How to improve the precision of silicon carbide laser cutting through process optimization

Silicon carbide (SiC), as a third-generation semiconductor material, is widely used in fields such as power electronics, new energy vehicles, and photovoltaics due to its high hardness, high thermal conductivity, and excellent electrical properties. However, its extremely high hardness and brittleness make traditional cutting processes face problems such as low efficiency, high losses, and rough surfaces. Laser cutting technology has become an important development direction for silicon carbide cutting due to its advantages of non-contact processing, high precision, and low thermal impact. This article explores how to improve the quality of laser cut silicon carbide by improving the cutting process from three aspects: technical path, process parameter optimization, and auxiliary technological innovation.

1、 Choose the appropriate laser cutting technology

The core of laser cutting of silicon carbide lies in achieving efficient and low damage processing through different technological paths. The current mainstream laser cutting technologies include:

1. Water guided laser cutting

By guiding the laser beam with high-pressure water jet, the water flow not only cools the cutting area but also carries away debris, reducing thermal damage. This technology has a cutting speed 3-5 times faster than traditional wire saws, and the roughness of the cut can be controlled within 2-3 μ m, significantly reducing material loss. Synova, a Swiss company, is leading in this field of technology, and many domestic laser companies are actively developing water guided cutting equipment that is compatible with silicon carbide.

2. Invisible cutting

Using ultra short pulse laser to form a modified layer inside the material, and achieving delamination through external stress. This technology has no incisions on the surface and high processing accuracy, especially suitable for cutting ultra-thin wafers. The KABRA technology of Japan's DISCO company decomposes silicon carbide into silicon and carbon through the principle of "amorphous black repeated absorption", increasing productivity by four times.

3. Cold cutting technology

Combining laser ablation and polymer cooling treatment, microcracks are generated inside the material and then propagate into the main crack. The material loss rate of this technology is as low as 80 μ m, the surface roughness Ra is less than 3 μ m, and the production cost is reduced by 30%. <>

4. Modified cutting

By using a precision laser beam to form a modified layer inside the wafer, the wafer is separated along the path by applying external stress. Domestic big family lasers have applied this technology to mass production, significantly reducing the need for subsequent grinding.

2、 Optimizing laser parameters and process control

The refinement of laser parameters and process settings is the key to improving cutting quality.

1. Beam quality and wavelength selection

Beam shaping: Using high refractive index lenses (such as fluorite lenses) to reduce chromatic aberration and improve focusing accuracy.

Wavelength adaptation: Near infrared lasers (such as 1064nm) are suitable for penetrating silicon carbide to form internal modified layers, while ultraviolet lasers are suitable for ultra fine cutting.

2. Power and pulse regulation

Adjust the laser power and pulse frequency according to the material thickness. For example, picosecond laser can reduce thermal effects and is suitable for invisible cutting; Nanosecond laser is suitable for processing thick materials, but it needs to be combined with cooling technology to prevent thermal deformation.

3. Dynamic focusing and path planning

Real time compensation of focal length offset during cutting process using autofocus algorithm and focus tracking sensor.

Optimizing cutting paths through computer control, reducing repetitive processing, and improving efficiency.

3、 Strengthen cooling and thermal management

The thermal conductivity of silicon carbide varies significantly with temperature and requires cooling techniques to suppress thermal damage.

1. Cooling optimization of water guide cutting

Regulate water flow pressure and velocity to enhance heat exchange efficiency. For example, increasing the water flow rate can quickly remove heat and prevent material thermal deformation.

Improve nozzle design to ensure even distribution of water flow and precise coordination with laser light path.

2. Auxiliary cooling system

Gas cooling: spraying inert gas (such as nitrogen) to form a protective gas curtain, preventing oxidation and accelerating heat dissipation.

Liquid cooling: Adopting a high thermal conductivity coolant circulation system such as ethylene glycol, suitable for different working conditions.

3. Intelligent temperature control feedback

Deploy temperature sensors and thermal imagers to monitor real-time temperature changes in the cutting area and dynamically adjust cooling parameters.

4、 Adapt material characteristics and intelligent monitoring

1. Crystal structure analysis

The thermal conductivity characteristics of different crystal types of silicon carbide vary significantly. For example, 4H SiC requires higher cooling intensity to prevent thermal stress accumulation, while 6H SiC can reduce the cooling intensity appropriately.

2. Crack propagation control

By using dual wavelength laser technology, the first wavelength is used to form a modified layer, and then the second wavelength is used to promote crack propagation, reduce the number of modified layers, and improve the quality of cutting.

3. Environmental stability guarantee

The constant temperature and humidity workshop reduces the problems of thermal expansion and contraction of optical components and fogging of lenses.

Isolation platform (such as air spring) blocks external vibrations to ensure stable laser focusing