Plasma Etching Power Modulation for Low-k Film Selectivity
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Solution Overview
Problem
Current plasma etching technologies face challenges in achieving high selectivity and etching rate, particularly when processing SiOC family Low-k films, and suffer from the micro-loading effect, which affects the uniformity and reproducibility of semiconductor manufacturing.
Innovation Solution
A plasma etching apparatus and method utilizing power modulation between two RF powers to control polymer deposition and etching, ensuring a polymer thickness greater than the ion penetration depth, thereby enhancing selectivity and suppressing the micro-loading effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fluorocarbon process gas is used for etching SiOC family Low-k film, then etching rate is maintained, but selectivity relative to underlying SiC film deteriorates
Solution Approach 1:
The patent applies periodic action by modulating the RF power in cycles between a first power level (for polymer deposition) and a second power level (for etching). This periodic modulation allows polymer layers to be deposited on the SiC film during low-power phases, preventing excessive etching during high-power phases, thereby maintaining high selectivity while achieving high overall etching rate through the cumulative effect of multiple cycles.
2Productivity
If high RF power is applied continuously for etching, then etching rate increases, but polymer deposition decreases causing loss of selectivity
Solution Approach 1:
The patent implements periodic action by alternating between high RF power (for etching) and low RF power (for polymer deposition) in predetermined cycles. During low-power phases, polymer deposits on the SiC film surface, and during high-power phases, etching occurs. This periodic alternation ensures that polymer layers are continuously replenished, maintaining selectivity while achieving high etching rates.
Solution Approach 2:
The patent applies parameter changes by dynamically modulating the RF power level between two distinct states (first power and second power) in a periodic manner. This parameter modulation allows optimization of both etching rate and selectivity by controlling the duration and intensity of each power state, ensuring that polymer deposition and etching processes are balanced throughout the etching cycle.
3Ease of operation
If conventional continuous RF power is used, then etching process is simple, but micro-loading effect occurs reducing uniformity
Solution Approach 1:
The patent applies periodic action by modulating the RF power in predetermined cycles between first and second power levels. This periodic modulation suppresses the micro-loading effect by controlling polymer deposition and removal in a rhythmic manner, ensuring uniform etching across different feature sizes and densities on the substrate, thereby improving etching uniformity while maintaining process controllability.
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 power modulation technique allows for high selectivity and high etching rates of SiOC family Low-k films relative to underlying SiC films, while alleviating the micro-loading effect, thereby improving the uniformity and reproducibility of the etching process.
Implementation Method 1
an RF power for plasma generation is applied to the upper electrode to generate plasma
Implementation Method 2
an RF (radio frequency) power is applied to at least one of the electrodes to form an electric field between the electrodes. The process gas is turned into plasma by the RF electric field
Implementation Method 3
an RF power for ion attraction is applied to the lower electrode
Implementation Method 4
an RF (radio frequency) power is applied to at least one of the electrodes to form an electric field between the electrodes
Implementation Method 5
a first power set to deposit polymers on a predetermined film on the target substrate
Implementation Method 6
The process gas is turned into plasma by the RF electric field, thereby performing plasma etching on a predetermined layer disposed on a semiconductor wafer
Data Source
Figure 1
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Figure 5~6
AI summary
There is provided a plasma etching apparatus comprising: a process container (10) configured to be vacuum-exhausted; a first electrode (34) disposed inside the process container; a second electrode (16) disposed opposite to the first electrode and configured to support a target substrate thereon; a first RF power supply unit (46, 48; 48', 89) configured to apply a first RF power for plasma generation to the first electrode or the second electrode; a second RF power supply unit (88, 90) configured to apply a second RF power for ion attraction to the second electrode; a process gas supply unit (66) configured to supply a process gas into the process container; and a controller (95) configured to control the second RF power supply unit, wherein the second RF power supply unit (88, 90) includes a second RF power supply (90) and a second matching unit (88), and the controller (95) is preset to control the second RF power supply unit (88, 90) to operate in a power modulation mode that executes power modulation in predetermined cycles between a first power and a second power set, while controlling the second matching unit (88) to switch a matching operation in synchronism with the power modulation.