Chinese scientists have developed insulation materials for new types of chips

With the continuous development of chip technology, the size of transistors is constantly shrinking and gradually approaching the physical limit. In this context, gate dielectric materials, as key insulating components in chips, have a significant impact on the overall performance of the chip. However, when the thickness of traditional gate dielectric materials is reduced to the nanometer level, the insulation performance will significantly decrease, leading to current leakage, increased chip energy consumption, and increased heat generation. Therefore, developing new high-quality gate dielectric materials has become the key to solving this problem.

Di Zengfeng, a researcher at the Chinese Academy of Sciences Shanghai Institute of Microsystems and Information Technology, has successfully developed a single crystal alumina gate dielectric material for two-dimensional integrated circuits - synthetic sapphire. This material has excellent insulation properties and can effectively prevent current leakage even when the thickness is only 1 nanometer. This achievement was published in the international academic journal Nature on August 7, 2024, marking significant progress in the field of new chip insulation materials in China.

"The two-dimensional integrated circuit is a new type of chip. It is constructed of two-dimensional semiconductor materials with a thickness of only one or several atomic layers, which is expected to break the physical limits of traditional chips. However, due to the lack of high-quality gate dielectric materials to match it, its actual performance is still quite different from the theory." said Di Zengfeng, a researcher at the Chinese Academy of Sciences Shanghai Institute of Microsystems and Information Technology.

Di Zengfeng stated that when the thickness of traditional gate dielectric materials is reduced to the nanometer level, the insulation performance will decrease, leading to current leakage and increasing the energy consumption and heat generation of the chip. To address this challenge, the team has innovatively developed in-situ intercalation oxidation technology. The core of this technology lies in precisely controlling the orderly embedding of oxygen atoms layer by layer into the lattice of metal elements, thereby obtaining stable, accurate stoichiometry, and uniform atomic thickness alumina thin film wafers. Compared with traditional disordered structure alumina materials, this ordered structure alumina material has significantly improved insulation performance at an extremely thin layer.

Specifically, the team first used germanium based graphene wafers as pre deposited substrates to grow single crystal aluminum metal. By utilizing the weak van der Waals forces between graphene and single crystal aluminum metal, they achieved non-destructive exfoliation of 4-inch single crystal aluminum metal wafers. After exfoliation, the surface of the single crystal aluminum metal exhibited defect free atomic level flatness. Subsequently, in an extremely low oxygen atmosphere, oxygen atoms are embedded layer by layer into the lattice on the surface of single crystal aluminum metal, ultimately resulting in stable, accurately stoichiometric, and uniformly thick aluminum oxide thin film wafers at the atomic level.