Carbon Gap-Fill Process Using Deposition-Etching Cycles
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Solution Overview
Problem
Existing amorphous carbon gap-fill films in semiconductor processing suffer from poor mechanical properties and large voids in trench-like gap features due to inadequate gap-fill capability, particularly with spin-on coating techniques, while PECVD deposited films have good overall properties but still exhibit voids.
Innovation Solution
A method involving a PECVD deposition process followed by an anisotropic etch and ashing process is used to deposit a carbon film into gap features, reducing the gap entry width, and then incrementally filling the gap with the {{Deposition+Etching}X+Ashing}Y process, which includes cycles of deposition, high ion sputtering etching, and ashing to remove localized carbon build-up, thereby minimizing voids and improving gap-fill efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spin-on coating techniques are used to deposit carbon film, then the process is simple and fast, but the mechanical properties are poor and chemical-mechanical planarization results are bad
Solution Approach 1:
The patent changes the deposition method from spin-on coating to PECVD (plasma-enhanced chemical vapor deposition), fundamentally altering the deposition parameters and mechanism. PECVD allows for better control of film properties through plasma activation, resulting in carbon films with superior mechanical properties while maintaining efficient deposition rates suitable for manufacturing.
2Strength
If PECVD deposited carbon films are used, then good overall film properties are achieved, but large voids are formed in trench-like gap features due to poor gap-fill capability
Solution Approach 1:
The patent segments the gap-fill process into multiple iterative cycles, each consisting of deposition and etch steps. Instead of attempting to fill the gap in a single deposition step, the process is divided into repeated cycles that progressively fill the trench while maintaining film quality and avoiding void formation.
Solution Approach 2:
The patent employs periodic alternation between deposition and etching operations. The etching step removes carbon buildup at the trench opening that would otherwise block further deposition, while the deposition step advances the fill. This periodic cycle continues until the gap is completely filled, ensuring uniform fill without voids.
3Device complexity
If conventional PECVD deposition-only method is used, then the process is simple, but voids are formed in high-aspect-ratio gap features
Solution Approach 1:
The patent divides the filling process into multiple small deposition-etch cycles rather than a single deposition step. Each cycle deposits a thin layer and then etches the opening to restore access, allowing the fill to progress through high-aspect-ratio trenches without forming voids, while keeping each individual step relatively simple.
Solution Approach 2:
The etching step is performed preliminarily within each cycle to remove carbon buildup at the opening before the next deposition step. This preliminary cleaning action prevents blockage and ensures continuous deposition progress into the trench, eliminating void formation in high-aspect-ratio structures.
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 effectively fills high-aspect-ratio gap features with minimal voids, enhancing the mechanical properties of the carbon films and improving process integration by maintaining seamless gap fill without the formation of voids, outperforming traditional PECVD deposition-only methods.
Implementation Method 1
performing a deposition process to deposit a carbon film layer on the substrate and on exposed surfaces of the at least one gap feature. The deposition process may be a plasma-enhanced chemical vapor deposition (PECVD) process
Implementation Method 2
performing an anisotropic etch process on the substrate with a dominant anisotropic axis substantially perpendicular to the substrate... The anisotropic etch process may be a plasma etch process with a high ion sputtering regime
Implementation Method 3
performing an ashing process to remove localized build-up of carbon film on the top surface of the substrate adjacent to the at least one gap feature produced as a result of (b) through (d)
Data Source
AI summary
Techniques, systems, and apparatuses for performing carbon gap-fill in semiconductor wafers are provided. The techniques may include performing deposition-etching operations in a cyclic fashion to fill a gap feature with carbon. A plurality of such deposition-etching cycles may be performed, resulting in a localized build-up of carbon film on the top surface of the semiconductor wafer near the gap feature. An ashing operation may then be performed to preferentially remove the built-up material from the top surface of the semiconductor wafer. Further groups of deposition-etching cycles may then be performed, interspersed with further ashing cycles.