3D Semiconductor Gap Filling With Alternating Plasma Deposition and Etch
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Solution Overview
Problem
In semiconductor manufacturing, existing methods for filling gaps in three-dimensional structures like trenches or holes often result in voids and seams due to the formation of overhangs or uneven deposition, especially in high aspect ratio features, which can be exacerbated by negative slopes and varying widths.
Innovation Solution
A method involving alternating cycles of thin film deposition using a reaction gas activated with high frequency RF power and etching with an etchant activated by low frequency RF power, allowing for more uniform deposition and targeted etching to fill gaps without voids or seams, particularly in high aspect ratio structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thin film is deposited directly in high aspect ratio trenches or holes, then the trench or hole can be filled with thin film, but an overhang or protruded portion is formed at the upper portion, causing voids and seams in the middle portion
Solution Approach 1:
The patent applies periodic action by alternating between deposition and etching cycles. During deposition, thin film is deposited on the trench walls. During etching, the overhang at the upper portion is selectively removed. This periodic alternation continues until the trench is completely filled without voids or seams, resolving the contradiction between filling the trench and avoiding overhang formation.
Solution Approach 2:
The patent changes process parameters by using different RF power settings for deposition versus etching. High RF power is used during deposition to ensure adequate film coverage, while low RF power is used during etching to selectively remove overhangs without excessive material removal. This parameter change enables precise control over the gap filling process.
2Manufacturing precision
If the trench has a negative slope with smaller width at upper portion and larger width at lower portion, then the structure can be formed, but the upper portion fills first with thin film, causing voids and seams in the middle portion
Solution Approach 1:
The periodic alternation between deposition and etching cycles addresses the negative slope geometry by continuously removing overhangs that form during deposition. Each etching cycle selectively targets the protruded portions at the upper portion of the trench, gradually transforming the negative slope into a more uniform or positive slope profile, enabling complete filling without voids.
Solution Approach 2:
The etching step acts as a preliminary action that prepares the trench profile before subsequent deposition cycles. By removing overhangs in advance, the trench geometry is optimized for the next deposition step, ensuring that thin film can progress uniformly toward the trench bottom without being blocked by protrusions.
3Productivity
If high RF power is used for deposition, then thin film can be deposited effectively, but overhang formation is exacerbated
Solution Approach 1:
The periodic alternation between high-power deposition and low-power etching cycles resolves this contradiction. During deposition, high RF power drives effective thin film formation. During etching, low RF power selectively removes the overhangs created by the high-power deposition, achieving both high productivity and good shape control.
Solution Approach 2:
The patent dynamically changes RF power parameters between deposition and etching modes. High RF power is applied during deposition to maximize deposition rate, then switched to low RF power during etching to remove overhangs. This parameter switching enables the system to achieve both high productivity and shape control that would be impossible with a single fixed power level.
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 method ensures a thin film is deposited uniformly and void-free within high aspect ratio features, improving the quality of semiconductor devices by eliminating seams and voids, and is applicable to various vapor deposition processes like ALD and PECVD.
Implementation Method 1
depositing a thin film on the three dimensional structure using at least one reaction gas activated with a first radio frequency (RF) power having a first frequency
Implementation Method 2
etching the deposited thin film using at least one etchant activated with a second RF power having a second frequency lower than the first frequency
Data Source
AI summary
This application relates to a method of filling a gap in a three-dimensional structure over a semiconductor substrate. The method may include depositing a thin film at least on a three-dimensional structure over a substrate using at least one reaction gas activated with a first radio frequency (RF) power having a first frequency, the three dimensional structure comprising a trench and/or hole. The method may also include etching the deposited thin film using at least one etchant activated with a second RF power having a second frequency lower than the first frequency. The method may further include repeating a cycle of the depositing and the etching at least once until the trench and/or hole are filled with the thin film. According to some embodiments, a thin film having substantially free of voids and/or seams can be formed in the three-dimensional structure.