Maskless Lithography for High-Density Package Redistribution Layers

Prahalad Murali, Pratik Nimbalkar, Mohanalingam Kathaperumal, Mark D. Losego, Rao Tummala, Madhavan Swaminathan

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Heterogeneous integration of chiplets requires high-density fine line/space (L/S) interconnections to enable system scaling. However, as Moore's law for transistors slows down, the dies are disaggregated based on their specific functions thereby increasing the package sizes to accommodate various dies of different functionalities. To enable a high-density redistribution layer (RDL) in the package, this paper studies the fine-line patterning capability of maskless aligner systems. The paper evaluates the smallest achievable feature size on four different thicknesses namely 5 µm, 7 µm, 25 µ m and 80 µ m of dry film photoresists (PRs). This work also investigates the effect of dose and defocus on photoresists. Two of the photoresists (5 µm and 80 µm) are positive tone and the other 2 are negative tone. The finest L/S obtained was 1.5µm with the positive tone 5 µ m dry film photoresist, 3 µ m using the 7 µ m negative tone and 20 µm using the 80 µm positive tone resist. This paper also investigates the throughput of the maskless aligners based on the dose, exposure area, and pattern density.

Original languageEnglish (US)
Title of host publicationProceedings - IEEE 73rd Electronic Components and Technology Conference, ECTC 2023
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages5
ISBN (Electronic)9798350334982
StatePublished - 2023
Event73rd IEEE Electronic Components and Technology Conference, ECTC 2023 - Orlando, United States
Duration: May 30 2023Jun 2 2023

Publication series

NameProceedings - Electronic Components and Technology Conference
ISSN (Print)0569-5503


Conference73rd IEEE Electronic Components and Technology Conference, ECTC 2023
Country/TerritoryUnited States

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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