Modern integrated circuits (ICs) increasingly rely on advanced chip packaging technologies to move beyond the limitations of single-die packages. These techniques are crucial for integrating multiple diverse chips and chiplets into single, powerful devices, enabling significant performance gains often coupled with relative cost reduction. Among these, Fan-Out Wafer-Level Packaging (FOWLP) has emerged as a critical approach. Unlike traditional packaging that keeps interconnects within the original die footprint, FOWLP fans out the connections to a larger area, allowing for higher I/O density and the integration of multiple dies side-by-side on a reconstructed wafer or panel.
Other important advanced packaging strategies and technologies enabling high-density integration include 2.5D and 3D-ICs (which focus on vertical stacking of dies, sometimes using Interposers with Through-Silicon Vias (TSVs) for vertical communication), System-in-Package (SiP) (a broader term encompassing the integration of various functional components), and the overarching concepts of Heterogeneous Integration and Chiplet Integration. A common element across many of these advanced packages is the need for high-density Redistribution Layers (RDLs) to reroute signals and connect the fine-pitch I/O pads on the dies to coarser connections on the package substrate or circuit board. Ultimately, the final package encapsulates these integrated ICs, providing necessary mechanical support and the essential electrical connections to the circuit board.
The Challenge: Precision on Imperfect Substrates
As the semiconductor industry pushes towards ultra-high density fan-out packaging, feature sizes are shrinking, often approaching 2 µm and below. This miniaturization encounters intrinsic sources of variation that challenge manufacturing yield. Common issues include:
- Die Shift: Individual dies may shift from their intended positions during placement and bonding.
- Substrate Warpage & Distortion: Wafers and panels can warp or distort during processing steps.
- Surface Topography: Uneven surfaces create challenges for maintaining focus and resolution.
Producing high-yield packages under these conditions demands depositing high-quality, high-resolution features precisely where they need to be, despite these inherent imperfections in the substrate and die placement. This requires structuring various materials like silicon (for TSVs), polymers, ceramics, and metals with exceptional accuracy to implement the necessary fan-out and mapping from the IC contact pads.
The Solution: Flexibility and Precision with Maskless Lithography
This is where the power of maskless lithography becomes evident. Heidelberg Instruments’ direct writing technology offers the critical flexibility needed to address these challenges head-on. Unlike traditional mask-based approaches, maskless systems can:
- Apply Individual Corrections: Incorporate customized corrections for die shift, substrate distortion, and warpage based on the specific measurements and characteristics of each individual substrate.
- Adapt to Topography: Utilize advanced auto-focus mechanisms to maintain high resolution even on non-planar surfaces.
- Enable Rapid Prototyping & Adjustment: Allow for quick design changes without the cost and lead time associated with new photomasks.
Heidelberg Instruments’ Expertise
Heidelberg Instruments’ MLA 300 and VPG+ systems are specifically designed for demanding advanced packaging applications. The MLA 300, in particular, offers exceptional flexibility, capable of exposing virtually any type of flat substrate, including glass, silicon, ceramics, and various organic materials. Our systems deliver:
- High Throughput: Ensuring cost-effective production.
- Automatic Distortion Compensation: Directly addressing die shift and substrate warping issues.
- Dynamic Autofocus: Maintaining optimal resolution across challenging topographies.
With 40 years of experience rooted in industrial photomask production, Heidelberg Instruments possesses the deep know-how required to deliver reproducible, high-quality exposures, even on the imperfect substrates common in advanced packaging. Our maskless lithography solutions provide the adaptability and precision necessary to achieve high yields and enable the next generation of integrated electronic systems.
Find out more about how our systems can solve your advanced packaging challenges by visiting their product pages listed below.
