Remote Plasma Etching for High Aspect Ratio Oxide Removal
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Solution Overview
Problem
Conventional etching methods, particularly wet etches, struggle with removing silicon oxide from high-aspect-ratio structures without causing pattern collapse or surface contamination, and dry etches may damage substrates due to electric arcs in local plasmas.
Innovation Solution
The method involves flowing fluorine-containing precursors into a remote plasma region to generate plasma effluents, which are then introduced into a semiconductor processing chamber with a substrate, accompanied by a hydrogen-containing precursor, while maintaining relative humidity below 50% and subsequently increasing it to enhance oxide removal without deforming the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching is used to remove silicon oxide, then oxide removal is achieved, but pattern collapse and surface contamination occur
Solution Approach 1:
The patent changes the physical state parameter of the etching medium from liquid (wet etch) to gaseous plasma (dry etch), and further modifies the plasma chemistry by using fluorine-containing precursors with controlled dissociation. This parameter change eliminates liquid surface tension effects that cause pattern collapse while maintaining effective oxide removal through chemical reactions.
Solution Approach 2:
The patent creates different plasma conditions in different spatial zones: a remote plasma region for precursor activation and a substrate processing region for controlled etching. The plasma is generated remotely and then transported to the substrate area, allowing different local conditions (plasma density, reactant concentration) in different regions to optimize both removal efficiency and pattern integrity.
2Object-generated harmful factors
If dry etching with local plasma is used to remove oxide, then pattern collapse is avoided, but substrate damage occurs due to electric arcs
Solution Approach 1:
The patent extracts the plasma generation function from the substrate processing region and places it in a separate remote plasma region. The plasma is generated remotely and then transported to the substrate area as plasma effluents, separating the high-energy plasma generation (which causes arcs) from the gentle etching process (which removes oxide without damage).
Solution Approach 2:
The patent introduces an intermediary medium (plasma effluents containing fluorine-containing radicals) that transports the etching chemistry from the remote plasma region to the substrate. This intermediary carries the reactive species needed for oxide removal without delivering the high-energy electrons and ions that cause substrate damage through electric arcs.
3Manufacturing precision
If remote plasma with fluorine-containing precursor is used, then selective oxide removal is achieved, but fluorine contamination may increase
Solution Approach 1:
The patent employs periodic or pulsed introduction of fluorine-containing precursors into the remote plasma region, followed by periods where hydrogen-containing precursors are introduced. This periodic action allows fluorine to perform oxide removal during active periods, while hydrogen periods help desorb or reduce fluorine contamination from the substrate surface, cycling between removal and cleaning functions.
Solution Approach 2:
The patent uses hydrogen-containing precursors to desorb and remove fluorine that has adsorbed onto the substrate surface during the oxide removal process. The hydrogen acts to recover the substrate by removing the harmful fluorine contamination, converting it to volatile species that can be pumped away, thus discarding the contamination rather than allowing it to accumulate.
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 allows for selective removal of silicon oxide with minimal substrate damage, reducing surface contamination and pattern collapse, and maintaining the integrity of high-aspect-ratio features by controlling humidity and precursor flow rates.
Implementation Method 1
forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor
Implementation Method 2
Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers
Data Source
AI summary
Exemplary cleaning or etching methods may include flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber. Methods may include forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor. The methods may also include flowing the plasma effluents into a processing region of the semiconductor processing chamber. A substrate may be positioned within the processing region, and the substrate may include a region of exposed oxide. Methods may also include providing a hydrogen-containing precursor to the processing region. The methods may further include removing at least a portion of the exposed oxide while maintaining a relative humidity within the processing region below about 50%. Subsequent to the removal, the methods may include increasing the relative humidity within the processing region to greater than or about 50%. The methods may further include removing an additional amount of the exposed oxide.