Fluorinated BARC Materials for Photoresist Scum Reduction
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Solution Overview
Problem
Conventional photolithography processes in semiconductor fabrication result in residual photoresist material, or scum, on the underlayer due to the affinity between the photoresist layer and the bottom antireflective coating (BARC) layer, which affects process efficiency and yield.
Innovation Solution
The use of coating solutions for underlayers that incorporate fluorine-containing groups to reduce the affinity between the photoresist and underlayer, either by cleaving off the fluorine-containing group after exposure or by permanently bonding it, thereby minimizing residual photoresist material through negative tone development (NTD) or positive tone development (PTD) processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photolithography processes are used with standard underlayer compositions, then the photolithography process can proceed normally, but residual photoresist material (scum) remains on the underlayer due to affinity between photoresist and BARC layer
Solution Approach 1:
The patent modifies the chemical composition parameters of the underlayer by incorporating fluorine-containing groups (such as CF3, CF2, or F atoms) in specific concentrations (0.1-10 atomic percent). This parameter change alters the surface energy and chemical affinity of the underlayer, reducing its interaction with photoresist materials and enabling complete photoresist removal without scum formation.
Solution Approach 2:
The patent creates a composite underlayer material combining conventional BARC components (such as polymers like polycycloolefin or crosslinkable groups) with fluorine-containing compounds. This composite structure maintains the antireflective properties of BARC while introducing fluorine's low surface energy characteristics to prevent photoresist adhesion and scum formation.
2Object-generated harmful factors
If fluorine-containing groups are added to reduce photoresist affinity, then scum formation is reduced, but the complexity of coating solution composition increases
Solution Approach 1:
The fluorine-containing groups serve multiple functions simultaneously: they reduce photoresist affinity to prevent scum formation, maintain the antireflective properties of the BARC layer, and provide chemical stability. This multi-functionality reduces the need for additional separate components, managing complexity despite the enhanced composition.
Solution Approach 2:
The fluorine-containing groups are incorporated at specific local concentrations (0.1-10 atomic percent) within the underlayer composition rather than uniformly throughout. This localized approach allows the fluorine to exert its effect where needed (at the photoresist-underlayer interface) while keeping the overall composition manageable and compatible with existing manufacturing processes.
3Reliability
If fluorine-containing groups are permanently bonded to reduce affinity, then photoresist removal is improved, but the flexibility to adjust affinity dynamically is lost
Solution Approach 1:
The fluorine-containing groups are pre-bonded to the underlayer before photoresist deposition, establishing the desired low-affinity surface characteristics in advance. This preliminary configuration ensures consistent photoresist removal performance without requiring dynamic adjustment during the photolithography process, trading flexibility for process reliability and simplicity.
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 reduces scum formation, enlarges process windows, and improves yield by facilitating the removal of unexposed photoresist material, enhancing the overall efficiency of semiconductor device fabrication.
Implementation Method 1
a polymer backbone, a fluorine-containing group bonded to the polymer backbone
Implementation Method 2
a photoacid generator, exposing a portion of the photoresist layer and a portion of the underlayer to a radiation source according to a pattern, thereby decomposing the photoacid generator in the exposed portion of the underlayer to generate an acidity moiety
Implementation Method 3
an acid labile group bonded between the first end group and the second end group, baking the photoresist layer and underlayer so that the acidity moiety reacts with the acid labile group to detach the second end group from the polymer backbone
Data Source
AI summary
A method according to the present disclosure includes depositing a material layer over a substrate using a solution. The solution includes a polymeric backbone, a fluorine-containing group directly bonded to the polymeric backbone, a polar group directly bonded to the polymeric backbone, and a photoresist affinity group directly bonded to the polymeric backbone. The method further includes curing the material layer, depositing a photoresist layer over the cured material layer, exposing a portion of the photoresist layer to a radiation source, and developing the photoresist layer.