Chinese scientists have developed a chip "self-carving" technology, allowing crystals to "grow" structures on their own.

Figure caption: In-plane etching and patterning strategy of 2D perovskites driven by internal stress

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Recently, a research team from the University of Science and Technology of China published an important study in the journal Nature. They invented a new process called "self-etching," which for the first time achieved precise, programmable construction of heterostructures of different materials inside a new type of semiconductor material called two-dimensional ionic soft lattices, similar to mosaic tiling.

Why Traditional Processes Can't Etch New Materials

In the world of semiconductors, the performance of devices often depends on the quality of the interface between different materials inside them. The manufacturing of traditional silicon-based chips relies on precise "top-down" technologies such as lithography and etching. These techniques are like using an extremely fine engraving knife to carve circuits onto a hard silicon wafer.

However, new types of semiconductors, such as two-dimensional halide perovskites, have a "soft" crystal structure. They are composed of ionic bonds, like a flexible sponge that is very sensitive to external stimuli. Traditional physical or chemical etching methods can easily damage this soft structure, leading to rough interfaces and numerous defects.

This is like trying to carve intricate patterns into tofu; even a slight force will make the tofu break. Therefore, how to build high-quality lateral heterostructures in such "soft lattice" materials has always been a challenging scientific problem in this field.

"Self-Etching": Let the Crystal "Grow" Its Structure

Faced with the dilemma of "not being able to etch," the team from the University of Science and Technology of China changed their approach: instead of forcing external "carving," they guided the material to "self-assemble" from within. Their inspiration came from a property inherent to the material itself—internal stress.

During the growth of two-dimensional perovskite crystals, internal stress accumulates naturally, like a compressed spring storing potential energy. Researchers designed a mild chemical microenvironment. This environment consists of specific organic ligands and solvents.

It can selectively "activate" the pre-designed regions of internal stress within the crystal. The activated regions experience a gentle weakening of atomic bonding forces, leading to controlled dissolution and forming neat square holes. This process is known as "self-etching."

The key step is "backfilling." After the holes form, the research team quickly introduces the raw materials of another semiconductor into the system. Due to the intact and exposed lattice at the edges of the holes, the new material can rapidly grow epitaxially and perfectly fill the holes.

Ultimately, they constructed a "mosaic" pattern with continuous lattices and atomically flat interfaces within a single crystal. Different regions of materials are seamlessly joined together with high quality.

Figure caption: Mosaic heterostructure within a two-dimensional perovskite

From Controllable Growth to Integrated Future

Miniaturization and integration of semiconductor devices are eternal themes. From vacuum tubes to transistors, from integrated circuits to today's nanochips, we continue to integrate more functions into smaller spaces. However, traditional silicon-based technology is gradually approaching its physical limits.

Take light-emitting devices as an example. Current Micro-LED display technology requires separately manufacturing red, green, and blue micrometer-level LED chips and then precisely assembling them through mass transfer technology. This process is extremely complex, costly, and faces significant yield challenges.

What the "self-etching" technology demonstrates is a completely new mode of "growth-integration." With this technology, it may be possible in the future to grow densely arranged, small pixel points that emit light of different colors directly on a very thin two-dimensional material wafer, like "planting crops."

This eliminates the steps of transfer and assembly, potentially significantly simplifying the process, reducing costs, and achieving higher device density and better interface performance. It provides a highly promising material and process platform for future technologies such as high-definition displays, on-chip optical interconnects, and even quantum light source arrays.

More importantly, this study offers a new model for utilizing the intrinsic properties of materials (such as internal stress and growth dynamics) to achieve functionalization. It tells us that sometimes the most precise "engraver" might be the material itself. Learning to communicate with materials, guiding rather than forcing, could become an important direction for future materials science and nanofabrication.

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Original article: toutiao.com/article/7595779848425980479/

Statement: This article represents the views of the author.