Gas Cluster Ion Beam Technology Research Articles

ガスクラスターイオンビーム研究開発の最近の動向

ガスクラスターイオンビーム研究開発の最近の動向

Current research topics and applications of gas cluster ion beam processes

Gas cluster ion beam technology employs accelerated ions consisting of clusters of a few hundreds to thousands of atoms (gas cluster ion beam technology, GCIB). This paper reviews recent novel GCIB process applications for (i) ultra-shallow junction (USJ) formation and doping in Si, (ii) surface smoothing of metals, (iii) selective smoothing of SOI, SiC and other compound semiconductor films, (iv) IC back end of the line (BEOL) processing and (v) high quality thin multi-layer film formation for reliable and durable optical filters.

Recent advances in R&D of gas cluster ion beam processes and equipment

This report reviews a new field of ion beam technology that employs accelerated ions consisting of clusters of a few hundreds to thousands of atoms (Gas Cluster Ion Beam technology, GCIB). Cluster ion-surface collisions have been found to produce low energy bombardment effects at very high density and GCIB processes exhibit unique non-linear effects that are useful for novel surface processing applications. The effects include low energy ion bombardment, lateral sputtering, and low temperature thin film formation. GCIB processing has been successfully applied for shallow junction formation; for high rate etching; for surface smoothing of materials including metals, dielectrics, superconductors and diamond; and for high-k oxide and DLC thin film deposition. Currently, industrial applications of GCIB processes are being conducted by several Japanese companies under the Nanotechnology program called “Advanced Nano-Fabrication Process Technology Using Quantum Beams” of NEDO/METI (New Energy and Industrial Technology Development Organization/the Ministry of economy and Technology Industry). In US, R&D especially for semiconductor applications are under way at Epion Corporation, International SEMATEC and their cooperated associations. Epion is the only company that is developing industrial GCIB equipment and has joined the NEDO/METI project.The review includes recent equipment and process developments. In nano-scale GCIB processes, the effect of cluster size (atoms/cluster) on surface processing, especially damage production, becomes important. In the project, GCIB equipment with cluster size selection system has been developed. Several industrial applications for surface smoothing of magnetic and semiconductor materials by the Japanese government and IC processing by US companies are summarized.

Current research and development topics on gas cluster ion-beam processes

This report reviews the developing field of ion-beam technology that employs accelerated ions consisting of clusters of a few hundreds to thousands of atoms (gas cluster ion-beam technology, GCIB). Cluster ion-surface collisions have been found to produce low-energy bombardment effects at very high density, and GCIB processes exhibit unique nonlinear effects that are useful for surface processing applications. The effects include low-energy ion bombardment, lateral sputtering, and low-temperature thin-film formation. GCIB processing has been applied to shallow junction formation; high rate etching; surface smoothing of materials including metals, dielectrics, superconductors, and diamonds; and high-k oxide and diamond-like carbon thin-film deposition. We describe the unique characteristics of GCIB-surface interactions and GCIB process applications for (i) ultrashallow junction formation and doping in Si, (ii) surface smoothing of metals, (iii) selective smoothing of silicon-on-insulator SiC, and other compound semiconductor films, (iv) integrated circuit back-end-of-the-line processing, and (v) high-quality multilayer thin-film formation for reliable and durable optical filters.

Direct simulation Monte Carlo method for gas cluster ion beam technology

A direct simulation Monte Carlo method has been developed and applied for the simulation of a supersonic Ar gas expansion through a converging–diverging nozzle, with the stagnation pressures of P 0=0.1–10 atm, at various temperatures. A body-fitted coordinate system has been developed that allows modeling nozzles of arbitrary shape. A wide selection of nozzle sizes, apex angles, with diffuse and specular atomic reflection laws from the nozzle walls, has been studied. The results of nozzle simulation were used to obtain a scaling law P 0T 0 19/8d αL n β= const. for the constant mean cluster sizes that are formed in conical nozzles. The Hagena’s formula, valid for the conical nozzles with a constant length, has further been extended to the conical nozzles with variable lengths, based on our simulation results.

Etching, smoothing, and deposition with gas-cluster ion beam technology

Gas cluster ion beam (GCIB) processing has recently been introduced as a commercial tool for processing ‘rough’ surfaces, such as polished substrates or thin films. The physical interaction of a gas cluster ion beam with a surface is strikingly different from that of better-known ‘monomer’ ion beams. Clusters are formed by the adiabatic expansion of gas through a nozzle, ionization by electron impact, acceleration, and then impingement upon the surface to be processed. The physics of the surface interaction of the cluster beam strongly depends upon gas composition, cluster size, cluster size distribution, and beam energy. Typical argon GCIBs are composed of clusters ranging from several hundred to several thousand atoms in size. It has been previously shown that Ar clusters can be used to smooth surfaces at a sub-nanometer level. Argon cluster beam smoothing typically occurs in the energy range between 15 and ∼30 keV. As such, the average energy per atom is of the order of 10 eV/atom upon cluster impact with the surface and subsequent dissociation. Ion cluster beams formed with reactive gases such as oxygen and nitrogen can also be formed, but at somewhat lower current densities than those obtainable with argon. Upon impact, reactive gas clusters undergo strong chemical reactions at the substrate surface. An extension of this chemical interaction is to utilize reactive clusters in an ion beam-assisted, thin-film physical vapor deposition process. This has been demonstrated with relatively low energy (E<∼10 keV) oxygen clusters in an electron-beam evaporator to form extremely low resistivity indium–tin oxide films on room-temperature substrates. This paper will describe the basics of GCIB formation and application to atomic scale smoothing of technologically interesting substrates and thin films, as well as reactive GCIB assisted deposition technology. The results presented demonstrate some of the unique physics and materials science that can be achieved with an emerging GCIB technology.

Advances in Ion and Laser Beam Technology: Achievements of Japanese Government and University Projects

ABSTRACTThis paper reviews recent R&amp;D activity in advanced beam technologies funded by MITI and JST. A large-scale national project known as AMMTRA (Advanced Material-Processing and Machining Technology Research Association) funded by MITI has made a significant contribution to industrial applications of beam processing by developing high density ion and laser beam equipment. A subsequent program, the ACTA (Advanced Chemical Processing Technology Research Association) project involves development of multi-beam deposition systems for metal and dielectric materials formation including several systems which combine ion and laser beams, ion beams and CVD and plasma, and laser beams with sputtering. NEDO Proposal Based Project and JST (The Japan Science and Technology Corporation)-Exploitation and Application Study Project are fundamentally aimed to transfer technology from university to industry. Research in gas cluster ion beam technology is currently being conducted in the following areas: (i) shallow ion implantation for 0.1 μ m PMOS junction formation, (ii) high rate etching and smoothing for Si, diamond, SiC and metal oxide films and (iii) thin film depositions for optical filter and transparent conductive film. The gas cluster ion beam processes are discussed in comparison with traditional ion beam processing methods which are presently limited by available atomic and molecular ion beams.