Detector substrate for use in a charged particle multi-beam assessment tool
A detector substrate (or detector array) for use in a charged particle multi-beam assessment tool to detect charged particles from a sample. The detector substrate defines an array of apertures for beam paths of respective charged particle beams of a multi-beam. The detector substrate includes a sensor unit array. A sensor unit of the sensor unit array is adjacent to a corresponding aperture of the aperture array. The sensor unit is configured to capture charged particles from the sample. The detector array may include an amplification circuit associated with each sensor unit in the sensor unit array and proximate to the corresponding aperture in the aperture array. The amplification circuit may include a Trans Impedance Amplifier and/or an analogue to digital converter.
1 . A detector substrate for use in a charged particle multi-beam assessment tool to detect charged particles from a sample, the detector substrate defining an array of apertures for beam paths of respective charged particle beams of a multi-beam, the detector substrate comprising:
a sensor unit array, a sensor unit of the sensor unit array adjacent a corresponding aperture of the aperture array and the sensor unit configured to capture charged particles from the sample; and
a plurality of amplification circuits, a respective amplification circuit from the plurality of amplification circuits associated with each sensor unit in the sensor unit array and proximate to the corresponding aperture in the aperture array, each amplification circuit of the plurality of amplification circuits comprising a Trans Impedance Amplifier and/or an analogue to digital converter.
2 . The detector substrate of claim 1 , further comprising a cell array of cells, wherein the cell array comprises circuitry associated with the sensor unit array, the cells correspond to the apertures of the aperture array defined in the detector substrate.
3 . The detector substrate of claim 2 , wherein the amplification circuit, associated with each sensor unit, comprises an associated cell of the cell array.
4 . The detector substrate of claim 2 , further comprising at least one circuit wire, wherein each circuit wire is associated with an associated cell of the cell array, and each circuit wire connecting to the circuitry of the associated cell so as to signally connect the cell for signal communication external to the cell.
5 . The detector substrate of claim 4 , wherein the at least one circuit wire is routed in a datapath layer of the substrate.
6 . The detector substrate of claim 5 , wherein the datapath layer comprises a circuit routing comprising the at least one circuit wire, the wiring route routed between the other cells of the cell array.
7 . The detector substrate of claim 6 , wherein the substrate comprises shielding elements configured to shield the wiring route.
8 . The detector substrate of claim 7 , wherein the shielding elements comprise:
a grounding layer within the substrate above and/or beneath the datapath layer; and/or
a shielding element in the datapath layer either side of the wiring route and/or between circuit wires in the wiring route.
9 . The detector substrate of claim 4 , wherein the or each circuit wire transceives data between a Trans Impedance Amplifier in the associated cell of the cell array and an analogue to digital converter remote from the cell array.
10 . The detector substrate of claim 2 , wherein the substrate comprises CMOS circuitry comprising amplifier circuitry and the cell array.
11 . The detector substrate of claim 2 , wherein a Trans Impedance Amplifier is located in the associated cell and an analogue to digital converter is remote.
12 . The detector substrate of claim 2 , wherein the cell array is a hexagonal or rectangular array.
13 . The detector substrate of claim 1 , wherein the amplification circuit comprises the Trans Impedance Amplifier and the Trans Impedance Amplifier comprises a pseudo resistor.
14 . The detector substrate of claim 1 , wherein the amplification circuit comprises the analogue to digital converter and the analogue to digital converter is a direct digital converter, directly electrically connected to the corresponding sensor unit.
15 . The detector substrate of claim 14 , wherein the amplification circuit comprises a comparator, an integrator and reference.
16 . A detector substrate for use in in a charged particle multi-beam assessment tool to detect charged particles from a sample, the detector substrate defining an array of apertures for beam paths of respective charged particle beams of a multi-beam, the detector substrate comprising:
a sensor unit array of a plurality of separate sensor units, each sensor unit having an electrode configured to have incident thereon charged particles from the sample, which incident charged particles induce current flow in the electrode;
a cell array of a plurality of cells, each cell of the cell array associated with a respective different aperture of an aperture array for the path of the multibeam and associated with a respective different sensor unit of the sensor unit array; and
a wiring route configured to transmit signals from an associated sensor unit between the associated cell to at least a perimeter of the cell array, the wiring route configured to be routed between other cells of the cell array.
17 . The detector substrate of claim 16 , wherein the wiring route comprises at least one circuit wire between an associated cell and the perimeter of the cell array.
18 . A detector substrate for use in a charged particle multi-beam assessment tool to detect charged particles from a sample, the detector substrate defining an aperture array for respective beam paths of a multibeam, the detector substrate comprising:
a sensor unit of a sensor unit array configured to capture charged particles from the sample;
a cell array, a cell of the cell array each associated with an aperture of the aperture array, and
a plurality of amplification circuitries, a respective amplification circuitry from the plurality of amplification circuitries associated with each cell of the cell array, each amplification circuitry of the plurality of the amplification circuitries comprising a variable amplifier and an analogue to digital converter.
19 . The detector substrate of claim 18 , wherein the variable amplifier is configured to have a variable amplification range dependent on a detected beam current detected by the sensor unit array.
20 . The detector substrate of claim 18 , wherein the variable amplifier is configured to subtract an offset for input into the analogue to digital converter.