Micro Copper Bonding Pads With [111] Grain Orientation
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Solution Overview
Problem
Conventional tin contacts and copper bonding structures in micro-scale or nano-scale electronic devices compromise the mechanical characteristics and reliability of electrical connections, necessitating a better electrical connection structure and forming method.
Innovation Solution
The electrical connection employs [111]-oriented copper grains in bonding pads with a maximum width of 8 microns or less, formed using periodic reverse electroplating, where the length covered by [111]-oriented copper grains accounts for 60% or more of the interface width, enhancing mechanical strength and electrical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tin contacts and copper bonding structures are used in micro-scale or nano-scale electronic devices, then electrical connection can be achieved, but the mechanical characteristics and reliability of the electrical connection deteriorate
Solution Approach 1:
The patent changes the crystallographic orientation parameter of copper grains from conventional random or other orientations to specifically [111]-oriented grains. This parameter change in grain orientation fundamentally alters the mechanical properties of the copper bonding pad, enabling it to maintain excellent mechanical strength and reliability even at micro-scale dimensions (≤8 microns) where conventional copper structures would fail.
Solution Approach 2:
The patent creates a composite structure by combining [111]-oriented copper grains with silicon dioxide, forming a heterojunction interface. This composite material approach leverages the complementary properties of copper (electrical conductivity) and silicon dioxide (mechanical support and insulation), resulting in a bonding structure that simultaneously achieves excellent electrical performance and mechanical characteristics.
2Length of moving object
If bonding pad size is reduced to micro-scale or nano-scale, then device miniaturization is achieved, but the quality and reliability of bonding deteriorates
Solution Approach 1:
By changing the grain orientation parameter to [111], the patent enables copper bonding pads to maintain high reliability at reduced sizes. The [111]-oriented grains provide enhanced mechanical strength and stability that compensates for the reduced cross-sectional area, allowing bonding pads with maximum width ≤8 microns to achieve bonding quality comparable to or exceeding conventional larger structures.
Solution Approach 2:
The patent applies local quality enhancement by creating a specific [111]-oriented grain structure within the bonding pad region, while other parts of the device may have different structures. This localized optimization of grain orientation in the bonding pad area provides targeted improvement in mechanical properties and bonding reliability without requiring changes to the entire device structure.
3Strength
If [111]-oriented copper grains are used in bonding pads with maximum width of 8 microns or less, then mechanical strength and reliability are improved, but the complexity of forming such structured grains increases
Solution Approach 1:
The patent employs preliminary action by preparing the substrate and controlling nucleation conditions before copper deposition, so that [111]-oriented grains are formed during the electroplating process itself. This preliminary preparation of surface conditions and deposition parameters enables the formation of desired grain structure during manufacturing, avoiding the need for complex post-processing steps to induce grain orientation.
Solution Approach 2:
The patent replaces mechanical grain alignment methods (such as rolling or forging) with an electrochemical approach using periodic reverse electroplating. This substitution of the grain formation mechanism from mechanical to electrochemical processes enables precise control of grain orientation through electrical parameters rather than mechanical forces, simplifying the overall manufacturing process for micro-scale bonding pads.
4Manufacturing precision
If periodic reverse electroplating is used to form bonding pads with controlled grain orientation, then manufacturing precision of grain structure is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies periodic action through reverse electroplating, where the electroplating process is cycled between deposition and dissolution phases. This periodic cycling allows precise control of grain nucleation and growth by repeatedly forming and refining the grain structure, achieving high manufacturing precision of [111]-oriented grains. The periodic nature of the process enables fine-tuning of grain orientation through parameter adjustment during each cycle.
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 improves the mechanical strength and reliability of micro-scale or nano-scale electrical connections by reducing thermal budget and promoting heterojunction of copper/silicon dioxide at low temperatures, while minimizing the impact of sidewall effects on grain orientation.
Implementation Method 1
forming a first bonding pad by using a first periodic reverse electroplating, in which the first bonding pad includes a plurality of [111]-oriented copper grains
Implementation Method 2
providing a pulse current to the first driving substrate, in which the pulse current comprises a plurality of pulse periods each comprising a forward current and a backward current
Data Source
AI summary
An electrical connection includes a first driving substrate, a first adhesive layer, a first bonding pad a first bonding pad and a second bonding pad. The first driving substrate includes a first substrate and a first dielectric layer on the first substrate. The first adhesive layer is at a sidewall of the first dielectric layer of the first driving substrate. The first bonding pad is on the first substrate of the first driving substrate and in contact with the first adhesive layer, and the first bonding pad includes a plurality of grains, the grains are connected with each other, the grains include [111]-oriented copper grains, and a maximum width of the first bonding pad is equal to or less than 8 microns. The second bonding pad is on the first bonding pad.