Conductive Pad Grain Structure for Low-Temperature Direct Bonding
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Solution Overview
Problem
Existing methods for forming conductive pads in microelectronic elements are limited in efficiency and effectiveness, particularly in achieving direct metal bonding without adhesives and with minimal thermal budget consumption.
Innovation Solution
The development of methods to engineer metallic grain structures with a 111 crystal plane orientation for conductive pads, allowing for direct hybrid bonding techniques that enable conductive pads to form metal-to-metal bonds at reduced temperatures and with lower thermal budgets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional methods are used to form conductive pads, then the manufacturing process is simpler, but the thermal budget required for annealing is high and direct metal bonding is difficult to achieve
Solution Approach 1:
The patent applies parameter changes by modifying the crystallographic orientation of metal grains in the conductive pad to have a predominant <111> orientation. This specific parameter change in grain structure enables direct metal bonding at reduced annealing temperatures (below 200°C), resolving the contradiction between achieving low-temperature bonding and maintaining manufacturing simplicity. The engineered grain structure is the key parameter change that facilitates the technical breakthrough.
2Reliability
If conventional conductive pads are used, then the bonding process is simpler, but direct metal bonding without adhesives cannot be achieved
Solution Approach 1:
The patent changes the crystallographic parameter of the metal grains to achieve predominant <111> orientation, which enables direct metal-to-metal bonding without adhesives. This parameter change in grain structure creates the necessary conditions for reliable direct bonding, resolving the contradiction between achieving strong bonding and avoiding process complexity. The engineered grain orientation is the critical parameter that enables adhesive-free bonding.
3Use of energy by stationary object
If conventional annealing processes are used, then the process is simpler, but the thermal budget consumption is high
Solution Approach 1:
The patent applies preliminary action by pre-engineering the metal grain structure to have predominant <111> orientation before the bonding process. This preliminary structuring of the grains reduces the subsequent thermal budget required for annealing, as the favorable grain orientation is already in place. This resolves the contradiction between reducing thermal energy consumption and achieving precise grain structure control, as the precision work is done in advance during metal formation.
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 facilitates high-density direct bonding of conductive pads with improved electrical and mechanical interconnects, reducing the thermal budget required for annealing and enabling more efficient manufacturing processes.
Implementation Method 1
cold working the upper side of the conductive material to modify a grain structure of the conductive material
Implementation Method 2
The element and the second element can be annealed to facilitate direct metal bonding between the conductive pad and the second conductive pad
Data Source
AI summary
An element is disclosed. The element can include a non-conductive structure having a non-conductive bonding surface, a cavity at least partially extending through a portion of a thickness of the non-conductive structure from the non-conductive bonding surface, and a conductive pad disposed in the cavity. The cavity has a bottom side and a sidewall. The conductive pad has a bonding surface and a back side opposite the bonding surface. An average size of the grains at the bonding surface is smaller than an average size of the grains adjacent the bottom side of the cavity. The conductive pad can include a crystal structure with grains oriented along a 111 crystal plane. The element can be bonded to another element to form a bonded structure. The element and the other element can be directly bonded to one another without an intervening adhesive.