Pattern modification schemes for improved FIB patterning
AssigneeFEI Company
InventorsTom Miller, Gene Mirro, Cornelis Sander Kooijman, Hendrik Jan de Vos
Life of this patent
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Abstract
An improved method of directing a charged particle beam that compensates for the time required for the charged particles to traverse the system by altering one or more of the deflector signals. According to one embodiment of the invention, a digital filter is applied to the scan pattern prior to digital-to-analog (D/A) conversion in order to reduce or eliminate over-shoot effects that can result from TOF errors. In other embodiments, analog filters or the use of signal amplifiers with a lower bandwidth can also be used to compensate for TOF errors. By altering the scan pattern, over-shoot effects can be significantly reduced or eliminated.
Claims15
A method of directing a charged particle beam in a charged particle beam system, comprising:
- selecting a desired scan pattern for the charged particle beam, the scan pattern for the charged particle beam being produced by applying at least a first voltage and a second voltage to at least one deflector plate in a deflector system;
- modifying the desired scan pattern by applying a digital filter to the desired scan pattern to compensate for time of flight errors resulting from charged particles being in transit through the charged particle beam system when the voltage applied is changed from the first voltage to the second voltage;
- converting the modified pattern to an analog signal;
- applying the analog signal to the deflector system in order to direct the charged particle beam.
A method of directing a charged particle beam in a charged particle beam system, comprising:
- selecting a desired scan pattern for the charged particle beam, the scan pattern for the charged particle beam being produced by applying at least a first voltage and a second voltage to at least one deflector plate in a deflector system;
- modifying the desired scan pattern to compensate for time of flight errors resulting from charged particles being in transit through the charged particle beam system when the voltage applied is changed from the first voltage to the second voltage, in which modifying the desired scan pattern comprises performing a Fast Fourier Transform (FFT) calculation to convert the desired scan pattern into a frequency domain representation, deriving an ideal frequency response correction based upon the known imperfect frequency response, multiplying the correction by the frequency domain representation, and converting the modified frequency domain representation via an inverse-FFT calculation in order to produce a modified scan pattern;
- converting the modified pattern to an analog signal;
- applying the analog signal to the deflector system in order to direct the charged particle beam.
A method of directing a charged particle beam in a charged particle beam system, comprising:
- selecting a desired scan pattern for the charged particle beam, the scan pattern for the charged particle beam being produced by applying at least a first voltage and a second voltage to at least one deflector plate in a deflector system;
- modifying the desired scan pattern to compensate for time of flight errors resulting from charged particles being in transit through the charged particle beam system when the voltage applied is changed from the first voltage to the second voltage, in which the digital filter is a one-pole filter adhering to the equation y(n)=b0x(n)−a1y(n−1), where x(n) is the signal input, y(n) is the signal output, and a1 and b0 are filter coefficients chosen to have a bandwidth that will reduce peaks in the frequency response of two or more combined deflector curves;
- converting the modified pattern to an analog signal;
- applying the analog signal to the deflector system in order to direct the charged particle beam.
Dependencies are inferred from the claim text.