Bond Pad Test Structure for Substrate Shift Detection
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Solution Overview
Problem
Existing methods for bonding integrated circuit substrates suffer from misalignment errors due to inaccuracies in the pick-and-place process, leading to increased resistance, poor bond strength, and potential connection failures, which are difficult to detect using optical inspection.
Innovation Solution
A bonding test structure with central and peripheral bond pads is used to detect substrate misalignment through electrical testing, measuring voltage thresholds to determine offset and rotation, independent of substrate surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical inspection is used to detect misalignment, then detection can be performed, but detection accuracy is insufficient and detection speed is slow
Solution Approach 1:
The patent replaces optical inspection with an electrical measurement system. Bond pads are configured as test structures where voltage measurements detect misalignment. A voltage source applies voltage to reference bond pads, and voltage measurements at corresponding bond pads indicate misalignment through voltage threshold comparisons, eliminating the need for optical systems.
Solution Approach 2:
The patent creates electrical copies of the bonding interface geometry through the bond pad arrangement. The reference bond pads and corresponding bond pads form an electrical replica of the bonding geometry, where voltage distribution patterns copy the physical misalignment state, enabling indirect detection through electrical measurements rather than direct optical observation.
2Productivity
If misalignment is not detected, then production continues, but bond strength deteriorates and connection failures occur
Solution Approach 1:
The patent performs misalignment detection before final bonding operations. The test structure is prepared in advance with reference bond pads and corresponding bond pads configured to detect misalignment. Voltage measurements are taken prior to completing the bonding process, allowing corrective actions to be taken before defective bonds are formed, thus preventing reliability issues while maintaining production flow.
Solution Approach 2:
The patent implements a feedback mechanism where voltage measurements provide real-time information about misalignment status. The voltage threshold comparison generates feedback signals that indicate whether misalignment exceeds acceptable limits, enabling corrective actions to be taken based on actual measured conditions, thus preventing bond strength deterioration while maintaining production continuity.
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 provides faster and more accurate detection of substrate misalignment, improving production yields by allowing for corrective actions in the pick-and-place process.
Implementation Method 1
measuring voltage thresholds to determine offset and rotation
Data Source
AI summary
Some embodiments relate to an integrated device, including: a first interconnect structure on a first substrate; a first central bond pad coupled to the first interconnect structure; a first peripheral bond pad on a first side of the first central bond pad separated by a first distance; a second peripheral bond pad on a second side of the first central bond pad and separated by a second distance substantially equal to the first distance; a second interconnect structure on a second substrate; a first overlying bond pad coupled to the second interconnect structure and bonded to the first central bond pad; and a plurality of exposed bond pads respectively coupled to the first central bond pad, the first peripheral bond pad, the second peripheral bond pad, and the first overlying bond pad, wherein the plurality of exposed bond pads extend past outer sidewalls of the second substrate.