Capacitively Coupled Plasma Etching (CCP Etching) is one mainstream vacuum plasma dry etching process. Radio-frequency power is applied between two parallel electrodes to generate plasma, creating reactive radicals and energetic ions for material removal. Compared with wet chemical etching, CCP etching achieves strong anisotropic etching profiles, enabling vertical sidewalls and high aspect ratio micro features without liquid chemical residues. This technology is widely adopted for manufacturing aerospace MEMS, optical and sensing components that demand ultra-clean surfaces, precise depth control and high pattern fidelity. It supports prototype R&D and low-volume pilot production for aircraft avionics, rocket instrumentation and satellite payload systems, meeting strict aerospace cleanliness and reliability requirements.

Process Flow

1. Substrate preparation & pre-cleaning: Remove organic contaminants and native oxide layers from aerospace-grade wafers or thin substrates.
2. Vacuum chamber loading: Load the workpiece onto the lower electrode, seal and pump down the chamber to high vacuum.
3. Process gas injection: Feed customized reactive gases into the chamber based on substrate material and etching requirements.
4. Plasma ignition: Apply RF power to generate capacitively coupled plasma containing reactive radicals and ions.
5. Anisotropic etching: Ions bombard vertically toward the substrate surface; chemical reaction combined with physical bombardment selectively etch the exposed regions.
6. In-situ endpoint detection: Monitor etching depth in real time to stop the process once target depth is achieved.
7. Chamber purging and unloading: Cut off RF power and process gas, purge chamber, then unload parts.
8. Post metrology & qualification inspection: Check sidewall profile, dimensional tolerance, surface quality and perform aerospace material qualification tests.

Core Advantages

1. Anisotropic vertical etching profile: Produces straight sidewalls and high aspect ratio microstructures which wet etching cannot easily achieve.
2. Ultra-clean dry process: No wet etchant, eliminating residual liquid contamination risk that causes failure in space or airborne environments.
3. Precise depth control: In-situ endpoint detection ensures consistent etch depth across wafers for high repeatability.
4. Low thermal damage: Tunable plasma parameters minimize thermal stress on delicate thin substrates and sensitive films.
5. Multi-material capability: Suitable for silicon, silicon oxide, silicon nitride, ceramics and thin metallic films used in aerospace MEMS.

Application Fields

• Satellite MEMS inertial sensors: Accelerometers, gyroscopes and pressure sensing microstructures
• Aerospace optical components: Micro optical gratings, apertures and optical alignment masks for onboard optical systems
• Aircraft avionics microfluidic chips: Microchannels for fuel monitoring, coolant and gas sampling modules
• Rocket instrumentation micro sensors: High-aspect-ratio micro cavities and through holes for harsh-environment sensing
• Aerospace packaging structures: Micro trenches and isolation features for hermetic packaging of high-reliability chips

Design Considerations

1. CCP etching performance is highly dependent on gas chemistry, RF power and chamber pressure; material selection must be validated in process trials.
2. Mask material must have high etch selectivity against the substrate to prevent mask erosion during long etching cycles.
3. Batch size is limited by vacuum chamber capacity; CCP is cost-effective for R&D and low-volume aerospace orders, not large-area bulk material removal.
4. Plasma-induced surface charging effect may damage sensitive dielectric thin films, requiring optimized process recipes.
5. Aerospace components require strict particle control; chamber conditioning and regular maintenance are mandatory to reduce particle contamination.