Cu Germanide Silicide Nitride Capping Layer for Copper Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Copper interconnects in semiconductor manufacturing face challenges with electro-migration and stress-migration reliability, particularly in narrow lines, due to the instability of copper silicide barrier layers which can diffuse into low-k dielectric materials, causing damage and performance issues.
Innovation Solution
A method involving pre-annealing of copper conductive structures followed by sequential deposition of nitrided capping layers comprising Cu, Si, and Ge, using GeH4 and SiH4 ambients with NH3 plasma treatment, to form stable copper germanide and silicide nitride layers, which are then covered with a dielectric barrier, effectively preventing copper diffusion and improving electromigration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If copper silicide barrier layers are used to prevent copper diffusion, then copper diffusion is reduced, but the barrier layer stability deteriorates and silicon diffuses into low-k dielectric materials
Solution Approach 1:
The patent applies composite materials by creating a multi-layer capping structure consisting of copper germanide (CuGe2) and copper silicide nitride (CuSiN3) layers. The copper germanide layer serves as the primary barrier to copper diffusion, while the copper silicide nitride layer provides stability and prevents silicon diffusion into the dielectric. This composite approach allows each layer to perform its specific function, resolving the contradiction between copper diffusion prevention and barrier layer stability.
Solution Approach 2:
The copper germanide layer acts as an intermediary between the copper interconnect and the copper silicide nitride barrier layer. It provides a stable interface that prevents direct interaction between copper and the silicide layer, thereby preventing silicon diffusion while maintaining effective copper diffusion blocking. The intermediary layer mediates the conflicting requirements of copper diffusion prevention and compositional stability.
2Stability of the object's composition
If plasma treatment is used to nitrate copper silicide, then barrier stability is improved, but damage is inflicted on low-k dielectric layer
Solution Approach 1:
The patent applies preliminary action by performing the nitridation process during the deposition stage rather than as a separate post-deposition plasma treatment. The copper silicide layer is nitrided in-situ during the CVD process using ammonia-containing precursors, which achieves the desired nitridation without requiring subsequent high-power plasma treatments that would damage the low-k dielectric layer.
Solution Approach 2:
The patent replaces the mechanical/physical plasma treatment process with a chemical vapor deposition approach. Instead of using high-power plasma to nitrate the copper silicide layer (which causes dielectric damage), the patent uses chemical precursors containing ammonia that decompose during CVD to deposit nitrided copper silicide directly, achieving the same chemical effect without the harmful physical plasma exposure.
3Reliability
If sequential deposition of nitrided capping layers is performed, then electromigration resistance is improved, but process complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated deposition process. The sequential deposition of copper germanide and copper silicide nitride layers is performed in one continuous CVD cycle without breaking vacuum or requiring separate processing equipment. The process combines precursor delivery, thermal decomposition, and nitridation steps into a unified sequence, achieving complex multi-layer formation with a single process tool and procedure.
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 enhances electromigration resistance, maintains low sheet resistance, and prevents copper out-diffusion, thereby improving the reliability and performance of copper interconnects while avoiding damage to surrounding dielectric materials.
Implementation Method 1
prior to said step of forming said at least one capping layer a pre-annealing step of said copper conductive structure is performed at a temperature range between 250°C up to 450°C
Implementation Method 2
forming (or providing, or depositing), at a temperature range between 200°C up to 400°C, at least one capping layer, preferably selectively, onto said copper conductive structure by exposing said structure to a GeH4 and/or a SiH4 comprising ambient
Implementation Method 3
performing a NH3 plasma treatment thereby forming an at least partly nitrided capping layer
Implementation Method 4
performing a NH3 plasma treatment thereby forming an at least partly nitrided capping layer
Data Source
Figure 1A~1D
Figure 2
Figure 3
AI summary
The present invention is related to a method for forming a capping layer (6) comprising Cu, N, and also Si and/or Ge onto a copper conductive structure (2), said method comprising the sequential steps of: - forming, at a temperature range between 200°C up to 400°C, at least one capping layer (4) onto said copper conductive structure (2) by exposing said structure to a GeH4 and/or a SiH4 comprising ambient (3), - performing a NH3 plasma treatment (5) thereby forming an at least partly nitrided capping layer (6), - forming a dielectric barrier layer (7) onto said at least partly nitrided capping layer (6), characterized in that: - prior to said step of forming said at least one capping layer a pre-annealing step of said copper conductive structure is performed at a temperature range between 250°C up to 450°C.