Multiphase Plasma Etching Pulses for Inner Spacer Protection
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Solution Overview
Problem
Conventional plasma processing methods lack independent control over etching and deposition, leading to inadequate protection of delicate nanostructures in 3D semiconductor devices, resulting in defects and material removal during the etching process, especially in high aspect ratio features like nanowires and nanosheets.
Innovation Solution
A multiphase, multifrequency periodic plasma process is employed, utilizing varying power levels and frequencies of source power and bias power pulses to control etching and deposition phases, allowing for precise modulation of etching and deposition processes through cyclic plasma processing, thereby reducing damage to the substrate and enhancing control over the etching of inner spacer structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing methods are used, then the etching process can be performed, but independent control over deposition is lacking causing inadequate protection of delicate nanostructures
Solution Approach 1:
The plasma process is segmented into multiple distinct phases (etching phase, deposition phase, and combined phase) with independently controllable parameters. Each phase can be optimized separately for its specific function, allowing precise control over etching and deposition while protecting delicate nanostructures through the deposition phase that deposits protective species on sidewalls and surfaces.
Solution Approach 2:
The patent implements dynamic control of plasma parameters by varying power levels, gas flows, and phase durations in real-time during the processing cycle. This dynamic adjustment allows the system to transition between etching and deposition modes, providing both precise manufacturing control and reliable protection of nanostructures during vulnerable stages.
2Productivity
If conventional plasma etching is used, then material removal can be achieved, but defects occur due to lack of independent deposition control
Solution Approach 1:
The patent employs periodic alternating phases of etching and deposition within a single plasma process. The cycle repeats with controlled durations, allowing material removal during etching phases while defect prevention occurs during deposition phases that deposit protective species. This periodic action enables both high productivity and manufacturing precision by combining aggressive etching with protective deposition in a rhythmic sequence.
3Productivity
If high power is used for etching, then etching rate increases, but damage to substrate and nanostructures increases
Solution Approach 1:
The deposition phase is positioned before and after the high-power etching phase to deposit protective species on the substrate and nanostructure surfaces. This preliminary and subsequent protection allows the high-power etching to proceed at maximum rate without causing damage, as the deposited species form a protective layer that absorbs the harmful effects of high-power plasma exposure.
Solution Approach 2:
The patent converts the potentially harmful high-power plasma into a beneficial process by alternating it with low-power deposition phases. The high-power phases aggressively remove material for high productivity, while the subsequent deposition phases use the same plasma environment to deposit protective species, turning the harsh plasma conditions into a protective mechanism that prevents damage during the high-rate etching intervals.
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 provides greater control over the etching process, reducing defects and preserving the integrity of inner spacer structures, enabling more precise fabrication of 3D semiconductor features by balancing etching and deposition phases, even in high aspect ratio structures.
Implementation Method 1
etching the substrate by cyclically performing a periodic plasma process
Implementation Method 2
applying a bias power (BP) to the substrate holder to etch the substrate
Implementation Method 3
deposit passivating species on the substrate
Implementation Method 4
concurrently etch the substrate and deposit passivating species on the substrate
Data Source
AI summary
In certain embodiments, a method includes positioning a substrate on a substrate holder in a processing chamber and etching the substrate by cyclically performing a periodic plasma process that includes multiple multiphase pulse cycles that each includes elevated etching, etching-and-deposition, and elevated deposition phases. The elevated deposition phase includes applying a source power (SP) to the chamber at a first SP level. The etching-and-deposition phase includes applying the SP to the chamber at a second SP level and applying a lower-frequency radio frequency (RF) bias power (LBP) to the chamber at an LBP level. The elevated deposition phase includes applying the SP to the chamber at a third SP level and applying a higher-frequency RF bias power (HBP) to the chamber at an HBP level, the third SP level being less than the first SP level. A same gas combination is supplied to the processing chamber during each cycle.