Fine composite mask supported by a silicon substrate

Abstract

The application discloses a kind of silicon substrate support's fine composite mask (SS-FHM), for OLED display manufacturing.The mask includes at least one layer of open hole metal layer and one layer of open hole ceramic layer, silicon substrate is used to provide structural support, and is selectively removed in display area to form self-supporting structure.Open hole ceramic layer has high shape retention, can maintain open hole precision and inhibit deformation;Open hole metal layer has good stress absorption capacity, can avoid rupture but is prone to deformation.By combining the stability of ceramic with the durability of metal, SS-FHM can improve the precision of OLED material deposition and long-term reliability, especially suitable for microOLED and other ultra-fine pattern processes, and is beneficial to improve manufacturing yield.

Description

Technical Field

[0001] This invention relates to fine masking technology for the manufacture of organic light-emitting diode (OLED) displays, particularly fine composite masks supported on silicon substrates (SS-FHMs) comprising an open-cell composite layer integrating ceramic and metallic materials. This mask is particularly suitable for ultra-fine patterning applications requiring high-precision RGB pixel deposition in microOLED manufacturing processes. Background Technology

[0002] Silicon-substrate supported fine metal mask (SS-FMM) and silicon-substrate supported fine ceramic mask (SS-FCM) were developed to address the resolution limitations of traditional Invar substrate fine metal masks (FMM). Traditional Invar masks are typically 20–40 µm thick, making it impossible to fabricate fine openings smaller than 10 µm, thus hindering the subpixel pattern requirements of microOLEDs with resolutions exceeding 2000 ppi. Due to the inability to deposit RGB OLEDs, current microOLEDs mostly employ a WOLED architecture with a color filter (CF). To overcome this limitation, SS-FMM and SS-FCM utilize a silicon substrate as a temporary support layer, enabling ultra-thin, high-resolution opening structures, improving opening shape stability and alignment accuracy, and making RGB microOLED fabrication possible.

[0003] SS-FMM (Silicon Substrate Supported Fine Metal Mask) typically consists of an aperture metal layer (such as Invar, nickel, or Alloy 42) and a silicon substrate. The silicon substrate provides temporary support, giving the mask a certain degree of mechanical stability and flexibility during manufacturing and deposition, which helps reduce aperture misalignment during OLED material deposition. However, after the silicon substrate is removed, the aperture metal layer loses its support and becomes susceptible to plastic deformation and creep. Especially when the metal layer becomes thinner, it is more prone to wrinkling, sagging, and shape distortion, which in turn affects the consistency and resolution of OLED pixel deposition.

[0004] SS-FCM (Silicon-Substrate-Supported Fine Ceramic Mask) uses ceramic materials such as silicon nitride (Si3N4) or alumina (Al2O3) as the opening layer. Ceramic materials possess high rigidity and extremely low creep, enabling them to maintain the shape and dimensional stability of the openings over long periods during repeated evaporation cycles. However, ceramics are brittle and have poor ductility, making them prone to cracking or fracture due to thermal stress or handling impacts. When the ceramic layer thickness is reduced to meet high-resolution requirements, its mechanical strength further decreases, limiting the lifespan and applicability of SS-FCM.

[0005] Although SS-FMM and SS-FCM each have their advantages, their structural characteristics still pose challenges to the long-term reliability and dimensional stability of microOLED manufacturing processes, making it difficult to achieve high-volume manufacturing without sacrificing precision.

[0006] In SS-FMM, the metal layer with openings exhibits plastic deformation characteristics, resulting in shape changes over time. This deformation is further exacerbated by creep during high-temperature evaporation. Furthermore, stress release during the removal of the silicon substrate after mask fabrication can cause opening deformation and positional misalignment, affecting the alignment accuracy of RGB pixels.

[0007] In SS-FCM, although the high rigidity of the open-cell ceramic layer helps maintain the geometric stability of the opening, its lack of plasticity and stress absorption capacity makes it prone to cracking or even fracture under handling or thermal stress, causing the open-cell structure to fail. Its brittle nature limits its application in high-precision patterning processes, especially under conditions of large-area masking or repeated use.

[0008] Therefore, while SS-FMM and SS-FCM can partially improve the limitations of traditional FMM, they still struggle to simultaneously meet the demands of mechanical durability, shape retention, and high-resolution processes. In light of this, it is necessary to develop a hybrid mask structure that integrates the ductility of metals with the shape stability of ceramics to overcome these problems and improve the process compatibility and micro-patterning capabilities of the mask. Summary of the Invention

[0009] To overcome the structural limitations of SS-FMM and SS-FCM, this invention proposes a fine composite mask supported by a silicon substrate (SS-FHM), which includes an open-cell composite layer. By integrating ceramic and metal materials, it improves mechanical stability and process compatibility, and is particularly suitable for high-resolution microOLED processes.

[0010] In microOLED applications, to achieve a resolution of over 2000ppi, the total thickness of the perforated composite layer needs to be less than 10µm, and it must possess extremely high patterning precision. While traditional metal materials are ductile, they are prone to plastic deformation under high temperatures or pressures; ceramic materials can maintain the shape of the perforations, but they are brittle and easily fractured. SS-FHM combines the shape stability of a perforated ceramic layer with the stress absorption capacity of a perforated metal layer through a perforated composite layer, providing the mechanical support and stability required for the fine perforation process while maintaining structural integrity.

[0011] Because microOLED evaporation requires repeated heating and cooling cycles, the aperture layer may suffer from creep and stress accumulation during long-term processes. SS-FHM's aperture composite layer design can effectively absorb stress and suppress deformation, ensuring that the OLED pixel apertures can maintain alignment accuracy and dimensional consistency even after multiple deposition cycles.

[0012] The mechanical balance design between the perforated ceramic layer and the perforated metal layer is crucial for suppressing deformation. The ceramic layer, with its low plasticity and high rigidity, helps maintain the stability of the perforation profile; the metal layer provides moderate ductility to distribute stress generated during handling or thermal cycling. Optimization of the thickness ratio and stacking order can effectively improve the reliability and lifespan of the overall mask structure.

[0013] In SS-FHM (Silicon-to-Hydraulic) systems, the ceramic layer with openings can also serve as a structural stabilizing factor to compensate for stress deformation. During the manufacturing process, when the silicon substrate is removed from the back side, the metal layer often warps or wrinkles due to the release of internal residual stress; at this time, the ceramic layer can maintain overall flatness and prevent distortion. During the service phase, the ceramic layer further resists geometric displacement caused by creep or stress accumulation in the metal layer, ensuring the long-term stability of the openings.

[0014] The SS-FHM structure supports the formation of right-angle and tapered apertures, and possesses high sidewall verticality and dimensional control capabilities, enabling aperture patterning at the sub-10µm level. This structure helps improve OLED evaporation resolution and yield, and is particularly suitable for the high-precision material deposition requirements of RGB microOLEDs.

[0015] By combining the shape retention of the perforated ceramic layer with the stress-buffering capability of the perforated metal layer, SS-FHM provides an effective solution for both suppressing deformation and preventing cracking. This invention's mask structure possesses high mechanical stability, high patterning accuracy, and excellent long-term reliability, making it particularly suitable for the fine-patterned perforation processes required for manufacturing ultra-high-resolution microOLED displays. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of SS-FMM, which includes a silicon substrate, an electrode metal layer, and an aperture metal layer, used for OLED material deposition.

[0017] Figure 2 This is a cross-sectional view of the SS-FCM, which includes a silicon substrate and an open-hole ceramic layer to ensure the stability and durability of the open-hole shape.

[0018] Figure 3 For metal and ceramic materials, n represents the strain hardening index (n value), creep resistance, and coefficient of thermal expansion.

[0019] Figure 4 This is a cross-sectional view of SS-FHM, including double-layer and triple-layer structures to balance mechanical stability and stress absorption capacity.

[0020] Figure 5 This is a cross-sectional view of the SS-FHM, including a three-layer and multi-layer structure to further improve the accuracy of the opening shape and durability.

[0021] Figure 6 (Example 1) is the SS-FHM manufacturing process, which forms right-angle openings.

[0022] Figure 7 (Example 2) is the first part of the SS-FHM manufacturing process, forming a negative cone angle opening.

[0023] Figure 8 (Example 2) is the second part of the SS-FHM manufacturing process, which completes the negative cone angle opening.

[0024] Figure 9 (Example 3) is the first part of the alternative SS-FHM manufacturing process, forming a negative cone angle opening.

[0025] Figure 10 (Example 3) is the second part of the alternative SS-FHM manufacturing process, which completes the negative cone angle opening.

[0026] Figure 11 (Example 4) is the first part of another alternative SS-FHM manufacturing process, forming a negative cone angle opening.

[0027] Figure 12 (Example 4) is the second part of another alternative SS-FHM manufacturing process, which completes the negative cone angle opening. Detailed Implementation

[0028] Figure 1 A fine metal mask supported on a silicon substrate (SS-FMM) is described, which includes a silicon substrate 13, an electrode metal layer 14, and an opening metal layer 15. Figure 1 A shows a top view of the display area 12 and the non-display area 11, which includes precisely patterned openings for OLED material deposition. Figure 1 B shows an enlarged cross-sectional view of the aperture metal layer 15 deposited on the electrode metal layer 14, with the electrode metal layer 14 in direct contact with the silicon substrate 13.

[0029] During the manufacturing process, the SS-FMM structure maintains dimensional stability through the silicon substrate 13 to prevent warping and shrinkage of the aperture metal layer 15. However, after removing the silicon substrate 13, the structural stability of the electrode metal layer 14 and the aperture metal layer 15 decreases, making them susceptible to stress relaxation, plastic deformation, and creep, which leads to changes in the geometry of the apertures and consequently affects the OLED deposition accuracy and overall manufacturing yield.

[0030] Figure 2A silicon substrate supported fine ceramic mask (SS-FCM) is described, which uses an open-cell ceramic layer 16 as the main open-cell defining layer. Compared to SS-FMM, it has higher open-cell shape stability, but its mechanical stress absorption capacity is reduced. Similar to SS-FMM, SS-FCM includes a silicon substrate 13 as structural support. Figure 2 A's top view and Figure 1 Similar to structure A, display area 12 is surrounded by non-display area 11. Figure 2 The cross-sectional view of B shows that the perforated ceramic layer 16 serves as the main perforation definition layer, ensuring perforation accuracy.

[0031] SS-FCM enhances the shape stability of the apertures by utilizing the low plasticity of the aperture ceramic layer 16, preventing shape changes over time. However, ceramic materials are inherently brittle and prone to cracking or fracture when subjected to mechanical stress or thermal cycling. Furthermore, the aperture ceramic layer 16 lacks ductility and cannot effectively absorb mechanical stress, making it susceptible to breakage during handling and repeated OLED deposition cycles. These limitations reduce the long-term durability and mechanical stability of SS-FCM; therefore, its mask lifetime needs further improvement when applied in OLED manufacturing environments requiring long-term reliability.

[0032] Figure 3 Data on strain hardening index (n-value) for various metal and ceramic materials are provided. This index is a key factor in evaluating material behavior in OLED mask applications, and it particularly affects the long-term stability and durability of the perforated metal layer 15 and the perforated ceramic layer 16.

[0033] Figure 3 The listed metals, such as Invar, SuperInvar, and Nickel, exhibit moderate strain hardening (n=0.2~0.4), indicating that they can increase strength and redistribute stress after plastic deformation, reducing the risk of immediate fracture. However, Figure 3 The results show that metals with higher n values, such as nickel (n=0.34) and Kovar (n=0.3), are more prone to gradual plastic deformation, causing the aperture metal layer 15 to deform over time. In OLED mask applications, this deformation can lead to aperture misalignment, especially after the silicon substrate 13 is removed.

[0034] Figure 3The listed ceramic materials, such as silicon nitride (Si3N4) and alumina (Al2O3), have n values ​​close to zero, indicating that they do not undergo plastic deformation but remain rigid until they reach their fracture limit. While this ensures long-term retention of the pore shape, ceramic materials are highly brittle and lack stress absorption capacity. When subjected to mechanical stress, cracks can propagate rapidly and lead to sudden fracture. This suggests that although the pore-forming ceramic layer 16 can maintain pore accuracy, it may still be damaged under mechanical stress.

[0035] Since the perforated metal layer 15 may gradually deform over time, and the perforated ceramic layer 16 is prone to cracking due to brittleness, using either material alone still has limitations in terms of high precision and long-term stability, and it is difficult to simultaneously achieve both shape retention and stress absorption capacity.

[0036] Creep resistance is another key factor in OLED mask applications, especially in manufacturing environments with high temperatures and long operating times. Figure 3 Creep resistance data for metallic and ceramic materials are provided, illustrating the behavior of these materials under long-term stress and thermal cycling.

[0037] The perforated metal layer 15 is composed of metals such as Invar, Nickel and SuperInvar, and may undergo creep deformation over time. Figure 3 The results show that metals such as nickel (0.6% strain / 1000 hours) and titanium alloys (0.5% strain / 1000 hours) are particularly sensitive to creep. During OLED manufacturing, the mask undergoes repeated heating and cooling cycles, causing the aperture metal layer 15 to gradually deform, thus affecting the accuracy of the aperture positions and OLED pixel alignment. However, the aperture composite layer 17 design using SS-FHM effectively reduces the effects of creep, improves the long-term stability of the mask, and ensures the consistency of OLED material deposition and high-resolution pixel alignment.

[0038] In contrast, the porous ceramic layer 16 exhibits near-zero creep, such as Figure 3 As shown, silicon nitride (Si3N4) and boron nitride (BN) have extremely high creep resistance (≤0.0001% strain / 1000 hours), ensuring dimensional stability under long-term use, and enabling the open-hole ceramic layer 16 to maintain precise opening shape and alignment accuracy during OLED material deposition.

[0039] However, although ceramic materials are highly resistant to creep deformation, they lack stress absorption capacity. Under mechanical impact, microcracks may form and propagate over time, affecting the aperture accuracy and long-term stability of the mask. During handling or removal of the silicon substrate 13, the aperture ceramic layer 16 may be affected by localized stress, thus requiring further optimization of its structural strength.

[0040] like Figure 3 As shown, metallic materials are susceptible to creep, while ceramic materials are highly brittle. Therefore, it is difficult to simultaneously meet the requirements of long-term durability and mechanical stability of OLED masks by using either metallic or ceramic materials alone.

[0041] consider Figure 3 Based on strain hardening index (n-value) and creep behavior data, SS-FMM and SS-FCM each have their own advantages and limitations in OLED material deposition applications, especially in ultra-fine pattern applications such as high-resolution microOLED, where their performance is limited by the characteristics of the material itself.

[0042] In SS-FMM, the open-cell metal layer 15 is composed of metals such as Invar, SuperInvar, and Molybdenum, which have moderate strain hardening exponents (n≈0.2–0.4). Figure 3 As shown. This characteristic allows for stress redistribution, reducing the risk of sudden brittle fracture and giving SS-FMM high resistance to mechanical shock and handling stress. Furthermore, the metal gradually hardens under repeated stress, enhancing mechanical durability during OLED deposition. However, this n-value characteristic also leads to cumulative deformation, and the creep behavior of metals such as Nickel, Alloy 42, and Kovar is significant, affecting aperture stability. When the silicon substrate 13 is removed, the release of internal stress may lead to plastic deformation, reducing aperture alignment accuracy.

[0043] In SS-FCM, the open-pore ceramic layer 16 is composed of materials such as silicon nitride (Si3N4) and alumina (Al2O3), which have extremely low n values ​​(~0.01), such as... Figure 3 As shown, no plastic deformation occurs, ensuring long-term aperture shape stability and maintaining high-precision aperture geometry. Furthermore, ceramic materials are virtually unaffected by creep, eliminating the risk of long-term deformation. However, ceramic materials lack stress redistribution capabilities, resulting in high brittleness and susceptibility to mechanical shock. In thin-film applications (≤10µm), even minute mechanical stresses during silicon substrate removal can lead to crack formation and propagation over time, affecting mask life.

[0044] During OLED deposition, SS-FMM benefits from a moderate n-value, enabling stress redistribution, improving mechanical durability and stress absorption capacity, and reducing the risk of immediate breakage. However, creep deformation can still affect aperture stability, thereby impacting OLED pixel alignment and display uniformity. In contrast, SS-FCM maintains aperture precision due to its low n-value and extremely low creep, but its high brittleness may reduce mask lifespan with long-term use.

[0045] Figure 4 and Figure 5 Different structural variations of the SS-FHM are demonstrated. This mask combines an open-aperture metal layer 15 with an open-aperture ceramic layer 16 to balance structural stability and mechanical durability. These configurations enable the SS-FHM to flexibly meet the manufacturing needs of microOLEDs at different resolutions, and it is particularly suitable for ultra-fine patterning applications requiring high precision and high stability.

[0046] Figure 4 A shows a structure in which an open-hole metal layer 15 is situated on an open-hole ceramic layer 16, providing mechanical flexibility while ensuring shape stability through the support of the ceramic layer.

[0047] Figure 4 B shows the structure of the open-hole metal layer 15 formed on the electrode metal layer 14 by an electroforming process (EF), achieving higher mechanical strength and reducing thermal expansion mismatch (E). Electroforming technology is particularly suitable for low thermal expansion alloys such as Invar, and it is widely used in sheet fine metal masks (FMMs) to ensure excellent dimensional stability.

[0048] Figure 4 C illustrates a structure where an open-cell ceramic layer 16 sits atop an open-cell metal layer 15. This design enhances heat resistance while utilizing the mechanical flexibility of the open-cell metal layer 15 to improve structural stability.

[0049] These SS-FHM structures help reduce the deformation risk of pure metal masks (SS-FMM) and improve the brittleness of pure ceramic masks (SS-FCM), enabling them to maintain more stable mechanical properties and aperture accuracy during long-term use.

[0050] Figure 5 An advanced multilayer SS-FHM structure was demonstrated, in which the perforated metal layer 15 and the perforated ceramic layer 16 are arranged in a stacked manner to optimize mechanical properties and structural stability.

[0051] Figure 5 A shows that the perforated metal layer 15 is located between two perforated ceramic layers 16, which enhances shape retention and durability by reducing metal deformation, while maintaining the crack resistance of the ceramic layers.

[0052] Figure 5 B shows that the perforated ceramic layer 16 is sandwiched between two perforated metal layers 15, which improves heat resistance and mechanical flexibility, making it suitable for applications requiring higher thermal stability.

[0053] Figure 5 C shows a multi-layered, staggered structure in which perforated metal layers 15 and perforated ceramic layers 16 are alternately distributed to maximize mechanical strength, ensure uniform stress distribution and structural stability, and is particularly suitable for mask structures required for high-precision microOLED material deposition.

[0054] SS-FHM has structural adaptability, and can be adapted to manufacturing conditions, mechanical durability requirements and thermal stability considerations by adjusting the composition of the perforated composite layer 17 according to the microOLED display size and resolution requirements.

[0055] For small-sized, high-resolution microOLED displays, where sub-micron level aperture precision is crucial, the aperture ceramic layer 16 typically constitutes a large proportion to ensure aperture shape stability and prevent long-term deformation. In such applications, it is recommended to use... Figure 5 A and Figure 4 As shown in structure B, the perforated ceramic layer 16 is located on top of the perforated composite layer 17 to improve pattern accuracy and thermal stability. Furthermore, if a three-layer configuration is used, with the perforated metal layer 15 sandwiched between the two perforated ceramic layers 16, stress distribution can be optimized, balancing the brittleness of the ceramic with the stress absorption capacity of the metal, thus preventing premature mask failure due to handling stress.

[0056] For microOLED applications requiring high mechanical stability, the proportion of the open-hole metal layer can be increased by 15% to improve structural strength and absorb stress during handling. Recommended use... Figure 5 The structure shown in B, where the perforated ceramic layer 16 is located between two perforated metal layers 15, achieves a balance between stress relief and stability. Furthermore, Figure 5 The multi-layered staggered arrangement structure shown in C can also be used to further improve the mechanical strength and aperture stability of microOLED masks.

[0057] The design of the perforated composite layer 17 can be optimized by adjusting the relative thickness of the perforated metal layer 15 and the perforated ceramic layer 16, based on the structural and functional requirements of the mask, to ensure that SS-FHM achieves a balance between mechanical durability, thermal stability, and stress absorption capacity. By adjusting the layer structure ratio, SS-FHM can be flexibly applied to the manufacturing needs of high-resolution microOLED panels.

[0058] Figure 6 The fabrication process for right-angle apertures in SS-FHM is demonstrated as a method for achieving high-precision patterning. Theoretically, to minimize the shading effect during material deposition from the back side, the aperture shape should have a negative cone angle, since the microOLED substrate is located on top of the SS-FHM. A cone angle of 40 to 70 degrees is considered ideal. However, when the aperture composite layer 17 is sufficiently thin, the shading effect decreases, making right-angle apertures still suitable for high-precision deposition, providing an aperture option that meets process requirements.

[0059] The initial structure uses a semiconductor-grade silicon substrate 13, such as an 8-inch or 12-inch single-crystal silicon wafer, which possesses high mechanical strength, excellent thermal stability, and chemical stability. This type of silicon substrate 13 is widely used in precision lithography and evaporation processes, providing excellent dimensional stability and structural support in mask manufacturing.

[0060] Above the silicon substrate 13, a porous ceramic layer 16 is deposited using silicon nitride (Si3N4) deposited via low-pressure chemical vapor deposition (LPCVD) to ensure high density and mechanical strength. The thickness of this ceramic layer ranges from 0.01µm to 20µm and can be adjusted according to application, display size, and resolution requirements. Furthermore, other ceramic materials, such as alumina (Al2O3), zirconium oxide (ZrO2), silicon carbide (SiC), boron nitride (BN), and zirconium tungstate, can also be selected based on the mechanical and thermal stability requirements of the OLED deposition process.

[0061] An open-cell metal layer 15, made of molybdenum (Mo), is formed on top of the open-cell ceramic layer 16 by sputter deposition. Molybdenum's low coefficient of thermal expansion (CTE) provides excellent dimensional stability during high-temperature OLED deposition processes. The thickness of the open-cell metal layer 15 ranges from 0.01 µm to 20 µm to ensure suitability for different display resolutions and evaporation requirements. Alternatively, other low-CTE metals such as Invar, SuperInvar, Kovar, Alloy 42, nickel (Ni), tungsten (W), tantalum (Ta), and rhenium (Re) can also be used.

[0062] exist Figure 6 In step A, photoresist PR(1)18 is applied and patterned on the aperture metal layer 15 to define the aperture region. PR(1)18 is a positively cross-linked photoresist, which can achieve high-resolution patterning to accurately form the aperture. Subsequently, dry etching is used as the main etching method, especially reactive ion etching (RIE), using Cl2, BCl3 and Ar plasmas to etch the aperture to ensure that the aperture sidewalls are vertical and to avoid the positive cone angle effect that may be caused by wet etching.

[0063] exist Figure 6 In step B, photoresist PR(2)19 is applied as a full-area protective layer to protect the front side of the mask and prevent subsequent back-side etching from affecting it. Next, photoresist PR(3)20 is coated and patterned on the back side to define the etching area of ​​the silicon display area 12. The display area 12 of the silicon substrate 13 is selectively removed by wet etching or dry etching.

[0064] like Figure 6As shown in Figure C, the non-display area 11 of the silicon substrate 13 is selectively removed from the back side to form a structural region supporting the aperture composite layer 17. To avoid the non-display area 11 causing a shadowing effect on the apertures of the aperture composite layer 17 during the OLED material evaporation process, the sidewall angle after etching needs to be optimized. If wet etching is used, silicon etchants such as KOH or TMAH can be used, and heating and stirring can be performed at 70–90°C to form a cone angle of approximately 54.7° on the ⟨100> crystal orientation silicon substrate 13. If a near-vertical sidewall structure is required, deep reactive ion etching (DRIE) can be used in conjunction with SF6 or CF4 plasma. Alternatively, wet and dry etching processes can be combined, with initial shape shaping first, followed by dry fine-tuning of the contour to ensure that the non-display area 11 does not cause evaporation masking interference to the aperture composite layer 17.

[0065] exist Figure 6 In step C, all photoresist layers, including PR(2)19 and PR(3)20, are removed by O2 plasma ashing or NMP solvent removal. After this step, the final SS-FHM structure is formed, which includes a silicon substrate 13, an open-cell ceramic layer 16 and an open-cell metal layer 15. The materials can be adjusted according to application requirements to adapt to different high-precision OLED evaporation processes.

[0066] Figure 7 and Figure 8 Example 2 illustrates the SS-FHM manufacturing process and demonstrates an alternative method for achieving right-angle or negative cone-angle openings based on etching process parameters.

[0067] exist Figure 7 In step A, an open-hole ceramic layer 16 and an open-hole metal layer 15 are deposited on a silicon substrate 13. The open-hole ceramic layer 16 is made of silicon nitride (Si3N4) and is deposited by low-pressure chemical vapor deposition (LPCVD). The open-hole metal layer 15 is made of molybdenum (Mo) and is formed by sputtering deposition to ensure dimensional stability during the OLED evaporation process.

[0068] Material selection and coating methods can also be referenced. Figure 6 The perforated ceramic layer 16 can be replaced with materials such as alumina (Al2O3) or zirconium oxide (ZrO2), while the perforated metal layer 15 can be made of metals with a low coefficient of thermal expansion (CTE), such as Invar, SuperInvar, tungsten (W), or rhenium (Re). The thickness of the perforated ceramic layer 16 and the perforated metal layer 15 ranges from 0.01µm to 20µm, depending on the application requirements, display size, and resolution.

[0069] exist Figure 7In step B, photoresist PR(2)19 is applied to the top surface of the aperture structure as a full-area protective layer. Subsequently, photoresist PR(3)20 is applied and patterned on the back side of the silicon substrate 13 to define the etching range of the display area 12.

[0070] like Figure 7 As shown in Figure C, the non-display area 11 of the silicon substrate 13 is selectively etched from the back side to retain the structural area required to support the via composite layer 17. The sidewall angle of the non-display area 11 needs to be designed and controlled according to the opening shielding conditions of the OLED evaporation. If a support structure with a tapered angle is required, wet etching with KOH or TMAH can be used to etch the silicon substrate 13 at 70–90°C to form a slope of approximately 54.7°. If vertical or near-vertical sidewalls are required, deep reactive ion etching (DRIE) can be used with SF6 or CF4 plasma to achieve high aspect ratio and sidewall control. Alternatively, wet and dry etching techniques can be combined according to process requirements to optimize the geometry of the non-display area 11 and the optical gap of the corresponding via composite layer 17.

[0071] In applications requiring alignment marks, the alignment mark areas within the silicon substrate 13 can be etched simultaneously in this step to ensure precise alignment in subsequent aperture patterning processes. However, since the silicon substrate 13 is transparent to visible and infrared light, alignment can be performed through the silicon substrate 13, so the alignment mark areas of the silicon substrate 13 may not require etching. Furthermore, the etching method and timing of the alignment marks can be adjusted according to manufacturing requirements to adapt to different OLED mask process conditions.

[0072] Figure 8 Figure A illustrates the process of patterning the aperture structure using photoresist PR(4)21 to define the aperture area. Although not explicitly shown in the figure, alignment marks can also be patterned simultaneously to ensure accurate positioning in subsequent processes.

[0073] Wet etching can be used to form negative cone angle openings, while dry etching (such as reactive ion etching, RIE) is typically used for right-angle openings. However, deep reactive ion etching (DRIE) can control the sidewall angle by adjusting process parameters to form negative cone angle or right-angle structures, ensuring adaptability to different OLED processes.

[0074] The resulting SS-FHM structure includes an open-aperture composite layer 17, in which an open-aperture ceramic layer 16 is integrated with an open-aperture metal layer 15, providing good mechanical stability and ensuring that the opening shape is suitable for high-resolution OLED deposition, meeting the mask requirements under different process conditions.

[0075] Figure 9 and Figure 10Example 3 illustrates the SS-FHM manufacturing process, which is similar to Example 2, but allows for the formation of right-angle or negative cone-angle openings by adjusting etching process parameters. (Compared to Example 1) Figure 6 Compared to this method, this method is... Figure 10 B adds an extra cone angle adjustment step to control the sidewall angle of the opening.

[0076] exist Figure 9 In step A, an open-hole ceramic layer 16 and an open-hole metal layer 15 are deposited on a silicon substrate 13. The open-hole ceramic layer 16 is made of silicon nitride (Si3N4) and is deposited by low-pressure chemical vapor deposition (LPCVD) process, while the open-hole metal layer 15 is made of molybdenum (Mo) and is formed by sputtering deposition to ensure dimensional stability in the OLED evaporation process.

[0077] For material selection, coating method, and thickness, please refer to [reference needed]. Figure 6 The perforated ceramic layer 16 can be replaced with materials such as alumina (Al2O3) or zirconium oxide (ZrO2), while the perforated metal layer 15 can be made of metals with a low coefficient of thermal expansion (CTE), such as Invar, SuperInvar, tungsten (W), or rhenium (Re). The thickness of the perforated ceramic layer 16 and the perforated metal layer 15 ranges from 0.01µm to 20µm, depending on the application requirements, display size, and resolution.

[0078] exist Figure 9 In B, photoresist PR(1)18 is applied and patterned to define the aperture area. The aperture metal layer 15 and aperture ceramic layer 16 are then etched by dry etching, including reactive ion etching (RIE) using Cl2, BCl3 and Ar plasma to ensure that the aperture shape is clear and the sidewalls are vertical.

[0079] exist Figure 9 In C, a protective photoresist PR(2)19 is applied to the front side of the aperture structure as a full-area protective layer, and a photoresist PR(3)20 is applied and patterned on the back side of the silicon substrate 13 to define the silicon etching area.

[0080] In applications requiring alignment marks, the alignment mark areas of the silicon substrate 13 can be etched simultaneously in this step to ensure accurate alignment in subsequent processes. However, depending on manufacturing requirements and alignment methods, the alignment mark areas of the silicon substrate 13 can also remain unetched for optical alignment via the silicon substrate 13.

[0081] Figure 10 Step B is a key step in Example 3; this step is used to adjust the cone angle of the opening. Figure 6In comparison, this method adds full-exposure dry etching and does not use an aperture photoresist mask. By precisely controlling the etching rate and selectivity, the photoresist PR(2)19 can be gradually consumed and the exposed aperture ceramic layer 16 can be etched to achieve a controllable reverse cone angle aperture structure. In addition, if wet etching is used, the sidewall angle of the aperture ceramic layer 16 can be further controlled by adjusting the etching conditions and time to ensure the best OLED evaporation effect.

[0082] exist Figure 10 In C, all photoresist layers, including PR(2)19 and PR(3)20, are removed by O2 plasma ashing or NMP solvent removal. The final SS-FHM structure includes an open-hole composite layer 17, in which an open-hole ceramic layer 16 is integrated with an open-hole metal layer 15. After optimization, it is suitable for high-precision OLED evaporation processes and the cone angle of the openings can be adjusted.

[0083] Figure 11 and Figure 12 Example 4 of the SS-FHM manufacturing process is shown, which differs from the previous examples by using electroforming (EF) technology to form the open-hole metal layer 15 instead of a sputtering process. Due to the use of electroforming, Invar is chosen as the material for the open-hole metal layer 15 instead of molybdenum (Mo) because Invar exhibits superior mechanical strength and stability during electroforming. Furthermore, Figure 10 The aperture cone angle adjustment technology of B is also applicable to this embodiment to further control the aperture shape.

[0084] exist Figure 11 In step A, an open-cell ceramic layer 16, made of silicon nitride (Si3N4), is deposited on a silicon substrate 13 using low-pressure chemical vapor deposition (LPCVD) to provide a stable substrate to support subsequent electroforming processes. Next, an electrode metal layer 14 is deposited over the open-cell ceramic layer 16. This layer can be formed by sputtering or vapor deposition to ensure appropriate adhesion and conductivity to facilitate the electroforming process.

[0085] exist Figure 11 In step B, a patterned photoresist PR(5)22 is applied to define the aperture region. This step also simultaneously patterns alignment marks to ensure precise alignment in subsequent processes. An electroforming process is then performed to grow an Invar aperture metal layer 15 on the exposed electrode metal layer 14, giving it controllable thickness and high stability. Because the photoresist PR(5)22 has a positive cone angle, the electroformed Invar aperture naturally forms a negative cone angle, conforming to the desired aperture shape.

[0086] exist Figure 11In step C, after the electroforming process is completed, PR(5)22 is removed, leaving a precisely defined Invar aperture structure. The final SS-FHM aperture composite layer 17 includes an electroformed Invar aperture metal layer 15, an aperture ceramic layer 16, and a residual electrode metal layer 14.

[0087] exist Figure 12 In step A, similar to Example 3, the alignment mark area of ​​the silicon substrate 13 is etched to ensure that the alignment marks can be accurately transferred to subsequent processes. At this time, a full-area photoresist PR(2)19 is applied as a protective layer, followed by back-side silicon etching. Wet etching (HF, BHF) or dry etching (RIE / DRIE, SF6, CF4 plasma) can be used to remove the silicon substrate 13 of the display area 12.

[0088] exist Figure 12 In section B, the hole taper angle adjustment process is implemented. Figure 10 B) Adjusting the aperture angle. Since no aperture photoresist mask is used in this step, dry etching can be performed on the entire area. By gradually consuming PR(3)20 and etching the exposed aperture ceramic layer 16, a reverse cone angle is naturally formed. In addition, by controlling the wet etching conditions and time, the aperture ceramic layer 16 can also be adjusted to produce a negative cone angle aperture, further improving the OLED evaporation accuracy. To ensure the consistency of the aperture outline, the cone angle of the aperture ceramic layer 16 and the electrode metal layer 14 must match that of the electroformed aperture metal layer 15.

[0089] exist Figure 12 In step C, all residual photoresist layers are removed by O2 plasma ashing or NMP solvent removal, ultimately forming a complete SS-FHM structure. The final structure includes an electroformed Invar open-hole metal layer 15, an open-hole ceramic layer 16, and an electrode metal layer 14, providing high mechanical stability and precise taper angle control, suitable for high-resolution OLED evaporation processes.

[0090] Although each step is not described in detail in the manufacturing process of Examples 1 to 4, all examples are consistent in terms of material selection, deposition method, etching process and thin film structure to ensure optimized high-precision OLED evaporation performance.

[0091] This embodiment uses a semiconductor-grade silicon substrate 13, such as an 8-inch or 12-inch single-crystal silicon wafer, which possesses high mechanical strength, excellent thermal stability, and chemical stability. This type of silicon substrate 13 is widely used in precision lithography and evaporation processes, providing excellent dimensional stability and structural support in mask manufacturing, and is suitable for various high-precision OLED deposition requirements.

[0092] The open-cell ceramic layer 16 is primarily composed of silicon nitride (Si3N4) and is fabricated using LPCVD (low-pressure chemical vapor deposition) to ensure high density and high mechanical strength. Depending on the thermal and mechanical performance requirements, alumina (Al2O3), zirconium oxide (ZrO2), silicon carbide (SiC), boron nitride (BN), or zirconium tungstate can also be selected as alternative materials. The open-cell ceramic layer 16 can be fabricated using LPCVD, PECVD (plasma-enhanced chemical vapor deposition), or ALD (atomic layer deposition), with a thickness ranging from 0.01µm to 20µm, ensuring structural stability and compatibility with the silicon substrate 13.

[0093] The material selection for the aperture metal layer 15 depends on the manufacturing method. For sputtering deposition, molybdenum (Mo) is preferred due to its low coefficient of thermal expansion (CTE) and high mechanical strength. Depending on the stability requirements of high-temperature OLED evaporation, Invar, SuperInvar, tungsten (W), rhenium (Re), tantalum (Ta), nickel (Ni), or alloy 42 can also be used as alternative materials. For electroforming (EF) deposition processes, Invar is the preferred material, as shown in Example 4, due to its excellent mechanical stability during electroforming. The aperture metal layer 15 can be prepared by sputtering, ALD, evaporation, or electroforming, with a thickness ranging from 0.01 µm to 20 µm, ensuring precise pattern retention and dimensional stability during OLED material deposition.

[0094] Electrode metal layer 14 is used only in embodiment 4 for electroforming and is disposed below the aperture metal layer 15 as a conductive base layer for electroforming aperture metal layer 15. This layer is deposited by sputtering or vapor deposition, and the material can be selected from nickel (Ni), copper (Cu), or chromium (Cr) to ensure proper adhesion and conductivity in order to provide uniform electroforming growth and mechanical reliability.

[0095] The aperture etching method is selected based on the desired aperture profile. Reactive ion etching (RIE) using Cl2, BCl3, and Ar plasmas can form right-angle apertures, as shown in Example 1. Figure 6 As shown in Example 3. Deep reactive ion etching (DRIE) uses SF6 or CF4 plasma, and the cone angle can be adjusted. Figure 10 As shown in B). Wet etching using HF or BHF can also form negative cone angle openings, as shown in Examples 3 and 4.

[0096] The silicon etching process for the display area 12 and the alignment marks is the same in all embodiments. Wet etching (HF, BHF) or dry etching (RIE / DRIE, SF6, CF4 plasma) can be used to selectively remove the silicon substrate 13, ensuring precise aperture alignment. During silicon removal, the silicon substrate 13 may be simultaneously etched in the alignment mark area, or left unetched as required by the process, to ensure precise positioning for OLED deposition and subsequent process steps, as described in claim 6.

[0097] Photoresist layers PR(1)18, PR(2)19, PR(3)20, PR(4)21 and PR(5)22 are used for different masking steps. Positively cross-linked photoresist is used for aperture patterning, while full-area photoresist coating is used for back-side etching protection.

[0098] The final SS-FHM structure includes an open-cell composite layer 17, which integrates an open-cell ceramic layer 16 and an open-cell metal layer 15, and additionally includes an electrode metal layer 14 during the electroforming process. This structure ensures high mechanical stability, precise opening control, and optimized OLED deposition accuracy, as described in claims 2–5.

[0099] Symbol Explanation 11: Non-display area 12: Display area 13: Silicon substrate 14: Electrode metal layer 15: Perforated metal layer 16: Perforated ceramic layer 17: Open-cell composite layer 18: PR(1) 19: PR(2) 20: PR(3) 21: PR(4) 22:PR(5).

Claims

1. A silicon substrate-supported fine composite mask (SS-FHM) for OLED display manufacturing, comprising: The silicon substrate, located in the non-display area, serves to provide structural support for the mask; An open-cell composite layer, located in the display area, forms openings for material deposition; The perforated composite layer comprises at least one perforated metal layer and at least one perforated ceramic layer to enhance structural strength, shape retention and mechanical stability, ensuring suitability for various OLED display applications.

2. The fine composite mask supported on a silicon substrate as described in claim 1, wherein the silicon substrate is selected from borosilicate glass, fused silica, or TFT-grade display glass, such as Corning Eagle XG, with a thickness ranging from 0.1 mm to 5.0 mm, to ensure structural integrity and chemical stability during the OLED deposition process.

3. The fine composite mask supported on a silicon substrate as described in claim 1, wherein the coefficient of thermal expansion (CTE) of the perforated ceramic layer is less than 20 ppm / K; the perforated ceramic layer may be selected from silicon nitride (Si3N4), alumina (Al2O3), zirconium oxide (ZrO2), silicon carbide (SiC), boron nitride (BN), or zirconium tungstate; the perforated ceramic layer is prepared by LPCVD, PECVD, or ALD, and has a thickness ranging from 0.01 µm to 20 µm to ensure structural stability and compatibility with the silicon substrate.

4. The fine composite mask supported on a silicon substrate as described in claim 1, wherein the coefficient of thermal expansion (CTE) of the aperture metal layer is less than 20 ppm / K; the aperture metal layer may be selected from molybdenum (Mo), Invar, SuperInvar, tungsten (W), rhenium (Re), tantalum (Ta), nickel (Ni), or alloy 42; the aperture metal layer is prepared by sputtering, ALD, evaporation, or electroforming, and has a thickness ranging from 0.01 µm to 20 µm to ensure accurate pattern retention and dimensional stability during OLED material deposition.

5. The fine composite mask supported on a silicon substrate as described in claim 4 further includes an electrode metal layer disposed below the aperture metal layer; The coefficient of thermal expansion (CTE) of the electrode metal layer is less than 20 ppm / K; The thickness of the electrode metal layer ranges from 0.01µm to 20µm; To ensure uniform electroforming growth and mechanical reliability.

6. The fine composite mask supported by a silicon substrate as claimed in claim 1, wherein the silicon substrate is a semiconductor-grade single-crystal silicon wafer with a diameter of 8 inches or 12 inches.

7. The fine composite mask supported on a silicon substrate as claimed in claim 1, wherein the aperture composite layer comprises apertures having a right angle or a negative cone angle shape; wherein the right angle aperture has a vertical sidewall, and the top opening of the negative cone angle aperture is smaller than the bottom opening to ensure the optimal OLED material deposition angle.

8. The fine composite mask supported on a silicon substrate as described in claim 1, comprising: An open-hole composite layer is deposited on a silicon substrate, and the openings are formed by photoresist patterning and etching from the front side. The silicon substrate of the display area is selectively etched and removed from the back side.

9. The fine composite mask supported on a silicon substrate as claimed in claim 8, wherein, after patterning, negative cone-angle openings are formed by further etching an opening composite layer from the back side.

10. The fine composite mask supported on a silicon substrate as described in claim 1, comprising: An open-hole composite layer is deposited on a silicon substrate, and the openings are formed by photoresist patterning and etching from the back side. The silicon substrate of the display area is selectively etched and removed from the back side.

11. The fine composite mask supported on a silicon substrate as described in claim 1 or claim 5, comprising: An open-hole ceramic layer and an electrode metal layer are deposited on a silicon substrate, and the openings are formed by photoresist patterning and etching from the front side. An open-hole metal layer with a negative cone angle is formed on the electrode metal layer by electroforming. The silicon substrate of the display area is selectively etched and removed from the back side; In this process, after the silicon substrate in the display area is removed, the negative cone angle shape of the opening is adjusted by further etching the opening ceramic layer and electrode metal layer from the back side.

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