This article is based on interviews with Wu Lingxiang and Ye Guoguang from Taiwan.
Rare earth elements play an indispensable role in semiconductor manufacturing, especially in advanced process nodes, high-precision equipment, and critical materials. China’s export controls on related rare earth materials have caused varying degrees of potential impact on the global semiconductor industry, among which,cerium oxide(CeO2) and permanent magnet materials have the most lethal impact on the military and semiconductor equipment supply chains..
1.Key Materials in Advanced Chip Manufacturing (High-k Dielectrics)
In advanced semiconductor manufacturing processes at 14 nanometers (nm) and below, high-k (high dielectric constant) materials are required to control quantum tunneling effects and gate leakage. This is because, after the 45nm node, traditional silicon dioxide (SiO2) insulating layers are prone to leakage due to their thinness.
1.Lanthanum(La):
Relation and Application: As lanthanum oxide (La2O3), it is one of the important high-k insulating materials in the HKMG(High-K/Metal Gate) structure. It is considered very important in TSMC’sN5, N3, N2, and other critical processes, as well as in future smaller nodes.
Impact: If China restricts the export of lanthanum oxide (La2O3), it may affect the ability of manufacturers like TSMC to produce finer chips. However, currently, hafnium oxide (HfO2) used in the semiconductor industry is not a rare earth element, so lanthanum oxide is not the only option in the short term.
2.Praseodymium(Pr) and Samarium (Sm):
Relation and Application: Praseodymium oxide(Pr2O3) and samarium oxide (Sm2O3) are also potential materials for high-k dielectrics.
Impact: Currently, they are not widely used in mainstream processes, but it is expected that they may be used for smaller nodes in the future.
2.Wafer Planarization and Polishing (CMP)
Chemical Mechanical Polishing (CMP) is a critical step in semiconductor manufacturing, used to precisely control wafer surface thickness and achieve high levels of planarization. This is crucial for advanced process nodes with numerous interconnections.
Cerium(Ce): Relation and Application: Cerium oxide (CeO2) is the main abrasive in high-performance colloidal CMP slurries. It meets the stringent defect rate requirements for nodes from 65nm to 14nm and below, widely used in the CMP processes of STI (Shallow Trench Isolation) and ILD (Inter-Layer Dielectric).
Impact:Cerium oxide(CeO2) is considered a critical limitation. Finding alternatives is challenging and will severely impact all semiconductor manufacturers, including TSMC.Related material inventory is available for about six months..
3.Semiconductor Equipment and Components
Rare earth elements are essential for manufacturing key semiconductor equipment (such as photolithography machines, etching/deposition equipment) and their core components, especially high-precision motors and corrosion-resistant coatings.
Neodymium(Nd) and Yttrium (Y):
Relation and Application (Laser Systems): Neodymium (Nd) and Yttrium (Y) are components of Nd-doped Yttrium Aluminum Garnet (Nd:YAG) laser materials. This laser system is used in detection components of photolithography (ASML) or exposure systems.
Neodymium(Nd), Dysprosium (Dy), and Terbium (Tb):
Relation and Application (Permanent Magnet Motors): Neodymium combines with iron and boron to form neodymium-iron-boron(NdFeB) permanent magnets, widely used in photolithography machines (ASML) for driving high-precision, high-speed platforms (such as twin scan). Dysprosium (Dy) and Terbium (Tb) are used to enhance the stability and magnetism of these magnets at high temperatures, preventing loss of magnetism.
Impact: Restricting the export of permanent magnet materials will not only affect semiconductor equipment (such as photolithography machines, DC servo systems) but will also have a more significant impact on the military industry (such as the F35 fighter jet), which requires higher temperature resistance.
Yttrium(Y):
Relation and Application (Cavity Coatings): Yttrium oxide(Y2O3) and Yttrium Fluoride (YF3) are used as surface coatings for etching and deposition chambers. This coating protects the chamber from being corroded by corrosive materials, thus extending the life of semiconductor equipment.
Impact: Export restrictions will affect the maintenance cycles of equipment manufacturers like Applied Materials (AMAT), requiring more frequent replacement of components.
4.Sputtering Targets for Functional Components
Scandium(Sc), Neodymium (Nd), Praseodymium (Pr), and Erbium (Er):
Relation and Application: AsPVD (Physical Vapor Deposition) sputtering targets, they are used to manufacture functional films. For example, Scandium (Sc) is widely used in the manufacture of piezoelectric materials such as filters, as well as in the coating of magnetic materials.
Impact:The main impact is on the coating of magnetic materials and piezoelectric materials, which may significantly affect related component manufacturers in Japan and other countries..