Direct Bonding Interconnects for RF Routing and Passive Integration
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Solution Overview
Problem
In multi-die IC packages, the use of top metal layers for die-to-die bonding limits the area available for radio frequency (RF) components and high-power/high-speed routing due to reduced routing space, as these layers are utilized for bonding rather than signal routing.
Innovation Solution
Implementing elongated conductive structures at the bonding interface, which are substantially overlapping, providing larger cross-sectional areas for routing paths and allowing these structures to be used for forming RF passive devices within or partially within the bonding interface, such as inductors, transformers, or filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the top metal layers are used for die-to-die bonding, then the bonding strength and electrical connection between dies are improved, but the routing area within each die is reduced
Solution Approach 1:
The patent extends routing paths into the vertical dimension by creating elongated conductive structures that penetrate through the bonding interface from one die into the other die. This transforms a 2D routing problem into a 3D solution, allowing routing to occur in the depth direction rather than only in the planar surface area.
Solution Approach 2:
The conductive structures are nested within the bonding interface itself, utilizing the bonding layer as a host for embedded routing paths. The routing conductors are integrated within the bonding structure, effectively nesting the routing function inside the bonding interface rather than requiring separate dedicated routing layers.
2Ease of manufacture
If the top thick metal layers are used for die bonding, then the bonding pads are provided for interconnecting dies, but the area available for RF components and high-power routing is reduced
Solution Approach 1:
The bonding interface is designed to serve multiple functions simultaneously: it provides bonding pads for electrical connection, creates elongated conductive structures for high-power routing, and enables integration of RF passive devices. This multi-functional design eliminates the need to dedicate separate areas for each function.
Solution Approach 2:
The patent merges the bonding function with the routing function by creating conductive structures that serve both as bonding interconnects and as routing paths for high-power and RF signals. The bonding interface itself becomes the routing medium, combining previously separate functions into a unified structure.
3Reliability
If standard bonding pads are used at the bonding interface, then die-to-die connection is achieved, but larger cross-sectional areas for routing paths cannot be provided
Solution Approach 1:
The routing paths transition from 2D planar conductors to 3D elongated structures that extend vertically through the bonding interface. This dimensional change increases the cross-sectional area available for current flow without increasing the planar footprint at the bonding surface.
Solution Approach 2:
The patent changes the geometric parameters of the conductive structures by creating elongated shapes with increased length and cross-sectional area. The conductive structures have dimensions optimized for both bonding contact area and routing current capacity, with lengths extending beyond standard pad dimensions.
Data Source
AI summary
Described herein are integrated circuit devices that include conductive structures formed by direct bonding of different components, e.g., direct bonding of two dies, or of a die to a wafer. The conductive structures are formed from a top metallization layer of each of the components. For example, elongated conductive structures at the top metallization layer may be patterned and bonded to form large interconnects for high-frequency and/or high-power signals. In another example, the bonded conductive structures may form radio frequency passive devices, such as inductors or transformers.