Silicon Hydrofluorocarbon Plasma Etching for Selective HAR Profiles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current dry etching methods for semiconductor devices face challenges in achieving high selectivity and controlling the profile of etched structures, particularly in high aspect ratio and multicolor etching processes, where polymer deposition on non-etching materials can lead to defects and require additional cleaning steps, compromising the integrity of the substrate.
Innovation Solution
A cyclic etching process utilizing Si-containing hydrofluorocarbon compounds, which allows for high selectivity by controlling the deposition of a polymer layer on non-etching materials, preventing thick polymer film growth and enabling precise control of etch profiles through the use of specific Si-containing hydrofluorocarbons like C4H9F3Si, C5H9F5Si, and C2H6F2Si, that form robust polymers with methyl groups attached to the Si atom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If selective etching process with infinite selectivity is used to etch Si-containing films, then etch selectivity is improved, but thick polymer film deposits on non-etching material requiring additional cleaning steps
Solution Approach 1:
The patent implements a cyclic etching process that alternates between a first etching step using Si-containing hydrofluorocarbon (which deposits polymer on non-etching material with high selectivity) and a second etching step using different chemistry (which removes the polymer). This periodic switching allows the system to achieve infinite selectivity during the etching phase while controlling polymer accumulation through the alternating cleaning phase, thus resolving the contradiction between high selectivity and polymer deposition.
2Manufacturing precision
If polymer is deposited on non-etching material to achieve infinite selectivity, then etch selectivity is improved, but additional cleaning steps are required which can damage films on substrate
Solution Approach 1:
The patent combines the etching function and the polymer removal function into a single cyclic process sequence. By merging the selective etching step (first etching gas) with the polymer removal step (second etching gas) into alternating cycles, the process achieves infinite selectivity while integrating cleaning within the same etching sequence, thereby reducing the need for separate additional cleaning steps that could damage substrate films.
3Manufacturing precision
If thick polymer film is deposited during etching process, then etch selectivity is improved, but profile control of etched structures deteriorates
Solution Approach 1:
The cyclic process alternates between depositing polymer (first etching step) and removing polymer (second etching step). By controlling the duration and conditions of each cycle, the process maintains an optimal thin polymer layer that provides selectivity enhancement without accumulating to thick films that would compromise profile control. The periodic removal prevents excessive polymer buildup while preserving the selectivity benefits.
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 enhances etch selectivity and maintains a defined profile without polymer deposition on non-etching materials, reducing the need for additional cleaning and improving the precision and efficiency of semiconductor device fabrication.
Implementation Method 1
addition of Si-containing hydrofluorocarbon to the process gas mixture at least one step of the cyclic etching allows to increase selectivity by growth of polymer on non-etching material
Implementation Method 2
converting the etching gas into a plasma; allowing an etching reaction to proceed between the plasma and the silicon-containing film
Data Source
AI summary
Methods of plasma dry etching employing an etching gas mixture containing a compound that has a general formula: where 1≤x≤6, 1≤y≤9, 1≤z≤15, n=1 or 2. In some embodiments, the compound contains one or more methyl group(s) and at least one methyl group is attached to the Si atom. The methods include HAR dry etching processes. selective dry etching processes and cyclic selective dry etching processes.