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US 4,736,107 AGranted
Ion beam implanter scan control system
AssigneeEaton Corporation
InventorDouglas D. Myron
Life of this patent
Estimating the term…
Abstract
An ion beam implantation system utilizing two pairs of mutually orthogonal scanning electrodes. Two sawtooth waveforms of approximately the same frequency are applied to the scanning electrodes to produce four sided scanning patterns. The dimensions of these scanning patterns are varied to sweep out a scan pattern that uniformly implants a circular wafer. By perturbing the scanning voltages the instantaneous beam speed is adjusted to compensate for small dose nonuniformities.
Claims17
An ion beam implant system for controllably treating a workpiece comprising:
- (a) source means for providing ions to treat the workpiece;
- (b) support means for orienting the workpiece at a location relative to the source means;
- (c) beam forming means for shaping said ions into an ion beam moving in a first trajectory to cause said ion beam to impinge upon a region of said workpiece;
- (d) scanning means for bending said ion beam away from said first trajectory to impinge upon other regions of said workpiece;
- said scanning means including one or more field creating electrodes;
- and
- (e) control means having an output coupled to said one or more field creating electrodes to apply control voltages to said electrodes;
- said control means including:
- (i) storage means to store a plurality of deflection signals corresponding to a position of a plurality of vertices in an ion beam scan pattern for controllably implanting said workpiece;
- (ii) conversion means for sequentially converting the deflection signals stored in the storage means to a time varying voltage output coupled to said scanning means for causing said ion beam to scan across the workpiece from a position of one vertex to a next subsequent vertex;
- and
- (iii) compensation means for adjusting the time varying voltage applied to the scanning means to control the instantaneous ion dose between vertices as said beam scans across said workpiece.
9 more elements
A method for uniform ion beam treatment of a generally circular workpiece comprising the steps of:
- storing a series of coordinate signals having magnitudes representing relative positions of a series of vertices spaced with respect to the workpiece and defining a two dimensional ion beam scanning pattern;
- directing an ion beam toward a central location on the circular workpiece along an initial trajectory;
- deflecting the ion beam away from the initial trajectory to a first vertex of the series of vertices by converting a first signal in the series of coordinate signals into first and second deflection voltages and coupling said first and second deflection voltages to two scanning electrodes to deflect said beam away from the initial trajectory to said first vertex;
- varying the first and second deflection voltages at controlled rates to cause the ion beam to scan across the workpiece toward subsequent vertices in the beam scanning pattern by comparing a signal related to the deflection voltages to subsequent coordinate signals and causing a transition of at least one of said first and second deflection voltages as said beam reaches each vertex in said scanning pattern.
1 more element
Apparatus for ion beam treatment of a generally circular workpiece comprising:
- means for storing a series of coordinate signals having magnitudes representing relative positions of a series of vertices in a two dimensional ion beam scanning pattern;
- means for directing an ion beam toward a central location on the circular workpiece along an initial trajectory;
- means for deflecting the ion beam away from the initial trajectory to scan across the surface of said workpiece;
- means for converting coordinate signals representing the positions of the vertices into first and second deflection voltages and coupling said first and second deflection voltages to the means for deflecting to deflect said beam away from the initial trajectory to said series of vertices;
- means for varying the first and second deflection voltages at controlled rates to cause the ion beam to scan across the workpiece toward a next subsequent vertex in the beam scanning pattern;
- and
- means for comparing a signal related to the deflection voltages to a next subsequent coordinate signal and causing a transition of one of said first and second deflection voltages as the ion beam reaches each subsequent vertex to cause the ion beam to sweep out the ion beam scanning pattern.
4 more elements
Dependencies are inferred from the claim text.