At the recent SUSS 3D workshop, held as part of Semicon West, three new temporary bonding solutions that SUSS is working on with Dow Corning, Dow Chemical and 3M were detailed. i-Micronews thought these presentations were worth …a closer look .

Chris Rosenthal of SUSS reported on their high throughput modular equipment platform for temporary bonding and debonding. SUSS has concluded that room temperature lift-off debonding  is fundamentally less risky than thermal slide debonding.

Jim Rosson of Dow Corning introduced a bi-layer, temporary bonding solution with a  room temperature de-bond. This silicone solution consists of a WL-30XX Release layer & Dow Corning® WL-40XX Adhesive layer. 

De-bonding consists of :
- After post bonding processes, the device wafer is mounted on wafer saw tape.
- Automated mechanical de-bonding at room temperature on SUSS de-bonders
De-bonding is always at the WL–30XX Release layer interface.

The cleaning process:
- the wafers are solvent cleaned on flex frame with compatible solvents
- Carrier wafers are cleaned with standard processes using “silicone remover”
Dow Corning is currently expanding their beta test program for this temporary bonding system.
Jeff Calvert introduced Dow Chemicals new BCB based temporary bonding solution XP-BCB.
AP-3000 adhesion promoter is coated onto a carrier wafer and  XP-BCB onto the active die wafer 

The temporary adhesive is cured at 210-230 C for 10 – 30 min. De bonding is done mechanically at RT due to the lower adhesion of BCB to the device wafer. 

Blake Dronen of 3M described their next generation Wafer Support System (WSS). The current WSS is in high volume production at multiple DRAM  and logic manufacturers. 3M claims there are  >  50 installed HVM tools world wide.

Their Gen II WSS process uses the conventional WSS materials but adds a high temperature thermoplastic primer layer to the substrate surface .  This primer layer creates a surface for the UV curable adhesive to bond, independent of the wafer surface passivation material. Upon laser degradation the LTHC layer and removal of the glass , the WSS adhesive joining layer can be peeled off the primer surface in a conventional manner.  The  thermoplastic primer is solvent rinsed, eliminating any opportunities for residue or imparting bump damage by the peel step.  This process should be ready for release in 4Q 2012.

An LTHC free process is also being developed to simplify glass recycle and reduce overall process cost by eliminating the debonder laser . It uses the conventional WSS materials but replaces the LTHC layer with a 100% solids UV curable “release layer” that is tuned to enable mechanical separation of the carrier at the interface.   The adhesive joining layer, when cured, becomes a single component with the release layer, peeled as one during debond. The LTHC free process is currently being developed and optimized. 

SUSS has developed temporary bonding processes with most of the temporary bonding suppliersa around the world.