Transcript Lecture 9 - Bama.ua.edu

Sputter Deposition
Lecture 9
G.J. Mankey
[email protected]
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
Sputter Deposition
• Magnetron sputtering is the most widely used method for
vacuum thin film deposition.
• Although the basic diode sputtering method (without
magnetron or magnetic enhanced) is still used in some
application areas, magnetron sputtering now serves over 90%
of the market for sputter deposition.
• Magnetron sputtering can be used to coat virtually anything
with a wide range of materials - any solid metal or alloy and a
variety of compounds.
ref: www.gencoa.com
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
Sputtering System
ref: http://www.teercoatings.co.uk
• A typical sputtering
system consists of a
vacuum chamber
with substrate
holders and
magnetron guns,
vacuum pumps and
gauging, a gas
supply system,
power supplies and a
computer control
system.
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
The Magnetron
• A Magnetron is comprised of :
• A CATHODE = electron source
• An ANODE = electron collector
• A combined ELECTRIC &
MAGNETIC FIELD B X E
ref: www.gencoa.com
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
The Plasma Discharge
•
•
•
ref: www.gencoa.com
Plasma is a fluid of positive ions
and electrons in a quasi-neutral
electrical state. The vessel that
contains this fluid is formed by
electric and magnetic fields.
In many plasma coating applications
positive ions are generated by
collisions between neutral particles
and energetic electrons. The
electrons in a plasma are highly
mobile, especially compared to the
larger ions (typically argon for
sputtering).
Control of the highly mobile plasma
electrons is the key to all forms of
plasma control.
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
Microscopic View of Sputtering
•
•
The impact of an atom or ion on a surface produces
sputtering from the surface as a result of the
momentum transfer from the incoming particle. Unlike
many other vapor phase techniques there is no melting
of the material.
History of Sputtering
– The verb to SPUTTER originates from Latin SPUTARE(To
emit saliva with noise).
– Phenomenon first described 150 years ago ...
Grove (1852) and plücker (1858) first reported vaporization
and film formation of metal films by sputtering.
– Key for understanding discovery of electrons and positive
ions in low pressure gas discharges and atom structure (J.J.
Thomson, Rutherford), 1897-– Other names for SPUTTERING were SPLUTTERING and
CATHODE DESINTEGRATION.
ref: www.gencoa.com
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
The Magnetron Gun
• A magnetron consists of a target with magnets arranged
behind it to make a magnetic trap for charged particles, such
as argon ions, in front of the target.
• Atoms are knocked out of the target surface by the ions - this
is sputtering. These sputtered atoms aren’t charged
negatively or positively, so they go straight out of the
magnetic trap to coat the substrate.
ref: http://www.teercoatings.co.uk
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
The Magnetron Plasma
• Confinement between a negatively biased target and closed magnetic
field produces a dense plasma.
• High densities of ions are generated within the confined plasma, and
these ions are subsequently attracted to the negatively biased target,
producing sputtering at high rates.
ref: www.gencoa.com
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
Target Erosion
• Target erosion is greatest where the magnetic field and the subsequent
plasma density is greatest.
• This leads to inefficient use of target material, particularly in the case
of ferromagnetic targets.
ref: www.gencoa.com
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
Sputtering Insulators
• For an insulator target, the ions bombarding the target will create
charging, and the electric field necessary to maintain a plasma is
greatly diminished.
• To alleviate this problem, an RF power supply is used to generate
the electric field.
ref: www.gencoa.com
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
Magnetron Guns
ref: www.lesker.com
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center
The Latest in UHV Sputtering
http://www.ajaint.com
• A UHV, magnetron sputter source that fits through the port of a 2.75" CF flange
complete with its tilt gimbals assembly.
• The AJA International new A310-XP only needs a 2.75" CF to accommodate the
source head, tilt gimbals and gas injection/isolation chimney.
• This revolutionary new design is true UHV - all ceramic to metal construction.
Center for Materials for Information Technology
an NSF Materials Science and Engineering Center