Fabrication and characterization of monolithically integrated microchannel plates based on amorphous silicon

Abstract

Microchannel plates are vacuum-based electron multipliers for particle—in particular, photon— detection, with applications ranging from image intensifiers to single-photon detectors. Their key strengths are large signal amplification, large active area, micrometric spatial resolution and picosecond temporal resolution. Here, we present the first microchannel plate made of hydrogenated amorphous silicon (a-Si:H) instead of lead glass. The breakthrough lies in the possibility of realizing amorphous silicon-based microchannel plates (AMCPs) on any kind of substrate. This achievement is based on mastering the deposition of an ultra-thick (80–120 μm) stress-controlled a-Si:H layer from the gas phase at temperatures of about 200°C and micromachining the channels by dry etching. We fabricated AMCPs that are vertically integrated on metallic anodes of test structures, proving the feasibility of monolithic integration of, for instance, AMCPs on application-specific integrated circuits for signal processing. We show an electron multiplication factor exceeding 30 for an aspect ratio, namely channel length over aperture, of 12.5:1. This result was achieved for input photoelectron currents up to 100 pA, in the continuous illumination regime, which provides a first evidence of the a-Si:H effectiveness in replenishing the electrons dispensed in the multiplication process.

Amorphous silicon-based micro-channel plate detectors with high multiplication gain

“…So far, the multiplication gain of AMCPs with aspect ratios of up to 12.5 has been characterized for a primary electron energy of 500 eV [5]. A plot of the logarithm of the gain versus the logarithm of the bias voltage is shown in Figure 5a.…”

“…For each aspect ratio, the number of collisions can be extrapolated. From [5] b) Number of collisions in AMCPs/MCPs plotted versus their respective aspect ratio. As for MCPs, the number of collisions in AMCPs grows linearly with their aspect ratio.…”

Review of amorphous silicon based particle detectors: the quest for single particle detection

“…While avalanche events could be demonstrated using EBIC measurements [97], this configuration did not allow us to separate the current induced by the avalanche from the leakage current through the AMCP structure. A new generation was designed featuring an additional electrode at the back, separated from the bottom readout electrode (anodes) by a thin insulating layer [101]. The overall device structure and detailed scanning electron microscope (SEM) images of the device are given in Figure 13.…”

“…This is performed by PE-CVD (as for other a-Si:H devices) under conditions that must minimize stress in the layer to avoid delamination of the stack or formation of blisters. Details on the fabrication can be found in [101] and [102].…”

Pure and conformal CVD nickel and nickel monosilicide in high-aspect-ratio structures analyzed by atom probe tomography

“…Thus semiconductor devices and interconnects must be made inside structures with high aspect ratios. 9,10 For example, fin-type field-effect transistors (Fin-FET) with high-aspect-ratio silicon fins need conformal coating of dielectrics, amorphous silicon (a-Si) gates, as well as the metal/silicide (e.g. Ni/NiSi) contacting with a-Si gates, as illustrated in Figure 1a.…”