Electron beam modulation in response to optical pump pulses applied to a sample is measured using SPAD elements. Individual detection events are used to form histograms of numbers of events in time bins associated with pump pulse timing. The histograms can be produced at a SPAD array, simplifying data transfer. In some examples, two SPAD arrays are stacked and a coincidence circuit discriminates signal events from noise events by determining corresponding events are detected within a predetermined time window.

Detectors and detection systems are disclosed. According to certain embodiments, a detector comprises a substrate comprising a plurality of sensing elements including a first sensing element and a second sensing element, wherein at least the first sensing element is formed in a triangular shape. The detector may include a switching region configured to connect the first sensing 5 element and the second sensing element. There may also be provided a plurality of sections including a first section connecting a first plurality of sensing elements to a first output and a second section connecting a second plurality of sensing elements to a second output. The section may be provided in a hexagonal shape.

The disclosure relates to charged-particle multi-beam columns and multi-beam column arrays. In one arrangement, a sub-beam defining aperture array forms sub-beams from a beam of charged particles. A collimator array collimates the sub-beams An objective lens array projects the collimated sub-beams onto a sample. A detector detects charged particles emitted from the sample. Each collimator is directly adjacent to one of the objective lenses. The detector is provided in a plane down-beam from the sub-beam defining aperture array.

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.

A detector for use in a charged particle device for an assessment tool to detect signal particles from a sample, the detector including a substrate, the substrate including: a semiconductor element configured to detect signal particles above a first energy threshold; and a charge-based element configured to detect signal particles below a second energy threshold.

A device includes a semiconductor fin, an isolation structure, a gate structure, source/drain structures, a sensing contact, a sensing pad structure, and a reading contact. The semiconductor fin includes a channel region and source/drain regions on opposite sides of the channel region. The isolation structure laterally surrounds the semiconductor fin. The gate structure is over the channel region of the semiconductor fin. The source/drain structures are respectively over the source/drain regions of the semiconductor fin. The sensing contact is directly on the isolation structure and adjacent to the gate structure. The sensing pad structure is connected to the sensing contact. The reading contact is directly on the isolation structure and adjacent to the gate structure.

A segmented detector device with backside illumination. The detector is able to collect and differentiate between secondary electrons and backscatter electrons. The detector includes a through-hole for passage of a primary electron beam. After hitting a sample, the reflected secondary and backscatter electrons are collected via a vertical structure having a P+/P−/N+ or an N+/N−/P+ composition for full depletion through the thickness of the device. The active area of the device is segmented using field isolation insulators located on the front side of the device.

A detector includes a plurality of sensing elements, section circuitry that communicatively couples a first set of sensing elements to an input of first signal processing circuitry, and a switch network that connects sets of sensing elements. Inter-element switches may connect adjacent sensing elements, including those in a diagonal direction. An output bus may be connected to each sensing element of the first set by a switching element. There may be a common output (pickup point) arranged at one sensing element that is configured to output signals from the first set. Various switching and wiring schemes are proposed. For example, the common output may be directly connected to the switch network. A switch may be provided between the output bus and first signal processing circuitry. A switch may be provided between the switch network and the first signal processing circuitry.

Electron beam modulation in response to optical pump pulses applied to a sample is measured using SPAD elements. Individual detection events are used to form histograms of numbers of events in time bins associated with pump pulse timing. The histograms can be produced at a SPAD array, simplifying data transfer. In some examples, two SPAD arrays are stacked and a coincidence circuit discriminates signal events from noise events by determining corresponding events are detected withing a predetermined time window.

An in-vacuum light sensor system, including a light sensor assembly comprising a photocathode configured for converting an impinging photon to a photoelectron, a semiconductor diode configured for multiplying the photoelectron impinging thereon, and a housing including vacuum-compatible materials configured for being placed in a vacuum chamber. The housing is configured for housing the photocathode and the semiconductor diode and for propagation of the photoelectron from the photocathode to the semiconductor diode. An electrical biasing subassembly is configured for electrically biasing at least the photocathode and the semiconductor diode, and the vacuum chamber is configured for positioning the light sensor apparatus therein.