Chiplet Bonding Pad Layout for Wafer-Level Signal Probing
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Solution Overview
Problem
In chiplet systems, the small size of bonding pads on integrated circuits (ICs) makes it difficult to probe and measure signals during wafer-level testing, which can lead to functional issues before packaging.
Innovation Solution
The implementation of two types of bonding pads - system pads for connections within the package and test pads for wafer-level testing - where test pads have a larger area for probing and are electrically connected to system pads, allowing for internal signal transmission and measurement without external probing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If bonding pads are made small to support large amount of connections, then connection density is improved, but probeability and signal measurability during wafer-level testing deteriorate
Solution Approach 1:
The bonding pads are segmented into two distinct types: first type bonding pads (small area) for system connections and second type bonding pads (large area) for testing. This segmentation allows each type to be optimized for its specific function, resolving the contradiction between connection density and probeability.
Solution Approach 2:
The second type bonding pad acts as an intermediary element that enables signal measurement. It is electrically connected to the first type bonding pad through the integrated circuit, allowing test signals to be transmitted through the small first type pad via the larger second type pad for easy probing and measurement.
2Productivity
If bonding pads are made small to increase connection density, then system performance is improved, but ease of probing during testing deteriorates
Solution Approach 1:
The bonding pad structure is segmented into first type (small, for connections) and second type (large, for probing). This allows the system to maintain high connection density through small first type pads while providing large second type pads for easy probing operations.
Solution Approach 2:
The second type bonding pad serves as a test copy or surrogate for the first type bonding pad. By electrically connecting the large second type pad to the small first type pad through the IC, we can probe the second type pad to indirectly test the first type pad's functionality without directly probing the small first type pad.
3Adaptability or versatility
If all bonding pads are used for external connections, then system connectivity is improved, but testability before packaging deteriorates
Solution Approach 1:
The bonding pads are divided into first type (for external connections in chiplet systems) and second type (for wafer-level testing). This segmentation ensures that while all first type pads are used for system connectivity, additional second type pads are available specifically for reliable pre-packaging testing.
Solution Approach 2:
The second type bonding pads are prepared in advance specifically for testing purposes. They are electrically connected to the first type bonding pads through the integrated circuit, enabling preliminary testing of connection functionality before the actual packaging process, thereby improving reliability.
Data Source
AI summary
Systems, methods, circuits, and apparatus including computer-readable mediums for testing bonding pads in multi-die packages, e.g., chiplet systems. An example integrated circuit device includes an integrated circuit, first type bonding pads and second type bonding pads. Each of the first type bonding pads is electrically connected to the integrated circuit and configured to be electrically connected to a corresponding external integrated circuit device. Each of the second type bonding pads is configured to have no electrical connection with the corresponding external integrated circuit device. Each of the first type bonding pads is configured to be electrically connected to a corresponding one of the second type bonding pads. A number of the first type bonding pads can be larger than a number of the second type bonding pads. Each of the second type bonding pads can have a larger pad area for probing than each of the first type bonding pads.