Plasma CVD Hard Mask Formation Using Organic Monomer Vapor
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Solution Overview
Problem
Conventional semiconductor processing techniques face challenges in forming thin, high-strength films on shrinking chip sizes due to limitations in coating methods, particularly in achieving optimal optical and mechanical properties for hard masks, especially at smaller feature sizes like 65 nm DRAM half pitch, where reflectivity and etching selectivity are critical.
Innovation Solution
A method using plasma CVD to form hydrocarbon-containing polymer films by plasma polymerizing organic monomers with high molecular weight, specifically with CO2 or H2 as additive gases, to create hard masks with controlled optical and mechanical properties, including low extinction coefficients and high mechanical hardness, which can reduce reflectivity and enhance etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a coating method is used to form polymer films, then highly functional polymer films can be formed by coating liquid material, but it is difficult to form thin films on substrate due to liquid viscosity
Solution Approach 1:
The invention transitions from liquid-phase coating to gas-phase deposition by vaporizing the organic monomer. The monomer is heated to vaporize it, then the vapor is deposited onto the substrate to form a thin film, eliminating the viscosity problem inherent in liquid coating methods
Solution Approach 2:
The invention replaces the mechanical coating process (spin coating, dip coating) with a chemical vapor deposition process. Instead of mechanically applying liquid material, the film is formed through vapor-phase polymerization and deposition, enabling precise thickness control
2Manufacturing precision
If DLC diamond-like carbon film or amorphous carbon film by plasma CVD is used, then thinner films can be achieved, but the wide variety of structures and characteristics cannot be obtained as with coating methods
Solution Approach 1:
The invention changes the material parameters by using high molecular weight organic monomers with specific molecular weight ranges (500-10,000) and specific structural characteristics. This allows tuning of film properties while maintaining thin film formation capability through plasma CVD
Solution Approach 2:
The invention creates composite functionality by combining the plasma CVD process with organic monomer materials. The resulting polymer films exhibit composite characteristics - the thin film morphology from plasma CVD combined with the structural versatility of organic polymers
3Ease of manufacture
If conventional coating method is used, then liquid material can be coated and sintered to form functional films, but reflectivity control and etching selectivity are insufficient for small feature sizes
Solution Approach 1:
The invention changes the physical state parameter from liquid to vapor, and controls deposition parameters (temperature, pressure, monomer concentration) to achieve films with optimized optical properties (reflectivity) and mechanical properties (etching selectivity) suitable for small feature sizes
4Manufacturing precision
If plasma CVD is used with gaseous monomers, then diamond-like carbon film or amorphous carbonous film can be formed, but the structural diversity and high molecular weight benefits cannot be achieved
Solution Approach 1:
The invention uses phase transition from solid/liquid monomer to vapor, then to deposited film. This allows handling of high molecular weight monomers that would be difficult to work with in gaseous form, while still achieving thin film deposition through controlled vaporization and plasma-enhanced polymerization
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 method enables the formation of hard masks with improved optical and mechanical properties, allowing for reduced reflectivity and increased mechanical strength, thereby facilitating more precise exposure and patterning processes, even at small feature sizes, and enhancing etching selectivity over oxide films.
Implementation Method 1
forming a polymer film on the substrate by plasma polymerizing the vaporized gas
Implementation Method 2
a diamond-like carbon film or an amorphous carbonous film is formed by decomposing the molecule by plasma
Implementation Method 3
By plasma polymerizing these organic monomers by including them in reaction gas as a source gas especially in combination with an additive gas of CO2 or H2
Data Source
AI summary
A method of forming a hydrocarbon-containing polymer film on a semiconductor substrate by a capacitively-coupled plasma CVD apparatus. The method includes the steps of: vaporizing a hydrocarbon-containing liquid monomer (CαHβXγ, wherein α and β are natural numbers of 5 or more; γ is an integer including zero; X is O, N or F) having a boiling point of about 20° C. to about 350° C. which is not substituted by a vinyl group or an acetylene group; introducing the vaporized gas and CO2 gas or H2 gas into a CVD reaction chamber inside which a substrate is placed; and forming a hydrocarbon-containing polymer film on the substrate by plasma polymerization of the gas, thereby reducing extinction coefficient (k) at 193 nm and increasing mechanical hardness.