Adhesion Layer Compressive Stress for Via Yield
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Solution Overview
Problem
Conventional integrated circuit fabrication methods face issues with via yield degradation due to copper void formation caused by undercutting and moisture absorption in adhesion layers during processing, particularly at the interface between the adhesion layer and copper plugs/vias.
Innovation Solution
Forming an electrically insulating adhesion layer with internal compressive stress greater than 100 MPa, preferably over 150 MPa, using silicon dioxide deposited with source gases like octamethylcyclotetrasilane (OMCTS) and helium, to reduce susceptibility to etch-induced undercutting and moisture absorption, and subsequently forming dual-damascene copper wiring patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional adhesion layer is used during processing, then the layer provides basic adhesion function, but the layer is susceptible to undercutting and moisture absorption causing via yield degradation
Solution Approach 1:
The patent applies parameter changes by modifying the internal stress state of the adhesion layer from conventional low or tensile stress to high compressive stress (>100 MPa). This parameter change fundamentally alters the layer's resistance to undercutting and moisture absorption, directly resolving the technical contradiction between reliability and susceptibility to harmful factors.
Solution Approach 2:
The patent employs composite materials by combining silicon dioxide with specific deposition conditions (OMCTS and helium source gases) to create an adhesion layer with unique properties. This composite approach produces a material that simultaneously provides adhesion function and exhibits high resistance to undercutting and moisture absorption, resolving the contradiction between basic function and reliability.
2Reliability
If the adhesion layer is made more resistant to undercutting and moisture absorption, then via yield improves, but the manufacturing process complexity increases due to specific deposition requirements
Solution Approach 1:
The patent changes the stress parameter of the adhesion layer to high compressive stress (>100 MPa) through controlled deposition parameters. While this improves via yield, it requires precise control of deposition conditions (gas composition, flow rates, temperature), thereby increasing manufacturing process complexity.
Solution Approach 2:
The patent uses a composite deposition approach combining OMCTS and helium source gases to create the enhanced adhesion layer. This composite material strategy achieves superior performance but requires sophisticated deposition equipment and process control, increasing manufacturing complexity.
3Strength
If high compressive stress is applied to the adhesion layer to prevent undercutting, then structural integrity improves, but the risk of stress-induced defects during deposition increases
Solution Approach 1:
The patent applies high compressive stress (>100 MPa) to the adhesion layer to enhance structural integrity and prevent undercutting. However, achieving and controlling this high stress level requires extremely precise deposition parameters (gas composition, temperature, pressure), increasing the risk of stress-induced defects if control is not meticulous.
Solution Approach 2:
The patent uses composite material deposition with specific gas combinations (OMCTS and helium) to achieve the desired stress state. This approach requires precise control of multiple deposition parameters simultaneously, demanding high manufacturing precision to avoid stress-induced defects while achieving the target structural integrity.
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 high-stress adhesion layer effectively blocks undercutting and moisture absorption, enhancing the reliability of copper interconnect structures by maintaining structural integrity and reducing void formation, thereby improving the yield of interconnect structures.
Implementation Method 1
This adhesion layer 16, which may also be referred to as a graded layer, is typically formed of a material having a strong adhesion strength, a low susceptibility to arching and undercutting (during processing) and a strong resistance to moisture absorption
Implementation Method 2
the occurrence of VYD may be related to an outgassing of moisture from the adhesion layer 16 during back-end processing steps
Data Source
AI summary
Methods of forming interconnect structures include forming a first metal wiring pattern on a first dielectric layer and forming a capping layer (e.g., SiCN layer) on the first copper wiring pattern. An adhesion layer is deposited on the capping layer, using a first source gas containing octamethylcyclotetrasilane (OMCTS) at a volumetric flow rate in a range from about 500 sccm to about 700 sccm and a second gas containing helium at a volumetric flow rate in a range from about 1000 to about 3000 sccm. The goal of the deposition step is to achieve an adhesion layer having an internal compressive stress of greater than about 150 MPa therein, so that the adhesion layer is less susceptible to etching/cleaning damage and moisture absorption during back-end processing steps. Additional dielectric and metal layers are then deposited on the adhesion layer.