Nitric Acid Stabilized Polysiloxane Underlayer Film
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Solution Overview
Problem
Polysiloxane solutions used in semiconductor manufacturing often contain high levels of ionic impurities, which are difficult to remove and can cause instability due to reactions with polar filters, leading to gelation and increased molecular weight, and volatile catalysts like hydrochloric acid can be removed but result in instability during filtration.
Innovation Solution
A polysiloxane solution with a specific amount of nitric acid is used, which remains stable when filtered through a polar group-containing filter, utilizing a hydrolysis condensate of hydrolyzable silane and nitric acid ions, and optionally including additional hydrolyzable silanes and additives like water or photoacid generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If filtration is performed using a polar group-containing filter to remove ionic impurities, then purity is improved, but the polysiloxane becomes unstable and gelation occurs
Solution Approach 1:
The patent changes the chemical parameter by introducing nitric acid into the polysiloxane solution. This parameter change modifies the solution's properties to prevent unwanted reactions with the polar filter, allowing filtration to proceed without gelation while still removing ionic impurities effectively.
Solution Approach 2:
Nitric acid acts as an intermediary substance that mediates between the polysiloxane and the polar filter. It prevents direct harmful interactions between the polysiloxane and filter material, enabling the filtration process to occur smoothly without causing instability or gelation.
2Speed
If a volatile catalyst like hydrochloric acid is used for hydrolysis, then reaction speed is improved, but the polysiloxane becomes unstable during filtration
Solution Approach 1:
The patent changes the catalyst parameter from volatile hydrochloric acid to nitric acid. This substitution maintains the hydrolysis reaction efficiency while eliminating the instability problem during filtration, as nitric acid does not cause gelation with polar filters.
3Strength
If polysiloxane solution with high polarity is used to improve adhesion, then adhesion is improved, but ionic impurities increase and become difficult to remove
Solution Approach 1:
The patent introduces nitric acid as a parameter change that enables effective removal of ionic impurities from high-polarity polysiloxane solutions. This allows the solution to maintain high adhesion properties while the nitric acid facilitates the filtration process to remove impurities without causing gelation.
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 solution forms a stable resist underlayer film that maintains its properties during filtration and etching, improving adhesion and preventing pattern collapse, and enhances lithographic characteristics by controlling the etching rate and reducing scum formation during development.
Implementation Method 1
a hydrolysis condensate (c) of a hydrolyzable silane (a) as a silane... wherein the hydrolyzable silane (a) contains a hydrolyzable silane of Formula (1)
Implementation Method 2
the polysiloxane solution may be subjected to filtration with a filter containing a polar group
Data Source
AI summary
A resist underlayer film-forming composition for lithography can produce a semiconductor device; specifically, for forming a resist underlayer film that can be used as a hard mask. It includes a hydrolysis condensate (c) of a hydrolyzable silane (a) as a silane, nitric acid ions, and a solvent, wherein the hydrolyzable silane (a) contains a hydrolyzable silane of the following Formula (1):R1aR2bSi(R3)4-(a+b) Formula (1)[wherein R1 is an organic group of the following Formula (2):and is bonded to a silicon atom via an Si—C bond]. The composition may further include the hydrolyzable silane (a) and/or a hydrolysate (b) thereof. The amount of the nitric acid ions may fall within a range of 1 ppm to 1,000 ppm. In the hydrolysis condensate (c), the functional group of Formula (2) in the hydrolyzable silane of Formula (1) may satisfy a (hydrogen atom)/(hydrogen atom+R5 group) ratio by mole of 1% to 100%.