Stress-Balanced Hard Mask Stack for Precise Substrate Patterning
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Solution Overview
Problem
Existing substrate processing methods using hard masks face challenges in managing stress, leading to substrate warping and inaccurate lithography due to unbalanced stress in single-layer hard masks, which affects the formation of high aspect ratio features and pattern precision.
Innovation Solution
A hard mask is formed by alternately stacking a carbon film with compressive stress and a ruthenium film with tensile stress, using chemical vapor deposition, to control and adjust the overall stress, thereby reducing warping and improving etching selectivity and pattern accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer hard mask is used, then the structure is simple, but substrate warping occurs due to unbalanced stress
Solution Approach 1:
The patent applies composite materials by stacking multiple film layers with different stress characteristics (compressive and tensile stress films) to form a hard mask. This composite structure balances the overall stress, preventing substrate warping while maintaining structural integrity during etching processes.
Solution Approach 2:
The patent uses the counterweight principle by alternating compressive stress films and tensile stress films in the hard mask stack. The tensile stress film counteracts the compressive stress film, creating a balanced stress state that prevents substrate warping, similar to how counterweights balance forces.
2Ease of manufacture
If a single-layer hard mask is used, then the deposition process is simple, but etching selectivity is insufficient
Solution Approach 1:
The patent employs composite materials with different etching selectivities in each layer of the hard mask stack. The alternating compressive and tensile stress films are made from materials that provide differentiated etching rates, enabling precise pattern transfer while maintaining process feasibility.
3Device complexity
If stress is not adjusted in the hard mask, then the process is simple, but pattern accuracy deteriorates
Solution Approach 1:
The patent uses composite materials with specifically engineered stress characteristics. By selecting and stacking films with known compressive and tensile stress properties, the overall stress of the hard mask is controlled to maintain pattern accuracy without requiring additional stress adjustment mechanisms.
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
This stress-adjusted hard mask reduces substrate warping, enhances etching selectivity, and allows for precise pattern formation, improving the productivity and accuracy of substrate processing.
Implementation Method 1
A hard mask is formed by alternately stacking a carbon film with compressive stress and a ruthenium film with tensile stress, using chemical vapor deposition
Data Source
AI summary
In a hard mask formed on a target film formed on a substrate, a first film having a stress in a first direction and a second film having a stress in a second direction opposite to the first direction are alternately stacked one or more times.