A Study on Fine-Pitch Convertors for Radiation Detectors with Interposers as an Alternative to Through Silicon Via Technology

Schneider, Andreas; Beckett, Dan; Ghorbanian, Navid; Cross, Simon P.; Veale, Matthew C.; Wilson, Mathew D.; Hart, M.; Lipp, J.; French, M.

doi:10.1109/estc55720.2022.9939380

Cited by 3 publications

(1 citation statement)

References 16 publications

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“…The alignment of the aperture array of the shadow mask to the pixel array on sensor/ASIC dies is carried out optically before the mask is fixed to the jig. Further details are given in [17,18].…”

Section: A Masking Of Sensors and Asic Diesmentioning

confidence: 99%

Deposition of Fine-Pitch Indium Bumps on Single Die

Schneider,

Ghorbanian,

Burt

et al. 2024

IMAPSource Proceedings

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Photolithographic lift-off at wafer level is a wellestablished method for depositing indium bumps onto pixels of electronic components such as sensors and application-specific integrated circuits (ASIC). These indium bumps form interconnects between pixels of the components during flip-chip bonding to make devices such as radiation detectors. Such components are not always available on wafer-scale, and single dies need to be processed in small-scale production, R&D, or for Cd(Zn)Te detector material. Photolithography on single dies is ineffective due to the edge-bead of photoresist that compromises perfect indium deposition onto pixels near the periphery of the die. To utilize the maximum surface area of a die, a rigid mask with apertures (shadow mask) is an adequate substitute for the photoresist. Different mask designs and production techniques for fine-pitch indium bump arrays are investigated by testing electroformed stencils or micromachined silicon (Si) membranes as shadow masks. For the indium deposition, the sensor and ASIC dies are clamped into custom-made jigs that include shadow masks. Alternatively, dies can be adhered to shadow masks with soluble adhesive. The apertures of a mask are aligned to the pixel array of the detector component. Bump arrays with 250μm- and 100μm-pitch were demonstrated with electroformed stencils. For smaller pitch (55μm) and bump diameter of ~20μm, specialized masks from Si membranes are tested. Components with successfully deposited indium bump arrays were subsequently flip-chip bonded at room temperature without reflowing the indium. A bond yield of at least 99.9% pixels for such flip-chip bonded radiation detector was shown using the read-out signal from exposure with a flat field X-ray radiation of an Am-241 sealed source.

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Section: A Masking Of Sensors and Asic Diesmentioning

confidence: 99%

Deposition of Fine-Pitch Indium Bumps on Single Die

Schneider,

Ghorbanian,

Burt

et al. 2024

IMAPSource Proceedings

View full text Add to dashboard Cite

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55 μm-pitch indium bump deposition on MEDIPIX single die without using photolithography

Schneider,

Koorikkat,

Ghorbanian

et al. 2024

J. Inst.

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Hybrid MEDIPIX detectors are widely used for a variety of applications including scientific experiments at synchrotrons, X-ray Free-Electron-Lasers (XFEL), or with other radiation sources. For many years, MEDIPIX Application-Specific Integrated Circuits (ASIC) and sensors are usually processed on large wafers using a photolithographic lift-off process in order to deposit interconnects such as indium bumps onto the pixel arrays of ASICs and sensors. After deposition, a wafer is singulated into the individual dies and subsequently sensor chips are connected with read-out MEDIPIX ASICs in a flip-chip process. Sensor and ASIC wafers are very expensive and once a process for the hybridization is chosen, a large number of chips are generated having all the same process parameters. For testing process parameters (e.g. flip-chip bonding) or developing detector prototypes, it is desirable to process smaller batches of single dies with a variety of different process parameters. However, applying photolithography to single die with spin-coated photoresist (PR) across the entire die is not a simple task. Due to the large edge bead of the PR, pixels at the periphery of the die will not be processed perfectly. Here we demonstrate a uniform indium bump deposition onto a 256×257 pixel array (55 μm-pitch) of a MEDIPIX individual die using a mechanical masking method that does not require photolithography. Such method will allow testing and optimizing indium bumps on a variety of MEDIPIX chips without processing a large number of expensive wafers. This masking method for single die is compared to the wafer-scale process of indium bump deposition on MEDIPIX ASICs using photolithography.

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Deposition of Fine-Pitch Indium Bumps on Single Die

Schneider,

Ghorbanian,

Burt

et al. 2023

2023 24th European Microelectronics and Packaging Conference &Amp; Exhibition (EMPC)

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Photolithographic lift-off at wafer level is a wellestablished method for depositing indium bumps onto pixels of electronic components such as sensors and application-specific integrated circuits (ASIC). These indium bumps form interconnects between pixels of the components during flip-chip bonding to make devices such as radiation detectors. Such components are not always available on wafer-scale, and single dies need to be processed in small-scale production, R&D, or for Cd(Zn)Te detector material. Photolithography on single dies is ineffective due to the edge-bead of photoresist that compromises perfect indium deposition onto pixels near the periphery of the die. To utilize the maximum surface area of a die, a rigid mask with apertures (shadow mask) is an adequate substitute for the photoresist. Different mask designs and production techniques for fine-pitch indium bump arrays are investigated by testing electroformed stencils or micromachined silicon (Si) membranes as shadow masks. For the indium deposition, the sensor and ASIC dies are clamped into custom-made jigs that include shadow masks. Alternatively, dies can be adhered to shadow masks with soluble adhesive. The apertures of a mask are aligned to the pixel array of the detector component. Bump arrays with 250µm-and 100µm-pitch were demonstrated with electroformed stencils. For smaller pitch (55µm) and bump diameter of ~20µm, specialized masks from Si membranes are tested. Components with successfully deposited indium bump arrays were subsequently flip-chip bonded at room temperature without reflowing the indium. A bond yield of at least 99.9% pixels for such flip-chip bonded radiation detector was shown using the read-out signal from exposure with a flat field X-ray radiation of an Am-241 sealed source.

show abstract

A Study on Fine-Pitch Convertors for Radiation Detectors with Interposers as an Alternative to Through Silicon Via Technology

Cited by 3 publications

References 16 publications

Deposition of Fine-Pitch Indium Bumps on Single Die

Deposition of Fine-Pitch Indium Bumps on Single Die

55 μm-pitch indium bump deposition on MEDIPIX single die without using photolithography

Deposition of Fine-Pitch Indium Bumps on Single Die

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