Charged particle beam column and method of its operation

A method for operating a charged particle beam column to provide selective operation of the column in a first mode of normal incidence of a primary charged particle beam onto a sample under inspection and a second mode of the primary beam incidence onto the sample with a certain non-zero angle of incidence, the method comprising passing the primary charged particle beam, while propagating towards a focusing lens arrangement, through a condenser arrangement including first and second condensers accommodated in a spaced-apart relationship along the primary beam path;

• and controlling the operation of the lower condenser to reduce a numerical aperture of the beam propagation while shifting the column from the first mode to the second mode.

A system for use in inspecting a sample with a charged particle beam, the system comprising a charged particle beam column including a cathode assembly, an anode tube that defines a primary beam drift space, and a lens arrangement;

• and a voltage supply unit operable to supply a certain given to the anode to provide a desired accelerating voltage for a charged particle beam, supply a certain negative voltage Vsample to the sample provide a desirably high effective voltage of the column at said given voltage of the anode, and supply to an electrode of the lens arrangement, closer to the sample than an objective lens of the lens arrangement, a certain voltage Vcap selected to satisfy one of the following conditions:
• Vcap slightly lower or substantially equal to Vsample enabling operation with a relatively low-gradient electric field in the vicinity of the sample, and Vcap is significantly higher than Vsample enabling operation with a relatively high gradient field in the vicinity of the sample.

A charged particle beam column for inspecting a sample, the column comprising a cathode assembly, a condenser arrangement, an anode tube that defines a primary beam drift space, and a focusing lens arrangement, said condenser arrangement comprising upper and lower condensers accommodated in a spaced-apart relationship along an optical axis of the column and operable to define a required numerical aperture of a primary charged particle beam propagation towards the focusing lens arrangement, the lower condenser being selectively operable to reduce the numerical aperture to thereby selectively shift the column operation from a first mode when the primary beam normally impinges onto the sample to a second mode when the primary beam impinges onto the sample with a certain non-zero angle of incidence.

A sample holder for use with a charged particle beam column, the sample holder comprising upper and lower electrodes, the lower electrode being formed with an array of space-apart projections for supporting the sample by distal ends of said projections, a voltage supplied to the lower electrode defining a voltage of the sample, said upper electrode being in the form of spaced-apart electrode-elements located within the spaces between said projections, a potential difference between the upper electrode elements defining electrostatic forces flattening the sample to reduce a working distance of the column.