Bipolar wafer charge monitor system and ion implantation system comprising same
A charge monitor having a Langmuir probe is provided, wherein a positive and negative charge rectifier are operably coupled to the probe and configured to pass only a positive and negative charges therethrough, respectively. A positive current integrator is operably coupled to the positive charge rectifier, wherein the positive current integrator is biased via a positive threshold voltage, and wherein the positive current integrator is configured to output a positive dosage based, at least in part, on the positive threshold voltage. A negative current integrator is operably coupled to the negative charge rectifier, wherein the negative current integrator is biased via a negative threshold voltage, and wherein the negative current integrator is configured to output a negative dosage based, at least in part, on the negative threshold voltage. A positive charge counter and a negative charge counter are configured to respectively receive the output from the positive current integrator and negative current integrator in order to provide a respective cumulative positive charge value and cumulative negative charge value associated with the respective positive charge and negative charge.
1. A charge monitor for an ion implantation system, the charge monitor comprising:
a Langmuir probe;
a positive charge rectifier operably coupled to the Langmuir probe and configured to pass only a positive charge therethrough;
a positive current integrator operably coupled to the positive charge rectifier, wherein the positive current integrator is biased via a positive threshold voltage, and wherein the positive current integrator is configured to output a positive dosage based, at least in part, on the positive threshold voltage;
a positive charge counter configured to receive the output from the positive current integrator and to provide a cumulative positive charge value associated with the positive charge;
a negative charge rectifier operably coupled to the Langmuir probe and configured to pass only a negative charge therethrough;
a negative current integrator operably coupled to the negative charge rectifier, wherein the negative current integrator is biased via a negative threshold voltage, and wherein the negative current integrator is configured to output a negative dosage based, at least in part, on the negative threshold voltage; and
a negative charge counter configured to receive the output from the negative current integrator and to provide a cumulative negative charge value associated with the negative charge.
2. The charge monitor of claim 1 , wherein the Langmuir probe is positioned along a plane of the workpiece on a scanning arm configured to scan the workpiece through an ion beam.
3. The charge monitor of claim 1 , wherein the Langmuir probe is generally planar and is generally coplanar with an implantation plane of a workpiece.
4. The charge monitor of claim 1 , further comprising a non electrically-conductive signal transmitter associated with the Langmuir probe, wherein the signal from the Langmuir probe is communicated to the controller via the non electrically-conductive signal transmitter, therein generally preventing stray capacitance associated with the communication of the signal.
5. The charge monitor of claim 4 , wherein the non electrically-conductive signal transmitter comprises a fiber optic signal transmitter, wherein the signal is communicated to the controller via a fiber optic cable.
6. The charge monitor of claim 4 , wherein the non electrically-conductive signal transmitter comprises a wireless transmitter, wherein the signal is communicated to the controller via the wireless transmitter to a wireless receiver associated with the controller.
7. The charge monitor of claim 1 , wherein the charge monitor comprises a battery, wherein the charge monitor is generally powered by the battery.
8. The charge monitor of claim 7 , further comprising a recharging unit, wherein the recharging unit is selectively electrically connected to the battery of the charge monitor, and wherein the recharging unit is configured to recharge the battery when electrically connected thereto.