In this paper a micro-machined discharge type ion source using the B.K.(Barkhausen-Kurz) oscillation for realizing high ion currents is developed for flexible and concurrent MEMS processes.
Ion beams play various important roles to fabricate LSI and MEMS (Micro Electro Mechanical System). Ion beams are commonly used for etching, implantation, sputtering, deposition, surface modification, and so on. Because of its facility investment, LSI has very huge number mass production and markets.
On the other hand, usually MEMS products do not have large markets and their fabrications processes are complicated and deferent from each product. MEMS process needs flexibility according to small amount and variety products. To realize MEMS process flexibility a micro-machined micro ion source is developed. The micro-machined micro ion source makes concurrent and simultaneous process easier in a chamber. It will reduce cost and power consumption of MEMS products.
To realize a high density micro ion source, B.K. oscillation of electrons in an ion source was applied. When a positive high voltage is applied to the center anode electrode, cold discharge occurs between the anode and cathode. Electrons produced during the glow discharge oscillate at a high-frequency backward and forward through the center anode. This B.K. oscillation was expected to increase the ion density of a source.
A mill-meter size micro ion source utilizing B.K. oscillation was successfully fabricated by micromachining. The discharge space of the cylindrical micro ion source was 2mm in diameter and 4.74mm in length. The upper cathode electrode of aluminum was deposited onto Si wafer having 370µm in thickness. The lower cathode electrode having aperture for extracting ions was also deposited onto Si wafer. The aluminum anode electrode at the center of the cylindrical discharge space was deposited onto bored Si wafer. Two of PYREX glass sheets bored by sand blast technique for the discharge space were put into between these electrodes for insulation. These Si wafers and PYREX glass sheets were bonded by the anodic bonding technique.
It was found that the micro ion source generated ion beam of the current of several µA by the experiment using Faraday cup.
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