Semiconductor Layer Etching With Cyclic Sidewall Protection
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in reliably etching material layers with high aspect ratios and small dimensions, as poor process control leads to irregular structure profiles and line edge roughness, which affects the integrity and accuracy of features in next-generation VLSI and ULSI devices, particularly in three-dimensional chip stacking applications.
Innovation Solution
A cyclic etching and deposition process is employed, involving the use of carbon-fluorine containing gases to form protection layers and selectively remove them, allowing for precise control over the etching process, including the application of RF bias powers to manage plasma and gas mixtures for effective etching and protection of sidewalls and bottom surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching process is used to etch high aspect ratio features, then etching speed is maintained, but profile control and line edge roughness deteriorate
Solution Approach 1:
The patent implements a cyclic etching process that alternates between etching steps and deposition steps. During etching steps, material is removed to form features; during deposition steps, protection layers are deposited on sidewalls and bottom surfaces. This periodic alternation allows the process to maintain both profile control and etching speed by resetting the protection layers at regular intervals rather than using a single continuous approach.
Solution Approach 2:
The deposition of protection layers occurs before the etching reaches the final depth, preparing the sidewalls and bottom surfaces in advance for the subsequent etching steps. This preliminary action prevents profile degradation and line edge roughness from developing during the etching process, enabling maintained precision throughout the etching sequence.
2Manufacturing precision
If etching process is performed without protection layers, then etching speed is high, but line edge roughness and profile irregularity increase
Solution Approach 1:
The process uses periodic cycles of etching and deposition rather than continuous deposition throughout the entire etching process. This reduces the overall complexity compared to continuous protection layer formation while still achieving the benefit of reduced line edge roughness and profile irregularity through intermittent protection and resetting.
3Manufacturing precision
If protection layer is formed on bottom surface, then sidewall protection is improved, but bottom surface etching is blocked
Solution Approach 1:
The cyclic process alternates between etching steps where the bottom surface is exposed and deposition steps where protection layers are formed. This periodic exposure and protection allows bottom surface etching to proceed while still providing sidewall protection during the deposition phases, resolving the contradiction between protecting sidewalls and enabling bottom surface etching.
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 enables the formation of high aspect ratio features with improved accuracy and integrity, reducing irregularities and by-product blockages, thus ensuring the formation of precise, vertical, and high-quality structures in semiconductor devices.
Implementation Method 1
forming a protection layer on the sidewalls and the bottom surface of the open feature from a protection layer gas mixture comprising at least one carbon-fluorine containing gas
Implementation Method 2
etching at least a portion of a material layer on a substrate in an etch chamber to form an open feature
Implementation Method 3
applying a first RF bias power to etching at least a portion of a material layer on the substrate in the etch chamber
Data Source
AI summary
An apparatus and method for etching a material layer with a cyclic etching and deposition process. The method for etching a material layer on a substrate includes: (a) etching at least a portion of a material layer (302) on a substrate (101) in an etch chamber (100) to form an open feature (360) having a bottom surface (312) and sidewalls in the material layer (302); (b) forming a protection layer (314) on the sidewalls and the bottom surface (312) of the open feature (360) from a protection layer (314) gas mixture comprising at least one carbon-fluorine containing gas; (c) selectively removing the protection layer (314) formed on the bottom surface (312) of the open feature (360) from a bottom surface (312) open gas mixture comprising the carbon-fluorine containing gas; and (d) continuingly etching the material layer (302) from the bottom surface (312) of the open feature (360) until a desired depth of the open feature (360) is reached.