Tri-layer mask line bending prevention via organic etch
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Solution Overview
Problem
Current etching processes using tri-layer masks in semiconductor device production face challenges in minimizing line bending and tilting, particularly in narrower lines adjacent to wider lines, due to geometric loading effects caused by the harder mask materials.
Innovation Solution
The method involves using a hydrogen-free organic etch gas to etch the organic mask layer, followed by selective removal of the hard mask, allowing the organic mask to act as an etch mask for the etch layer, thereby reducing the geometric loading effect and minimizing line bending or tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a hard mask is used in the tri-layer mask structure, then the etching process can be performed, but line bending and tilting occur due to geometric loading effects
Solution Approach 1:
The patent removes the hard mask layer from the tri-layer mask structure, leaving only the organic mask layer. This extraction eliminates the geometric loading effect caused by the hard mask's higher etch resistance, thereby preventing line bending and tilting while maintaining the necessary etching functionality through the organic mask alone
Solution Approach 2:
The patent modifies the etch selectivity parameters by using a hydrogen-free organic etch gas (such as CF4, C4F8, or C2F6) that provides high selectivity between the organic mask and the etch layer. This parameter change allows the organic mask to effectively protect the etch layer without requiring the hard mask, thus eliminating the geometric loading effect
2Manufacturing precision
If hydrogen-containing organic etch gas is used, then the organic mask can be etched, but ion and radical attacks on sidewalls cause line bending and tilting
Solution Approach 1:
The patent changes the chemical composition parameter of the etch gas by removing hydrogen from the organic etch gas formula. Hydrogen-free gases like CF4, C4F8, and C2F6 produce fewer hydrocarbon radicals that would otherwise attack and erode the sidewalls of etched features, thereby preventing line bending and tilting while maintaining effective etching of the organic mask
Solution Approach 2:
The patent converts the potential harm of organic etch gas sidewall attack into a benefit by carefully selecting hydrogen-free organic gases that provide high etch selectivity for the organic mask while minimizing sidewall erosion. The organic etch gas effectively removes the organic mask material needed for the process while avoiding the harmful sidewall attack that would cause line deformation
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 approach effectively reduces line bending and tilting by minimizing ion and radical attacks on the sidewalls, achieving more precise feature etching with improved aspect ratios and reduced tilting, especially in narrower lines next to wider lines.
Implementation Method 1
providing a hydrogen free organic etch gas, forming the hydrogen free organic etch gas into a plasma, and etching the organic mask using the plasma
Data Source
AI summary
A method for etching features in an etch layer is provided. An organic mask layer is etched, using a hard mask as an etch mask. The hard mask is removed, by selectively etching the hard mask with respect to the organic mask and etch layer. Features are etched in the etch layer, using the organic mask as an etch mask.