Sputtering is a process whereby coating material is dislodged and ejected from the solid surface due to the momentum exchange associated with surface bombardment by energetic particles.
Processes:
- Gas ions are accelerated by a high voltage, producing a glow discharge or plasma
- A source (the cathode, also called the target ) is bombarded in high vacuum by gas ions
- Atoms from the target are ejected by momentum transfer and move across the vacuum chamber
- Atoms are deposited on the substrate to be coated and form a thin film.
Sputtering Mechanism
The exact mechanisms by which atoms are ejected from a surface under ion bombardment are unknown, but we can deduce some of the details of the interaction involved.
The kinetic energy of the impinging particles largely dictates which event will happen
- Bounce back :
- when very low energy (<5eV);
- when the collision is head-on or nearly so
- Embedded : when much higher energy (>10KeV), the impinging particles are most likely to be embedded in the target, which is the basis of Ion Implantation
- Energy between the two extremes, two other effects also arise:
- some fraction of the energy of the impinging ions is transferred to the solid in the form of heat, and lattice damage
- another fraction of such energy causes atoms from the surface to be dislodged and ejected into the gas phase----Sputtering
Unique Characteristics
- Uniform thickness over large area.
- Simple thickness control.
- The alloy composition maintains stoichiometry with the original target composition.
- Deposition rates do not differ a great deal from one material to another.
- Sputtering-cleaning prior to initiating film deposition. The surface is not again exposed to ambient after such cleaning.
- The lifetime of a sputtering target may be as long as hundreds of runs and is seldom less than 20.
Coating Materials
Metals Al, Cu, Zn, Au, Ni, Cr, W, Mo, Ti
Alloys Ag-Cu, Pb-Sn, Al-Zn, Ni-Cr
Nonmetals i-C, graphite, MoS2, WS2, PTFE
Refractory oxides Al2O3, Cr2O3, Al2O3-Cr2O3, SiO2, ZrO2-Y2O3
Refractory carbides TiC, ZrC, HfC, NbC, Tic-Ni, Tic-ZrC
Refactory nitrides TiN, Ti2N, ZrN, HfN, TiN-ZrN, TiN-AlN-ZrN
Refractory borides TiB2, ZrB2, HfB2, CrB2, MoB2
Refactory silicides MoSi2, WSi2, Cr3Si2
Details of Sputtering Processes
- Gas ions are accelerated by a high voltage, producing a glow discharge or plasma
- A source (the cathode, also called the target ) is bombarded in high vacuum by gas ions
- Atoms from the target are ejected by momentum transfer and move across the vacuum chamber
- Atoms are deposited on the substrate to be coated and form a thin film.
Sputtering Mechanism
The exact mechanisms by which atoms are ejected from a surface under ion bombardment are unknown, but we can deduce some of the details of the interaction involved.
The kinetic energy of the impinging particles largely dictates which event will happen
- Bounce back :
- when very low energy (<5eV);
- when the collision is head-on or nearly so
- Embedded : when much higher energy (>10KeV), the impinging particles are most likely to be embedded in the target, which is the basis of Ion Implantation
- Energy between the two extremes, two other effects also arise:
- some fraction of the energy of the impinging ions is transferred to the solid in the form of heat, and lattice damage
- another fraction of such energy causes atoms from the surface to be dislodged and ejected into the gas phase----Sputtering
Unique Characteristics
- Uniform thickness over large area.
- Simple thickness control.
- The alloy composition maintains stoichiometry with the original target composition.
- Deposition rates do not differ a great deal from one material to another.
- Sputtering-cleaning prior to initiating film deposition. The surface is not again exposed to ambient after such cleaning.
- The lifetime of a sputtering target may be as long as hundreds of runs and is seldom less than 20.
Coating Materials
Metals Al, Cu, Zn, Au, Ni, Cr, W, Mo, Ti
Alloys Ag-Cu, Pb-Sn, Al-Zn, Ni-Cr
Nonmetals i-C, graphite, MoS2, WS2, PTFE
Refractory oxides Al2O3, Cr2O3, Al2O3-Cr2O3, SiO2, ZrO2-Y2O3
Refractory carbides TiC, ZrC, HfC, NbC, Tic-Ni, Tic-ZrC
Refactory nitrides TiN, Ti2N, ZrN, HfN, TiN-ZrN, TiN-AlN-ZrN
Refractory borides TiB2, ZrB2, HfB2, CrB2, MoB2
Refactory silicides MoSi2, WSi2, Cr3Si2
Details of Sputtering Processes
The kinetic energy of the impinging particles largely dictates which event will happen
- Bounce back :
- when very low energy (<5eV);
- when the collision is head-on or nearly so
- Embedded : when much higher energy (>10KeV), the impinging particles are most likely to be embedded in the target, which is the basis of Ion Implantation
- Energy between the two extremes, two other effects also arise:
- some fraction of the energy of the impinging ions is transferred to the solid in the form of heat, and lattice damage
- another fraction of such energy causes atoms from the surface to be dislodged and ejected into the gas phase----Sputtering
Unique Characteristics
- Uniform thickness over large area.
- Simple thickness control.
- The alloy composition maintains stoichiometry with the original target composition.
- Deposition rates do not differ a great deal from one material to another.
- Sputtering-cleaning prior to initiating film deposition. The surface is not again exposed to ambient after such cleaning.
- The lifetime of a sputtering target may be as long as hundreds of runs and is seldom less than 20.
Coating Materials
Metals Al, Cu, Zn, Au, Ni, Cr, W, Mo, Ti
Alloys Ag-Cu, Pb-Sn, Al-Zn, Ni-Cr
Nonmetals i-C, graphite, MoS2, WS2, PTFE
Refractory oxides Al2O3, Cr2O3, Al2O3-Cr2O3, SiO2, ZrO2-Y2O3
Refractory carbides TiC, ZrC, HfC, NbC, Tic-Ni, Tic-ZrC
Refactory nitrides TiN, Ti2N, ZrN, HfN, TiN-ZrN, TiN-AlN-ZrN
Refractory borides TiB2, ZrB2, HfB2, CrB2, MoB2
Refactory silicides MoSi2, WSi2, Cr3Si2
Details of Sputtering Processes
- Uniform thickness over large area.
- Simple thickness control.
- The alloy composition maintains stoichiometry with the original target composition.
- Deposition rates do not differ a great deal from one material to another.
- Sputtering-cleaning prior to initiating film deposition. The surface is not again exposed to ambient after such cleaning.
- The lifetime of a sputtering target may be as long as hundreds of runs and is seldom less than 20.
Coating Materials
Metals Al, Cu, Zn, Au, Ni, Cr, W, Mo, Ti
Alloys Ag-Cu, Pb-Sn, Al-Zn, Ni-Cr
Nonmetals i-C, graphite, MoS2, WS2, PTFE
Refractory oxides Al2O3, Cr2O3, Al2O3-Cr2O3, SiO2, ZrO2-Y2O3
Refractory carbides TiC, ZrC, HfC, NbC, Tic-Ni, Tic-ZrC
Refactory nitrides TiN, Ti2N, ZrN, HfN, TiN-ZrN, TiN-AlN-ZrN
Refractory borides TiB2, ZrB2, HfB2, CrB2, MoB2
Refactory silicides MoSi2, WSi2, Cr3Si2
Details of Sputtering Processes
Metals Al, Cu, Zn, Au, Ni, Cr, W, Mo, Ti Alloys Ag-Cu, Pb-Sn, Al-Zn, Ni-Cr Nonmetals i-C, graphite, MoS2, WS2, PTFE Refractory oxides Al2O3, Cr2O3, Al2O3-Cr2O3, SiO2, ZrO2-Y2O3 Refractory carbides TiC, ZrC, HfC, NbC, Tic-Ni, Tic-ZrC Refactory nitrides TiN, Ti2N, ZrN, HfN, TiN-ZrN, TiN-AlN-ZrN Refractory borides TiB2, ZrB2, HfB2, CrB2, MoB2 Refactory silicides MoSi2, WSi2, Cr3Si2
Details of Sputtering Processes