Enabling Next-Generation Plasma Dicing with Ultrasonic Spray Coating and Digital Lithography

By JOHANNA RIMBÖCK and JAKOB HOLZAPFEL, EV Group

Plasma dicing offers clear advantages over saw and laser singulation for thin wafers, hybrid bonding and HBM: throughput that doesn’t depend on die count, dicing streets as narrow as 5 µm and less mechanical stress. But bumps, copper pillars and cavities make it hard to protect the die surface during plasma etching, and conventional spin coating struggles to cover that topography.

Johanna Rimböck and Jakob Holzapfel of EV Group evaluate ultrasonic spray coating as a way to apply a conformal, photo-sensitive resist layer over these structures, then define the dicing streets with EVG’s LITHOSCALE maskless digital lithography. Their tests on 200mm and 300mm wafers showed good thickness uniformity, conformal coverage of bumps, pillars and cavities, and high-resolution street patterns with steep sidewalls and clean edges.

Because photoresist avoids the laser step needed with water-soluble coatings and can exclude film frame and tape, the authors say the combination provides a low-stress, contamination-free and scalable approach for wafers with complex bump structures, thin wafers and wafers on film frame, supporting the move to finer pitches and thinner dies.

Click here to read the full article in Semiconductor Digest magazine.

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