A femtosecond laser processing device and method for fast and deep etching of silicon carbide

Abstract

The invention discloses a femtosecond laser processing device and method for rapid deep etching of silicon carbide. The femtosecond laser processing device mainly comprises a laser source module, a laser motion module, a shaping and focusing module, an auxiliary gas module and a laser etching module. According to the device and method, a focal plane is calibrated, a protection layer is prepared, an etching path is planned, layer-by-layer scanning etching is carried out according to parameter groups, and micro-chips are removed, so that deep etching of silicon carbide is realized. According tothe method, due to the fact that a femtosecond laser is used for processing silicon carbide, factors influencing the etching quality are controlled, namely, the laser energy density, the light spot overlapping rate and the line overlapping rate, and therefore silicon carbide is subjected to rapid and high-quality deep etching in a layer-by-layer scanning manner and a continuous feeding processingmanner according to the planned etching path.

Description

technical field [0001] The invention relates to the field of silicon carbide (silicon carbide) material etching processing, in particular to a femtosecond laser processing method and device for high-quality, fast and deep etching of silicon carbide. Background technique [0002] Silicon carbide (SiC) material is a compound material with unique physical and chemical properties. It not only has superior mechanical properties and physical and chemical stability, but also exhibits superior electrical properties and has a wide band gap (2.3-3.3eV) , high critical electric field strength (0.8~3MV / cm), high saturation drift rate (2×10 7 cm / s) and high thermal conductivity (4.9Wcm -1 K -1 ) characteristics, these characteristics make silicon carbide have important application value in the field of wide bandgap semiconductor high temperature, high power, high frequency and radiation resistant electronic devices. [0003] However, due to the high hardness of the silicon carbide mat...

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Problems solved by technology

Among them, molten salt corrosion requires the use of mixed and molten NaOH / KOH at 480 ° C. This molten salt has the characteristics of high temperature and high corrosion, and has the following disadvantages: ① expensive Pt is required to make the beaker and clamping device for corrosion, ② it is difficult to etch The sample of the mask and the expected structure are obtained, because it is difficult to find a mask material that can withstand high temperature and strong corrosion environment. Even if Pt is used to make the mask, the wet etching is isotropic and will form undercutting

[0005] At present, the femtosecond laser only performs superficial (less than 100 μm) etching processing on materials (such as amorphous silicon, sapphire), and has no effect on the etching quality (depth error of the etching area, surface roughness, and steep sidewalls). degree) to make clear requirements, and currently there is a lack of effective means for fast, high-quality deep etching of silicon carbide using femtosecond lasers

[0006] In addition, the focal plane calibration of laser processing generally adopts three methods: one is to use the laser beam to cut different grooves on the reference workpiece to find the minimum groove width; this method has more cutting times and is relatively complicated

The second is to use the CCD camera to capture the spot of the laser beam irradiated on the surface of the workpiece, and find the minimum value of the spot area; this method requires additional equipment and requires high precision for the graphics processing software

The third is to use a photodiode to measure the light intensity of the laser beam after it is reflected on the surface to be processed, and find the maximum light intensity value; this method also requires additional equipment, and requires high precision for the light intensity processing software

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