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Handling ultra thin die for bonding: Pulse Vacuum Reverse Multi Step (PV-RMS)
The thickness of multilayered NAND flash memories has been reduced to less than 30 um including an adhesive layer. Although silicon is a relatively hard material, it will bend readily and break easily at this thickness. In making a device, a die pickup technique is necessary, but it is extremely difficult to remove an ultra thin die attached to the wafer tape.
You may have experienced that peeling off a bandage quickly caused pain. Alleviating this pain is compared to the function of Pulse Vacuum-Reverse Multi Step (PV-RMS) that picks up thin dies from wafer tape. By pulsing vacuum from the outside of wafer tape, the PV-RMS promotes peeling of the die while reducing the adhesive force – corresponding to the reduced pain that would result from a similar method of bandage removal. It is effective not only for thin dies but also for dies with a fragile TSV structure. This is a key technique for future electronic device packaging.
Cleaning before connecting is important: Dust Free Cleaner (DFC)
Die Attach Film (DAF), an adhesive used for NAND flash memories, is as thin as 5 um. The NAND flash memories are often stacked in multiple stages. When a new die is stacked, if fine particles of 5 um or more are present on an object to be bonded, die cracking may occur and the productivity may decrease. Cleaning before die stacking is, therefore, an essential factor for successful multi-stack bonding.
Shinkawa was among the first to address this issue and developed a dust free cleaner (DFC) unit, which has a cleaning speed 60 times faster than the conventional model. Its high-speed cleaning capability is recognized by the industry’s leading manufacturers as a contributor to total productivity improvement.
In addition to DFC, Shinkawa will strive to develop technologies related to cleanliness control and provide tools to increase customers' productivity.
3D-NRS Technology: (three-dimensional non reaction servo system)
In order to ensure bonding accuracy and increase productivity, it is necessary to reduce mutual interference due to vibration of the drive units. In the SPA-1000, the 3D-NRS technology controls vibration of the two high-speed bonding heads, enabling high productivity as well as high precision. The model has bonding accuracy of XY±5 µm (3σ) and θ±0.05° (3σ), achieving twice the UPH of a conventional model.
