Moisture resistance of SU-8 and KMPR as structural material for integrated gaseous detectors

This paper treats the moisture resistance of SU-8 and KMPR, two photoresists considered as structural material in microsystems. Our experiments focus on the moisture resistance of newly developed radiation imaging detectors containing these resists. Since these microsystems will be used unpackaged, they are susceptible to all kinds of environmental conditions. Already after one day of exposure to a humid condition the structural integrity and adhesion of SU-8 structures, measured by a shear test is drastically reduced. KMPR photoresist shows much stronger moisture resistance properties, making it a suitable alternative in our application. © 2008 Elsevier Science. All rights reserved

Moisture resistance of SU-8 and KMPR as structural material

This paper treats the moisture resistance of SU-8 and KMPR, two photoresists considered as structural material in microsystems. Our experiments focus on the moisture resistance of newly developed radiation imaging detectors containing these resists. Since these microsystems will be used unpackaged, they are susceptible to all kinds of environmental conditions. Already after 1 day of exposure to a humid condition the structural integrity and adhesion of SU-8 structures, measured by a shear test is drastically reduced. KMPR photoresist shows much stronger moisture resistance properties, making it a suitable alternative in our application

A Radiation Imaging Detector Made by Postprocessing a Standard CMOS Chip

An unpackaged microchip is used as the sensing element in a miniaturized gaseous proportional chamber. Thisletter reports on the fabrication and performance of a complete radiation imaging detector based on this principle. Our fabrication schemes are based on wafer-scale and chip-scale postprocessing.\ud Compared to hybrid-assembled gaseous detectors, our microsystem shows superior alignment precision and energy resolution, and offers the capability to unambiguously reconstruct 3-D radiation tracks on the spot.\u

Technological aspects of gaseous pixel detectors fabrication

Integrated gaseous pixel detectors consisting of a metal punctured foil suspended in the order of 50μm over a pixel readout chip by means by SU-8 insulating pillars have been fabricated. SU-8 is used as sacrificial layer but metallization over uncrosslinked SU-8 presents adhesion and stress problems. In this paper we describe the several methods we have investigated to fabricate a metal layer on top of a partially crosslinked SU-8 film and the challenges we have encountered. The fabrication process using wafer post processing has been proven, but in cases where single chip processing is desirable, edge bead is a major problem to overcome as it can cover a considerable chip area, reducing the detector performance; we show different techniques to reduce this edge bead and improve detection efficiency

Suspended membranes, cantilevers and beams using SU-8 foils

This paper presents a fast, easy and low-cost method to create suspended structures using SU-8 photoresist. The method consists of laminating SU-8 foils on top of previously defined topographies, followed by SU-8 foil patterning. This surface-micromachining approach has been successfully employed to fabricate a variety of structures, including high-voltage electrodes over CMOS chips, stacked vias, closed cavities, channels, cantilevers and double-clamped beam

A CMOS compatible Microbulk Micromegas-like detector using silicon oxide as spacer material

We present a new Micro Pattern Gaseous Detector (MPGD) fabricated with non polymeric materials. The device structure is similar to a Microbulk Microme gas design, consisting of a punctured metalgrid supported by a continuous perforate dinsulating structure.\ud In this detector, the supporting structure is made out of silicon oxide. Devices were tested in He/iC4H10 (80/20) and Ar/iC4H10 (80/20)gas mixtures under 55Fe irradiation. Gas gain of 20,000 and energy resolution below 13%FWHM were achieved. The CMOS compatibility of the fabrication process has been studied in Timepix chips as well as individual 0.13-mm technology CMOS transistors. Complete detectors have been fabricated on top of Timepix chips. In an Ar/iC4H10 (80/20) gas mixture 55Fe decay events were recorded operating the Timepix chip in 2D readout mode.\u

Direct readout of gaseous detectors with tiled CMOS circuits

A coordinated design effort is underway, exploring the three-dimensional direct readout of gaseous detectors by an anode plate equipped with a tiled array of many CMOS pixel readout ASICs, having amplification grids integrated on their topsides and being contacted on their backside

On the geometrical design of integrated micromegas detectors

This paper presents the operational characteristics of several integrated Micromegas detectors. These detectors called InGrids are made by means of micro-electronic fabrication techniques. These techniques allow a large variety of detector geometry to be made and studied. Gain, gain homogeneity and energy resolution were measured for various amplification gap sizes, hole pitches and hole diameters in Argon/Isobutane. Gain measurements as a function of gap thickness are compared to the Rose and Korff formula and a model of the detector gain. Our model uses electric field maps and MAGBOLTZ calculated amplification coefficients

An integrated gaseous detector using microfabrication post-processing technology

this paper presents the operational characteristics of several integrated Micromegas detectors. These detectors called InGrids are made by means of micro-electronic fabrication techniques. These techniques allow a large variety of detector geometry to be made and studied. Gain, gain homogeneity and energy resolution were measured for various amplification gap sizes, hole pitches and hole diameters in Argon/Isobutane. Gain measurements as a function of gap thickness are compared to the Rose and Korff formula and a model of the detector gain. Our model uses electric field maps and MAGBOLTZ calculated amplification coefficients.\u