Semiconductor Gapfill Deposition Using RF Duty-Cycle Etch-Deposition
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Solution Overview
Problem
Existing methods struggle to achieve uniform gapfill processes in semiconductor structures with features of varying critical dimensions (CDs), often resulting in voids and non-uniform overburden layers.
Innovation Solution
A method involving a radio-frequency (RF) power duty cycle is applied in a semiconductor processing chamber, where a first RF power is used during a first time duration to deposit material in the bottom portion of features while etching at the top, and a second RF power is used during a second time duration to continue deposition on both bottom and top portions, ensuring uniformity and preventing voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single RF power level is used for gapfill deposition, then the deposition process is simple and fast, but features with different CDs cannot finish gapfill simultaneously resulting in non-uniform overburden
Solution Approach 1:
The patent applies periodic action by implementing a duty cycle that alternates between high RF power (etching mode) and low RF power (deposition mode). This periodic switching enables uniform gapfill across features with different critical dimensions by controlling when etching and deposition occur, allowing all features to finish simultaneously with uniform overburden.
2Productivity
If high RF power is applied continuously, then deposition rate is high and process time is reduced, but voids form in features with larger CDs
Solution Approach 1:
The duty cycle implements periodic action by alternating between high RF power (for rapid etching) and low RF power (for controlled deposition). This prevents continuous high power deposition that would cause voids in larger features, while still achieving high overall productivity through the etching-deposition cycles.
Solution Approach 2:
The patent changes the RF power parameter dynamically through the duty cycle, switching between high and low power levels. This parameter change allows optimization of both etching and deposition rates at different times, preventing void formation while maintaining productivity.
3Manufacturing precision
If low RF power is applied continuously, then uniform deposition occurs, but process time becomes excessively long
Solution Approach 1:
The duty cycle uses periodic action to alternate between high RF power (fast etching) and low RF power (uniform deposition). This approach maintains deposition uniformity during the low power phases while reducing total process time through the efficiency of high power etching phases.
Solution Approach 2:
The patent implements continuity of useful action by ensuring that during each duty cycle period, both etching and deposition activities are performed without idle time. The alternating high and low power phases continuously advance the gapfill process, reducing total time while maintaining uniformity.
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 allows features with different CDs to complete the gapfill process simultaneously and forms a substantially uniform overburden layer, preventing voids and enhancing the uniformity of subsequent deposition processes.
Implementation Method 1
applying a radio-frequency (RF) power to the processing chamber to perform a deposition process
Implementation Method 2
the etchant may be configured to etch the gapfill material
Data Source
AI summary
A gapfill precursor may be provided to a processing chamber for filling features in a semiconductor structure. The features may have different critical dimensions. An etchant configured to etch the gapfill material may also be provided with the precursor. A plasma power in the chamber may have a duty cycle of a first RF power provided during a first time duration and a second RF power provided during a second time duration, where the second RF power is less than the first RF power. The RF power levels may be selected such that the gapfill material is deposited in the bottom of the features while being etched at a top of the features during the first time, and deposited on both the bottom and top of the features during the second time, where the features having different CDs finish the gapfill process at about the same time.