Selective SAQP SADP Self-Aligned Via Patterning
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Solution Overview
Problem
Conventional SAV processes face process margin loss due to critical dimension uniformity and overlay alignment limitations in the 7 nm technology node, leading to challenges in extending metal hardmask patterns and maintaining edge placement accuracy.
Innovation Solution
The method employs selective self-aligned quadruple patterning (SAQP) or self-aligned double patterning (SADP) processes using titanium nitride layers, alternating mandrels and non-mandrel fillers, spacers, and metal cut plugs, with specific etching steps to form trenches and fill them with metal, leveraging etch selectivity between different materials to enhance process margins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography processes are used for SAV formation, then the process is simple and fast, but critical dimension uniformity and overlay alignment deteriorate at 7 nm node
Solution Approach 1:
The patterning process is divided into multiple stages: forming mandrels, depositing spacers, removing mandrels, depositing additional spacers, and selective etching. Each stage creates intermediate patterns that are combined to achieve the final high-precision SAV structure, breaking down the complex patterning task into manageable segments that maintain CDU at 7 nm node
Solution Approach 2:
The patent transitions from planar 2D patterning to 3D self-aligned patterning by utilizing vertical spacer deposition around mandrels. This dimensional transition enables precise lateral pattern definition through vertical material deposition, achieving superior CDU and overlay alignment that cannot be obtained with conventional 2D lithography alone
2Productivity
If metal pitch is shrunk to increase density, then device capacity increases, but process margin loss occurs in conventional SAV processes
Solution Approach 1:
The self-aligned patterning process uses the deposited spacers themselves as the alignment reference for subsequent etching steps. The spacers automatically define the via locations with precise edge placement, eliminating the need for separate alignment marks and processes. This self-service mechanism maintains edge placement accuracy even as metal pitch shrinks to increase device density
Solution Approach 2:
The patent performs preliminary spacer deposition and mandrel removal steps before the final via etching. These preliminary actions pre-establish the precise via locations and dimensions, ensuring that when the actual SAV etching occurs, the process margins are already optimized for the shrunk metal pitch, preventing edge placement errors
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 improves critical dimension and edge placement margins during SAV formation, enabling more precise and reliable metal pitch shrinkage in semiconductor devices, particularly for the 7 nm technology node and beyond.
Implementation Method 1
etching the first and second trenches through the TiN and dielectric layers
Data Source
AI summary
Methods of forming a SAV using a selective SAQP or SADP process are provided. Embodiments include providing on a TiN layer and dielectric layers alternating mandrels and non-mandrel fillers, spacers therebetween, and a metal cut plug through a mandrel or a non-mandrel filler; removing a non-mandrel filler through a SAV patterning stack having an opening over the non-mandrel filler and adjacent spacers, forming a trench; removing a mandrel through a second SAV patterning stack having an opening over the mandrel and adjacent spacers, forming a second trench; etching the trenches through the TiN and dielectric layers; forming plugs in the trenches; removing the mandrels and non-mandrel fillers, forming third trenches; etching the third trenches through the TiN layer; removing the metal cut plug and spacers and etching the third trenches into the dielectric layer; removing the plugs; and filling the trenches with metal.