Blade Milling For Quantum Computing

Inhalt:
Thin-film flex interposers, created on temporary carrier wafers with multiple copper redistribution layers (RDLs) and polyimide (PI) dielectrics through repeated metal and polymer deposition possess RDL densities comparable to RDL densities on rigid substrates, while offering greater potential and flexibility than conventional coreless organic interposers. The technology also enables the attachment of thin ICs or sensor components by bonding directly to the polymer layers or by flip-chip packaging via solder bumps. Commonly, the multilayer structure is detached from the carrier wafer using a full-area debonding process. Or the substrate is removed locally via deep reactive ion etching (DRIE), so that both, rigid substrate and flexible bridge zones are created within a single circuit. This work presents a novel approach using blade dicing for Si removal between rigid interposer sections to release the flexible section of the interposer. This blade milling technique is advantageous over DRIE as it allows shorter process times. And it can be applied in the final steps of the process chain in combination with the device singulation, so that the wafer rigidity and stability is not impaired until the very end. Due to the low thermal conductivity of PI, one very important future application for such rigid-flex interposers is expected to be the bridging between different cooling stages in the field of quantum computing.