Detection of Stealth Dicing Laser Wavelength in Sapphire

In order to produce a green-violet laser diode with high efficiency, the quality of its reflecting face must be high. This can be difficult to achieve in sapphire substrates as they are difficult to cleave cleanly. Stealth dicing involves using a pulsed laser to damage the wafer material while multi-photon absorption scours the surface to create stress points. The process also produces a high-quality surface.

Detection of stealth dicing laser wavelength

Detection of stealth dication laser wavelength in sapphire wafers is an important step in manufacturing this high-quality optical material. In this technique, a pulsed laser is focused inside a brittle wafer, scanning it along a predetermined path. Once the beam hits the wafer, it creates a stress layer and separates the material. The cutting process involves the use of multi-photon absorption and laser focusing to melt the crystal near the focusing zone. The resulting cracks in the recrystallized wafer are the result of local melting zones.

This process is possible using a stealth dicing laser with two different pulse energies. For our experiments, we used the 25 mJ pulse energy, focused at a depth of 330-270 mm from the top surface of the sample. We exposed the sample to the laser in 50 mm steps, with an exposure time of 100 ms. The minimum exposure time was limited by the shutter speed, which blocked the beam. For each of the three pulse energies, we observed that the corresponding damage area was surrounded by craters.

Technique

The technique for stealth dicing quartz plates employs ultrashort laser pulses. There are some important parameters of this laser that affect the efficiency and quality of the cuts. The following is an overview of the main parameters that are considered. To learn more, read on:

At the Ep of 15 uJ, there is little overlap between the two lasers. However, as the repetition rate increases, the laser induced stress accumulates. This may result in cracking or dicing. Further research is needed to determine the optimal wavelength to cut various materials. Ultimately, this technique has the potential to become the most versatile stealth dicing laser. Here are a few of the key characteristics that can be expected.

This technique is gentle on the environment and has the potential to cut ultrathin semiconductor wafers. The process can be used on MEMS, low-k materials, and specialty wafers. It may even be useful on sapphire. It also reduces water consumption by 622 tons per year. The technique also produces a clean, sharp edge. It is a highly effective cutting method for many applications.

Cutting edge quality

Using the same laser wavelength as for scribing, the cutting-edge laser used for stealth dicing creates perforations beneath the surface of the SD layer. The back and front surfaces of the wafer remain intact. This technique is particularly effective in high-volume production of semiconductor devices. Moreover, it has many advantages over conventional scribing. Here are some of the key ones.

A low-k material (such as nitride) is a very sensitive material. As a result, traditional dicing methods can lead to chipping, debris, and delamination. But with stealth dicing, you can have a clean cut that is free from these defects. It is also more environmentally-friendly and can significantly reduce water consumption by up to 622 tons per year.

To create highly efficient green-violet laser diodes, the reflective face of a sapphire wafer is critical. The substrate itself is difficult to cleave cleanly. Using an ultra-short pulsed laser, you can achieve high-quality stealth dicing in sapphire. The ultra-short laser pulses can damage the material and generate stress points on the wafer's surface.

Damage threshold

The damage threshold for stealth dicing of sapphire is around 2 mm, which is within the range of the spectral range used for the procedure. The method is also effective on other materials, such as sapphire, and has been demonstrated by Lopez et al., using ultrashort pulsed Bessel beams. The damage threshold varies according to the wavelength used and the amount of sidewall roughness, as measured by spectral gradations.

Two different pulse energies were used for the study. One was a 25 mJ pulse energy that was focused at a depth of 330-270 mm from the top surface. The sample was exposed to the laser beam in 50-mm steps over a 100-ms time period. The shutter speed was chosen to limit the maximum exposure time to 1 mm. Using this technique, the laser delivered one hundred pulses during the opening and closing of the shutter.