Silane Composition for Resist Underlayer Film
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the difficulty in forming a resist underlayer film that acts as a hard mask and anti-reflective coating, particularly with chromophores like anthracene or phenanthrene, which have high molecular weights, making distillation purification of metals impurities challenging, and requiring a composition that absorbs KrF laser with a low molecular weight.
Innovation Solution
A resist underlayer film-forming composition comprising a hydrolyzable silane with a specific structure, including a hydrolysis product or hydrolysis-condensation product, where the ratio of sulfur atoms to silicon atoms is 7% by mole or more, allowing for easy distillation purification and high dry etching rates, and is used in conjunction with other hydrolyzable silanes to form a polysiloxane-based film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If chromophores with high molecular weight (anthracene or phenanthrene) are used to absorb KrF laser, then the anti-reflective effect is improved, but the difficulty of distillation purification of metal impurities increases
Solution Approach 1:
The patent changes the molecular weight parameter of the chromophore from high (anthracene/phenanthrene) to low (specific structured silane compounds). This parameter change maintains the KrF laser absorption capability while enabling easy distillation purification, as lower molecular weight compounds are more volatile and easier to purify through distillation processes.
2Reliability
If a resist underlayer film is formed to serve as a hard mask, then the etching selectivity is improved, but the film thickness control becomes more critical
Solution Approach 1:
The patent optimizes the sulfur atom content parameter (7% by mole or more) in the silane structure to achieve high etching selectivity. This compositional parameter change ensures that the underlayer film removes faster than the resist during dry etching, providing reliable hard mask functionality while maintaining manageable film thickness control through standard deposition processes.
3Productivity
If the ratio of sulfur atoms to silicon atoms is increased to 7% by mole or more, then the dry etching rate is improved, but the complexity of composition design increases
Solution Approach 1:
The patent creates a composite silane structure combining silicon, sulfur, and organic groups in a specific ratio (S:Si ≥ 7% by mole). This composite material approach achieves high dry etching rates through the sulfur content while the systematic molecular design (using defined silane structures) keeps the composition design manageable rather than overly complex.
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 resist underlayer film that functions effectively as a hard mask and anti-reflective coating, allowing for excellent resist pattern shape formation and high dry etching rates, while facilitating easy purification of metal impurities, even at the KrF exposure wavelength of 248 nm.
Implementation Method 1
a hydrolyzable silane, a hydrolysis product thereof, or a hydrolysis-condensation product
Implementation Method 2
a composition that absorbs KrF laser with a low molecular weight
Implementation Method 3
making distillation purification of metals impurities challenging
Data Source
AI summary
The present invention provides a resist underlayer film-forming composition for lithography for forming a resist underlayer film that can be used as a hard mask with use of hydrolysis-condensation product of a hydrolyzable silane which also absorbs KrF laser. A resist underlayer film-forming composition for lithography comprising, as a silane, a hydrolyzable silane, a hydrolysis product thereof, or a hydrolysis-condensation product thereof, wherein the hydrolyzable silane includes a hydrolyzable silane of Formula (1):R1aR2bSi(R3)4−(a+b) Formula (1)[where R1 is an organic group of Formula (2):and is bonded to a silicon atom through a Si—C bond; R3 is an alkoxy group, an acyloxy group, or a halogen 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], and a ratio of sulfur atoms to silicon atoms is 7% by mole or more in the whole of the silane. A resist underlayer film obtained by applying the resist underlayer film-forming composition onto a semiconductor substrate and baking it.