High-efficient chip to wafer self-alignment and bonding for flexible and size-free MEMS-IC integration

The large-scale and low-cost integration of various MEMS devices with ICs is significantly important for MEMS ubiquitous applications and commercialization. This paper presents our flexible and size-free MEMS-IC integration approach by a two-step process: MEMS and IC known-good-dies (KGD) are temporarily bonded onto carrier wafer first, and then those KGDs were transferred from carrier wafer to target IC wafer or interposer wafer by permanent bonding. In this work, surface self-assembled monolayer (SAM) fine pattern was introduced by a simple and low-cost lift-off process to define the binding-sites, which was demonstrated effective for rapid (in milliseconds) and high-accurate (< 1 μm) self-alignment of KGDs onto carrier wafer for temporary bonding. Plasma activated Au-Au bumpless bonding was applied for low-temperature permanent bonding (≤ 200 °C) of KGDs onto target wafer with less damage to MEMS and IC devices.