Low Aspect Ratio Stack Patterning via Cyclical Etch and Capping
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Solution Overview
Problem
Low aspect ratio stacks in substrate processing exhibit line edge roughness (LER) and wiggle issues due to inadequate etch control in organic films and dielectric materials, which affects the fidelity of features formed during lithography and other processing techniques.
Innovation Solution
A cyclical process involving partial etching of the dielectric layer and deposition of a capping material on a patterned organic planarizing layer (OPL) mask is employed, where the capping material is primarily deposited on the OPL surfaces, allowing for controlled etching to a target depth, thereby reducing LER and improving feature fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous etch process is used to remove the dielectric layer, then the etching speed is high, but line edge roughness increases significantly
Solution Approach 1:
The patent applies periodic action by alternating between etching steps and capping material deposition steps. The etch process is interrupted at intervals, and a capping material is deposited on the OPL mask surface between etching cycles. This periodic interruption allows the etch front to be replenished with fresh chemistry, maintaining high etching speed while preventing the accumulation of roughness that would occur in a continuous etch process.
Solution Approach 2:
The capping material serves as an intermediary substance deposited on the OPL mask surface during the cyclical process. This intermediary layer protects the mask surface during etching interruptions and allows for controlled replenishment of etch chemistry without directly exposing the mask to prolonged etching conditions, thereby reducing line edge roughness while maintaining productivity.
2Length of stationary object
If the etch process is extended to achieve deeper etching, then the target depth is reached, but line edge roughness and feature fidelity deteriorate
Solution Approach 1:
To achieve deeper etching while maintaining feature fidelity, the patent employs periodic action through multiple cycles of partial etching followed by capping material deposition. Each cycle advances the etch depth incrementally, and the intermediate deposition steps replenish the etch chemistry and protect the mask, preventing the degradation of line edge roughness that would occur in a single prolonged etch process.
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 cyclical process effectively reduces line edge roughness by approximately 20% and line width roughness by up to 40%, enhancing the precision and quality of features in low aspect ratio stacks.
Implementation Method 1
depositing a capping material on a surface of the OPL mask
Implementation Method 2
performing a partial etch of the dielectric layer in a region exposed by the OPL mask
Data Source
AI summary
Embodiments of methods and systems for patterning of low aspect ratio stacks are described. In one embodiment, a method may include receiving a substrate comprising a patterned organic planarizing layer (OPL) mask wherein a surface of the OPL mask is exposed, the OPL mask landing on a dielectric layer. The method may also include performing a partial etch of the dielectric layer in a region exposed by the OPL mask. Additionally, the method may include depositing a capping material on a surface of the OPL mask. The method may also include performing a cyclical process of the partial etch of the dielectric layer and deposition of the capping material on a surface of the OPL mask until the dielectric layer is removed to a target depth. In such embodiments, the cyclical process generates an output patterned substrate with a target line edge roughness (LER).