Ion beam scanning control methods and systems for ion implantation uniformity

1. A method for measuring the flux of a ribbon ion beam, comprising:

providing a scan waveform having a time-varying potential to scan an ion beam across a scan path, wherein a first value of the time-varying potential corresponds to a first location of the ion beam on the scan path and a second value of the time-varying potential corresponds to a second location of the ion beam on the scan path;

measuring a beam current signal comprising a plurality of beam current values as the ion beam is scanned across the scan path; and

assigning beam current values from the beam current signal and corresponding to the first value to a first dynamic beam profile; and

assigning beam current values from the beam current signal and corresponding to the second value to a second dynamic beam profile.

2. The method of claim 1 wherein the time-varying potential relates to at least one of: a time-varying voltage or a time-varying magnetic field.

3. A method for adjusting the flux of a ribbon ion beam, comprising:

providing a scan waveform having a time-varying potential to scan an ion beam across a scan path at an initial scan rate, wherein a first value of the time-varying potential corresponds to a first location of the ion beam on the scan path and a second value of the time-varying potential corresponds to a second location of the ion beam on the scan path;

moving a beam profiler at a profiling rate across a profiling path that at least partially overlaps the scan path;

measuring with the beam profiler as the ion beam is scanned a beam current signal comprising a plurality of beam current values;

assigning beam current values from the beam current signal and corresponding to the first value to a first dynamic beam profile;

assigning beam current values from the beam current signal and corresponding to the second value to a second dynamic beam profile; and

calculating a corrected scan rate that differs from the initial scan rate based on the first and second dynamic beam profiles.

4. The method of claim 3 , further comprising:

scanning the ion beam at the corrected scan rate to produce a corrected ribbon ion beam.

5. The method of claim 3 , wherein calculating the corrected scan rate based on the first and second dynamic beam profiles comprises:

(a) processing the dynamic beam profiles to generate a ribbon beam flux profile;

(b)calculating a difference between the ribbon beam flux profile and a desired ribbon beam flux profile;

(c) relating the difference in (b) to the dynamic beam profiles by an instantaneous scan velocity; and

(d) calculating a the corrected scan rate based on the relationship in (c).

6. The method of claim 5 , wherein calculating a corrected scan rate based on the dynamic beam profiles further comprises:

determining if the ribbon flux profile meets requirements; and

if the ribbon beam flux profile does not meet the requirements, repeating acts (a), (b), (c), and (d) until it does meet the requirements.

7. The method of claim 3 , wherein a plurality of dynamic beam profiles are measured in a limited time.

8. The method of claim 7 , wherein the limited time is less than 90 seconds.

9. The method of claim 7 , wherein the limited time is less than 15 seconds.

10. The method of claim 7 , wherein the limited time is less than a time that corresponds to three passes of the beam profiler across the profiling path.

11. The method of claim 7 , wherein the limited time is less than or approximately equal to a time that corresponds to a single pass of the beam profiler across the profiling path.

12. The method of claim 4 , further comprising: interpolating additional dynamic beam profiles from the measured dynamic beam profiles.

13. A calibration system for calibrating an ion beam scanned in an ion implantation system, the calibration system comprising:

a beam scanner adapted to utilize a time-varying scan waveform to scan an ion beam across a scan path;

a beam profiler adapted to traverse a profiling path which at least partially overlaps the scan path and measure a beam current of the scanned ion beam; and

a controller adapted to assign beam current measurements corresponding to a first value of the time-varying scan waveform to a first dynamic beam profile, and assign beam current measurements corresponding to a second value of the time-varying scan waveform to a second dynamic beam profile.

14. The calibration system of claim 13 , wherein the beam scanner is adapted to scan the ion beam at a scan rate which is higher than a profiling rate at which the beam profiler travels along the profiling path.

15. The calibration system of claim 13 , wherein the controller is further adapted to process the dynamic beam profiles to generate a ribbon flux profile indicative of the flux of the ion beam as the ion beam is scanned across the scan path.

16. The calibration system of claim 15 , wherein the controller is further adapted to compare the ribbon flux profile to a desired ribbon flux profile and provide a correction signal to the beam scanner to alter the scan waveform so the ribbon flux profile conforms to the desired ribbon flux profile.

17. The method of claim 1 , further comprising:

processing the plurality of dynamic beam profiles to obtain a ribbon flux profile; and

comparing the ribbon flux profile to a desired beam profile.

18. The method of claim 17 , further comprising:

calculating a corrected scan rate based on the comparison of the ribbon flux profile to the desired beam profile.

19. The method of claim 18 , further comprising:

scanning the ion beam at the corrected scan rate to produce a ribbon beam with the desired beam profile.