Silicon Resist Underlayer Film for Lithography Anti-Reflection
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Solution Overview
Problem
In the manufacture of semiconductor devices, the reflection of shorter-wavelength active rays used in lithography processes poses a significant challenge, and existing underlayer films fail to provide an effective anti-reflective coating and suitable dry etching rates for precise pattern transfer without intermixing with the resist.
Innovation Solution
A resist underlayer film-forming composition incorporating a hydrolyzable silane with an aliphatic polycyclic structure, such as norbornene, which forms a stable film that acts as a hard mask and anti-reflective coating, allowing for higher dry etching rates and preventing intermixing with the resist, using specific etching gases to transfer patterns effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hard mask containing metal elements (silicon, titanium) is used as an underlayer film, then the anti-reflection effect is achieved, but the film thickness of the photoresist is significantly reduced during dry etching
Solution Approach 1:
The patent introduces a resist underlayer film as an intermediary layer between the photoresist and the substrate. This underlayer film serves as a mediator that provides anti-reflection properties while having a different etching rate characteristic than the photoresist, thereby protecting the photoresist film thickness during the etching process.
Solution Approach 2:
The resist underlayer film is formed from a composition containing a specific polymer (polycarbonate with pendant carboxyl groups) and a silane compound. This composite material structure provides both the anti-reflection effect and the appropriate etching rate differential to protect the photoresist layer.
2Ease of manufacture
If the photoresist and hard mask have significantly different components, then the hard mask can be removed by dry etching, but the selection of gas type becomes complex and critical
Solution Approach 1:
The patent changes the chemical composition parameters of the underlayer film by using a specific polymer-silane composition. This composition provides controlled etching rate differences that allow for simpler gas selection during the etching process, reducing the complexity of process parameter optimization.
3Manufacturing precision
If a resist underlayer film is introduced between the substrate and photoresist, then anti-reflection effect and pattern transfer are improved, but the composition development becomes more complex due to diverse characteristics demanded
Solution Approach 1:
The resist underlayer film composition is designed to perform multiple functions simultaneously: providing anti-reflection properties, enabling effective pattern transfer, and offering appropriate etching rate differential. The specific polymer-silane composition achieves this multi-functionality, reducing the need for separate layers or complex composition development.
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 enables the formation of a stable underlayer film that enhances pattern transfer and prevents film thickness reduction, maintaining the integrity of the resist pattern and allowing for precise processing of semiconductor substrates with improved etching efficiency.
Implementation Method 1
a hydrolyzable silane, a hydrolysis product thereof, or a hydrolysis-condensation product
Implementation Method 2
achieve various effects such as an anti-reflection effect
Implementation Method 3
the rates to remove these by dry etching are greatly dependent on the types of gas used for dry etching
Data Source
AI summary
A resist underlayer film-forming composition for lithography having an aliphatic polycyclic structure including, as a silane, a hydrolyzable silane, a hydrolysis product thereof, a hydrolysis-condensation product thereof, or a combination thereof, in which the aliphatic polycyclic structure is a structure which a hydrolyzable silane of Formula (1):R1aR2bSi(R3)4-(a+b) Formula (1)(where R1 is an organic group having an aliphatic polycyclic structure and bonded to a Si atom through a Si—C bond; R3 is an ethoxy group; a is an integer of 1; b is an integer of 0 to 2; and a+b is an integer of 1 to 3) has, or a structure included in a compound added as an aliphatic polycyclic compound, an aliphatic polycyclic dicarboxylic acid, or an aliphatic polycyclic dicarboxylic acid anhydride, each optionally having a double bond, a hydroxy group, or an epoxy group.