Mask absorber layer structure with low three-dimensional effect
By introducing a partitioned modulation structure along the Z-axis in the absorption layer structure of the photolithography mask, the light field distribution and the phase of the transmitted light are controlled, which solves the problem of focus shift and pattern distortion caused by the three-dimensional effect of traditional photolithography masks at advanced nodes, and improves the photolithography accuracy and pattern transfer fidelity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU LUXIN SEMICONDUCTOR TECHNOLOGY CO LTD
- Filing Date
- 2026-05-25
- Publication Date
- 2026-06-19
Smart Images
Figure CN122239359A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor lithography technology, and more specifically to a mask absorption layer structure with low three-dimensional effects. Background Technology
[0002] As semiconductor lithography processes continue to advance towards advanced nodes, the requirements for lithography imaging accuracy and pattern transfer fidelity are constantly increasing. The absorption layer structure of traditional lithography masks is prone to significant mask three-dimensional effects during application, which in turn leads to a series of problems such as focus shift, pattern distortion, and decreased pattern size control accuracy during the lithography imaging process. This makes it impossible to meet the lithography accuracy requirements of advanced process nodes and has become a key bottleneck restricting the mass production and application of advanced lithography technology. Summary of the Invention
[0003] To solve or at least partially solve the above-mentioned technical problems, the present invention provides a mask absorption layer structure with low three-dimensional effect.
[0004] This invention provides a mask absorption layer structure with low three-dimensional effects, including a quartz substrate, a bottom anti-reflection layer, an absorption layer body, and a top anti-reflection layer. The bottom anti-reflection layer is deposited on the surface of the quartz substrate, the absorption layer body is deposited on the side of the bottom anti-reflection layer opposite to the quartz substrate, and the top anti-reflection layer is deposited on the side of the absorption layer body opposite to the bottom anti-reflection layer. The absorption layer body forms a patterned trench structure required for photolithography in the XY plane. The absorption layer body has a partitioned modulation structure in the Z-axis direction perpendicular to the XY plane, which matches the diffraction characteristics of the patterned trench structure. The partitioned modulation structure is used to regulate the light field distribution and transmitted light phase of the incident light in the absorption layer body, and to eliminate multiple reflections and phase distortions of the incident light in the patterned trench structure.
[0005] Optionally, the absorption layer body includes at least two segmented absorption unit layers, with an anti-reflection unit layer spaced between adjacent segmented absorption unit layers; the patterned trench structures of each segmented absorption unit layer are aligned face to face, and the cumulative optical density of each segmented absorption unit layer meets the light-shielding performance requirements of the photolithography mask absorption layer; thereby forming the partitioned modulation structure.
[0006] Optionally, the material of the spaced antireflective unit layer is the same as the material of the bottom antireflective layer and the top antireflective layer; thereby forming the partitioned modulation structure.
[0007] Optionally, the sidewall edge of the patterned trench structure of the absorption layer body is provided with a thickness gradient region along the Z-axis direction; the thickness of the absorption layer in the thickness gradient region gradually decreases from the flat area of the absorption layer body towards the trench sidewall, and the sidewall of the patterned trench structure remains vertical; thereby forming the partitioned modulation structure.
[0008] Optionally, the thickness gradient region and the main flat region of the absorption layer are integrally formed; thereby forming the partitioned modulation structure.
[0009] Optionally, the absorption layer body includes a main absorption layer, a resonant cavity layer, and an auxiliary absorption layer; the resonant cavity layer is disposed between the main absorption layer and the auxiliary absorption layer, the pattern of the resonant cavity layer is aligned with the patterned trench structure of the main absorption layer and the auxiliary absorption layer, and the resonant cavity layer is embedded inside the absorption layer body and is not exposed on the sidewall surface of the patterned trench structure; thereby forming the partitioned modulation structure.
[0010] Optionally, the absorption layer body is composed of at least two sets of alternately stacked periodic absorption unit layers and periodic anti-reflection unit layers; the patterned trench structures of each periodic absorption unit layer and the periodic anti-reflection unit layer are aligned with each other, and the cumulative optical density value of all periodic absorption unit layers meets the light-shielding performance requirements of the photolithographic mask absorption layer; thereby forming the partitioned modulation structure.
[0011] Optionally, the main body of the absorption layer is made of molybdenum-silicon-based material, and the bottom antireflective layer and the top antireflective layer are made of molybdenum-silicon oxide material.
[0012] Optionally, the patterned trench structure of the absorption layer body is divided into at least two patterned partitions according to the feature size, linewidth-to-spacing ratio, and pattern period; the absorption layer body in each patterned partition is provided with an independent partitioned modulation structure in the Z-axis direction that matches the diffraction characteristics of the corresponding patterned partition.
[0013] Optionally, the independent partition modulation structures within different graphic partitions may employ different Z-axis thickness designs and layering arrangements.
[0014] The structure provided by this invention has the following beneficial effects:
[0015] This invention, by setting a partitioned modulation structure in the Z-axis direction of the absorption layer body that matches the diffraction characteristics of the patterned trench structure, can effectively control the light field distribution and transmitted light phase of the incident light within the absorption layer body. This eliminates multiple reflections and phase distortions of the incident light within the patterned trench structure, reduces the adverse effects of mask 3D effects on photolithography imaging, and improves focusing accuracy and pattern size control during the photolithography process. This solution uses existing, commercially available, mature molybdenum-silicon-based materials as the absorption layer body and molybdenum-silicon oxide materials as the anti-reflection layer. It requires no introduction of new material components, film-forming targets, or production equipment, and is compatible with the entire production process of existing mask mass production lines. It does not require additional production investment and has a solid foundation for mass production.
[0016] This solution offers multiple partitioned modulation structure implementations, tailored to various lithography application scenarios. Through segmented stacked structures, sidewall edge thickness gradient structures, embedded resonant cavity structures, and alternating periodic stacked structures, it addresses issues such as multiple reflections, pattern edge distortion, and transmitted light phase distortion under different incident conditions, effectively improving the transfer fidelity of lithographic patterns. The differentiated pattern partitioning structure design allows for precise control of the diffraction characteristics of different patterns, eliminating focus offsets between patterns and significantly expanding the effective depth of focus and process window during lithography. This allows for flexible adaptation to the lithography application requirements of different advanced process nodes, demonstrating promising application prospects. Attached Figure Description
[0017] Figure 1 A schematic diagram of a mask absorption layer structure with low three-dimensional effect provided in an embodiment of the present invention;
[0018] Figure 2 A schematic diagram of another low-three-dimensional effect mask absorption layer structure provided in an embodiment of the present invention;
[0019] Figure 3 A schematic diagram of another low-three-dimensional effect mask absorption layer structure provided in an embodiment of the present invention;
[0020] Figure 4 A schematic diagram of another low-three-dimensional effect mask absorption layer structure provided in an embodiment of the present invention;
[0021] Figure 5 This is a schematic diagram of another low-three-dimensional effect mask absorption layer structure provided in an embodiment of the present invention.
[0022] Reference numerals: 1. Quartz substrate; 2. Bottom antireflective layer; 3. Absorption layer body; 4. Top antireflective layer; 5. Patterned trench structure; 51. Patterned partition; 301. Segmented absorption unit layer; 302. Interval antireflective unit layer; 311. Main absorption layer; 312. Resonant cavity layer; 313. Secondary absorption layer; 321. Periodic absorption unit layer; 322. Periodic antireflective unit layer; 501. Gradual thickness region. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings, not all of them. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.
[0024] The technical solutions of the embodiments of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.
[0025] See Figures 1 to 5 This invention provides a mask absorption layer structure with low three-dimensional effect, including a quartz substrate 1, a bottom antireflection layer 2, an absorption layer body 3, and a top antireflection layer 4. The bottom antireflection layer 2 is deposited on the surface of the quartz substrate 1, the absorption layer body 3 is deposited on the side of the bottom antireflection layer 2 away from the quartz substrate 1, and the top antireflection layer 4 is deposited on the side of the absorption layer body 3 away from the bottom antireflection layer 2. The absorption layer body 3 forms a patterned trench structure 5 required for photolithography in the XY plane. The absorption layer body 3 is provided with a partitioned modulation structure in the Z-axis direction perpendicular to the XY plane, which matches the diffraction characteristics of the patterned trench structure 5. The partitioned modulation structure is used to regulate the light field distribution and the phase of the transmitted light in the absorption layer body 3, and to eliminate multiple reflections and phase distortions of the incident light in the patterned trench structure 5.
[0026] In some embodiments, the main body 3 of the absorption layer is made of molybdenum-silicon-based material, and the bottom antireflective layer and the top antireflective layer are made of molybdenum-silicon oxide material.
[0027] As semiconductor lithography processes continue to advance towards advanced nodes, the precision requirements for lithographic imaging are constantly increasing. As the core carrier for transferring lithographic patterns, the structural design of the mask determines the fidelity of the transferred patterns and the final imaging quality. Traditional lithographic masks employ a globally uniform, continuous, and homogeneous absorption layer design. In lithography applications at 28nm and below advanced process nodes, this results in a significant mask 3D effect (M3D), leading to a series of problems during the lithography imaging process, such as focus shift, pattern distortion, and decreased pattern size control precision. This fails to meet the requirements of advanced process node lithography applications and has become one of the key bottlenecks restricting the mass production and application of advanced process lithography technology.
[0028] To address the aforementioned issues, this solution provides a mask absorption layer structure with low three-dimensional effects. The overall structure includes a quartz substrate 1, a bottom antireflective layer 2, an absorption layer body 3, and a top antireflective layer 4. The bottom antireflective layer 2 is deposited on the surface of the quartz substrate 1, the absorption layer body 3 is deposited on the side of the bottom antireflective layer 2 facing away from the quartz substrate 1, and the top antireflective layer 4 is deposited on the side of the absorption layer body 3 facing away from the bottom antireflective layer 2.
[0029] The main body of the absorption layer 3 is made of molybdenum-silicon-based material, while the bottom antireflective layer 2 and the top antireflective layer 4 are made of molybdenum-silicon oxide material. This material system is a mature material commonly used in the production of existing mass-produced photolithography masks. It does not require the introduction of new material components, new film-forming targets, or new film-forming chemicals. It is compatible with the entire production process of existing mask mass production lines, including film formation, etching, and cleaning. It will not increase equipment investment or process costs in the production process. It has a mature foundation for mass production and can be directly adapted to the existing mask production process control standards without requiring additional adjustments to the existing production system.
[0030] Figure 1The diagram illustrates the Z-direction, and the XY plane is perpendicular to the Z-direction. The absorption layer 3, located within the XY plane perpendicular to the surface of the quartz substrate 1, forms the patterned trench structure 5 required for photolithography through photolithography and etching processes. The morphology of the patterned trench structure 5 corresponds to the photolithographic pattern to be transferred, and it is the core structural unit for realizing the transfer of the photolithographic pattern from the mask to the wafer. Off-axis illumination is commonly used in advanced photolithography processes, where incident light is incident on the mask surface at an angle. Under this incident method, the optical behaviors such as reflection and diffraction of the incident light within the patterned trench structure 5 are more pronounced. In traditional continuous and uniform absorption layer structures, the thickness is on the same order of magnitude as the wavelength of the incident light in photolithography and the feature size of the patterned trench structure 5. The light rays incident at an angle will form long-range multiple reflections inside the patterned trench structure 5. After the incident light at different angles passes through the absorption layer, the phase of the transmitted light will show significant differences, which will cause the optimal focusing plane corresponding to different morphologies to shift. The effective depth of focus in the photolithography process is greatly compressed, the fidelity of pattern transfer decreases, and in severe cases, it will lead to the failure of the photolithography pattern, which cannot meet the production requirements of advanced processes.
[0031] In this scheme, the absorption layer body 3 has a partitioned modulation structure in the Z-axis direction perpendicular to the XY plane, which matches the diffraction characteristics of the patterned trench structure 5. The Z-axis direction is the absorption layer thickness direction perpendicular to the surface of the quartz substrate 1. Traditional mask absorption layers are only patterned in the XY plane, maintaining a globally uniform continuous structure in the Z-axis direction. Regardless of the morphology, size, and distribution characteristics of the patterned trench structure 5, the structural design of the absorption layer in the Z-axis direction is consistent, which cannot adapt to the differentiated diffraction characteristics of different patterns. This is the core root cause of the mask three-dimensional effect of traditional masks. After the incident light enters the patterned trench structure 5, it will undergo optical behaviors such as reflection and diffraction inside the trench. The diffraction characteristics of the incident light corresponding to patterned trench structures 5 with different morphologies, sizes, and distributions are significantly different. The traditional globally uniform absorption layer structure cannot specifically control the optical behavior of the incident light, resulting in multiple reflections of the incident light inside the trench and phase distortion of the transmitted light, ultimately causing the mask three-dimensional effect and affecting the lithography imaging quality.
[0032] Matching the diffraction characteristics of the partitioned modulation structure with the patterned trench structure 5 allows for corresponding structural designs in the Z-axis direction of the absorption layer body 3, tailored to the incident light diffraction characteristics of different patterned trench structures 5. This Z-axis structural design modulates the light field distribution and transmitted light phase within the absorption layer body 3, eliminating multiple reflections and phase distortions of the incident light within the patterned trench structure 5, thereby reducing the adverse effects of mask 3D effects on photolithography imaging. This structural design effectively reduces focus shift and pattern distortion caused by mask 3D effects, improving focusing accuracy and pattern size control during photolithography, meeting the lithography accuracy requirements of advanced process nodes. Furthermore, the entire structure utilizes existing mature mass-produced materials, is compatible with the entire process of existing mask production, requires no additional production investment, and possesses excellent mass production adaptability and application prospects. This solution extends the structural design of the absorption layer to the Z-axis direction, effectively suppressing mask 3D effects through structural design optimization.
[0033] The above describes the overall design concept and core architecture of the mask absorption layer structure with low three-dimensional effect. The following section will elaborate on the specific implementation of the partitioned modulation structure in this structure.
[0034] Example 1
[0035] See Figure 1 In some embodiments, the absorption layer body 3 includes at least two segmented absorption unit layers 301, and an anti-reflection unit layer 302 is provided between two adjacent segmented absorption unit layers 301; the patterned trench structures 5 of each segmented absorption unit layer 301 are aligned with each other, and the cumulative optical density of each segmented absorption unit layer 301 meets the light-shielding performance requirements of the photolithography mask absorption layer; thereby forming a partitioned modulation structure.
[0036] In some embodiments, the material of the spacer antireflective unit layer 302 is the same as the material of the bottom antireflective layer 2 and the top antireflective layer 4, thereby forming a partitioned modulation structure.
[0037] One implementation of the partitioned modulation structure is as follows: the main body of the absorption layer 3 includes at least two segmented absorption unit layers 301, with an anti-reflection unit layer 302 disposed between adjacent segments of the absorption unit layers 301. The segmented absorption unit layers 301 are made of molybdenum-silicon-based material, consistent with the material system of the main body of the absorption layer 3. The material of the anti-reflection unit layer 302 is consistent with the materials of the bottom anti-reflection layer 2 and the top anti-reflection layer 4, both being molybdenum-silicon oxide material. The entire film deposition process of the stacked structure can be completed using existing mass-produced and mature magnetron sputtering technology. Only the atmosphere ratio during the sputtering process needs to be adjusted to achieve the alternating deposition of different material layers.
[0038] After the segmented absorption unit layers 301 and the spaced anti-reflection unit layers 302 are deposited, a patterned trench structure 5 penetrating all film layers is formed within the stacked structure through a unified photolithography and etching process. The patterned trench structures 5 of each segmented absorption unit layer 301 are aligned face-to-face, and the sidewalls of the patterned trench structures 5 remain continuously perpendicular in the Z-axis direction. The linewidth dimensions of each segmented absorption unit layer 301 are kept consistent to avoid interlayer pattern misalignment and ensure the dimensional accuracy and morphological fidelity of the photolithographic pattern transfer. The cumulative optical density of each segmented absorption unit layer 301 meets the light-shielding performance requirements of the photolithographic mask absorption layer, effectively blocking non-target transmission of incident light and avoiding background exposure problems caused by light leakage during photolithography, thus ensuring the imaging contrast of the photolithographic pattern.
[0039] In traditional continuous and uniform absorption layer structures, when obliquely incident light enters the patterned trench structure 5, it undergoes long-range multiple reflections and interferences across the entire thickness of the absorption layer. After long-range transmission, the phase of the transmitted light from different angles exhibits significant distortion, leading to masking three-dimensional effects such as focus shift and pattern distortion. In this implementation, the spaced anti-reflection unit layer 302 divides the continuous absorption layer into multiple independent segmented absorption unit layers 301. When obliquely incident light enters the patterned trench structure 5, it is rapidly absorbed and dissipated within each segmented absorption unit layer 301, preventing long-range multiple reflections across the entire thickness of the absorption layer and eliminating the core cause of masking three-dimensional effects. Simultaneously, the optical interface formed between the spaced anti-reflection unit layer 302 and the adjacent segmented absorption unit layers 301 can achieve destructive reflection of the interface light through optical interference, significantly reducing the light field disturbance caused by interface reflection and further eliminating reflection and phase distortion of the incident light within the patterned trench structure 5.
[0040] The above structural design can effectively suppress the adverse effects of mask 3D effects on photolithography imaging, significantly reduce the focus offset problem of different morphological patterns, expand the effective depth of focus and process window in the photolithography process, and improve the accuracy of pattern size control and pattern transfer fidelity.
[0041] Example 2
[0042] See Figure 2 In some embodiments, the sidewall edge of the patterned trench structure 5 of the absorption layer body 3 is provided with a thickness gradient region 501 along the Z-axis direction; the thickness of the absorption layer in the thickness gradient region 501 gradually decreases from the flat area of the absorption layer body 3 toward the trench sidewall direction, and the sidewall of the patterned trench structure 5 remains vertical; thereby forming a partitioned modulation structure.
[0043] In some embodiments, the thickness gradient region 501 and the main flat region of the absorption layer body 3 are integrally formed; thereby forming a partitioned modulation structure.
[0044] One implementation of a partitioned modulation structure involves providing a thickness gradient region 501 along the Z-axis on the sidewall edge of the patterned trench structure 5 of the absorption layer body 3. The thickness gradient region 501 is distributed between the sidewall of the patterned trench structure 5 and the main flat area of the absorption layer body 3, covering all sidewall edge areas of the patterned trench structure 5, including key morphological areas such as line ends and corners. The absorption layer thickness in the thickness gradient region 501 gradually decreases from the main flat area of the absorption layer body 3 towards the trench sidewall. The sidewall of the patterned trench structure 5 remains continuously vertical in the Z-axis direction. The linewidth definition position of the patterned trench structure 5 is consistent with that of a traditional mask structure, avoiding linewidth dimensional deviations due to the thickness gradient region 501 and ensuring the dimensional control accuracy of the photolithographic pattern transfer.
[0045] The thickness gradient region 501 and the main flat region of the absorption layer 3 are integrally formed structures. Both use the same molybdenum-silicon base material and there is no interlayer interface. The overall structure has good stability and consistency and can withstand wet cleaning, dry etching and other processes in the mask production process. It can also withstand laser irradiation in the photolithography process, ensuring the service life of the mask and the performance stability during use.
[0046] The preparation process of the thickness gradient region 501 is compatible with the mature production process of existing mask mass production lines. It can be achieved through the proximity effect correction function of existing electron beam exposure equipment. An exposure pattern with a gradient exposure dose is designed at the edge of the sidewall of the patterned trench structure 5. The difference in etching depth in the subsequent etching process is controlled by the gradient change of the exposure dose, thereby forming a thickness gradient morphology along the Z-axis. The preparation of the overall structure can be completed with only one film formation, one electron beam exposure, and one dry etching.
[0047] In traditional continuous uniform thickness absorption layer structures, the sidewall edges of the patterned trench structure 5 are vertical thick-layer boundaries. When obliquely incident light reaches the sidewall edge, strong edge diffraction, scattering, and polarization loss occur, resulting in extremely uneven light field distribution at the trench edge. This leads to a sharp decrease in the contrast of the pattern edge during photolithography imaging, ultimately causing problems such as line shortening, corner rounding, and deterioration of line edge roughness. These problems are further amplified in advanced process nodes, affecting the fidelity of the photolithography pattern and production yield. In this implementation, by setting a thickness gradient region 501 at the sidewall edge, the strong diffraction effect of the traditional thick vertical boundary is transformed into a weak diffraction effect of the gradient thickness boundary, significantly reducing the diffraction and scattering intensity at the sidewall edge. This makes the light field distribution at the pattern edge more uniform. At the same time, the thickness gradient structure design allows obliquely incident light to be quickly absorbed and dissipated at the edge, preventing multiple reflections and light field disturbances at the trench sidewall, thus eliminating light field distortion at the edge from the root.
[0048] The above structural design can effectively solve the problem of pattern edge distortion caused by the three-dimensional effect of the mask, significantly improve the phenomenon of line end shortening and corner rounding, reduce the line edge roughness of the pattern, and greatly improve the transfer fidelity and dimensional control accuracy of the lithographic pattern.
[0049] Example 3
[0050] See Figure 3 In some embodiments, the absorption layer body 3 includes a main absorption layer 311, a resonant cavity layer 312, and an auxiliary absorption layer 313; the resonant cavity layer 312 is disposed between the main absorption layer 311 and the auxiliary absorption layer 313, and the pattern of the resonant cavity layer 312 is aligned with the patterned trench structure 5 of the main absorption layer 311 and the auxiliary absorption layer 313. The resonant cavity layer 312 is embedded inside the absorption layer body 3 and is not exposed on the sidewall surface of the patterned trench structure 5; thereby forming a partitioned modulation structure.
[0051] One implementation of a partitioned modulation structure is as follows: the main body 3 of the absorption layer includes a main absorption layer 311, a resonant cavity layer 312, and an auxiliary absorption layer 313. The resonant cavity layer 312 is disposed between the main absorption layer 311 and the auxiliary absorption layer 313. The main absorption layer 311 is deposited on the side of the bottom antireflective layer 2 facing away from the quartz substrate 1, and the side of the auxiliary absorption layer 313 facing away from the resonant cavity layer 312 is connected to the top antireflective layer 4. Both the main absorption layer 311 and the auxiliary absorption layer 313 are made of molybdenum-silicon-based material, consistent with the material system of the main body 3 of the absorption layer. The material of the resonant cavity layer 312 is consistent with the materials of the bottom antireflective layer 2 and the top antireflective layer 4, both being molybdenum-silicon oxide material. The entire stacked structure does not require the introduction of new material components and film-forming targets. The film-forming process can be completed using existing mature mass-produced magnetron sputtering technology. Only the atmosphere ratio during the sputtering process needs to be adjusted to achieve the alternating deposition of different film layers.
[0052] After the main absorption layer 311, resonant cavity layer 312, and auxiliary absorption layer 313 are deposited, a patterned trench structure 5 penetrating the main absorption layer 311 and auxiliary absorption layer 313 is formed through a unified photolithography and etching process. The pattern of the resonant cavity layer 312 is aligned with the patterned trench structure 5 of the main absorption layer 311 and auxiliary absorption layer 313. The resonant cavity layer 312 is embedded inside the absorption layer body 3 and is not exposed on the sidewall surface of the patterned trench structure 5. This embedded structure design avoids the material of the resonant cavity layer 312 from being directly exposed to the etching, cleaning, and other process environments, preventing problems such as material corrosion, interface damage, and morphology deterioration. At the same time, it avoids direct interface reflection between the resonant cavity layer 312 and the incident light in the trench, ensuring the stability and consistency of the structure's optical performance. The sidewalls of the patterned trench structure 5 of the main absorption layer 311 and auxiliary absorption layer 313 remain continuously perpendicular in the Z-axis direction, with consistent linewidth dimensions, avoiding interlayer pattern misalignment and ensuring the dimensional accuracy of photolithographic pattern transfer. The cumulative optical density of the main absorption layer 311 and the auxiliary absorption layer 313 meets the light-shielding performance requirements of the photolithography mask absorption layer, effectively blocking non-target transmission of incident light, avoiding background exposure problems caused by light leakage during photolithography, and ensuring the imaging contrast of the photolithography pattern.
[0053] In traditional continuous and uniform absorption layer structures, light incident at different angles, after passing through the thick absorption layer, generates a significant optical path difference, leading to severe phase distortion of the transmitted light. Patterns with different morphologies and densities exhibit significant phase differences in the transmitted light, ultimately causing a shift in the optimal focusing plane for different patterns. This drastically reduces the effective depth of focus during photolithography, and is one of the core factors contributing to the impact of mask 3D effects on photolithography imaging quality. In this implementation, the resonant cavity layer 312, located between the main absorption layer 311 and the auxiliary absorption layer 313, forms a closed optical resonant structure. This structure can actively control the phase of the transmitted light incident at different angles without introducing additional optical loss, keeping the phase of the transmitted light synchronized and thus eliminating the phase distortion problem caused by different incident angles. Meanwhile, the main absorption layer 311 can efficiently absorb vertically incident and small-angle obliquely incident light, while the auxiliary absorption layer 313 can efficiently absorb large-angle obliquely incident light, achieving full coverage absorption of incident light at all angles. This avoids multiple reflections and light field disturbances caused by obliquely incident light within the patterned trench structure 5, further suppressing the generation of mask three-dimensional effects.
[0054] Through the above structural design, the phase distortion and multiple reflections of incident light in the patterned trench structure 5 can be eliminated, the focusing offset problem of different patterns can be greatly reduced, the effective depth of focus and process window in the lithography process can be significantly expanded, the size control accuracy and transfer fidelity of the lithography pattern can be improved, and it can adapt to the lithography application requirements of advanced process nodes with higher precision requirements, and has good mass production adaptability and application prospects.
[0055] Example 4
[0056] See Figure 4 In some embodiments, the absorption layer body 3 is composed of at least two sets of alternately stacked periodic absorption unit layers 321 and periodic anti-reflection unit layers 322; the patterned trench structures 5 of each periodic absorption unit layer 321 and periodic anti-reflection unit layer 322 are aligned with each other, and the cumulative optical density of all periodic absorption unit layers 321 meets the light-shielding performance requirements of the photolithography mask absorption layer; thereby forming a partitioned modulation structure.
[0057] One implementation of a partitioned modulation structure is as follows: the main body 3 of the absorption layer consists of at least two sets of alternately stacked periodic absorption unit layers 321 and periodic antireflection unit layers 322. The periodic absorption unit layers 321 are made of molybdenum-silicon-based material, consistent with the material system of the main body 3 of the absorption layer. The material of the periodic antireflection unit layers 322 is consistent with the materials of the bottom antireflection layer 2 and the top antireflection layer 4, both being molybdenum-silicon oxide material. The entire stacked structure does not require the introduction of new material components, film-forming targets, or film-forming chemicals. It can be prepared using existing mass-produced and mature magnetron sputtering or atomic layer deposition processes. During the film formation process, only the sputtering atmosphere ratio or the deposition precursor needs to be adjusted to achieve the alternating deposition of different material layers.
[0058] After the periodic absorption unit layers 321 and periodic anti-reflection unit layers 322 are alternately stacked and deposited, a patterned trench structure 5 penetrating all film layers is formed within the stacked structure through a unified photolithography and etching process. The patterned trench structures 5 of the periodic absorption unit layers 321 and periodic anti-reflection unit layers 322 are aligned face-to-face, and the sidewalls of the patterned trench structures 5 remain continuously perpendicular in the Z-axis direction. The linewidth dimensions of the periodic absorption unit layers 321 are kept consistent to avoid problems such as interlayer pattern misalignment and sidewall tilting, ensuring the dimensional accuracy and morphological fidelity of the photolithographic pattern transfer. The cumulative optical density value of all periodic absorption unit layers 321 meets the light-shielding performance requirements of the photolithographic mask absorption layer, effectively blocking non-target transmission of incident light, avoiding background exposure problems caused by light leakage during photolithography, ensuring the imaging contrast of the photolithographic pattern, and preventing the overall light-shielding performance of the absorption layer from being reduced due to the design of the stacked structure.
[0059] In traditional continuous and uniform absorption layer structures, the overall thickness of the absorption layer is much greater than the incident light wavelength for short-wavelength lithography. Inclined incident light will generate strong multiple reflections, shadowing effects, and polarization losses within the patterned trench structure 5. After transmission through the thick absorption layer at different angles, incident light will produce significant phase distortion, further amplifying the effects of the mask's three-dimensional effect. This approach cannot meet the requirements of higher-precision advanced process nodes in lithography applications. In this implementation, the alternately stacked ultrathin periodic absorption unit layer 321 and periodic anti-reflection unit layer 322, through the design of the stacked structure, can efficiently absorb light incident at different angles across the entire angular range. This avoids long-range multiple reflections and light field disturbances within the patterned trench structure 5 caused by inclined incident light. Simultaneously, the optical characteristics of the stacked structure can be used to control the light field distribution within the main body of the absorption layer 3, ensuring a uniform distribution of the light field across the entire thickness of the absorption layer. This avoids the phase distortion problem caused by the light field concentration at the interface position in traditional single-layer absorption layers, thereby suppressing the generation of the mask's three-dimensional effect.
[0060] Through the above structural design, the adverse effects of the mask three-dimensional effect on photolithography imaging can be effectively suppressed, the multiple reflections and phase distortions of incident light in the patterned trench structure 5 can be significantly reduced, the size control accuracy and transfer fidelity of the photolithography pattern can be significantly improved, the effective depth of focus and process window in the photolithography process can be expanded, and it can be adapted to advanced process node application scenarios with higher precision requirements such as short-wavelength photolithography.
[0061] Example 5
[0062] See Figure 5 In some embodiments, the patterned trench structure 5 of the absorption layer body 3 is divided into at least two patterned partitions 51 according to the feature size, line width-to-spacing ratio, and pattern period; the absorption layer body 3 in each patterned partition 51 is provided with an independent partitioned modulation structure in the Z-axis direction that matches the diffraction characteristics of the corresponding patterned partition 51.
[0063] In some implementations, the independent partition modulation structures within different graphic partitions 51 employ different Z-axis thickness designs and stacking arrangements.
[0064] One implementation of the partitioned modulation structure is as follows: the patterned trench structure 5 of the absorption layer body 3 is divided into at least two patterned partitions 51 according to the feature size, linewidth-to-spacing ratio, and pattern period. The absorption layer body 3 within each patterned partition 51 has an independent partitioned modulation structure in the Z-axis direction that matches the diffraction characteristics of the corresponding patterned partition 51.
[0065] Different regions of the patterned trench structure 5 exhibit completely different diffraction characteristics due to variations in feature size, linewidth-to-spacing ratio, and pattern period. When incident light illuminates these regions, it produces entirely different diffraction characteristics. The light field distribution, reflection behavior, and phase changes of incident light with different diffraction characteristics within the absorption layer all show significant differences. If the mask absorption layer adopts a globally uniform structural design, it cannot adapt to the differentiated diffraction characteristics of different patterned partitions 51, achieving only a globally average optimization effect. It cannot specifically eliminate the mask's three-dimensional effects corresponding to different patterns, and especially cannot solve the problem of optimal focal plane offset between patterns of different densities. This results in a significant compression of the effective depth of focus during photolithography, narrowing the process window and failing to meet the mass production yield requirements of advanced process nodes.
[0066] The independent partition modulation structures within different pattern partitions 51 employ different Z-axis thickness designs and stacking arrangements. The design of the independent partition modulation structure matches the diffraction characteristics of the corresponding pattern partition 51, enabling the control of the optical behavior of the corresponding pattern. Figure 5 Only graphic partition 51 is shown; the different independent partition modulation structures are not displayed. For information on partition modulation structures, please refer to [link / reference needed]. Figures 1 to 4 For example, for graphic partition 51 corresponding to densely arranged patterns, a multi-layered segmented stacked structure design can be adopted to specifically eliminate multiple reflections of large-angle oblique incident light within the trench; for graphic partition 51 corresponding to isolated patterns, a stacked structure design with embedded resonant cavities can be adopted to actively control the phase of transmitted light, ensuring that the optimal focusing plane of this partition pattern is consistent with the optimal focusing plane of the densely arranged pattern partition; for graphic partition 51 with a large number of line ends and corner patterns, a structure design with gradually varying sidewall edge thickness can be adopted to improve the diffraction distortion problem at the edge of the pattern. The independent partition modulation structure of all graphic partitions 51 uses a uniform molybdenum-silicon-based absorber layer material and molybdenum-silicon oxide antireflective layer material.
[0067] Through the aforementioned partitioned structural design, the mask's three-dimensional effects can be accurately suppressed across the entire domain, rather than achieving a global average optimization effect, targeting the differentiated diffraction characteristics of different patterns. This design can actively adjust the phase of transmitted light in different pattern partitions 51, ensuring that the optimal focal planes of all patterns within the entire mask coincide, eliminating focus offset issues between different patterns, significantly expanding the effective depth of focus and process window during lithography, and significantly improving the pattern size control accuracy and transfer fidelity across the entire mask. Furthermore, this implementation method is flexibly adaptable to all the aforementioned partitioned modulation structures, allowing for the matching of corresponding structural designs within different pattern partitions 51 according to the actual needs of the lithography pattern. It possesses extremely strong design flexibility and scenario adaptability, meeting the lithography application requirements of different advanced process nodes, and demonstrating good mass production adaptability and application prospects.
[0068] Example 6
[0069] One implementation of the partitioned modulation structure is based on the scheme of Embodiment 1, and further incorporates a segmented absorption unit layer 301 and an interleaved anti-reflection unit layer 302 structure for the absorption layer body 3. Each segmented absorption unit layer 301 has a progressively decreasing thickness along the propagation direction of the incident light. The thickness of the interleaved anti-reflection unit layer 302 between adjacent segmented absorption unit layers 301 is synchronously adjusted to match the thickness gradient of the corresponding segmented absorption unit layer 301. This structure matches the light intensity attenuation law of the incident light within the absorption layer, enabling efficient absorption of the incident light step-by-step. The synchronously matched thickness of the interleaved anti-reflection unit layer 302 ensures accurate destructive interference of reflected light at each interface, further eliminating multiple reflections of the incident light within the patterned trench structure 5. Compared to a segmented structure with equal thickness, this structure offers superior suppression of the mask's three-dimensional effects, further expanding the photolithography process window and improving the precision of pattern size control.
[0070] Example 7
[0071] One implementation of the partitioned modulation structure is based on the scheme of Embodiment 2, and can also be based on the thickness gradient region 501 structure on the sidewall edge of the patterned trench structure 5 of the absorption layer body 3. The thickness gradient region 501 adopts an asymmetrical gradient slope design on the upper and lower surfaces of the absorption layer body 3, with a gentler gradient slope near the top anti-reflection layer 4 and a steeper gradient slope near the bottom anti-reflection layer 2. This structure matches the propagation law of incident light entering from the top side and the light intensity gradually decreasing along the thickness direction. The gentle gradient slope on the incident side can weaken the edge diffraction effect of the incident light in advance, and the steep gradient slope on the exiting side can ensure the boundary clarity of the lithographic pattern. Compared with a gradient structure with a single slope, it can more effectively improve the problems of line end shortening, corner rounding and line edge roughness deterioration, and further improve the pattern transfer fidelity.
[0072] Example 8
[0073] One implementation of the partitioned modulation structure is based on the scheme of Embodiment 3, which can be further based on the structure of the main absorption layer 311, the resonant cavity layer 312, and the auxiliary absorption layer 313 of the absorption layer body 3. The resonant cavity layer 312 adopts a differentiated thickness design that matches the diffraction characteristics of the patterned trench structure 5. The thickness of the resonant cavity layer 312 is set differently according to the phase modulation requirements of the corresponding positions for different pattern morphologies and different densities. This structure can provide matching transmitted light phase modulation for the diffraction characteristics of different patterns. Compared with the globally uniform thickness resonant cavity structure, it can more effectively eliminate phase distortion and optimal focus plane offset between different morphologies, further compress the focal plane deviation within the entire mask range, and significantly expand the effective focal depth of photolithography.
[0074] Example 9
[0075] One implementation of the partitioned modulation structure is as follows: based on the scheme of embodiment four, it can also be based on the alternating stacking structure of periodic absorption unit layer 321 and periodic anti-reflection unit layer 322 of the absorption layer body 3. Along the propagation direction of incident light, the thickness ratio of the alternating stacked periodic absorption unit layer 321 and periodic anti-reflection unit layer 322 is set to change in a continuous gradient. The thickness ratio of periodic anti-reflection unit layer 322 is higher in the incident side stack near the top anti-reflection layer 4, and the thickness ratio of periodic absorption unit layer 321 is higher in the emitting side stack near the bottom anti-reflection layer 2. The total thickness and total optical density of all stacks are consistent with the original uniform alternating structure. This structure matches the light intensity attenuation law of incident light along the thickness direction of the absorption layer. The periodic anti-reflection unit layer 322 with a high proportion on the incident side can significantly reduce the interface reflection of incident light and avoid the reflected light from forming multiple light field disturbances in the patterned trench structure 5. The periodic absorption unit layer 321 with a high proportion on the exit side can achieve efficient absorption of transmitted light and eliminate the phase distortion of residual light. Compared with the uniformly alternating periodic stacked structure, it has stronger adaptability to incident light at all angles and can further suppress the three-dimensional effect of the mask and improve the imaging accuracy in short-wavelength lithography scenarios.
[0076] Example 10
[0077] One implementation of the partitioned modulation structure is as follows: based on Embodiment 1 and Embodiment 2, the segmented absorption unit layer 301, the spaced anti-reflection unit layer 302 structure of the absorption layer body 3 can be integrated and optimized with the thickness gradient region 501 structure. Each segmented absorption unit layer 301 has an intralayer micro-gradient region matching the thickness of the layer on its sidewall edge of the patterned groove structure 5. The intralayer micro-gradient regions of each layer together constitute the overall thickness gradient region 501. The intralayer micro-gradient region and the corresponding segmented absorption unit layer 301 are integrally formed structures, and the overall sidewall of the patterned groove structure 5 remains vertical. This structure, through layer-by-layer edge micro-gradient design, simultaneously weakens edge diffraction effects within each segmented layer in the propagation of incident light, avoiding edge reflection and light field disturbance at the interlayer interface. Compared to a single overall thickness gradient structure, it can more effectively eliminate edge light field distortion within a multi-layer stacked structure, further improving issues such as line end shortening, corner rounding, and line edge roughness. At the same time, it fully retains the core suppression capability of the segmented structure for mask three-dimensional effects, and can flexibly adapt to the lithography requirements of different advanced process nodes.
[0078] The above description is merely a preferred embodiment of the present invention and the technical principles employed. The present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions that can be made by those skilled in the art will not depart from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention.
Claims
1. A mask absorption layer structure with low three-dimensional effect, comprising a quartz substrate (1), a bottom antireflective layer (2), an absorption layer body (3), and a top antireflective layer (4); wherein the bottom antireflective layer (2) is deposited on the surface of the quartz substrate (1), the absorption layer body (3) is deposited on the side of the bottom antireflective layer (2) away from the quartz substrate (1), and the top antireflective layer (4) is deposited on the side of the absorption layer body (3) away from the bottom antireflective layer (2); the absorption layer body (3) forms a patterned trench structure (5) required for photolithography in the XY plane, characterized in that, The absorption layer body (3) is provided with a partitioned modulation structure in the Z-axis direction perpendicular to the XY plane, which matches the diffraction characteristics of the patterned trench structure (5); the partitioned modulation structure is used to regulate the light field distribution and transmitted light phase of the incident light in the absorption layer body (3) and eliminate multiple reflections and phase distortions of the incident light in the patterned trench structure (5).
2. The mask absorption layer structure with low three-dimensional effect according to claim 1, characterized in that, The absorption layer body (3) includes at least two segmented absorption unit layers (301), and an anti-reflection unit layer (302) is provided between two adjacent segmented absorption unit layers (301); the patterned trench structures (5) of each segmented absorption unit layer (301) are aligned face to face, and the cumulative optical density of each segmented absorption unit layer (301) meets the light-shielding performance requirements of the photolithography mask absorption layer; thereby forming the partitioned modulation structure.
3. The mask absorption layer structure with low three-dimensional effect according to claim 2, characterized in that, The material of the spaced antireflective unit layer (302) is the same as that of the bottom antireflective layer (2) and the top antireflective layer (4); thus forming the partitioned modulation structure.
4. The mask absorption layer structure with low three-dimensional effect according to claim 1, characterized in that, The sidewall edge of the patterned trench structure (5) of the absorption layer body (3) is provided with a thickness gradient region (501) along the Z-axis direction; the thickness of the absorption layer in the thickness gradient region (501) gradually decreases from the flat area of the main body of the absorption layer body (3) towards the trench sidewall, and the sidewall of the patterned trench structure (5) remains vertical; thereby forming the partitioned modulation structure.
5. The mask absorption layer structure with low three-dimensional effect according to claim 4, characterized in that, The thickness gradient region (501) and the main flat region of the absorption layer body (3) are integrally formed; thus forming the partitioned modulation structure.
6. The mask absorption layer structure with low three-dimensional effect according to claim 1, characterized in that, The absorption layer body (3) includes a main absorption layer (311), a resonant cavity layer (312), and an auxiliary absorption layer (313). The resonant cavity layer (312) is disposed between the main absorption layer (311) and the auxiliary absorption layer (313). The pattern of the resonant cavity layer (312) is aligned with the patterned trench structure (5) of the main absorption layer (311) and the auxiliary absorption layer (313). The resonant cavity layer (312) is embedded inside the absorption layer body (3) and is not exposed on the side wall surface of the patterned trench structure (5). This forms the partitioned modulation structure.
7. The mask absorption layer structure with low three-dimensional effect according to claim 1, characterized in that, The absorption layer body (3) is composed of at least two sets of alternately stacked periodic absorption unit layers (321) and periodic anti-reflection unit layers (322); the patterned trench structures (5) of each periodic absorption unit layer (321) and periodic anti-reflection unit layer (322) are aligned with each other, and the cumulative optical density of all periodic absorption unit layers (321) meets the light-shielding performance requirements of the photolithography mask absorption layer; thereby forming the partitioned modulation structure.
8. The mask absorption layer structure with low three-dimensional effect according to claim 1, characterized in that, The main body of the absorption layer (3) is made of molybdenum-silicon-based material, and the bottom anti-reflection layer and the top anti-reflection layer are made of molybdenum-silicon oxide material.
9. The mask absorption layer structure with low three-dimensional effect according to claim 1, characterized in that, The patterned trench structure (5) of the absorption layer body (3) is divided into at least two patterned partitions (51) according to the feature size, line width-to-spacing ratio and pattern period; the absorption layer body (3) in each patterned partition (51) is provided with an independent partitioned modulation structure in the Z-axis direction that matches the diffraction characteristics of the corresponding patterned partition (51).
10. The mask absorption layer structure with low three-dimensional effect according to claim 9, characterized in that, The independent partition modulation structures within different graphic partitions (51) employ different Z-axis thickness designs and stacking arrangements.