Copper Interconnections with (111) and (200) Surface Orientations
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Solution Overview
Problem
Conventional copper interconnection structures in semiconductor devices often experience stress-induced voids (SIV) due to void migration along grain boundaries, leading to contact failures and increased resistance, particularly at the interface between copper interconnections and via plugs.
Innovation Solution
The solution involves configuring copper interconnections with different surface orientations: narrow-width interconnects with a (111) surface orientation and wide-width interconnects with a (200) surface orientation, which reduces grain boundaries and inhibits void migration, thereby suppressing SIV and improving electromigration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional copper interconnection structure is used, then copper interconnection can be formed, but stress-induced voids occur due to void migration along grain boundaries
Solution Approach 1:
The patent applies different surface orientations to different regions of copper interconnections based on their width characteristics. Narrow-width interconnects (≤0.5 μm) use (111) surface orientation which provides higher density and better electromigration resistance, while wide-width interconnects (>0.5 μm) use (200) surface orientation which reduces grain boundaries and suppresses void migration. This local differentiation resolves the contradiction by optimizing each region's crystal structure for its specific dimensional requirements.
Solution Approach 2:
The patent changes the crystallographic orientation parameter of copper interconnections based on their width. By controlling the surface orientation to be (111) for narrow interconnects and (200) for wide interconnects, the patent modifies the fundamental structural parameters to achieve both high density and reduced void migration, thereby improving reliability while suppressing stress-induced voids.
2Productivity
If narrow-width copper interconnection is used, then interconnection density increases, but electromigration resistance decreases
Solution Approach 1:
The patent specifically assigns (111) surface orientation to narrow-width interconnections (≤0.5 μm). The (111) orientation provides higher atomic density and closer-packed crystal structure, which significantly improves electromigration resistance. This local optimization allows narrow interconnects to maintain high current carrying capacity despite their small dimensions.
Solution Approach 2:
The patent creates a composite copper interconnection system where different crystallographic orientations are combined in different regions. The (111)-oriented narrow interconnects provide high electromigration resistance, while (200)-oriented wide interconnects provide structural stability and reduced void migration. This composite approach allows the overall system to achieve both high density and high reliability.
3Reliability
If wide-width copper interconnection is used, then electromigration resistance improves, but void migration along grain boundaries increases
Solution Approach 1:
The patent assigns (200) surface orientation to wide-width interconnections (>0.5 μm). The (200) orientation characteristics reduce the number of grain boundaries in the lateral direction, which suppresses void migration along grain boundaries. This local optimization addresses the specific vulnerability of wide interconnects to void formation at interfaces with via plugs.
4Ease of manufacture
If single surface orientation is used for all copper interconnections, then manufacturing process is simplified, but performance cannot be optimized for different width characteristics
Solution Approach 1:
The patent incorporates surface orientation control into the barrier metal formation step, which is performed before copper deposition. By using selective sputtering conditions (different gas pressures, power settings, or barrier metal compositions) during the barrier metal deposition, the desired (111) or (200) orientation is established in advance. This preliminary action ensures that subsequent copper growth inherits the optimized orientation without requiring additional processing steps.
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 effectively reduces the generation of SIV and enhances the reliability of semiconductor devices by minimizing void concentration and improving the resistance to electromigration in both narrow and wide-width copper interconnections.
Implementation Method 1
a barrier metal film 14 typically composed of Ta/TaN is formed in the interconnect trench 14, and a Cu film is formed
Implementation Method 2
Cu is plated using an electroplating technique to thereby fill the interconnect trench 14 with Cu
Implementation Method 3
the plated film is then annealed at a temperature of 150° C. or above for growth of the grains
Data Source
AI summary
A semiconductor device includes: a semiconductor substrate; an insulating film provided on the semiconductor substrate; a plurality of copper interconnections provided on the same level in the insulating film. The copper interconnection includes: a first copper interconnection having a relatively narrow width; and a second copper interconnection having a relatively wide width. The first copper interconnection has the top surface thereof principally composed of copper, and the second copper interconnection has the top surface thereof principally composed of copper.