Chip Scale Review January • February • 2019[ChipScaleReview.com
nlike mechanical debonding, which generates
significant peel stress on a device’s surface, air-jetting
) injects air streams between
the carrier and the device, pushing the carrier up from underneath
while compressing the device down. As a result, this jetting
technology allows a higher strength bonding adhesive at an elevated
temperature, which is typically associated with excessive warpage
control. Furthermore, the airflow produces the most uniform stress
distribution, and the debonding is instant at room temperature—
characteristics that are best suited for large-area debonding.
Air jetting debonding
This article describes the advancements in air jetting debonding
and the material developments for high-temperature temporary
support of thin-wafer fabrication, fan-out wafer-level packaging
(FOWLP), and integrated circuit (IC) package assembly with a large
The fabrication of a thin IC wafer requires a temporary support for
grinding, polishing, dry reactive ion etching, dielectric development,
metal deposition, chemical etching, photoresist development and/
or solvent soaking, plasma ashing, and wafer cleaning. Panel-level
packaging also requires temporary support for redistribution layer
(RDL) build-up, flip-chip bonding, fluxing cleaning, molding, and
even the solder reflow process. After fabrication, the thin-wafer/panel
requires debonding from its carrier. The bonding adhesive needs to be
completely removed without any trace of residue contamination.
While a carrier and a device typically bond together under pressure
in vacuum, debonding mechanisms to separate the carrier from the
device vary with the adhesive. It is desirable to have the debonding
done with the shortest cycle time, the minimum tensile stress exerted
on the device surface, the elimination of heat damage on the device’s
structure, and easy cleaning with an environmentally friendly cleaner.
The concept of injecting air for carrier debonding was first
introduced in 2016 for thin-wafer processing . Unlike mechanical
peeling, air jetting debonding introduces air streams to push the carrier
up from underneath while compressing the device down (
The structure and pattern of the device are being protected from the
airflow. Furthermore, AirDebond
allows the carrier made by materials,
such as silicon, ceramic and metal (as well as glass) to best match the
coefficient of thermal expansion (CTE) of the device wafer for better
warpage control at a high temperature.
summarizes the application and materials with the air
Temporary bonding for a wafer process >400°C
The thermal stability of an adhesive often refers to its ability to resist decomposition and outgassing during high thermal processing.
Z-coat 451 (Z451) is a single-layer bonding adhesive for up to a 400°C processing application.
illustrates a typical process flow
shows the thermogravimetric (TGA) curve of Z451 under a constant heating rate of 10°C/min to 700°C. We can see
that the weight loss of the Z451 is highly stable up to 450°C. The decomposition temperature is around 500°C.
Air jetting debonding for thin-wafer/panel and fan-out
wafer-level package processing
By Hao Tang, My Nguyen, Joshua Huffaker, Anastasia Banner
[Micro Materials Inc.]
Illustration of the air jetting process.
Summary of the application and materials with AirDebond
Typical process flow with Z451.