A novel negative-tone, photosensitive, polymeric bonding material is proposed that can be used as a dielectric enabling polymer/metal hybrid bonding.
Wafer-level hybrid bonding techniques, which provide simultaneous bonding between metal-metal and dielectric-dielectric layers, have attracted more attention in recent years for fabricating 3D integrated circuits with high bandwidth and high interconnect density. However, there are some issues for conventional hybrid bonding using silicon oxide as the dielectric, such as the high stress and low tolerance to height difference of the bonding interface, which limits its applications for 3D heterogeneous integration.
In this paper, a novel negative-tone, photosensitive, polymeric bonding material is proposed that can be used as a dielectric enabling polymer/metal hybrid bonding. Compared to silicon oxide, the polymeric material with low Young’s modulus is able to absorb thermally induced stress created during the bonding process and results in lower bow for the bonded substrates. The key features for the photosensitive permanent bonding material include 1) low dielectric constant and dissipation factor; 2) superior thermal stability up to 350°C; 3) excellent fine-pitch capability <10 µm; and 4) low processing and curing temperatures <200°C. The photosensitive permanent bonding material has also demonstrated good patternability with good adhesion when bonded to another Si or glass substrate without obvious defects. The details of the material characterization, process optimization, reliability, and preliminary polymer/polymerhybrid bonding results will be presented in this paper.
This white paper is available for download at the bottom of this blog.