SiC Via Hole & Trench Dry Etching Process (ICP-RIE)

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Material Properties and Applications of Silicon Carbide (SiC)

Silicon Carbide (SiC) is a compound semiconductor material. While there are some types of crystalline structures including 3C-SiC, 6H-SiC and 4H-SiC, it is considered that 4H-SiC is the most promising material as a substrate of power devices. 4H-SiC has a wide band gap, a high breakdown field and a high thermal conductivity compared to silicon.

• Band Gap : 3.26 eV
• Breakdown Field : 3 (V/cm) x 10⁶ (ten times that of Si)
• Thermal Conductivity : 4.9 W/(cm·K) (three times that of Si)

Due to unique these properties, SiC power devices can replace conventional silicon power devices in specific applications such as electric vehicle components and wind power generators.

Not only power devices, SiC has some interesting applications.
• High-brightness (HB) Light-emitting-diodes (LEDs)
• RF and microwave devices for military and aerospace use
• MEMS sensors in harsh environments (airplane engines and gas turbines)

SiC Via Hole Etching

SiC backside via hole etching process is crucial to form a contact with electrodes in the fabrication of GaN-on-SiC high-electron-mobility transistor (HEMT) and monolithic-microwave-integrated-circuits (MMICs) .
There are some requirements in the backside via hole etching process.
• High etch rate
• Minimum plasma damage to dies
• Control of sample temperature during SiC plasma etching process (lower than 150°C)

SAMCO developed a highly anisotropic SiC via hole etching process.

Low-temperature Processing
Ø60 µm hole pattern
Etch Rate : 1.0 µm/min
Sample Temperature : lower than 150°C
Selectivity : 95 (over Ni mask)
Etch Depth : 89.2 µm
No pillars on the bottom

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Low-temperature Processing
Ø60 µm hole pattern
Etch Rate : 1.3 µm/min
Sample Temperature : lower than 150°C
Selectivity : 19 (over Ni mask)
Etch Depth : 83.6 µm

No pillars on the bottom

Silicon Carbide (SiC) Backside Via Hole Etching

High-rate Processing
Ø60 µm hole pattern
Etch Rate : 2.1 µm/min
Selectivity : 70 (over Ni mask)
Etch Depth : 116 µm

SiC Trench Etching

SiC trench etching is used for SiC trench-type metal-oxide-semiconductor field-effect transistor (MOSFET) fabrication. To achieve high breakdown voltage of the device as designed, etch profile control is critical. Micro-trenches and surface roughness on trench sidewalls after etching cause a gate oxide breakdown with the concentration of electric fields on the bottom. The gate oxide breakdown causes lower breakdown voltage of the device.