Cu Alloy Bonding Wire Crystal Orientation for Low-Defect LSI Bonding
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Solution Overview
Problem
Bare Cu wires experience a high occurrence rate of peelings and bonding defects, particularly when wedge-bonded to Pd-PPF electrodes, which is not effectively addressed by existing techniques, and face challenges in low-temperature bonding and ball bond area longevity in high-density LSI applications.
Innovation Solution
A Cu alloy bonding wire with a specific crystal orientation abundance ratio of 25% to 70% having an angular difference of 15 degrees or less from the direction perpendicular to the wire center axis, optionally containing Ni, Pd, Pt, Au, P, In, Ga, Ge, and Ag, to improve bonding characteristics and reduce peelings and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bare Cu wires are used to reduce cost, then cost is reduced, but the occurrence rate of peelings and bonding defects increases
Solution Approach 1:
The invention changes the material parameters by adding specific alloying elements (Ni: 0.01-3.00 mass%, Pd: 0.01-3.00 mass%, Pt: 0.01-3.00 mass%, Au: 0.01-3.00 mass%) to the copper wire, which modifies the surface properties and oxidation behavior. This parameter change reduces peelings and bonding defects while maintaining cost effectiveness compared to coated wires
Solution Approach 2:
The invention creates a composite material structure by combining copper with multiple alloying elements that have different properties. The synergistic effect of these elements (Ni for strength, Pd for oxidation resistance, Pt for stability, Au for bonding performance) produces a wire that exhibits reduced peelings and bonding defects while remaining cost-effective
2Productivity
If wire diameter is reduced for high-density LSI applications, then density is improved, but the occurrence rate of peelings increases
Solution Approach 1:
The invention changes the material composition parameters by adding alloying elements in specific quantities (total 0.01-6.00 mass%). This parameter modification improves the mechanical properties and surface characteristics of the wire, enabling it to maintain low peeling occurrence even at reduced diameters suitable for high-density LSI applications
3Temperature
If bonding temperature is reduced for low-temperature bonding applications, then damage to sensitive components is reduced, but bonding strength decreases
Solution Approach 1:
The invention changes the chemical composition parameters by incorporating alloying elements that lower the melting point and improve ductility. This allows the wire to achieve adequate bonding strength at reduced temperatures, protecting sensitive components while maintaining connection integrity
Solution Approach 2:
The composite material structure with multiple alloying elements creates a eutectic system that facilitates bonding at lower temperatures. The combined effects of Ni, Pd, Pt, and Au modify the thermal and mechanical properties, enabling low-temperature bonding with sufficient strength
4Reliability
If alloying elements are added to Cu wire, then bonding characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The invention specifies precise parameter ranges for alloying elements (Ni: 0.01-3.00 mass%, Pd: 0.01-3.00 mass%, Pt: 0.01-3.00 mass%, Au: 0.01-3.00 mass%) that can be achieved through standard metallurgical processes. These parameter specifications improve bonding characteristics while remaining compatible with existing manufacturing capabilities
Solution Approach 2:
The invention focuses the alloying elements primarily at the wire surface and near-surface regions, where they most effectively influence bonding characteristics. This localized distribution achieves the desired bonding performance with minimal impact on bulk material properties and manufacturing complexity
Data Source
Figure 1A~1B
Figure 2
AI summary
The present invention provides a Cu alloy bonding wire for a semiconductor device, where the bonding wire can satisfy requirements of high-density LSI applications. In the Cu alloy bonding wire for a semiconductor device, the abundance ratio of a crystal orientation <110> having an angular difference of 15 degrees or less from a direction perpendicular to one plane including a wire center axis to crystal orientations on a wire surface is 25% or more and 70% or less in average area percentage.