Copper Conductor Dopant Implantation for Electromigration
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Solution Overview
Problem
As semiconductor devices shrink, electromigration in conductive lines, such as copper, leads to increased line resistance and reliability issues due to atom movement and scattering, which existing methods like capping layers and single-species implantation fail to adequately address simultaneously.
Innovation Solution
Implanting specific species like germanium, phosphorus, arsenic, boron, silicon, nitrogen, and carbon into copper layers to form compounds that reduce diffusion and electromigration, while minimizing line resistance, using techniques like plasma doping and ion implantation to control the depth and distribution of these species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high current density is used to maintain performance as feature sizes shrink, then device performance is maintained, but electromigration increases causing reliability degradation
Solution Approach 1:
The patent changes the physical and chemical parameters of the copper conductor by implanting dopant species (such as silicon, carbon, nitrogen) into the copper lattice. This modifies the crystal structure and electronic properties of copper, enabling it to withstand higher current densities without electromigration while maintaining low resistivity. The dopant concentration and distribution are precisely controlled to achieve optimal performance.
Solution Approach 2:
The patent creates a composite material system by combining copper with implanted dopant species forming compounds such as Cu-Si, Cu-C, and Cu-N compounds. This composite structure within the copper conductor provides both the electrical conductivity of copper and the electromigration resistance of the compound phases, resolving the contradiction between performance and reliability.
2Reliability
If conventional methods like capping layers or single-species implantation are used, then some electromigration protection is achieved, but line resistance increases and reliability is not fully addressed
Solution Approach 1:
The patent segments the electromigration protection function by using multiple dopant species targeting different mechanisms and depth zones within the copper conductor. Each species (e.g., silicon for shallow zones, carbon for intermediate zones, nitrogen for deep zones) addresses specific electromigration pathways, providing comprehensive protection without the resistivity penalty of uniform capping layers.
Solution Approach 2:
The patent transitions from surface-level protection (capping layers) to volumetric protection by implanting dopants throughout the bulk copper conductor. This three-dimensional distribution of protective species provides electromigration resistance throughout the entire conductor volume while maintaining low line resistance, unlike surface-only approaches that increase overall resistance.
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 method effectively reduces electromigration and line resistance, enhancing the reliability of semiconductor devices by forming compounds like SixNyCz that mitigate atom movement and scattering, thereby improving the stability and performance of conductive layers.
Implementation Method 1
Implanting specific species like germanium, phosphorus, arsenic, boron, silicon, nitrogen, and carbon into copper layers
Implementation Method 2
using techniques like plasma doping and ion implantation to control the depth and distribution of these species
Implementation Method 3
Electromigration is the transport of material in a conductor caused by gradual movement of atoms or ions due to the momentum transfer between conducting electrons and the atoms or ions
Implementation Method 4
This increased resistance may lead to joule heating, or heat released when a current passes through a conductor
Data Source
AI summary
A first species and a second species are implanted into a conductor of a substrate, which may be copper. The first species and second species may be implanted sequentially or at least partly simultaneously. Diffusion of the first species within the conductor of the substrate is prevented by the presence of the second species. In one particular example, the first species is silicon and the second species is nitrogen, although other combinations are possible.