The growing demand for heterogeneous integration is driven by the 5G market. This includes smartphones, data centers, servers, high-performance computing (HPC), artificial intelligence (AI) and internet of things (IoT) applications. Next-generation packaging technologies require tighter overlay to accommodate larger package sizes with fine-pitch chip interconnects on large-format flexible panels. Heterogeneous integration enables device performance gains by combining multiple silicon nodes and designs inside one package. The package size is expected to grow significantly, increasing to 75mm x 75mm and 150mm x 150mm, within the next few years. For these requirements, an extremely large exposure field fine-resolution lithography solution was proposed to enable packages well over 250mm x 250mm without the need for image stitching, while exceeding the overlay and critical uniformity requirements for these packages.
One of the challenges of extremely large exposure field fine-resolution lithography is to achieve an aggressive overlay number. Formation changes experienced by the panel as a result of thermo, high-pressure and other fan-out processes shift the design location from nominal coordinates; this causes inaccurate overlay and low-overlay yield in the lithography process. Addressing this critical lithography challenge becomes an important task in heterogeneous integration.
In this paper, a 515mm x 510mm Ajinomoto build-up film (ABF)+copper clad laminate (CCL) substrate is selected as the test vehicle. We will analyze the pattern distortion of an ABF+CCL substrate to understand the distribution of translation, rotation, scale, magnification, trap, orthogonality and other errors in the substrate, and then use extremely large exposure field fine-resolution lithography to address the pattern distortion of the substrate. This demonstration will provide an analysis of panel distortion and detail how the extremely large exposure field fine-resolution lithography solution addresses panel distortion to achieve an aggressive overlay number.