CHARGED PARTICLE DETECTOR
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Accused Products
Abstract
A charged particle beam system for imaging and processing targets is disclosed, comprising a charged particle column, a secondary particle detector, and a secondary particle detection grid assembly between the target and detector. In one embodiment, the grid assembly comprises a multiplicity of grids, each with a separate bias voltage, wherein the electric field between the target and the grids may be adjusted using the grid voltages to optimize the spatial distribution of secondary particles reaching the detector. Since detector lifetime is determined by the total dose accumulated at the area on the detector receiving the largest dose, detector lifetime can be increased by making the dose into the detector more spatially uniform. A single resistive grid assembly with a radial voltage gradient may replace the separate grids. A multiplicity of deflector electrodes may be located between the target and grid to enhance shaping of the electric field.
24 Citations
38 Claims
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11. A method of reducing the rate of damage or contamination in a secondary particle detector in a charged particle system, comprising:
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focusing a charged particle beam with a charged particle beam onto the surface of a target, wherein the impact of the charged particle beam with the target induces the emission of secondary particles from the target; collecting a portion of the secondary particles emitted from the target with a secondary charged particle detector; providing a magnetic field to deflect the secondary charged particles to reduce the maximum current density of the charged particles impinging on the charged particle detector by spreading the charged particles impingements over the detector, thereby prolonging the useful life of the charged particle detector. - View Dependent Claims (12, 13, 18, 19, 20, 21, 23, 35, 36, 37, 38)
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24. A charged particle system, comprising:
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a charged particle column for focusing a primary charged particle beam onto the surface of a target; a charged particle detector assembly including; a detector for producing an electrical signal corresponding to the number of charged particles impacting the detector; a source of a magnetic field that deflects the secondary charged particles to reduce the maximum current density of the charged particles impinging on the charged particle detector, thereby prolonging the useful life of the charged particle detector. - View Dependent Claims (26, 27, 29, 30, 31, 32, 33, 34)
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Specification