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The preferred material for precision components of lithography machines – silicon carbide ceramics:

Silicon carbide ceramics have high elastic modulus and specific stiffness, are not easily deformed, and have high thermal conductivity and low thermal expansion coefficient, and high thermal stability. Therefore, silicon carbide ceramics are an excellent structural material, which has been widely used in aviation, aerospace, petrochemical industry, mechanical manufacturing, nuclear industry, microelectronics industry and other fields. However, as silicon carbide is a covalent compound with strong Si-C bonds, it has extremely high hardness and significant brittleness, making precision machining difficult; In addition, the high melting point of silicon carbide makes it difficult to achieve dense and nearly net size sintering. Therefore, the preparation difficulty of precision silicon carbide structural components with large and complex irregular hollow structures is high, which limits the widespread application of silicon carbide ceramics in high-end equipment manufacturing fields such as integrated circuits. At present, only a few companies from developed countries such as Japan and the United States (such as Kyocera from Japan and CoorsTek from the United States) have successfully applied silicon carbide ceramic materials to key equipment in integrated circuit manufacturing, such as silicon carbide workbenches, guides, mirrors, ceramic suction cups, arms, etc. for lithography machines.

Generally speaking, the workpiece table structural components used in lithography machines need to meet the following requirements:

① Highly lightweight: In order to reduce motion inertia, reduce motor load, improve motion efficiency, positioning accuracy, and stability, structural components are generally designed with lightweight structures, with a lightweight rate of 60% to 80%, with a maximum of 90%;

② High form and position accuracy: In order to achieve high-precision motion and positioning, structural components are required to have extremely high form and position accuracy, with flatness, parallelism, and perpendicularity requirements less than 1 μ m. The shape and position accuracy requirement is less than 5 μ M;

③ High dimensional stability: In order to achieve high-precision motion and positioning, structural components are required to have extremely high dimensional stability, not easily generate strain, and have high thermal conductivity and low thermal expansion coefficient, which are not easy to generate large dimensional deformation;

④ Clean and pollution-free: Structural components are required to have extremely low friction coefficient, minimal kinetic energy loss during movement, and no pollution from grinding particles. The use of silicon carbide as a precision structural component material for critical integrated circuit equipment such as lithography machines has great advantages. However, traditional ceramic preparation processes such as grouting and dry pressing are difficult to achieve the preparation of complex components such as lithography workbenches. To this end, China National Institute of Building Materials has developed a series of forming and sintering technologies to solve the localization problem of using silicon carbide materials to produce such components.

Preparation process of precision structural components of silicon carbide ceramics:

The use of silicon carbide as a precision structural component material for critical integrated circuit equipment such as lithography machines has great advantages. However, traditional ceramic preparation processes such as grouting and dry pressing are difficult to achieve the preparation of complex components such as lithography workbenches. To this end, China National Institute of Building Materials has developed a series of forming and sintering technologies to solve the localization problem of using silicon carbide materials to produce such components. Silicon carbide ceramics have excellent properties such as high strength, high hardness, high elastic modulus, high specific stiffness, high thermal conductivity, and low thermal expansion coefficient. It is an ideal high-performance structural material. On the basis of near net size molding process – gel injection molding, China National Academy of Building Materials has developed a process technology for preparing new large size, complex shape, and high-precision silicon carbide ceramic components.

Firstly, the structural characteristics of ceramic components are analyzed, and simple or complex molds are designed and manufactured for gel casting to prepare the blank of ceramic components; Then, precision machining is carried out on the ceramic component blank to improve the dimensional accuracy and surface smoothness of the ceramic component; Finally, high-temperature sintering is performed to obtain the product. For hollow structure silicon carbide ceramic components, the bonding process is used to bond the single ceramic components to form a whole component, and then place them in a vacuum sintering furnace for sintering to obtain the designed silicon carbide ceramic components. Process flow diagram for preparing silicon carbide ceramic components:

The key processes in the preparation process include gel casting process, ceramic blank processing process and ceramic blank connection process. Among them, the gel casting process is the basis for the preparation of silicon carbide ceramic parts. This process is a fine colloidal forming process, which can achieve high strength, high uniformity, and near net size molding of large size, complex structure green bodies. It has obtained extensive research in the field of special ceramic material preparation. The ceramic blank processing process can achieve rapid, low-cost, and precise manufacturing of complex shaped ceramic components, effectively improving the dimensional accuracy and surface finish of ceramic components.

The ceramic blank connection process can achieve the preparation of hollow ceramic components, mainly using ceramic binders to connect ceramic monomer components to obtain an overall hollow component. The industry pattern of silicon carbide ceramic structural components for lithography machines currently has a global expenditure of $50 billion on integrated circuit manufacturing equipment, with ceramic structural components accounting for over 20% of the expenditure. Currently, 70% of high-end silicon carbide ceramic components used in IC manufacturing equipment are monopolized by Kyocera and CoorsTek, while the remaining portion is also occupied by European, American, and Japanese companies. The characteristics of Kyocera and CoorsTek products are a complete range and wide market coverage. Taking semiconductor ceramic components as an example, CoorsTek provides a series of precision ceramic structural components, including lithography machine specific components, plasma etching equipment specific components, PVD/CVD specific components, ion implantation equipment specific components, chip adsorption fixed transmission specific components, etc; Kyocera provides specialized ceramic components such as lithography machines, wafer manufacturing equipment, etching machines, deposition equipment (CVD, PVD), and liquid crystal panel (LCD) manufacturing equipment.