is less than the second pressure.

3. The dry etching method according to claim 2, characterized in that, The fluorine-containing etching gas includes at least one of carbon tetrafluoride, sulfur hexafluoride, or nitrogen trifluoride; the carbon-fluorine passivation gas includes at least one of octafluorocyclobutane, octafluorocyclopentene, or trifluoromethane.

4. The dry etching method according to claim 2, characterized in that, The main etching step also includes introducing oxygen into the reaction chamber to inhibit polymer formation; The gas introduced in the sidewall passivation step does not contain oxygen, or the oxygen flow rate in the sidewall passivation step is lower than the oxygen flow rate in the main etching step, so as to promote the deposition of the polymer passivation layer.

5. The dry etching method according to claim 2, characterized in that, The first bias power is applied in a pulsed manner, or the plasma source of the reaction chamber is operated in a pulsed manner to dissipate the accumulated charge on the surface of the glass substrate.

6. The dry etching method according to claim 1, characterized in that, During the alternating cycle of the main etching step and the sidewall passivation step, the temperature of the glass substrate is maintained between -20°C and 90°C.

7. The dry etching method according to claim 1, characterized in that, The glass substrate is borosilicate glass or aluminosilicate glass.

8. The dry etching method according to claim 1, characterized in that, The mask opening is formed by a hard mask layer covering the surface of the glass substrate, the material of which is selected from at least one of chromium, titanium, nickel, silicon dioxide or silicon nitride.

9. The dry etching method according to claim 2, characterized in that, The gas introduced in the main etching step also includes an inert gas, which is selected from at least one of argon, helium, or xenon.

10. A reactive ion etching apparatus, characterized in that, include: The reaction chamber is used to provide a closed etching environment; A gas supply system, connected to the reaction chamber, is configured to alternately supply fluorine-containing etching gas and carbon-fluorine passivation gas to the reaction chamber; A substrate support device is disposed in the reaction chamber for supporting a glass substrate. The substrate support device integrates a heating module and a cooling module to form a closed-loop temperature control system. A plasma generation module, disposed above or to the side of the reaction chamber, is used to ionize the gas within the reaction chamber; and A bias power supply, electrically connected to the substrate carrier, is used to apply a radio frequency bias voltage to the glass substrate; The plasma generation module and the bias power supply are configured to be controlled independently, and the bias power supply is configured to output pulsed radio frequency bias.

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