The next revolution in microelectronics is achieved by laser writing

Crossing the threshold of ultrafast laser writing in bulk silicon was recently published in the journal Nature Communications by Margaux Chanal and others from France, Qatar, Russia and Greece. The paper says that in previous attempts to write ultra-fast lasers in silicon, femtosecond lasers were structurally unable to process volume silicon, and the use of extreme NA values allowed laser pulses to ionize enough to destroy the chemical bonds in silicon, resulting in permanent structural changes.

Since the late 1990s, researchers have been writing ultra-short pulses of femtosecond lasers into blocky materials with broad gaps, usually insulators. But until now, precise ultra-fast lasaer pointer writing has not been possible for materials with narrow band gaps, such as silicon and other semiconductor materials. People have been committed to creating more conditions for the application of 3D laser writing in silicon photonics and the research of new physical phenomena in semiconductors, thus expanding the huge market of silicon applications.

In this experiment, scientists found that femtosecond lasers could not treat bulk silicon structurally, even if they increased the laser energy to the technical maximum pulse intensity. However, when the femtosecond laser is replaced with an ultrafast laser, there is no physical constraint on the operation of the induced bulk silicon structure. They also found that laser energy must be transmitted quickly through the medium to minimize the loss of nonlinear absorption. The problem was caused by the laser’s small numerical aperture (NA), the range of angles that can be projected when the laser is focused. The researchers solved the problem of numerical aperture by using silicon spheres as solid immersion media. When the laser is focused on the center of the sphere, the refraction of the silicon sphere is completely suppressed and the numerical aperture is greatly increased, thus solving the problem of writing silicon photons.

In fact, 3D laser writing in silicon photonics applications could dramatically change the way silicon photonics is designed and prepared. Silicon photonics is seen as the next revolution in microelectronics, affecting the speed at which lasers can be processed at the chip level.