Copper Alloy Sputter Seed Layer for High Density Interconnects
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Solution Overview
Problem
Current package substrates face challenges in achieving high density interconnects due to limitations in via size, line/space pitch, and material properties, leading to issues like delamination, copper loss, and electromigration, especially in very high density routing applications.
Innovation Solution
A sputtered copper alloy seed layer is used, which acts as an electromigration barrier, enables thinner seed layer deposition, and provides strong adhesion to dielectric and photoresist layers, allowing for narrower traces and thinner dielectric layers, and is formulated with elements like nickel, aluminum, tungsten, cobalt, manganese, or ruthenium to enhance adhesion and electromigration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional seed layers are used, then standard interconnect density is achieved, but delamination and copper loss occur in high density routing
Solution Approach 1:
The patent uses a composite seed layer structure consisting of a copper alloy layer (containing nickel, cobalt, manganese, or ruthenium) combined with a ruthenium barrier layer. This composite structure provides both the electrical conductivity needed for high density interconnects and the adhesion/em electromigration resistance required for reliability in high density routing applications.
Solution Approach 2:
The patent changes the compositional parameters of the seed layer by incorporating copper alloys with specific elements (nickel, cobalt, manganese, or ruthenium) at controlled concentrations. This parameter change enables the seed layer to simultaneously achieve thin deposition (improving density) while maintaining adhesion and electromigration resistance (improving reliability).
2Reliability
If thicker seed layers are deposited, then adhesion is improved, but routing density and electrical performance deteriorate
Solution Approach 1:
The patent changes the material composition parameters of the seed layer by using copper alloys with specific elements that provide enhanced adhesion properties. This allows the seed layer to achieve sufficient adhesion at reduced thickness, thereby enabling higher routing density without sacrificing reliability.
Solution Approach 2:
The composite seed layer structure with copper alloy and ruthenium barrier provides synergistic effects where the copper alloy component ensures adhesion and the ruthenium component provides electromigration resistance, allowing thin deposition while maintaining reliability.
3Quantity of substance
If narrower traces are created, then routing density is improved, but manufacturing precision and alignment become more difficult
Solution Approach 1:
The patent changes the physical and chemical parameters of the seed layer material to achieve better patterning characteristics. The copper alloy composition provides improved etch selectivity and pattern definition, enabling precise fabrication of narrower traces with better alignment even at high routing densities exceeding 100 IO per mm.
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
The sputtered copper alloy seed layer enables the creation of high density interconnects with improved adhesion and electromigration resistance, reducing delamination and copper loss, and allowing for more precise patterning and alignment, thereby enhancing electrical performance and routing density.
Implementation Method 1
a sputter seed layer formed on the first dielectric layer, wherein the seed layer comprises a copper alloy
Data Source
AI summary
Integrated circuit (IC) package substrates having high density interconnects with a sputter seed layer containing a copper alloy, as well as related structures, devices, and methods, are disclosed herein. For example, in some embodiments, a package substrate may include a first dielectric layer, a sputter seed layer disposed on the first dielectric layer, wherein the seed layer includes a copper alloy, a patterned conductive layer disposed on the seed layer, and a second dielectric layer over the patterned conductive layer.