Semiconductor Redistribution Layer via Selective Thermal Fusing
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Solution Overview
Problem
Current methods for forming a redistribution layer on semiconductor die are cumbersome and add numerous process steps and expense to the fabrication process, limiting the efficiency and cost-effectiveness of semiconductor device packaging.
Innovation Solution
A tape assembly with a b-stage adhesive film and conductive material is applied to the semiconductor wafer, and focused heat is used to selectively fuse the adhesive layer to the wafer surface, creating a redistribution layer pattern that relocates die bond pads from one edge to another, streamlining the process by reducing the number of steps and increasing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional photolithography methods are used to form a redistribution layer, then the bond pads can be relocated to different edges of the die, but the process becomes cumbersome with numerous fabrication steps and increased expense
Solution Approach 1:
The redistribution layer formation process is segmented into distinct functional layers: a carrier substrate, an adhesive layer, and a conductive trace layer. This segmentation allows each layer to be optimized and processed independently, then combined through lamination, thereby simplifying the overall fabrication process while maintaining the capability to relocate bond pads to different edges of the die
Solution Approach 2:
The conductive traces and adhesive layer are prepared and patterned on the carrier substrate before being attached to the semiconductor die. This preliminary action allows the redistribution layer to be pre-fabricated with precise trace patterns, eliminating the need for complex step-by-step formation processes on the die itself and enabling flexible bond pad relocation
2Area of stationary object
If more bond pads are placed along two adjacent sides of the die to utilize space, then space utilization improves, but wire bond connections cannot be established on all edges due to substrate real estate limitations
Solution Approach 1:
The redistribution layer acts as an intermediary between the original bond pads on the die and the wire bonds on the substrate. It provides additional bond pad locations on edges of the die that would otherwise not be accessible for wire bonding, enabling space utilization improvement without compromising wire bond connection capability
Solution Approach 2:
The redistribution layer extends the bond pad connectivity into a new dimensional configuration by adding bond pads on previously unusable edges of the die. This allows wire bonds to be routed from multiple edges of the substrate to the die, effectively utilizing the three-dimensional space available in the package rather than being constrained to a single plane
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method simplifies the formation of a redistribution layer, reducing fabrication costs and complexity while enabling efficient relocation of bond pads, thereby addressing space constraints in semiconductor packages and enhancing the integration of semiconductor die into compact devices.
Implementation Method 1
focused heat is used to selectively fuse the adhesive layer to the wafer surface
Data Source
AI summary
A semiconductor device having a redistribution layer, and methods of forming same, are disclosed. After fabrication of semiconductor die on a wafer, a tape assembly is applied onto a surface of the wafer, in contact with the surfaces of each semiconductor die on the wafer. The tape assembly includes a backgrind tape as a base layer, and a film assembly adhered to the backgrind tape. The film assembly in turn includes an adhesive film on which is deposited a thin layer of conductive material. The redistribution layer pattern is traced into the tape assembly, using for example a laser. Thereafter, the unheated portions of the tape assembly may be removed, leaving the heated redistribution layer pattern on each semiconductor die.