Anisotropic Native Oxide Removal via Remote Fluorine Plasma
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional etching processes for semiconductor substrates are often isotropic, leading to unintended removal of liner, spacer, and hardmask materials, and can damage delicate structures, particularly when trying to remove native oxide from silicon-containing materials, which affects device performance and reliability.
Innovation Solution
The method involves forming an inert plasma within a semiconductor processing chamber, using plasma effluents from a remote plasma unit, specifically a fluorine-containing precursor, to selectively modify and remove native oxide from silicon-containing materials, maintaining high selectivity and minimizing damage to surrounding structures by controlling plasma power and pressure, allowing for precise removal of unwanted materials without significantly affecting underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etch is used to remove silicon oxide, then etching speed and selectivity are improved, but the process cannot penetrate constrained trenches and may deform remaining material
Solution Approach 1:
The patent transitions from wet chemical etching to dry plasma etching, fundamentally changing the etching mechanism from liquid-phase chemical reaction to gas-phase plasma reaction. This parameter change enables penetration into constrained trenches while maintaining selectivity through controlled plasma chemistry and ion bombardment energy
Solution Approach 2:
The patent replaces the wet chemical etching mechanism with a dry plasma etching mechanism using fluorocarbon-based plasma. The plasma provides both chemical reaction capability for selective oxide removal and ion bombardment for physical sputtering, enabling deep trench penetration without deformation
2Length of moving object
If local plasma is used to etch constrained trenches, then trench penetration and reduced material deformation are improved, but substrate damage from electric arcs occurs
Solution Approach 1:
The patent introduces a remote plasma unit as an intermediary that generates plasma in a separate chamber and transports reactive species to the substrate through a showerhead. This eliminates direct plasma contact and electric arc formation at the substrate location while maintaining etching capability through transported reactive species
Solution Approach 2:
The patent divides the plasma generation and substrate processing into separate spatial zones. The remote plasma unit generates plasma in one chamber while the substrate is processed in another chamber, with only reactive species being transported between them. This segmentation prevents electric arc damage while maintaining etching effectiveness
3Quantity of substance
If conventional isotropic etching is used to remove native oxide, then complete oxide removal is achieved, but liner, spacer, and hardmask materials are unintentionally removed
Solution Approach 1:
The patent applies local quality by creating different plasma conditions in different spatial regions. The remote plasma provides selective chemical reactivity that attacks oxide materials while the controlled ion bombardment and process parameters preserve liner, spacer, and hardmask materials. This local differentiation of etching aggressiveness enables selective oxide removal without collateral damage
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 enables controlled, anisotropic removal of native oxide with etching selectivity greater than 100:1, maintaining the integrity of critical dimensions and reducing material loss, thus improving semiconductor device quality and performance.
Implementation Method 1
forming an inert plasma within a processing region of a processing chamber. Effluents of the inert plasma may be utilized to modify a surface of an exposed material
Implementation Method 2
contacting the modified silicon oxide with plasma effluents of a fluorine-containing precursor. The methods may also include etching the modified silicon oxide
Data Source
AI summary
Processing methods may be performed to remove unwanted materials from a substrate, such as a native oxide material. The methods may include forming an inert plasma within a processing region of a processing chamber. Effluents of the inert plasma may be utilized to modify a surface of an exposed material on a semiconductor substrate within the processing region of the semiconductor chamber. A remote plasma may be formed from a fluorine-containing precursor to produce plasma effluents. The methods may include flowing the plasma effluents to the processing region of the semiconductor processing chamber. The methods may also include removing the modified surface of the exposed material from the semiconductor substrate.