Doped Spacer Hardmask for Tight Pitch Patterning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Tight pitch patterning in semiconductor fabrication faces challenges with precise cutting of lines due to lithography overlay and critical dimension variations, leading to issues of excessive or incomplete cuts, which affect chip yield.
Innovation Solution
A method involving forming mandrels and spacers on a substrate, filling gaps with a sacrificial dopant material, and using a mask to selectively remove the sacrificial material and perform an anneal to create doped spacers, which are then used as a hardmask for patterning, allowing for precise cutting without compromising patterning fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the cut opening is made larger to ensure complete cutting, then the cutting completeness is improved, but adjacent lines are undesirably cut (excessive cut)
Solution Approach 1:
The patent applies local quality by creating doped spacers with different properties from undoped spacers. The doped regions provide selective etch resistance, allowing the cut opening to be precisely defined where undoped material is removed while protecting adjacent doped regions from excessive cutting. This local differentiation of material properties enables precise boundary control.
Solution Approach 2:
The patent uses preliminary action by forming doped spacers before the cutting step. The dopant is introduced into the spacer material in advance, creating a protective characteristic that will be activated during the subsequent etching process. This preliminary doping prepares the structure to resist unwanted etching in specific regions while allowing controlled removal in the cut region.
2Object-generated harmful factors
If the cut opening is made smaller to avoid excessive cutting, then excessive cut is prevented, but the line cutting becomes incomplete
Solution Approach 1:
The doped spacers create local quality differences that define the cut boundary. The doped regions have different etch characteristics compared to undoped regions, allowing the cut opening to be precisely confined. This enables complete cutting within the desired region without encroaching on adjacent structures, as the dopant provides a protective effect at the boundaries.
Solution Approach 2:
The dopant acts as an intermediary that mediates between the cut opening size and the actual cutting result. By introducing the dopant into the spacer material, it serves as a intermediate layer that controls the etching process, allowing the cut to proceed completely where needed while automatically preventing excessive cut where the dopant is present.
3Manufacturing precision
If lithography overlay and critical dimension variations are reduced to improve cut precision, then cutting precision is improved, but process complexity and cost increase
Solution Approach 1:
The patent changes the material parameter of the spacer by introducing dopant, transforming it from undoped to doped spacer. This parameter change creates a new property (etch selectivity) that enables precise cutting control without requiring tighter lithography overlay or critical dimension control. The dopant concentration and distribution become the controlling parameters for cut precision.
Solution Approach 2:
The patent substitutes the mechanical/lithographic control system with a chemical/material-based control system. Instead of relying on precise lithography overlay and critical dimension control to define the cut boundary, the invention uses dopant distribution and selective etching chemistry to define the cut region. This replaces the need for tight mechanical tolerances with a material property-based approach.
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 technique enlarges the process window for patterning, preventing excessive or incomplete cuts and maintaining patterning fidelity, even with encroachment or partial exposure of adjacent lines, thereby improving chip yield.
Implementation Method 1
performing an anneal to diffuse the dopant from the sacrificial material into the spacers to form doped spacers outside of the cut region
Data Source
AI summary
Techniques for tight pitch patterning are provided. In one aspect, a patterning method includes: forming mandrels on a substrate; forming spacers that are undoped alongside the mandrels, wherein gaps are present between the spacers; filling the gaps with a sacrificial material having a dopant; forming a mask having an opening marking a cut region of at least one of the spacers; removing the sacrificial material from the cut region of the at least one spacer via the mask; removing the mask; performing an anneal to diffuse the dopant from the sacrificial material into the spacers to form doped spacers, wherein following the anneal the cut region of the at least one spacer remains undoped; removing the cut region of the at least one spacer selective to the doped spacers; and patterning features in the substrate using the doped spacers as a hardmask. A patterning structure is also provided.