Cyclic Plasma Etch Process for Silicon Substrates
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Solution Overview
Problem
Current plasma technologies face challenges in accurately patterning semiconductor devices at atomic scale dimensions with precision and uniformity, especially when dealing with silicon-based materials and organic layers, due to issues like deformation of features and defects caused by etch byproducts.
Innovation Solution
A cyclic plasma etch process is implemented, comprising three segregated components: a plasma chemical dry etch using non-polymerizing fluorine compounds to remove silicon-based materials, a cooldown and cleanup process to suppress chemical reactions and remove residual byproducts, and a plasma surface modification process using hydrogen radicals to activate the surface and prevent further etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching is used to remove silicon-based materials, then etching efficiency is improved, but deformation of patterned features and defects increase
Solution Approach 1:
The plasma etching process is divided into multiple cycles, where each cycle includes an etching step followed by a surface modification step. This segmentation allows the etching process to be controlled in discrete increments, preventing excessive deformation while maintaining overall etching efficiency. The cyclic approach separates the material removal function from the surface damage accumulation, enabling precision control.
Solution Approach 2:
The patent employs periodic cycling between plasma etching and surface modification steps. By repeatedly applying short etching pulses followed by surface recovery steps, the process achieves cumulative material removal without the continuous exposure that causes deformation. This periodic action transforms a continuous damaging process into a controlled, intermittent one.
2Productivity
If plasma etching is used to remove silicon-based materials, then material removal speed is improved, but defects caused by etch byproducts increase
Solution Approach 1:
The patent converts the harmful effect of plasma exposure on the organic layer into a beneficial surface modification. By carefully controlling the plasma parameters and exposure time, the process creates a surface layer that actually protects the underlying material and facilitates controlled removal of byproducts. The harmful plasma exposure is transformed into a surface preparation step that enables cleaner subsequent etching.
Solution Approach 2:
The surface modification step acts as an intermediary between the harsh plasma etching environment and the sensitive organic layer. This intermediate step prepares the surface in a way that reduces direct damage from etch byproducts, creating a buffer zone that protects the underlying structure while still allowing material removal to proceed.
3Adaptability or versatility
If aggressive plasma etching is used to achieve high selectivity, then silicon-based material removal is improved, but deformation of organic layer increases
Solution Approach 1:
The etching process is segmented into multiple low-aggression cycles rather than one aggressive step. Each cycle removes a small amount of material with controlled selectivity, and the surface modification step between cycles prevents cumulative deformation. This segmentation maintains high overall selectivity while avoiding the shape damage caused by aggressive continuous etching.
Solution Approach 2:
The patent applies partial action by using multiple small etching steps instead of one complete removal step. Each partial etching step is followed by surface modification, ensuring that selectivity is achieved through accumulation of small, controlled removals rather than through aggressive single-step etching that would deform the organic layer.
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 method efficiently removes silicon-based materials while preserving the integrity of patterned features, reducing deformation and defects, and maintaining the original dimensions and shape of the organic layer, achieving high selectivity and low defect counts.
Implementation Method 1
exposing a surface of the substrate to fluorine radicals extracted from a first gas discharge plasma formed using a first gaseous mixture including a non-polymerizing fluorine compound
Implementation Method 2
causing chemical reactions with the surface of the substrate by exposing a surface of the substrate to fluorine radicals
Implementation Method 3
exposing the surface of the substrate to hydrogen radicals extracted from a second gas discharge plasma formed using a third gaseous mixture including gases including nitrogen and hydrogen
Implementation Method 4
performing a plasma surface modification process on the substrate
Implementation Method 5
cooling the substrate and concurrently removing residual gaseous byproducts
Data Source
AI summary
A method for processing a substrate includes performing a cyclic plasma etch process including a plurality of cycles, where each cycle of the plurality of cycles includes: causing chemical reactions with the surface of the substrate by exposing a surface of the substrate to fluorine radicals extracted from a first gas discharge plasma formed using a first gaseous mixture including a non-polymerizing fluorine compound; cooling the substrate and concurrently removing residual gaseous byproducts by flowing a second gaseous mixture over the substrate, and at the same time, suppressing the chemical reactions with the surface of the substrate; and performing a plasma surface modification process by exposing the surface of the substrate to hydrogen radicals extracted from a second gas discharge plasma formed using a third gaseous mixture including gases including nitrogen and hydrogen.