Piezoelectric Bond Pad Heating for Low-Temperature Hybrid Bonding
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Solution Overview
Problem
Existing semiconductor packages face challenges with increased height and signal propagation delays due to bond wires, and the post bond annealing process can degrade electrical characteristics of semiconductor components.
Innovation Solution
The use of piezoelectric materials to generate localized thermal energy for CTE-based expansion of conductive components, allowing for metallurgical bonding at a lower temperature or without post bond annealing, thereby reducing the thermal budget and avoiding adverse effects on integrated circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If post bond annealing is performed at high temperature to achieve metallurgical bonding, then bonding strength is improved, but electrical characteristics of semiconductor components are degraded
Solution Approach 1:
The patent applies local quality by providing thermal energy locally at the bonding interface through piezoelectric materials rather than heating the entire semiconductor die uniformly. This localized heating approach allows metallurgical bonding to occur at the bond pad region while keeping the rest of the semiconductor components at lower temperatures, thus achieving strong bonding without degrading the electrical characteristics of sensitive circuitry.
Solution Approach 2:
The patent changes the temperature parameter distribution across the semiconductor device by using piezoelectric materials to generate heat only where needed. Instead of uniform high-temperature annealing, the system creates a temperature gradient with high temperature localized at the bonding interface and lower temperature elsewhere, enabling bonding strength improvement while preserving component reliability.
2Reliability
If bond wires are used to connect bond pads, then electrical connection is achieved, but package height is increased and signal propagation delays are introduced
Solution Approach 1:
The patent extracts and eliminates the bond wire component from the packaging structure by implementing direct hybrid bonding between dies. The bond pads are brought into direct contact through precise alignment and bonding processes, removing the intermediate bond wire connection. This extraction reduces package height and eliminates the signal propagation delays associated with wire length while maintaining reliable electrical connection.
3Ease of manufacture
If shingle stacking or zig-zag patterns are used to arrange semiconductor dies, then accessibility for bonding is improved, but overall package height is increased
Solution Approach 1:
The patent merges the bonding process with the stacking process by implementing direct hybrid bonding at the die interface during assembly. Instead of requiring complex shingle stacking or zig-zag patterns to access bond pads, the methodology enables direct face-to-face bonding between adjacent dies in a compact vertical stack, achieving both manufacturing ease and minimal package height.
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 approach enables efficient hybrid bonding with reduced risk of degrading semiconductor components, while minimizing the overall height of semiconductor packages and improving signal propagation.
Implementation Method 1
exposing the piezoelectric material to an externally-applied electric field to supply thermal energy to at least the first bond pad
Implementation Method 2
supply thermal energy...such that at least the first top surface of the first bond pad expands toward the bonding interface
Data Source
AI summary
A semiconductor die is provided, comprising a semiconductor substrate; a dielectric layer over the semiconductor substrate; a bond pad in the dielectric layer, the bond pad including an exposed top surface that is recessed with respect to a surface of the dielectric layer opposite to the semiconductor substrate; and a region of piezoelectric material in the dielectric layer, wherein the region is located proximate to the bond pad to supply thermal energy to the bond pad in response to exposing the piezoelectric material to an externally-applied field.