Optimization of laser release process for throughput enhancement of fan-out wafer-level packaging

Chia Hsin Lee, Jay Su, Xiao Liu, Qi Wu, Jim Wein Lin, Puru Lin, Cheng Ta Ko, Yu Hua Chen, Wen Wei Shen, Tzu Ying Kou, Shin Yi Huang, Yu Min Lin, Kuan-Neng Chen, Ang Ying Lin

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

8 Scopus citations


Fan-out wafer-level-packaging (FOWLP) technology has been developed with various advantages, such as smaller form factor, lower cost, and simplified supply chain for heterogeneous integration. There have been several process schemes like chip-first or chip-last FOWLP integration discussed widely in conferences in recent years. One process in all of these process schemes has in common is the use of a temporary carrier for subsequent redistribution layer (RDL) formation, chip stacking and molding processes. Although the separation of a temporary carrier from the reconstituted wafer could be achieved without significant hurdles, there were few studies addressing optimization of carrier separation for throughput enhancement. Thus, this paper is designed to address the needs in optimizing carrier separation process based upon laser ablation technology. Two phases of experiments were designed to select the appropriate laser release layer and define optimal laser settings. The first experiment was used to evaluate correlation of the laser absorption, laser energy, and spot pitch versus completeness of laser ablation. The second experiment included RDL-first FOWLP integration. At first, 300-mm glass carriers (1000 μm thick) with coefficient of thermal expansion of 8 ppm/°C were treated by selected laser release layers. After deposition of 0.05-μm Ti/0.15 μm Cu on the glass carrier, passivation of around 8 μm was coated and patterned by lithography for electroplating Cu interconnections with a density of approximately 10% of the surface area. Subsequently, die bonding, build-up layers, or molding compound were applied on top to form a 200-μm reconstituted wafer. The reconstituted wafer was then separated from the glass carrier through a laser ablation process using a 355-nm laser to determine optimal throughput. Experiments to study correlation of laser release layer with laser settings along with a demonstration of full RDL-first FOWLP integration are discussed thoroughly to address the need of throughput enhancement, which could serve as cornerstone for realizing cost-effective RDL-first FOWLP.

Original languageEnglish
Title of host publicationProceedings - IEEE 68th Electronic Components and Technology Conference, ECTC 2018
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages6
ISBN (Print)9781538649985
StatePublished - 7 Aug 2018
Event68th IEEE Electronic Components and Technology Conference, ECTC 2018 - San Diego, United States
Duration: 29 May 20181 Jun 2018

Publication series

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


Conference68th IEEE Electronic Components and Technology Conference, ECTC 2018
CountryUnited States
CitySan Diego


  • Fan out wafer level packaging
  • Laser release
  • RDL first

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