Ion implantation apparatus and a method of monitoring high energy neutral contamination in an ion implantation process
First Claim
1. A method of monitoring in an ion implantation process high energy neutral contamination of an ion beam caused by beam ions neutralised as they are temporarily accelerated at a field electrode before being decelerated again to the desired implant energy, comprising the step of monitoring the current drain on the field electrode to indicate the flow rate of said neutralised ions to the target.
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Accused Products
Abstract
High energy neutral contamination in an ion implanter can be caused by beam ions neutralised as they are temporarily accelerated at an electrode before being decelerated again to the desired implant energy. This occurs for example in the decel lens arrangement which includes an electrode at a relatively high negative potential to provide the required focusing. The level of this contamination is monitored by measuring the current drain on this negative field electrode.
50 Citations
14 Claims
- 1. A method of monitoring in an ion implantation process high energy neutral contamination of an ion beam caused by beam ions neutralised as they are temporarily accelerated at a field electrode before being decelerated again to the desired implant energy, comprising the step of monitoring the current drain on the field electrode to indicate the flow rate of said neutralised ions to the target.
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5. Ion implantation apparatus comprising a vacuum chamber containing:
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a holder for a target substrate to be implanted, a source of ions, a flight tube to carry a beam df ions from said source at a transport energy, said flight tube having an exit aperture and a mass selector to select only ions of a desired mass for delivery in a beam at said transport energy from said exit aperture of the flight tube, a first voltage potential supply connected between said exit aperture and said substrate holder to decelerate ions in the beam to an implant energy at the holder, a field electrode located between said exit aperture and said substrate holder, a second voltage potential supply connected to provide a potential difference between said field electrodes and said exit aperture which temporarily accelerates ions in the beam above said transport energy, a current meter to provide a signal indicating the current drain on said field electrode, and means responsive to said current drain signal to provide an indication of the quantity of accelerated neutral particles in the beam leaving the field electrode. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification