Plasma Etching Mask Shape Control via Bias Voltage Modulation
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Solution Overview
Problem
Existing etching processes for semiconductor manufacturing face challenges in maintaining mask pattern stability for small feature sizes, particularly below 20 nm, due to limitations in etching selectivity and mask shape control.
Innovation Solution
A plasma processing method and device that perform a combination etching and deposition process, where the bias voltage supplied to the sample stage is modulated between different voltage values to control the etching and deposition rates, thereby stabilizing the etching mask shape and achieving high etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deposition is performed to increase etching mask height, then etching selectivity is improved, but mask shape stability deteriorates due to side-deposition and weight increase
Solution Approach 1:
The patent applies periodic modulation of bias voltage during plasma processing to alternately perform etching and deposition. The bias voltage is modulated between a first voltage value (performing etching) and a second voltage value (performing deposition), creating a periodic cycle that prevents mask destabilization while achieving required etching selectivity. This periodic action allows controlled material removal and addition without continuous deposition that would cause side-deposition and mask collapse.
Solution Approach 2:
The patent changes the bias voltage parameter dynamically during the plasma processing operation. By modulating the bias voltage between different values, the process transitions between etching-dominant and deposition-dominant phases. This parameter change enables precise control over the net etching rate and net deposition rate, allowing the mask to maintain stability while achieving the required etching selectivity through controlled deposition during specific phases of the cycle.
2Manufacturing precision
If simple deposition is used to extend mask effective selectivity, then etching selectivity is improved, but mask pattern integrity deteriorates due to destabilization
Solution Approach 1:
The periodic modulation of bias voltage creates alternating etching and deposition phases that prevent the continuous deposition-induced destabilization. During etching phases, mask material is removed to maintain shape; during deposition phases, material is added to extend effective selectivity. This periodic cycle preserves mask pattern integrity while achieving the required etching selectivity extension.
Solution Approach 2:
The patent performs etching and deposition in a continuous combined process without interrupting the plasma operation. The bias voltage modulation enables both etching and deposition to occur sequentially within the same continuous process, maintaining mask integrity through controlled etching phases while achieving continuous effective selectivity extension through deposition phases, without requiring mask re-fabrication or process interruption.
3Stability of the object's composition
If multiple separate processes (etching then deposition then reshaping) are used, then mask stability is maintained, but process complexity increases
Solution Approach 1:
The patent merges etching and deposition processes into a single combined plasma processing operation. By modulating the bias voltage within the same plasma chamber and process cycle, both etching and deposition are performed sequentially without interrupting the plasma operation or requiring separate process chambers. This merging maintains mask stability through controlled etching phases while achieving the required net deposition for selectivity extension, all within one unified process step.
Solution Approach 2:
The plasma processing device performs multiple functions (etching and deposition) within a single operation by modulating the bias voltage. The same plasma environment and process chamber are used for both material removal and material addition, making the process universally capable of achieving both mask reshaping and selectivity extension without requiring separate specialized equipment or process steps.
4Adaptability or versatility
If frequent process gas exchanges are performed, then process flexibility is improved, but productivity decreases due to time loss
Solution Approach 1:
The patent combines etching and deposition processes into a single continuous plasma operation, eliminating the need for process gas exchanges between separate etching and deposition steps. The bias voltage modulation enables both processes to occur within the same plasma environment using the same process gas, thereby maintaining process flexibility while avoiding the productivity loss associated with frequent gas exchanges and process interruptions.
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
The method effectively stabilizes the mask pattern and achieves high etching selectivity for small feature sizes, reducing the risk of mask instability and pattern degradation, and allowing for efficient plasma processing without the need for frequent process gas exchanges.
Implementation Method 1
a combination etching and deposition process in which a bias voltage supplied to a sample stage is modulated between a first voltage value and a second voltage value lower than the first voltage value
Implementation Method 2
performing a combination etching and deposition process with respect to the wafer
Data Source
AI summary
Provided is a plasma processing method and device capable of controlling the etching mask shape during a single-step process that etches a target material disposed below the etching mask. The plasma processing method includes performing selective deposition on the etching mask in separate phases, which are controlled via a periodic bias voltage signal. By tuning the bias voltage power, duration and timing, the mask height and width can be controlled and stabilized while etching on the substrate proceeds. Thus, the present method provides an etching process that allows fine control of the etching mask shape for small pattern sizes and provides high etching selectivity through deposition.