C-209 Material Science Aspects of Plasma Processing (half-day)
Numerous plasma processes are used to either produce or modify inorganic and organic thin film coatings. Among the more commonly used approaches are physical and reactive sputtering, plasma chemical vapor deposition, ion plating, and surface modification. Within these process categories there exist several plasma modes operating in different power, frequency, and gas throughput regimes and in a variety of plasma apparatus configurations. It is the intent of this tutorial to introduce the student to the basic plasma features that all the above-mentioned process variations have in common, and only then bring out the ways in which they differ in kind or degree. Special attention will be given to the importance and methods of control of key unique plasma species and their energetic state, their subsequent impact on the coating growth processes, and ultimate film composition and microstructure, as well as the consequences on a variety of functional properties.
- General Plasma Basics—Description of collision processes in the gas phase as well as at various plasma/surface interfaces and their impact on coating composition and microstructure and functional properties.
- Prototype examples:
- Sputtering of metals, alloys, and compounds in inert gases and reactive gases
- Plasma polymerization leading to a variety of polymer coatings, including a discussion of the role of reactive ion etching (RIE) and sputtering at various plasma/surface interfaces
- Role of polymer deposition in semiconductor micro-feature processing
- Plasma synthesis and physical properties of inorganic/organic polymer composite thin films made up of granular nanoparticle dispersions and examples of applications
- Surface structure modification of pre-existing organic coatings, depending on type and energetics of incident plasma particles
Numerous plasma processes are used to either synthesize or modify inorganic and organic thin film coatings. Among the more commonly used approaches are physical and reactive sputtering, plasma chemical vapor deposition (PCVD), plasma polymerization and surface modification. Within these process categories there exist several low and high density plasma modes operating in different power, frequency, gas throughput and duty cycle regimes and in a variety of plasma apparatus configurations. It is the intent of this tutorial to introduce the student to the basic processes that all the above mentioned plasma modes have in common, and only then concentrate on the ways in which they differ, mainly in degree rather than in kind.
We shall deal with the key collisional processes both in the gas phase and at plasma/surface interfaces that are relevant to film nucleation and growth in various plasma modes. Control of film composition and microstructure and morphology as well as inert gas trapping will be described, with tyipcal examples of consequences on various properties of the resultant coatings.
Initially, the emphasis will be on processes in a chemically ‘inert’ plasmas followed by a description of key additional processes to be considered in reactive plasmas. In inert gas plasmas the role of short and long-lived electronically excited as well as energetic ions and neutrals will be described in the context of film growth issues. In reactive plasmas, emphasis will be on competing deposition and etching processes at the various plasma/surface interfaces (target, substrate, walls, fixtures) and their dependence on the flux and energy of various incident specie.
As prototype examples of film growth in ‘inert’ plasmas we shall consider
metal, alloy and composite coatings made by physical sputtering in DC or capacitively coupled RF diode (including magnetron) systems. In chemically reactive plasmas, polymerization of a variety of materials in either an inductively or capacitively coupled RF plasma system will serve as prototype examples. Overlap with processes taking place in reactive plasma approaches leading to oxide, nitride and carbide coatings will be indicated.
The role of plasma polymerization of fluorocarbons versus reactive ion etching, (RIE), in controlling the geometry of micro-features in semiconductor processing will be outlined as well as selective etching concepts.
Plasma approaches leading to the dispersion of inorganics (metals, oxides and composites) in polymer coatings during film growth will be described in some detail. Control of electrical, optical, mechanical, magnetic and thermal properties as a function of volume fraction of the nano-particle dispersant both below and above the onset of percolation will be demonstrated. Potential applications, such as fine line circuit writing, will be described using laser or electron beams as scanning heat sources
Reference will be made to a variety of ex & in-situ plasma diagnostic techniques as well as coating characterization approaches. Extensive experimental data and literature references will be provided.Instructor: Eric Kay, Consultant, IBM Emeritus
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