| dc.description.abstract | The ongoing technological advances in the field of flexible electronics using ultra-thin chips due to their extraordinary properties, offer lightweight and adaptable electronic systems for multiple applications. These properties can be of great use in the detectors in the experiments at CERN, for instance, the ALICE detector use silicon sensors that provide particle identification using the ultra-thin ALPIDE chip (~50 μm). These sensors need to be adjusted to the cylindrical layers closer to the beam pipe to increase efficiency and precision. However, in the ALPIDE chip, the Silicon layer is the most brittle part and can cause the chip to fracture when bent. Embedding these chips can enhance their mechanical robustness and reliability.
This work covers methods for thinning and embedding silicon dies, as well as a literature review on common materials used in this process. Additionally, a method of embedding a Monolithic Active Pixel Sensor (MAPS) into polyimide films using the Chip-Film Patch process and a via-opening technique using Reactive Ion etching are presented. A first series of dummy samples that helped to develop the embedding method have been produced and a proper photoresist mask for the polyimide etching was selected and successfully tested.
Two Ultra-thin ALPIDE chips have been embedded between polyimide films using the presented method with a final thickness of 77 μm. One embedded chip was electrically tested and showed positive signs of a working chip after being exposed to the complete process. Even though the proposed method was tested at a chip level, since it uses widely adopted manufacturing techniques, it can be scaled and be a good candidate for large-volume production. | |