Single bend energy filter for controlling deflection of charged particle beam
A single bend energy filter for controlling deflection of a charged particle beam is provided. It includes a first array of electrodes and a second array of electrodes to define a beam channel for the charged particle beam to pass through; an unmatched steering electrode among the first array of electrodes for tuning the bend angle of the charged particle beam; and a plurality of electrical biases applied to the first array of electrodes, the second array of electrodes and the unmatched steering electrode, wherein portion or all of the electrodes have different shapes. A method for controlling deflection of a charged particle beam is also provided. Depending on use of an unmatched steering electrode, the bend angle of the charged particle beam may be fine-tuned, so as to effectively control the deflection of the charged particle beam to achieve a centered beam at the wafer plane.
1. A single bend energy filter for controlling deflection of a charged particle beam, comprising:
a first array of electrodes and a second array of electrodes corresponding to each other to define a beam channel for the charged particle beam to pass through;
an unmatched steering electrode among the first array of electrodes for tuning a bend angle of the charged particle beam; and
a plurality of electrical biases applied to the first array of electrodes, the second array of electrodes and the unmatched steering electrode.
2. The single bend energy filter for controlling deflection of a charged particle beam according to claim 1 , wherein the first array of electrodes and the second array of the electrode both comprise:
a terminal electrode set, for the charged particle beam entering the beam channel;
a suppression electrode set, adjacent the terminal electrode set and at opposite sides of the beam channel for adjusting divergence of the charged particle beam in addition to blocking back-streaming electrons;
a ground electrode set, at opposite sides of the beam channel; and
a plurality of decelerating electrode sets, at opposite sides of the beam channel and between the suppression electrode set and the ground electrode set, wherein portion of the decelerating electrode sets have different shapes and have different applied electrical biases.
3. The single bend energy filter for controlling deflection of a charged particle beam according to claim 2 , wherein the plurality of decelerating electrode sets comprises:
a pair of first decel electrodes adjacent the suppression electrode set;
a pair of second decel-bend electrodes near the pair of first decel electrodes;
a pair of third decel-bend electrodes adjacent the pair of second decel-bend electrodes; and
wherein the unmatched steering electrode is arranged between one first decel electrode of the first array of electrodes and one second decel-bend electrode of the first array of electrodes, to tune the bend angle of the charged particle beam.
4. The single bend energy filter for controlling deflection of a charged particle beam according to claim 3 , wherein the pair of first decel electrodes are at opposite sides of the beam channel for commencing deceleration of the charged particle beam.
5. The single bend energy filter for controlling deflection of a charged particle beam according to claim 4 , wherein the pair of second decel-bend electrodes are at opposite sides of the beam channel, and the pair of second decel-bend electrodes have different shapes and applied different voltages.
6. The single bend energy filter for controlling deflection of a charged particle beam according to claim 5 , wherein two opposite surfaces of the pair of second decel-bend electrodes have different slopes, for defining a rotated final decelerating field to start the bending process.
7. The single bend energy filter for controlling deflection of a charged particle beam according to claim 6 , wherein the pair of third decel-bend electrodes are at opposite sides of the beam channel, and two opposite surfaces of the pair of third decel-bend electrodes respectively are bent, for defining another rotated final decelerating field to complete the bending process of an ion beam.
8. The single bend energy filter for controlling deflection of a charged particle beam according to claim 7 , wherein the ground electrode set is a pair of ground electrodes at opposite sides of the beam channel, and two opposite surfaces of the pair of ground electrodes are parallel.
9. The single bend energy filter for controlling deflection of a charged particle beam according to claim 4 , wherein the pair of first decel electrodes are either flat plates or rod-shaped.
10. The single bend energy filter for controlling deflection of a charged particle beam according to claim 3 , wherein one first decel electrode among the first array of electrodes, one second decel-bend electrode among the first array of electrodes, one third decel-bend electrode among the first array of electrodes and the unmatched steering electrode are biased negative, and the other of first decel electrode among the second array of electrodes, the other of second decel-bend electrode among the second array of electrodes and the other of third decel-bend electrode among the second array of electrodes are biased positive.
11. The single bend energy filter for controlling deflection of a charged particle beam according to claim 1 , wherein the charged particle beam travels in the centerline of the beam channel.
12. A method for controlling deflection of a charged particle beam, comprising:
providing a first array of electrodes and a second array of electrodes corresponding to each other to define a beam channel for the charged particle beam to pass through;
arranging an unmatched steering electrode among the first array of electrodes for tuning a bend angle of the charged particle beam; and
providing a plurality of electrical biases to the first array of electrodes, the second array of electrodes and the unmatched steering electrode.
13. The method for controlling deflection of a charged particle beam according to claim 12 , wherein the first array of electrodes and the second array of the electrode both comprise:
a terminal electrode set for the charged particle beam entering the beam channel;
a suppression electrode set for adjusting divergence of the charged particle beam in addition to blocking back-streaming electrons;
a pair of first decel electrodes for commencing deceleration of the charged particle beam;
a pair of second decel-bend electrodes for defining a rotated decelerating field to start the bending process;
a pair of third decel-bend electrodes for defining another rotated decelerating field to complete the bending process of an ion beam; and
a ground electrode set at ground potential.
14. The method for controlling deflection of a charged particle beam according to claim 13 , wherein the unmatched steering electrode is arranged between one first decel electrode and one second decel-bend electrode.
15. The method for controlling deflection of a charged particle beam according to claim 13 , wherein one first decel electrode among the first array of electrodes, one second decel-bend electrode among the first array of electrodes, one third decel-bend electrode among the first array of electrodes and the unmatched steering electrode are biased negative, and the other of first decel electrode among the second array of electrodes, the other of second decel electrode among the second array of electrodes and the other of third decel electrode among the second array of electrodes are biased positive.
16. The method for controlling deflection of a charged particle beam according to claim 12 , wherein the first array of electrodes and the second array of the electrode both comprise:
a terminal electrode set, for the charged particle beam entering the beam channel;
a suppression electrode set, adjacent the terminal electrode set and at opposite sides of the beam channel for adjusting divergence of the charged particle beam in addition to blocking back-streaming electrons;
a ground electrode set, at opposite sides of the beam channel; and
a plurality of decelerating electrode sets, at opposite sides of the beam channel and between the suppression electrode set and the ground electrode set, wherein portion of the decelerating electrode sets have different shapes and have different applied electrical biases, and the unmatched steering electrode is arranged among the decelerating electrode set.