Takao Sakase

Control of metal contamination in the Varian Extrion 1000 ion implantation system

Abstract The rapid development of higher-density device structures in recent years has focussed increased attention on all defect-producing by-products of the ion implantation process. In the past, the well-known effects of alkali and transition metals have constrained the materials technology used in ion-source and beam-transport systems of ion implanters. The next generation of high-current ion implanters is being challenged with requirements for minimization of defects caused by other contamination sources. This paper presents data on the levels of metal contamination produced in typical high-dose implants on the Varian Extrion 1000 implanter. It is shown that the aluminum contamination level has been reduced by greater than a factor of 13 using masking techniques.

Ion beam system for the new high current ion implantation system Extrion-1000

Abstract To meet the challenging performance requirements of next generation high current ion implanters, several new technologies have been developed for the ion beam system of the new Varian high current ion implanter, Extrion-1000. A novel strong focussing accel/decel scheme with a new ion source guarantees high beam output even down to very low energies. Its multiple crucible vaporizer is based on a new concept and allows easy maintenance, longer lifetime, improved time response and rapid species change. Great care was taken in the design of the vacuum system to provide appropriately low pressures at critical points ensuring high beam purity and high dosimetry accuracy.

Control of wafer charging on the Varian EXTRION 1000 ion implanter

Abstract Wafer charging during high current implantation has been one of the major concerns to implanter users not only because of ever-shrinking device structures, but especially because of two to three-fold increases of beam currents available on next-generation high current implanters. In this paper, wafer charging on the Varian EXTRION 1000 was studied under various beam, electron flood gun and vacuum conditions and it was found that it can provide a much better environment in terms of wafer charging control than the previous generation machines. A relatively new technique, J-t test, has been used to measure the charge to breakdown as well as the traditional breakdown voltage measurement. The device yields from the tests were close to 100% for all the tested device wafers. The Qbd results from J-t tests showed good correlation with flood/vacuum conditions and pinpointed the best operating condition. However some results posed difficulty in interpretation, which suggests wafer charging is a very complex phenomenon.

Applied Quantum X Implant System: Technology Enhancements to Enable Production‐Worthy Performance at the 45 nm Node

Mechanical scanning of the wafer in 2 dimensions is one approach that has been used to achieve single wafer processing for high current ion implantation. This approach simplifies the beamline design, compared to scanned beam or ribbon beam architectures, but has required a number of new technologies and methods in the scanner hardware and in dosimetry control. The Applied® Quantum X Implant system was designed to incorporate these new technologies, and has achieved the process performance and low energy productivity required for advanced junction formation at the 65 nm technology node. Since its introduction, extensive qualification and development work has been carried out, to extend its capability to the next technology generation. A number of further innovations and improvements to the beamline and platform have been developed, extending its throughput and process control capability to be production‐worthy at 45 nm.This paper will review the process control challenges associated with the 2d mechanical ...

A New Technique for Wafer Charge Neutralization for High Current Ion Implanters

To generate low energy electrons required for prevention of wafer charging during high current ion implantation, electron flood guns based on secondary electron emission from either solid or gas targets have been used almost exclusively throughout the industry. With industry-wide effort, the performance of those electron flood guns has steadily improved, although the control of electron energy spectrum and transport of the electrons to the wafers still remain major difficulties. Recently, a new technique of charge neutralization has been developed based on plasma bridging, where a low voltage plasma generator provides a copious supply of electrons with well controlled energy distribution to the ion beam. Dramatic improvements in charge neutralization were obtained using this scheme. This paper will describe the basic configuration of the scheme and the device yield improvements obtained using the plasma flood gun.

SINGLE CUSP ION SOURCE FOR A HIGH CURRENT IMPLANTER

A single cusp ion source has been developed and employed on the E1000 high current ion implanter. A cusp shaped magnetic field produced by permanent magnets is used as source field. The source has many desirable features for ion implanters. It produces over 27 mA of arsenic and phosphorus and 10 mA of boron. It provides long filament life and consumes less gas than a Freeman source does. Plasma density distribution at the exit slit is relatively uniform. There is no need for a massive external electromagnet or a magnet power supply, which makes the source system very compact. A key feature of the source is the prevention of metal or carbon impurities for all species, especially BF2+. The source technology has been accepted among users of high current ion implanters as an alternative to the Freeman source. A description of the basic geometry and parameters of this source, such as beam currents, arc conditions and lifetime, is presented.