Low Temperature Sapphire to Silicon Flip Chip Interconnects by Copper Nanoparticle Sintering

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

2 Citations (Scopus)
33 Downloads (Pure)


The continuous trend to integrate more multi-functions in a package often involves, Heterogeneous Integration of multi-functional blocks in some kind of 3D stacking. The conventional flip chip for die-on-substrate technology applies solder for integration. However, solder joint integration has the disadvantages of restricting height, reflow issues and re-melting at high operating temperatures. Nanometallic particle sintering offers a potential solution for these solder related issues. Nanometallic particle sintering occurs at low temperature and does not reflow and melt at higher temperatures. Hence, it can be applied for quite precise alignment and integration technologies, such as photonic components on silicon for harsh environment applications. In order to test this concept, we use sapphire and Si wafers with different mechanical properties, which can lead to the coefficient of thermal expansion mismatch. The sapphire chip can operate at a higher temperature applied for ultraviolet photonics application. This report describes a novel approach using copper nanoparticles paste patterned through photolithographic stencil printing. The photoresist acts as the stencil mask, and a photoresist lift-off process is applied to strip the photoresist stencil. This process has the advantages of lithographic form factor and precision and provides a chip to chip interconnect with a standard height of 20 µm.
Original languageEnglish
Title of host publicationProceedings of the 2022 IEEE 9th Electronics System-Integration Technology Conference (ESTC)
Number of pages5
ISBN (Electronic)978-1-6654-8947-8
ISBN (Print)978-1-6654-8948-5
Publication statusPublished - 2022
Event2022 IEEE 9th Electronics System-Integration Technology Conference (ESTC) - Sibiu, Romania
Duration: 13 Sept 202216 Sept 2022


Conference2022 IEEE 9th Electronics System-Integration Technology Conference (ESTC)

Bibliographical note

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care

Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.


  • flip chip
  • heterogeneous integration
  • copper nanoparticle
  • nano Cu bump
  • low temperature sintering


Dive into the research topics of 'Low Temperature Sapphire to Silicon Flip Chip Interconnects by Copper Nanoparticle Sintering'. Together they form a unique fingerprint.

Cite this