The French team uses laser direct writing to realize the internal material processing of the wafer, with higher integration density

Recently, researchers announced the development of a direct laser writing technology that can achieve local material processing in the 3D space of semiconductor chips. It is reported that this method can use the sub wafer surface space of the chip to achieve higher integration density and provide additional new functions.

Semiconductor is widely used. However, the market demand for miniaturized and powerful chips continues to rise, and the current semiconductor manufacturing technology is facing increasing pressure. According to researchers from LP3 Laboratory in France, the current mainstream manufacturing technology - lithography technology has great limitations in completely solving these challenges. For this reason, they believe that it will be a key breakthrough to realize the fabrication of structures under the wafer surface, so that the space inside the materials can be fully utilized.

The researchers of LP3 Laboratory in France have demonstrated this ability through the newly developed direct laser writing technology, which enables them to manufacture embedded structures in various semiconductor materials. Recently, it has been published in the International Journal of Extreme Manufacturing.

Image source: LP3 Laboratory

Yan team said: "Laser writing will provide the possibility for the direct digital manufacturing of 3D construction materials to meet the challenges that cannot be realized by the current manufacturing technology. In the future, these new laser forms may greatly change the current manufacturing method of advanced microchips."

During the experiment, they successfully modified the silicon and GaAs under the wafer surface. Si and GaAs are two important materials in the microelectronic industry, which cannot be 3D processed with traditional ultra fast laser pulses. The difficulty is that strong light generates efficient nonlinear ionization in the narrow gap material, and the free electrons generated can quickly convert any semiconductor into a metal like material, so that light cannot propagate deep inside the material. This transition deteriorates the focusing process and prevents the use of ultrafast lasers to modify semiconductor materials under the wafer surface.

To solve this problem, the team used unconventional ultra fast short wave infrared pulse (SWIR) to bypass the metallization transformation.

According to analysis, previous studies used too strong light pulses, so that it was too easy to excite the active state of electrons. Instead of using strong light pulses, they split the pulse energy into a large number of weak pulses with extremely fast repetition rates. These pulse sequences (also known as pulses) will avoid strong pulse excitation before light focusing. In addition, the pulses will repeat very quickly, so the transmitted laser energy can be effectively accumulated and penetrated through the modified layer.

According to the researchers, their research results provide the first "very practical" solution for ultrafast laser writing in semiconductor materials. In the next step, they will focus on the types of transformation that can be achieved in these materials, and the control of refractive index will become a key challenge.

Source: Sohu