Core Viewpoint - The article discusses the current state and future directions of photomask manufacturing, emphasizing the importance of curved masks and advanced computational tools in extending the viability of non-EUV lithography technologies [1][3][4]. Group 1: Innovations in Photomask Technology - The use of curved photomasks is a significant innovation that leverages current writing technologies to create complex shapes previously unattainable [3]. - Advanced computational tools, such as Mask Process Correction (MPC) and high-level simulations, are increasingly used in the mask design flow, reducing the need for expensive experiments and pushing technological limits [3][6]. - The evolution of variable shape beam (VSB) writing technology to multi-beam writing technology has made curved mask shapes feasible without increasing writing time or costs [5]. Group 2: Challenges and Infrastructure Needs - There is a substantial need for infrastructure development to support the complexity of curved shapes, as traditional rectangular descriptions are simpler to manage [8]. - The transition to curved processes is seen as an exception rather than the norm, impacting economics and infrastructure, particularly in the reliance on GPU-based computing [9]. - Measurement technologies must evolve to handle the complexities of curved shapes, requiring higher resolution and faster measurement tools [11]. Group 3: EUV Masking Issues - EUV masks face challenges such as lower durability compared to 193i masks, necessitating frequent replacements that increase costs and complexity [13]. - The performance of EUV pellicles is currently suboptimal, leading to significant wafer throughput losses due to energy loss during transmission [13][15]. - The balance between using pellicles and the associated costs is contingent on the specific use case, with larger, high-value chips benefiting more from pellicles than smaller, redundant designs [16]. Group 4: Future Directions and Research - Research is ongoing into alternative materials for pellicles, such as carbon nanotube films, which could address current limitations but are not yet in mass production [17]. - The industry is exploring ways to improve the durability and transmission rates of EUV pellicles, which could lead to broader applications if successful [15][16].

Core Viewpoint - The article discusses the evolving challenges and innovations in photomask manufacturing, particularly focusing on the shift towards curved mask designs and the implications for lithography technology [2][3][4]. Group 1: Innovations in Photomask Technology - The use of curved masks is identified as a significant innovation that enhances the capabilities of current writing technologies, allowing for more complex shapes that were previously unattainable [3]. - Advanced computational tools, such as Mask Process Correction (MPC) and high-level simulations, are increasingly utilized in the mask design process, reducing the need for expensive experiments and pushing technological boundaries [3][5]. - The transition to curved mask designs is seen as a way to improve device performance without the need for new exposure equipment, even in older wafer fabs [3][4]. Group 2: Challenges in Implementation - The industry faces substantial infrastructure challenges when transitioning from rectangular to curved designs, as the complexity of defining and adjusting curved shapes is significantly higher [6][7]. - Measurement techniques need to evolve to accommodate the full 2D profiles of curved masks, requiring higher resolution and faster measurement tools [9]. - The current reliance on CPU-based workflows in many mask shops limits the adoption of GPU-based processes that are essential for curved mask technology [7][8]. Group 3: EUV Masking Issues - EUV masks face durability challenges, requiring frequent replacements that add to costs and complexity, with some needing replacement weekly [10][11]. - The performance of EUV protective films is currently suboptimal, leading to significant wafer throughput losses due to energy loss during the masking process [10][12]. - The balance between using protective films and the associated costs is contingent on the specific application, with larger, high-value chips benefiting more from protective measures compared to smaller, redundant designs [11][13]. Group 4: Future Directions - The industry is exploring alternative materials, such as carbon nanotube films, to address the limitations of current DGL films used in EUV applications, although these alternatives still face challenges [14]. - Continuous research and development are necessary to improve the performance and durability of EUV masks, as well as to streamline the processes involved in their maintenance and replacement [12][14].