A Novel High-Intensity Metal Ion Source for Plasma Immersion Implantation and Deposition (MPIII&D), 18-9292

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Principal Investigator
Ronghua Wei

Inclusive Dates: 01/02/02 - 07/01/03

Background - Plasma Immersion Ion Implantation (PIII) and Plasma Immersion Ion Deposition (PIID) are two fairly new technologies, which have been used to combat against wear, corrosion, and fatigue. PIII is a process in which ions (typically nitrogen or carbon) are accelerated at a high energy (for instance, 50 - 100 keV) and then injected into the surface to form a layer of hard nitrides or carbides. In contrast, PIID is a coating process in which ions are accelerated at a much lower energy (0.5 - 5 keV) and then deposited on the surface to form an "add-on" layer. Regardless of these differences, both have received significant attention because they share a significant advantage over conventional Beamline Ion Implantation (BII) and Ion Beam Assisted Deposition (IBAD) in that they are non line-of-sight processes, allowing complex surfaces to be treated without manipulation.

Though PIII and PIID have advantages over conventional BII and IBAD, their applications have been limited to only the areas where a suitable precursor can be found. In particular, the ability to implant metal ion species or deposit metal-based coatings using these methods has been extremely difficult. Although some metal-containing precursors are available, many of them are air sensitive and flammable, and some are even pyrophoric, corrosive and dangerous to the health of the operators. In addition, many of these chemical compounds are also very expensive. Besides, it is nearly impossible to obtain a pure metal (such as Ti or Cr) or desired metal compound (such as TiN or CrN) from most precursors.

Approach - To accomplish metal plasma immersion ion implantation and deposition (MPIII&D), we utilize a new method to generate metal plasma and accelerate the metal ions. This technology utilizes a metal plasma source to evaporate and ionize the metal. When the metal vapor exits the source, an RF power is used to further ionize the metal vapor and spread it out to fill the processing chamber. Then by applying a series of negative voltage pulses the components, metal ions are drawn to the surfaces. Ions are implanted into the surfaces when the acceleration voltage is high. But when the bias voltage is low, metal deposition is accomplished. A schematic of the MPIII&D system is shown in Figure 1.

Accomplishments - Using this metal plasma immersion implantation and deposition (MPIII&D) system, we have demonstrated to implant or deposit Ti, Cr, and Cu into or onto various metals. Shown in Figure 2 (a) is Auger depth profiling of Cr implanted Si while Figure 2(b) shows the Ti distribution in the Si samples on a large worktable. This technology has also been demonstrated on solid oxide fuel cell interconnect to increase its oxidation resistance. This state-of-the-art technology can be used in improving wear, fatigue and corrosion resistance for many components including gears, bearings, and shafts that are subject to severe environments. It can also be combined with other treatments such as diamondlike carbon (DLC) coatings that are commonly used in surface treatments. This technology is a clean process so it can be used to reduce or eliminate Cr plating, which is hazardous to the environment and the health of operators.

Figure 1. MPIII&D schematic
Figure 2. (a) Depth profile for Cr implantation and (b) Distribution of Ti coated samples on large work table

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