Silicon Nitride Gap Fill Deposition With Selective Top Etching
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Solution Overview
Problem
The challenge in semiconductor fabrication is filling gaps and trenches with dielectric material without clogging at the top, leading to voids or seams, and existing methods often result in uneven deposition due to differential etching rates.
Innovation Solution
A method involving the formation of a silicon-nitride based dielectric film through a process that includes forming an amorphous silica layer, followed by thermal etching with a fluorine-containing compound, reacting with radicals from a remote plasma source, and a hydrogen recovery process to achieve uniform deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If selective etching is implemented to limit bottom of the gap from etching at the same rate as the top, then etching selectivity is improved, but bubbles form in the dielectric material due to adjusted process conditions
Solution Approach 1:
The patent applies parameter changes by systematically adjusting multiple process parameters during the etching and deposition sequence. The process conditions (such as gas flow rates, pressure, temperature, and precursor delivery) are dynamically modified between the first etching step and the second etching step, and during subsequent dielectric deposition. These parameter changes enable selective etching at the top while minimizing bottom etching, and simultaneously prevent bubble formation by optimizing the deposition conditions to ensure proper dielectric material quality throughout the gap.
2Quantity of substance
If dielectric material is deposited to fill high aspect ratio gaps, then the gap filling is attempted, but the deposition is prone to clog at the top before the gap is completely filled, producing a void or seam in the middle of the gap
Solution Approach 1:
The patent applies segmentation by dividing the gap filling process into multiple distinct stages: (1) a first etching step to prepare the gap and remove any initial clog at the top, (2) a second etching step with different conditions to further refine the gap geometry, and (3) a dielectric deposition step to fill the prepared gap. This segmentation of the filling process into controlled stages prevents material clogging by ensuring the gap is properly prepared and maintained throughout deposition, thereby achieving complete gap filling without voids or seams.
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 ensures uniform filling of gaps and trenches by selectively etching the top while minimizing bottom etching, reducing defects, and maintaining film quality.
Implementation Method 1
A thermal etching process is performed on the modified amorphous silica layer by flowing a fluorine-containing compound at a temperature of about 400° C. to about 600° C.
Implementation Method 2
A silicon-nitride based dielectric film is formed by reacting the modified amorphous silica layer with one or more radicals generated by a remote plasma source
Implementation Method 3
A silicon-nitride based dielectric film is formed by reacting the modified amorphous silica layer with one or more radicals generated by a remote plasma source
Implementation Method 4
An etched silicon-nitride based dielectric film is formed by flowing a fluorine-containing compound to the processing chamber in the presence of a plasma
Data Source
AI summary
The present disclosure provides methods of gap fill deposition. The methods include forming a silicon-nitride based dielectric film by providing a substrate into a processing chamber. An amorphous silica layer is formed on a surface of the substrate by flowing a dielectric precursor on the substrate. A modified amorphous silica layer is formed by flowing a reactive gas into the processing chamber. A thermal etching process is performed on the modified amorphous silica layer by flowing a fluorine-containing compound at a temperature of about 400° C. to about 600° C. A silicon-nitride based dielectric film is formed by reacting the modified amorphous silica layer with one or more radicals generated by a remote plasma source. An etched silicon-nitride based dielectric film is formed by flowing a fluorine-containing compound to the processing chamber with plasma. The etched silicon-nitride based dielectric film is exposed to a hydrogen recovery process.