High Metal Bump Packaging on Ultra-Thin Semiconductor Substrates
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Solution Overview
Problem
Existing semiconductor packages require thicker substrates (larger than 50 microns) to accommodate high metal bumps (at least 40 microns) without generating wafer cracks during back-side grinding, which limits the miniaturization of semiconductor devices.
Innovation Solution
A semiconductor package with a thin semiconductor substrate thickness ranging from 15 to 35 microns, combined with metal bumps of at least 35 microns height, and a metal layer thickness up to 30 microns, which allows for the formation of high metal bumps without increasing the substrate thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate thickness is increased to accommodate high metal bumps, then the reliability is improved by avoiding wafer cracks, but the device size increases and miniaturization is limited
Solution Approach 1:
The substrate is segmented into a thin active layer (15-35 microns) and a separate thick carrier substrate. The active layer is thinned to achieve miniaturization while the carrier substrate provides mechanical support to prevent wafer cracks during back-side grinding and metal bump formation. This segmentation allows the thin substrate to be processed with the support of a thicker carrier structure.
Solution Approach 2:
A carrier substrate acts as an intermediary between the thin semiconductor substrate and the processing equipment. The carrier provides mechanical strength during back-side grinding and metal bump formation, enabling the thin substrate (15-35 microns) to withstand processing without cracking while maintaining its thin profile for miniaturization.
2Manufacturing precision
If the substrate thickness is increased to support high metal bumps, then the manufacturing precision is improved by preventing wafer cracks, but the device complexity increases
Solution Approach 1:
The device is segmented into a thin active semiconductor layer (15-35 microns) mounted on a separate carrier substrate. This segmentation allows the active layer to maintain manufacturing precision for high metal bumps while the carrier handles mechanical support functions, simplifying the overall structure compared to a single thick substrate.
Solution Approach 2:
The mechanical support function is extracted from the semiconductor substrate itself and transferred to a separate carrier substrate. This allows the semiconductor layer to be optimized for thinness (15-35 microns) and electrical performance while the carrier provides the necessary mechanical strength for manufacturing precision during metal bump formation.
Data Source
AI summary
A semiconductor package comprises a semiconductor substrate, a plurality of contact pads, a plurality of metal bumps, a metal layer, and a molding encapsulation. A thickness of the semiconductor substrate is less than 35 microns. A first method comprises the steps of providing a device wafer; attaching a first carrier; applying a thinning process; forming a metal layer; applying a first tape; removing the first carrier; applying a first singulation process; removing the first tape; attaching a second carrier; forming a molding encapsulation; removing the second carrier; forming a plurality of metal bumps; applying a second tape; and applying a singulation process and removing the second tape. A second method comprises the steps of providing a device wafer; attaching a carrier; applying a thinning process; forming a metal layer; forming a molding encapsulation; removing the carrier; forming a plurality of metal bumps; and applying a singulation process.