ION IMPLANTATION

[summer project pal]

ION IMPLANTATION
Ion implantation refers to a process whereby dopant ions are introduced into a semiconductor material to change its carrier concentration and conductivity type.
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OBJECTIVES
The desired quantity of dopant should be implanted
The dopant should be implanted at the correct depth
The dopant implanted should be restricted to the desired areas of the wafer
The implanted dopants should be electrically active
There should be no damage to the implanted areas

DISCUSSIONS
The basic ion implantation process
Ion implantation equipment principles
Ion implantation process variables
Ion implantation performance variables
The main ion implantation measurement equipment

Ion Implantation Process
A source of the required dopant (solid, liquid or gas) is introduced
The dopant source is then ionized to form positive ions
These positive ions are then accelerated through a high voltage field to acquire the necessary energy
The high energy ions are then projected towards the target (the wafer surface)
The ions collide with the surface and lose energy due to collisions with the silicon atoms
The dopant ions finally come to rest within the substrate

DOPANT DISTRIBUTIONS
ION STOPPING
IMPLANT PROCESS VARIABLES
Acceleration voltage
Mass analyzer setting
Substrate impact angle
Scanning frequency
Pressure
Temperature
Beam current

IMPLANT PERFORMANCE VARIABLES
Dopant density
Dopant distribution
Sheet resistance

ION IMPLANT EQUIPMENT
FILTERING
SCANNING SYSTEM
electrostatic systems
mechanical systems
magnetic systems
hybrid systems
ELECTROSTATIC SYSTEMS
MECHANICAL SYSTEMS
TYPES OF ION IMPLANTER
Medium current implanter
High current implanter
High energy implanter
Pre-deposition implanter
IMPLANTATION MEASUREMENT TECHNIQUE
Thermal wave probe
Capacitance-voltage measurement
High voltage probe

CONCLUSION
Originally developed for using semi conductor applications and in fact still used extensively that capacity today- ion implantation utilizes highly energetic beams of ion to modify surface structure and chemistry of materials at low temperature.
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