I consider myself to be fairly savvy when it comes to knowing who the players are in 3D IC technology research, so when I first saw the news article in EDN reporting that TNO, an Eindhoven-based scientific research company, had approached BESI/Datacon to develop a high-end pick-and place tool for die-to-wafer (D2W) stacking, I felt a bit chagrined; I had never heard of TNO. So I set out to find out as much as I could. It occurred to me that maybe there were others like me out there who had been in the dark.
It turns out that TNO has a fairly broad reach in scientific research, with one arm extending into the development of high-end equipment for specific markets. One of the projects falling under this division is the Bluebird Project, led by R.M.W. (Roger) Gortzen. Its aim is to develop integrated equipment for the purpose of manufacturing 3D IC devices cost effectively and at high volume.
According to the website page about the program, this equipment is intended for 3D stacking using TSVs, rather than wire bonding, as the method of interconnect. Gortzen talks about an integrated system with processed wafers prior to via construction as input, and outputs stacked die. Steps to be eliminated include optical inspection, wafer feeders, transportation between separate machines, and some materials. The long-term goal of this project (target completion 2016) is to achieve stacked-die 300 mm wafers at $100/wafer.
To this end, Gortzen has worked with IMEC to identify the current bottlenecks in the process. The first phase will focus on standardization for the project, thin wafer and die handling, pick and place for die-to-wafer (D2W), bonding, and particle inspection.
Gortzen has clearly been listening to other players in the industry. Citing presentations given at IMAPS 2008, SEMICON West, and by members of EMC3D, here’s what he heard; there isn’t a tool on the market that is appropriate to stack 3D packages. He proposes that a new platform design with more placement-per-second and higher-accuracy aligment at low cost is required. This brings us to the recent news about the collaboration with BESI/Datacon.
Datacon brings experience in advanced D2W technologies, as they have been collaborating on these processes for quite some time with EV Group. That work resulted in a toolset consisting of high-volume flip chip bonding equipment for a pre-bond process, at which point fully assembled wafers were transferred to a die-to-wafer bonder for permanent bond.
Hannes Kostner, of BESI, was happy to answer some questions regarding BESI/Datacon’s involvement in Bluebird. “The project between BESI/Datacon and TNO is one part of Bluebird,” he explained.”This subproject is called BlueHawk and the target is to develop a high accuracy flip chip bonder with a placement accuracy of the already mentioned 2.5µm at 3sigma.”
I asked why a project targeting TSV stacking would be based on a flip chip platform. He explained that Datacon’s 8800 FC Quantum is a perfect platform to start a high accuracy development because it already achieves a performance mix of throughput and accuracy in the order of 10µm at 3sigma at approx. 8000 uph. Additionally, he said it’s not to a drawback to start from a flip-chip only machine, because it’s really just a question of presenting dies on the dicing tape for D2W production. “A flip chip machine is potentially faster since the handling of dies is split into two parallel processes; ejection and flipping and measurement and placement,” he said. With this process, Kostner said the TSVs are formed before die placement so the diebonder can handle the current TSV approach.
A prototype of the TNO/BESI/Datacon tool is scheduled for introduction by the end of this year, with commercial launch sometime in 2010. The companies say they are confident that this tool will be the production tool of the future for D2W processes in the emerging market of 3D stacking.
So there you have it. Now you know what I know. And now that the Bluebird project is on my radar, I’ll be sure to stay on top of it.–F.v.T.