Self-Aligned Via Formation Using Selective Liner Removal
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Solution Overview
Problem
Conventional via manufacturing techniques in integrated circuit (IC) manufacturing often result in misalignment between vias and metal lines, leading to increased via resistance, device failures, and higher manufacturing costs due to the inability to provide full via self-alignment and selective removal of liners.
Innovation Solution
A method for forming fully self-aligned vias involves depositing a liner on recessed conductive lines, growing pillars orthogonal to the insulating layer, and selectively removing the pillars and liner using hydrogen peroxide, allowing for precise alignment and connection between metallization layers without damaging dielectric material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional via manufacturing techniques are used, then the manufacturing process is simpler, but via alignment precision deteriorates leading to misalignment between vias and metal lines
Solution Approach 1:
The patent applies preliminary action by forming pillars on the first conductive lines before depositing the second insulating layer. These pillars serve as pre-positioned alignment structures that define the exact locations where vias will be formed, ensuring precise alignment is achieved before the via formation process begins. The pillars are formed using atomic layer deposition (ALD) which provides conformal coverage and precise thickness control, enabling sub-10nm alignment precision.
Solution Approach 2:
The patent introduces pillars as intermediary structures that mediate between the first conductive lines and the second insulating layer. These pillars act as alignment templates and sacrificial structures that enable precise via placement. The pillars are selectively removed after via formation to complete the self-aligned via process, demonstrating the intermediary role in achieving high precision alignment.
2Reliability
If conventional via formation methods are used, then the process steps are fewer, but via resistance increases due to misalignment
Solution Approach 1:
The patent implements self-service through the self-aligned via formation process where the pillars automatically define the via locations based on their position on the first conductive lines. The atomic layer deposition process used to form the pillars and insulating layers is inherently self-aligning, requiring no additional alignment steps or manual intervention, thus reducing via resistance through precise alignment while maintaining manufacturing efficiency.
Solution Approach 2:
The patent replaces traditional mechanical alignment systems with a chemical deposition-based alignment system. Instead of using photolithography and etching to define via locations, the patent uses atomic layer deposition to form pillars that self-align to the conductive lines. This substitution of mechanical alignment with chemical deposition processes achieves lower via resistance through better alignment precision.
3Ease of manufacture
If liners are used in conventional processes, then adhesion is improved, but selective removal of liner relative to metal becomes difficult
Solution Approach 1:
The patent applies local quality by using different materials with distinct chemical properties in different locations. The pillars are formed with a specific material composition that allows selective removal, while the conductive lines maintain their original adhesion properties. The atomic layer deposition process creates locally optimized structures where the pillars can be selectively removed without affecting the adhesion of the conductive lines to the insulating layers.
Solution Approach 2:
The patent changes the chemical parameters of the pillar material to enable selective removal. By controlling the composition and structure of the pillars through atomic layer deposition, the patent creates structures that can be selectively removed using specific chemical etchants without affecting the conductive lines or insulating layers. This parameter change enables easy selective liner removal while maintaining adhesion where needed.
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 achieves error-free alignment between vias and conductive lines, reducing via resistance and capacitance, increasing device yield, and lowering manufacturing costs by eliminating the need for high aspect ratio dielectric etches.
Implementation Method 1
The liner is removed from the recessed first conductive lines using one or more of a base and hydrogen peroxide
Implementation Method 2
At least one of the pillars is selectively removed to form at least one opening in the second insulating layer
Data Source
AI summary
Apparatuses and methods to provide a fully self-aligned via are described. Some embodiments of the disclosure provide an electronic device having a liner that is selectively removable when compared to conductive lines. The liner may be selectively removed by utilizing one or more of a base (e.g. sodium hydroxide) and hydrogen peroxide.