Titanium Silicon Underlayer Film for EUV Lithography
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Solution Overview
Problem
In semiconductor device production, existing underlayer films for photoresists and EUV resists face challenges such as intermixing with the resist, low dry etching rates, and inadequate anti-reflective properties, particularly with the increasing use of shorter wavelength light sources like ArF excimer lasers, which affects pattern quality and resolution.
Innovation Solution
A thin film forming composition comprising a mixture of titanium compounds, silicon compounds, and their hydrolysis products, which form a hardmask and anti-reflective coating, enhancing dry etching rates and preventing intermixing with the resist, while efficiently absorbing out-of-band wavelengths like UV and DUV light to improve pattern resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hardmask containing metal elements such as silicon and titanium is used as an underlayer film, then the reflection preventing effect is improved, but the removal rate of the hardmask by dry etching decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the hardmask by incorporating specific metal compounds (titanium and silicon) in controlled ratios. This composition optimization allows the film to maintain anti-reflective properties while improving etch selectivity and removal rate through controlled chemical reactivity with etching gases.
Solution Approach 2:
The patent uses a composite material system combining titanium and silicon compounds in a specific formulation. This composite approach leverages the complementary properties of both metals: titanium provides anti-reflective characteristics while silicon enhances etch removal rate, achieving a balance between the two contradictory requirements.
2Manufacturing precision
If the resist and hardmask have largely different components, then the hardmask can be removed by dry etching without large decrease in photoresist film thickness, but the development of novel materials for resist underlayer film is desired due to diversity of characteristics required
Solution Approach 1:
The patent creates a multi-functional hardmask material that simultaneously provides anti-reflective coating, etch selectivity, and pattern definition capabilities. The titanium-silicon compound formulation is designed to fulfill multiple roles: preventing light reflection during lithography, enabling selective dry etching removal, and serving as an effective hardmask for pattern transfer, thereby reducing the need for multiple separate layers.
3Manufacturing precision
If shorter wavelength active ray is used for lithography, then fine processing capability is improved, but the influence of reflection of active ray on semiconductor substrate increases
Solution Approach 1:
The patent introduces a titanium-silicon based hardmask layer as an intermediary between the photoresist and semiconductor substrate. This intermediate layer serves as a reflection-preventing interface that absorbs or scatters reflected light, preventing it from reaching the substrate and causing unwanted effects such as standing waves or reflections that would degrade pattern quality.
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 composition provides a high dry etching rate for the underlayer film, prevents pattern collapse, and enhances resolution by blocking undesirable light, ensuring accurate pattern transfer and maintaining resist film thickness during the semiconductor fabrication process.
Implementation Method 1
comprising a mixture of a titanium compound (A) selected from a group consisting of a compound of Formula (1), a titanium chelate compound, and a hydrolyzable titanium dimer, and a silicon compound (B) of Formula (2), a hydrolysis product of the mixture, or a hydrolysis-condensation product of the mixture
Implementation Method 2
a composition for forming a thin film coated as an upper layer of an EUV resist for absorbing out-of-band wavelength light of EUV
Data Source
AI summary
A thin film forming composition for forming resist underlayer film useable in the production of a semiconductor device, and a resist upper layer film absorbs undesirable UV light with a thin film as an upper layer of the EUV resist before undesirable UV light reaches the EUV resist layer in EUV lithography, an underlayer film (hardmask) for an EUV resist, a reverse material, and an underlayer film for a resist for solvent development. The thin film forming composition useable together with a resist in a lithography process, comprising a mixture of titanium compound (A) selected from:R0aTi(R1)(4-a) Formula (1)a titanium chelate compound, and a hydrolyzable titanium dimer, and a silicon compound (B):R2a′R3bSi(R4)4-(a′+b) Formula (2)a hydrolysis product, or a hydrolysis-condensation product of the mixture, wherein the number of moles of Ti atom is 50% to 90% relative to the total moles in terms of Ti atom and Si atoms in the composition.